Zoo Volunteer

New World Primates 6: Howling for help

2012-02-12T14:55:00.000-08:00

One of the South American monkeys Bristol has been most successful with is one of the most resonant voices of the rainforest, the howler monkey. The IUCN red list has a total of thirteen different species, which are found from Central America as far south as Argentina, wherever there is suitable forest. The species we have at Bristol is more or less the only one likely to be seen outside a South American zoo, the Black and Gold Howler Alouatta caraya. They get their name from the sexual dimorphism in the species – adult males are jet black while females and juveniles are golden brown.

Female A.caraya

Most of the howler monkeys have fairly large ranges, and can survive in fairly small pockets of forest, but a few are only found in very small areas and as a result are at risk from hunting pressure and deforestation. Two are listed as Endangered, the Yucatan Black Howler monkey A.pigra and the Maranhao Red-handed Howler monkey A.ullulata.from Brazil. The main threats from humans to howlers are hunting – they are important subsistence prey everywhere they are found- , and habitat alteration, especially deforestation and dams. Howlers can swim, but are very reluctant to do so, and the ranges of the various species are defined by major rivers.

Howlers are very heavy-bodied animals, and are not very agile, especially compared to their close relatives the Spider monkeys. Males are much larger than females, with an average mass of 6 to 8 kg, with females usually around 5kg. Rather than hanging from slender branches and reaching out to pick fruit, howlers are specialist in feeding on leaves. As these take far more digestion to extract nutrients, howlers give the impression of being more sluggish, and sleep up top 70% of each day digesting their food. As a plus however, because they do not need to travel long distances in search of ripe fruit, they can survive in small forest areas at very high densities, with home ranges as small as 0.1 sq.km for an average sized troop. They sometimes descend to the ground, but most of their time is spent high in the canopy.

Howler groups vary in size, but typically comprise 1-3 adult males, a similar number of females, plus offspring. Usually only a single adult male breeds, and the subordinate males may in fact be older juveniles who have not yet dispersed to found groups of their own. Eventually almost all males and a majority of females will emigrate from the natal group. Juvenile males may band together to form bachelor groups until they can either attract females or take over an existing group by defeating the resident alpha male. As in many other animals with a similar breeding system, take-overs are usually followed by infanticide of small infants. In one study of Red howlers more than 44% of infant mortality was due to infanticidal attacks.

The group defends their territory by the dawn chorus of their howls, which can carry several kilometres. Both males and females will join in the group howls, but males are much louder as a result of an enlarged hyoid bone, which supports the resonating chamber in their throats. When not howling, they are surprisingly silent creatures, and do not spend a lot of time in socialising even within the group.

Harpy eagle in flight

A large, slow-moving animal is quite vulnerable to predators, and although howlers can defend themselves against most mammalian predators large birds of prey, especially the world’s largest eagle, the Harpy Eagle Harpia harpyja, are a major threat. Perhaps as a result, howlers are surprisingly prolific for a large monkey, and at Bristol the interval between births has been as short as nine months. The young mature fast, with females having their first infant around 4 years, but males not being in a position to breed until nearer seven. Lifespan in captivity is around 20 years, probably nearer 12 in the wild.

One very odd feature of some species of howler monkeys is that their sex chromosomes have a different pattern to those found in all other mammals. As a standard pattern, mammals have a standard arrangement where females have an XX and males an XY pair of chromosomes in addition to the autosomes which carry the bulk of the genetic material. In A.fusca there is a much more complicated arrangement where there are two different types of X chromosomes, X1 and X2, and there is variation in the diploid number, with the result there are at least four different possible karyotypes, XY/XX; X1X2Y/,X 1X1X2X2, X1X2Y. Some other species of howler monkey have similar variations. There may also be differences in the number of autosomes, so the diploid number of an adult howler can vary extensively. Whether the variation has anything to do with the odd sex-linked colour vision variation in New World primates I talked about in an earlier post is not clear.

In captivity howlers are not often seen compared to many other monkeys. Their status as slow-moving prey animals means they tend to be quite nervous, especially when they cannot retreat as high as possible, and the Black and Gold howler is the only one with a regularly breeding captive population, with around 250 animals in zoos worldwide. This population took a long time to establish, as wild-caught howler monkeys are very prone to stress-related diseases and seldom breed. The captive population of Black and Gold howler has enabled some elucidation of best practise in husbandry, especially housing and diet and the species is now managed genetically – in fact Bristol holds the EAZA stud book for this species. Even though we bred then successfully for many years, as soon as their new enclosure was built they took to spending as much time at the top of the enclosure as possible, and hardly ever come lower than 2m off the ground. This is especially obvious when the zoo is busy and there are crowds around their enclosure. They have in some zoos been kept with other primate species from their range, but seem easily intimidated, even by much smaller species such as tamarins.

The diet of howlers also requires special consideration. In the wild they can eat many hundreds of different plants, especially the leaves although they take some fruit. The captive diet is a specially formulated high-fibre biscuit, supplemented with browse (cut branches and leaves of various trees and shrubs), plus various leafy vegetables and some other green vegetables such as beans or okra. Even with fruit-eating primates, recent thinking in zoos is to avoid commercial fruit in their diet, the reason being that fruits bred for human consumption are far too high in sugar compared to wild fruits, and are a cause of diabetes and tooth decay in many species.

As a result of these difficulties with maintaining captive howlers, there is no co-ordinated captive breeding programme for the endangered howler species, and protection in the wild is likely to be far more effective and easier to carry out than ex-situ conservation breeding. Nonetheless, studies on the captive population is extremely useful for throwing light on the social organization and exact requirements of wild howlers, which could be vital in the future. Although zoos tend to headline captive breeding and release as the main goal for their keeping various animals, research is at least as important, as we cannot conserve a species in the wild unless we know what it actually needs, and a captive study population is often the easiest way to obtain vital information.

Next week, one of the many medium-sized monkeys of South America, the Red Titi.

(Images from wikipedia)

New World Primates 5: Squirrel Monkeys

2012-02-04T02:50:00.000-08:00

S.sciureus

On one of the islands in the lake can be found our group of a very familiar, but little understood, small monkey, the South American Squirrel monkey Saimiri sciureus. Squirrel monkeys are widely spread throughout central and South American rainforests, but until recently it was thought that there were only two species, The South American S.sciureus and the Central American S.oerstedti. More recent work has elevated some subspecies to specific status, and identified other new forms, with the result that there are now considered to be at least five species, some of which themselves may contain several subspecies.

S.oerstedti

This causes some problems in analysing past studies, as the different species differ in important aspects of their behaviour, especially group size and breeding patterns. In the captive population, several subspecies or even species may have been hybridised, which may account for some of the problems experienced in captive breeding. At Bristol our group is believed to be pure S.sciureus sciureus, the nominate subspecies. The various forms differ slightly in size, but the most obvious difference is in the shape of the ‘V’ between the eyes as the darker fur of the crown of the head points down. In S.sciureus this is a very distinct and narrow ‘V’ whereas in S.bolivensis it is much shallower.

S.bolivensis

In the wild, squirrel monkeys are mostly found in lowland tropical forests, all though in some areas they range to an altitude of 2000 metres. They are habitat generalists however, and can live almost anywhere there is sufficient food sources, especially edge forests or abandoned farmland with regenerating woodland. In fact, untouched primary forest with a mature canopy often has lower densities than areas with at least some human disturbance. As long as an area is not heavily felled, the main problem is logging roads – squirrel monkeys are very reluctant to descend to the ground and will not leap gaps over 2m, so roads cut through the forest can seriously disrupt their habitat.

S.vanzolinii

As with many monkeys, squirrel monkeys will eat almost anything, but the bulk of their diet is fruit – as with most monkeys, they are important seed disbursers. Their animal prey is mostly insects, especially grasshoppers and caterpillars, but they also eat birds eggs, frogs, lizards, and even bats, which they catch at their roosts in trees or under leaves. Because they feed on smaller fruits and can forage further out onto branches, they can associate with other monkey species without much competition, and consequently benefit from travelling in company with them for protection. Capuchin monkeys (to which squirrel monkeys are closely related) are favoured companions, and as capuchins are powerful, aggressive, and highly intelligent they provide much-needed protection. An animal the size of a squirrel monkey has many predators, especially birds of prey and snakes, so it needs all the help it can get.

S.sciureus

The various species of Saimiri differ widely in their group structure, which is probably due to the different food types available to them. The most social species is probably S.bolivensis, which is found in groups of up to 75 or more animals (one troop of 300 was reported). By caontrast, S.sciureus lives in groups of 15-30 animals, and at much lower densities. The relations between males and females differ greatly as well, with males in S. bolivensis subordinate to the females and mostly on the periphery of the group as it moves, whereas S.sciureus has a fully integrated multi-male/multi-female group with a strong hierarchy incorporating both sexes. How young animals disperse also differs, with males remaining and females dispersing in S.oerstedti, females remaining and males dispersing in S.bolivensis, and both leaving in S.sciureus. This variation in social behaviour is another issue with management of captive Saimiri species, as the best way of integrating new individuals can be very different depending on the species involved.

Squirrel monkeys are seasonal breeders, with all the females in a troop giving birth within a few weeks of each other. Prior to the breeding season, males undergo a remarkable physiological change called ‘fatting up’ when they put on a lot of weight – up to 20% of their normal weight. As there is intense competition among males for mating rights, this weight gain is vital to their success, in the same way that bull seals put on a lot of weight prior to the breeding season at their rookeries. Squirrel monkeys reach maturity at 2-3 years and can live up to 20 in captivity, but probably nearer 10-15 in the wild.

As a result of their adaptability, most squirrel monkey species are less vulnerable to human modifications of their forest than some other species, but at least one species, S.ustus, is classed as near Threatened by the IUCN as a result of deforestation. S.ustus has the smallest range of any of the Saimiri species, and is consequently more at risk. It is alsoone of the least studied, and its own unique social structure is little understood. Other human threats to squirrel monkeys are capture for the pet trade, both internally and internationally, and use in medical research (it is one of the commonest laboratory primates).

Even though squirrel monkeys are widely kept, the captive breeding record is pretty poor. The main cause is probably the size groups they are kept in – they do not often breed successfully in groups of under 15 animals, even for S.sciureus, and for species with larger group size such as S.oerstdti and S.bolivensis the groups probably need to be at least twice that size. To compound the problem, smaller groups seem to be more likely to produce male offspring. These kind of effects occur in many other animal species, and is probably a result of stress hormones differentially affecting pregnancy success in male and female embryos. It is notable that the most successful groups, with the most female offspring, are large and long-established groups. From the lifespan of captive animals, the dietary requirements seem to be mostly met, but the social requirements are harder for zoos, especially small ones, to meet successfully owing to the large number of animals that must be maintained.

Next week, a much larger monkey – the Black and Gold Howler, one of the species we have been much more successful with.

(images from primateinfo.net)

New World Primates 4: Brown Spider Monkey

2012-01-27T12:53:00.000-08:00

A.hybridus

As you enter the zoo, the first large enclosure you encounter contains two young male Brown Spider Monkeys, Ateles hybridus. This Critically Endangered monkey originates from Columbia, where it lives in an ever decreasing area of primary rainforest.

Spider monkeys can be thought of as the ecological equivalents of the apes (especially the gibbons) of the Old World – large bodied fruit eaters with complicated societies. They spend almost all their time high in the canopy on a continuous search for fruit of numerous species, and are very important seed dispersers as a result. In hard times they may also eat leaves, some insects, or even decaying wood, but without an extensive variety of fruiting trees they cannot survive for long.

A.fuscus feeding

The most obvious feature of any spider monkey is the long prehensile tail. This enables them to gather fruit with both hands, as the tail can grip well enough to support the 9-10kg weight of the whole animal. They will also brachiate, or run through the trees on all fours. This enables them to cover considerable distances when needed with minimal energy expenditure. Many South American monkeys have tails that are prehensile to some degree, but the Spider Monkeys are undoubtedly the supreme examples of this feature.

The society of spider monkeys is much more complex than one might think. In a fashion somewhat similar to chimpanzees, they have a ‘fission-fusion’ society, with a group comprising 20-30 individuals at any one time. This group however does not move around in a body, instead much smaller bands of 2-4 individuals, usually with a single adult male, move around and meet peaceably with other subgroups as they encounter each other. Different groups show more aggression, but this is usually vocal rather than physical, and it is not unknown for females to transfer from one major group to another and then return to their home band.

As part of this social structure, spider monkeys do not show the disparity in size that is common in primates where a dominant male monopolises reproduction. Males are slightly larger, but the difference is hard to observe from the ground. The fission-fusion structure is probably an adaptation to maximise the use of widely scattered fruit sources, which can only sustain a few animals the size of a spider monkey at one time. Also, there is no obvious automatic male dominance – both females and males may take precedence in a group, depending on the individuals involved. This lack of male dominance is a feature of many South American monkeys, which are far more variable in their social structure than Old World monkeys are.

Part of the reason for this difference may be the polymorphism in vision in New World monkeys, which means that some females may have superior fruit-finding skills than other females and males. Colour vision in primates is the result of opsin pigments in retinal cone cells, which can be sensitive to Short (S), Medium (M) or Long (L) wavelengths. The S pigment is common to all primates and other mammals, and is held on an autosome. The M and L pigments are produced on the other hand by genes on the X chromosome. Old world primates have a duplication of the pigment genes, and normally carry both an M and an L pigment gene on each X chromosome. New World primates have only space for a single gene, which may be either an M or an L pigment. As male mammals are XY, and only have a single X chromosome, whereas females are XX, this makes for the situation as follows:

Male spider monkeys: SM or SL opsins
Female spider monkeys: SML, SLL, or SMM opsins

Females with the SML configuration are the best at colour discrimination, important when searching out coloured fruit of the best quality. Other configurations may each have their own advantages, but it is not clear what they may be. Any advantages of one type over another may only be temporary, perhaps at particular seasons. All the South American primates seem to exhibit this variation, so it has obviously worked for at least 17 million years, when it is believed the ancestral form began to diverge into the variety of species we see today.

Unfortunately, the need of spider monkeys for primary rainforest is a major cause of their current status as endangered animals. An effective breeding population needs a large area of untouched forest, as they cannot make use of secondary forest in the way that smaller species such as marmosets can. They also have a very low reproductive rate, with an age at maturity of at least 5 years and an interval between births of 2-3 years. As a result, any loss of a population cannot be replaced easily, and many species are quite heavily hunted.

The two young males we currently have at Bristol are part of the globally managed breeding programme for this species. It is hoped that females may join the group as they become available, but the captive population of this species is small (only around 85 animals worldwide) and reproduction is slow as mentioned above. With a long lifespan – potentially over 40 years- there is however time to find a suitable mate. With the ongoing deforestation and hunting in Columbia however, the need for protection in the wild is dire. The well known political problems do seem to be being gradually resolved, but by the time the Columbia people, or at least their politicians, take effective action it may be too late. As far as Bristol Zoos’ influence is concerned, we are gradually getting more involved with conservation projects in the country, and in particular with husbandry and veterinary help in rescue centres and Columbian zoos, as I described last week.

Nect week, a much smaller monkey – the Squirrel Monkey, which also has a more complicated society than you might expect.

(images from wikipedia, Arkive)

New World Primates 3: Silvery Brown Tamarin

2012-01-21T15:24:00.000-08:00

As well as the animals we have on show at Bristol, the zoo supports numerous conservation projects around the world. One of these is for a rare Columbian monkey, the Silvery Brown Tamarin Saguinus leucpos.

Columbia is second only to Brazil in terms of biodiversity, and no less than 37 different species of primate are found within its borders. With the destruction and fragmentation of forest cover, many of these species are increasingly threatened, especially those with small geographic ranges. The Silvery Brown Tamarin is found only in the Central Magdalena valley, and none of its range is inside a protected area at present. It is also the target for a large internal pet trade in wild caught animals, and is currently the most confiscated animal to be found in Columbia rescue centres. Historically, survival rates have been very poor, as a result of lack of knowledge of their requirements and capture stress (many species of marmoset and tamarin are very sensitive to this). As a result of this, the population in the last 18 years is estimated on the IUCN Red Book to have declined by over 50%, and it is classed as Endangered.

In 2006 Bristol and other European zoos in the Callitrichid Taxon Advisory Group began a cooperative venture to foster the conservation of the tamarin. Efforts have been focussed on studies of animals in the wild, and improving care and possible captive breeding programmes in both Columbian and other zoos. So far seven zoos in Columbia hold the species, and there have been some births, but work still needs to be done. Experience with the Lion Tamarins shows that this kind of programme can be successful, but is a long struggle to get to a point where the species can be reintroduced to the wild. Columbian law is rigid in the regulations concerning the transfer of any of the rescue animals out of the country, so we are unlikely to see them at Bristol any time soon – we will have to wait until animals at least 2 generations from the wild founders are available. I have however found a film of one on Youtube here: http://www.youtube.com/watch?v=G5vW6n148N8

Despite their high diversity, the various small callitrichids have fairly similar social structures. A group will be centred around a single breeding female and her mate, plus offspring of various ages. The young are carried by the adult male and their older siblings until they become independent at a few months old. The main difference between marmosets and tamarins lies in their feeding ecology – marmosets have specialised dentition which enables them to gouge grooves in the bark of trees to release sap and gum, which are major components in their diet. Tamarins lack the gouging jaws, so can only use pre-existing wounds in trees as a source of this food. Aside from this, both groups feed heavily on insects, especially orthopterans, and also catch frogs and lizards, and raid birds nests. They will also take some fruit, and where forest edge meets agricultural land they will raid fruit trees. Differences between species, which often move in mixed species groups, centre on the proportions of the various dietary elements and the parts of the trees from forest floor to canopy that they use.

In captivity, most marmosets are now supplied with a diet that is tailored to meet nutritional needs. Developing a diet for a captive animal is quite a tricky process, as even when you know what an animal feeds on in the wild you generally do not have enough knowledge of how the wild food source compares nutritionally with that available in captivity, even if for example you are feeding the same plant, as growing conditions, soil composition, even the time of year can all affect results. The Callitichid husbandry manual has a long chapter on diet for callitrichids, which lists nutrient requirements as follows:

Nutrient Concentration in diet*
Energy (kcal/g) **
Crude protein (%) **
Fat (%) —
Fiber (%) —
Linoleic acid (%) 1
Vitamin A (IU/g) 14
Vitamin D (IU/g) 2.2 or less
Vitamin E (mg/kg) 56
Thiamin (mg/kg) 5.6
Riboflavin (mg/kg) 5.6
Niacin (mg/kg) 55.6
Pyridoxine (mg/kg) 2.8
Folacin (mg/kg) 0.2
Vitamin B12 (mg/kg) 0.6
Pantothenic acid (mg/kg) 16.7
Choline (mg/kg) —
Biotin (mg/kg) 0.1
Vitamin C (mg/kg) 500 or more
Calcium (%) 0.6
Phosphorous (%) 0.4
Magnesium (%) 0.2
Potassium (%) 0.9
Sodium (%) 0.3
Iron (mg/kg) 200 or less (80-200)
Zinc (mg/kg) 11.1
Copper (mg/kg) 1.5
Manganese (mg/kg) 44.4
Selenium (mg/kg) —
Iodine (mg/kg) 2***

* Probable requirements for New World primates. Depending on the interpretation of the NRC (1978), the requirements for magnesium, iron, and manganese may be overestimated.
** The requirements for these nutrients are higher for marmosets and tamarins than for other New World primates. Energy required is 150-160 Kcal/Kg body mass/day (d) (Morin 1980); protein for small primate species is 3.5- 4.5 g/Kg body mass/day of high-quality protein (NRC 1978); vitamin D3 required is 110 IU/d/100 g body mass (Takahashi et al. 1985).
*** NRC may have overestimated the quantity needed. For most other animals the requirement is about 0.1.
— No NRC requirement stated for this nutrient. This does not mean there is no requirement, just that studies have not been performed. For selenium, the level in many mammals is about 0.1 ppm.

With this as a basis, several different usable diets have been formulated. As marmosets have been used as laboratory animals, specialised commercial diets are available which can be adapted to other callitrichid species. Examples of these diets can be found in the husbandry manual, which is available here: http://nwptag.com/Download%20Text.htm. Even this has a lot of space for variation – for example ‘fruits’ in a captive diet in the UK will usually be apple, pear, grape, or other similar plants grown in the UK. In the native Columbia, fruits available in a typical market might include guava, prickly pear, passion fruits (of several species), cherimoya, papaya, tomatillo or many others. How these compare and interact with other diets is a major research item for an animal collection, and nutritionists are still developing recommendations. For example, high dietary vitamin C in birds and probably some mammals promotes iron absorption, which can lead to liver problems in animals used to low iron diets in the wild.

For the Silvery Brown Tamarin the year has started well, with the association of South American Zoos and Aquaria (ALPZA) accrediting the programme as a cpnservation leader for South American zoos. For more information, check out the ALPZA website at http://www.alpza.com/

Next week, we move on to the larger primates, starting with one of the most iconic of South American monkeys, the Spider Monkeys

Information and images from Bristol Zoo website, ARKive, ALPZA

New World Primates 2: Lion Tamarins

2012-01-14T02:25:00.000-08:00

Golden Lion Tamarin

Here at Bristol we currently have on show two of the four living species of Lion Tamarins, leontopithecus. These are a now aging pair of Golden-Headed Lion Tamarins L. chrysomelas, and more importantly a growing family group of Golden Lion Tamarins, L.rosalia. The other two species are the Black Lion Tamarin L. chrysopygus and the Black-faced Lion Tamarin L. caissara.

Golden-headed Lion Tamarin

The various forms of Lion Tamarin were once found in Atlantic rainforest all along the coast of Brazil, but development of the area (the most densely populated part of the country) has caused major habitat loss and fragmentation of the habitat. By 1992 they were found only in a total area of 104.5km2 of forest in three regions of Rio de Janeiro province, with under 600 individual known. After 30 years of intensive conservation efforts, this number has been raised to over 1,000 in the wild, which is still far too low for long term survival without intensive help and population management. Captive bred individuals have been reintroduced to the wild, and in fact about 1/3 of the wild individuals have at least one captive bred ancestor, but the ongoing problem is still the fragmentation of the habitat.

Black Lion Tamarin

Each family group of Lion Tamarins needs between 40-100 ha of rainforest. They are actually fairly adaptable in their habitat selection, and are well able to make use of secondary and degraded forest as long as there are sufficient resources and especially tree holes they use as sleeping quarters. They are quite omnivorous, feeding on fruits, flowers, plant exudates, insects, and also catching frogs, lizards, and sometimes birds. There nearest ecological equivalent in the Old World monkeys would be a sort of miniaturised macacque.

Black-faced Lion Tamarin

As with almost all the callitrichids, they have twins at each birth, sometimes triplets. In captivity they can have litters twice a year, but in the wild they seem to have only one, probably as a result of food scarcity during the dry season. The babies are actually carried by the father or older juveniles in the group, returning to the mother to feed.

The group dynamics of Lion Tamarins are quite interesting. A single animal is at extremely high risk of predation, so they are extremely dependent on family groups. Typically these are a single pair plus offspring, but cases where there are two adult males (usually brothers) or two adult females (usually a mother and daughter) are also known. Young disperse at around three years, but if an adult female dies one of her daughters may inherits the territory. Both males and females may leave to try and set up their own families, but males are much more successful at immigrating into groups than females are. When males leave, it is common for two to leave together for mutual protection. They may try to evict a male from an existing family, or try to get a dispersing female to join their groups. As they are so rare, there is still much to be studied in their behaviour, and it is not entirely clear what the ‘normal’ structure of their society is in some cases.

One of the oddest features of the biology of the marmosets and tamarins is a result of their tendency to produce multiple births. As with other monkeys, they have a simplex uterus, with gestation taking place in a single central horn (by contrast, dogs have a bicornuate uterus). With multiple foetuses developing in a single uterus, the placentas of the twins or triplets fuse, and cells can pass between them. As a result, baby tamarins are chimaeric, with cells from two separate fertilized eggs forming their bodies. This is true even if the twins are of different genders, and both XX and XY cells can be found in the blood of each twin from a mixed litter. Whether this just affects blood and bone marrow, or possibly other parts of the body, is not yet clear and may in any case vary between species.

In addition to the wild population, there are around 400 Golden Lion Tamarins in zoos around the world. In the UK, standard accommodation is a heated indoor house with the nest boxes, and access to a planted outside screen cage or lake island. This enables the group to forage for insects and other prey as they would in the wild, and improves their general level of activity. In some places they can even be kept at semi-liberty. The habit of callitrichids of always sleeping in the same tree hole means that an established family group will always stay close to home base without additional confinement. In the past Bristol had a group of Geoffroys marmosets running loose in this way, and they bred successfully, but unfortunately as the group size grew they decided they needed more room and one summer evening left the zoo grounds. After that they had to be confined for their own safety. In zoos with more extensive woodland areas they have had more success, and if you visit Jersey you can walk through Tamarin Wood and find them running past you on the fence.

There is one more marmoset to cover before we move on to the next group of South American primates. This is one we do not yet have on show, but are working with in the wild – more on that next week.

Sources: IUCN, Primateinfo.net, wikipedia, Bristol zoo)

New World Primates 1: Goeldi's marmoset

2012-01-07T10:16:00.000-08:00

Mother carrying baby - December 2011

I am going to start 2012 with a series on the eight species of New World Monkeys we have here at Bristol. Between them the species Bristol holds covers all five families of the Platyrrhine monkeys, the scientific term for the monkeys of Central and South America. Their ancestors are believed to have crossed the Atlantic from Africa around 40 million years ago, and they have either developed or retained several adaptations that distinguish them from the monkeys and apes of the Old World. They do not have as good colour vision as Old World monkeys for example, with only two colour sensitive cone types in the retina in males, and either two or three cone types in females. In addition, their physiology is different, and they require much higher blood levels of Vitamin D than Old World monkeys do. Before this last requirement was realised, it was hard to maintain Platyrrhine monkeys in good health at high latitudes, even with exposure to sunlight, as they were very prone to Vitamin D deficiency diseases.

The first of our monkeys I am going to cover is surely one of the cutest, the Goeldi’s marmoset Callimico goeldii. In December our pair had another baby, bringing the family group to six. Goeldi’s are rather untypical marmosets, and appear to have adapted to a habitat and lifestyle somewhat different to the other marmosets and tamarins of South America. They exist at low densities throughout their range, and often associate with other species as they range around their territories. They prefer a densely vegetated understorey, usually staying under 5m from the ground, and streamside vegetation, regenerating secondary forest (including abandoned farmland) and bamboo seem to be preferred. The range extends from northern Bolivia into southern Columbia, east of the Andes.

Feeding on a Morpho butterfly

Most marmosets feed heavily on insects, especially grasshoppers, katydids and phasmids, and Goeldi’s are no exception. However, they differ in not feeding much on saps and gums, instead feeding heavily on various fungi, especially in the dry season. Other important dietary items are fruits and small vertebrates such as frogs and small lizards, with birds’ eggs when available.

Marmosets are highly social creatures, and Goeldi’s fit the general pattern – a single breeding pair plus offspring of various ages. The group size is smaller then their relatives, with usually 6-10 animals in a group. There is some variation, as both polyandrous and polygynous groups have been observed. The territory size can be as much as 1.5km2, several times the size of that of other marmoset species.

Most marmoset species have twins sometimes even triplets at each birth, and when resources are available can have two litters each year. Goeldi’s are much less prolific, with only a single youngster at a time and in the wild at least often only a single baby each year. This probably reflects the lower energy and mineral resources in their diet, and also the energy expenditure in getting around much larger territories. They may also experience less predation than the more visible marmosets, who often feed at higher levels in more exposed positions.

An animal the size of a Goeldi’s marmoset has numerous enemies of course. Mammalian predators are probably not the main enemy, but birds of prey and snakes are probably much more serious threats. I am not aware of any studies on the issue, but Goeldi’s have at least 40 recorded calls, and it is probable that some alarm calls are specific to the type of predator being observed. Many species that have such alarm calls, from Vervet monkeys in Africa to prairie dogs in North America and even some pheasant species in Asia have such predator-specific calls. Given that they associate with other marmoset and tamarins it would not be surprising if they can also understand the alarm calls of their companion species as well.

The main threats to Goeldi’s today are probably those related to development and deforestation. They will have trouble crossing roads, and this can cause fragmentation of their territories and the isolation of non-viable groups in small patches of forest. On the other hand, their ability to utilize secondary regrown forest can count in their favour.

The various species of marmoset and tamarin make good exhibit animals, being sociable and diurnal, and around 500 Goeldi’ marmosets are listed on ISIS. The typical exhibit in the UK will comprise heated indoor quarters with access to either a screen cage or sometimes an island. Access to planted enclosures is highly beneficial where possible, as it provides opportunities for natural behaviour and especially foraging for insects. The captive diet is a variety of fruits and vegetables, combined with a proprietary prepared biscuit and added insects in the form of mealworms, locusts, and crickets.

Next week: Lions tamarins – beauties from the Brazil!

(images from Bristol Zoo website, wikipedia)

Goodbye Mum

2011-12-31T08:36:00.000-08:00

The last post of this year is a sad one for me. In October my mother passed away after being diagnosed with cancer some years ago. She could stay at home up until only a few days before she died, and fortunately was able to look after herself, with some help, more or less to the end. I will always be grateful to her next door neighbour who helped her so much, and to the hospice where she spent her last days and whose outpatient day centre she so enjoyed visiting.

Mum was born in London in 1924 and was a keen Girl Guide. She should have been on a trip to Switzerland when WWII broke out – she was very annoyed at this and much enjoyed travelling in later life. I once said she should leave an itinerary letting us know which continent she was on! We have relatives on her side of the family in Australia and New Zealand – in fact a relative of hers, William Burton, was the last surviving member of Scot’s expedition to the Antarctic when he died just short of his 100th birthday in 1988 (he was a stoker on the Terra Nova). I am glad to say Mum and Dad met him in Christchurch before he died.

When war broke out Mum was evacuated to a safer location. Unfortunately, the evacuation plans were not exactly well thought out, and she was evacuated to Luton, opposite the Vauxhall works that were turning out munitions! As soon as she could, she left school and returned home. Given a choice of working in a munitions factory or for the post office, she chose the post office and spent the war years in a typing pool in central London, volunteering with the Red Cross and spending some nights in London underground stations during the blitz. She never spoke much about the war years to me, except that at one of the buildings she was working at the chief safety warning was to stay away from the glass doors during an air raid. The blitz itself lasted for eight months and by the end of it one million London houses were destroyed or damaged, and 40,000 civilians had been killed. In 1944 there was another series of bombings by V2 rockets, the first ballistic missiles, which lasted until March 1945, which killed and injured several thousand more people.

Meanwhile, my father was also working for the post office in London, though their paths didn’t cross then – they met on holiday in the Lake District after the war, and married in 1949. Mum worked as a secretary with various solicitors, typing complicated legal documents that had to be right first time – no corrections allowed!

Dad was working for the Crown Agents and was sent to their Washington DC office in 1956 for a year. It must have been quite difficult for Mum, living with a toddler in a flat with no air conditioning and cockroaches! However, she enjoyed the trip and made some good friends there. Some years later the whole family went on a second posting to Washington DC, this time for two years.

When dad retired they moved to Fordingbridge, just south of Salisbury, but Dad died of a heart attack when he was 67 (he was a fairly heavy smoker). Mum was still driving ‘old dears’ as she called them to community lunches when she was 80, and often volunteered at Fordingbridge museum.

One of her biggest interests was the W.I. She was a member of the Sanderstead branch, and naturally joined Fordingbridge WI after their move. (insert details of roles taken)

Mum was always determined to make the most of life. She enjoyed many great holidays with friends; loved cooking and needlework of different kinds; and was always delighted to see the family. She loved spending time with her grandchildren, who remember her gift for light verse, making up poems on different subjects. This was something she always enjoyed; in fact she was very annoyed when a poem she helped my sister write for homework only received a B+! She loved going out for meals and became a bit of an expert on local pubs, probably because of all those W.I. walks! We were all very grateful that she was well enough to attend my niece’s wedding in May, an event which she was determined to see and which she loved looking back on afterwards.

That closes this years’ series of posts. In the New Year, pheasants, marmosets, wild birds, and conservation projects will be among the topics covered. Please leave comments or make requests for any animals you would like posts on!

Review of 2011 - Part 2

2011-12-28T02:32:00.000-08:00

Gorilla statues at Bristol Harbourside

11th July marked the zoos’ 175th birthday, having opened on that date in 1836. In its early days, the Zoo received the gift of a lioness from Queen Victoria, and in 1868 the Maharajah of Mysore sent over Zebi the Asian elephant, which became renowned for removing and eating straw hats! Rajah, who gave rides to children for many years, replaced her.

Bristol Zoo also found international fame in 1934 when Adam, the first chimpanzee to be conceived and born in captivity in Europe, was born. Another well loved character was Alfred the gorilla, who lived at the Zoo from 1930 to 1948. Alfred was, at the time, the only gorilla in captivity in the country and was a very popular Bristol citizen.

Many people also have particularly fond memories of Rosie the elephant, who gave rides to 80,000 children a year throughout the 1940s and 50s; Roger, a black rhino, who was the first rhino ever born in the UK, in 1958; and the Zoo’s more recent elephants, Wendy and Christina who were taken for walks to Whiteladies Road during the 1960s.

Even those who lived too far to visit Bristol Zoo got to know some of its inhabitants as they found fame with Johnny Morris’ popular television series, Animal Magic, broadcast from the Zoo during the 1960s.

For Bristol, July also saw the launch of the Wow! Gorillas campaign, in which 60 fibreglass gorilla sculptures painted by a variety of artists were placed all over the city for the summer. This was a great event, and enormously popular with the local press, as a lot of people made a point of visiting each one to have their photo taken with them.

Greater Flamingos with chicks

August saw the hatching of the ninth flamingo chick of the year. We eventually managed to raise seven to independence, including two that were hand reared by the keepers.

New Stream Garden

September kicked off to a good start with the zoo winning the Bristol in Bloom gold medal. The award reflects the whole Zoo, as the judges not only take in to consideration the landscape, but many other factors such as cleanliness and recycling initiatives.

Judges gave particular credit to the Zoo’s new stream garden area that opened earlier this year. The gardening team made the area as interesting as possible by including a variety of features, including a stream, pond, aviaries, stumpery and a variety of plantings, such as poppies, peonies and roses.

Chills being grown in off-show greenhouse

Over the weekend of the 17th of September there was the chilli and chocolate festival, which proved very popular with visitors. I blogged about this at the time, but the plants display was so popular we extended it for another weekend. The plants we grew were sold off, and we could have sold many more if we had had the growing space.

Baby gorilla Kukena

The two big events though were the birth of a new baby gorilla, a male called Kukena, very well timed for the week before the Wow! Gorillas campaign ended with the retrieval of the gorilla sculptures from round Bristol for a mass display on the lawn for one weekend before their being auctioned for charity. We raised £427,000 eventually, which went to the Bristol Wallace & Gromit appeal and Ape Action Africa, the ape rehabilitation and conservation charity we support in Cameroon (check out their website on the links section)

Earl of Wessex with Gorisambard

In October we had a visit from the new Earl of Wessex, who was presented at the end with a small copy of one of the gorilla sculptures we had made and decorated. This one was in the style of one of Bristol’s most famous sons, Isambard Kingdom Brunel. The original Gorisambard sculpture was the highest earner at the auction, fetching £23,000 for the charity funds.

Utila island iguanas

November started with baby Utila island Iguanas going on show. This is the first time we have bred this species, and the youngsters are doing well. When larger, they will go to various collections around Europe.

In November we also collected awards from BIAZA for the “best education project” and “best research project” for the year. The research project award has been given for an in-depth study on the nocturnal northern giant mouse lemur in Sahamalaza National Park, north-western Madagascar.

The education project award was given for the Zoo’s project called ‘All Creatures Great and Small’, which aimed to highlight the importance of biodiversity in celebration of the International Year of Biodiversity in 2010. Commendations were also awarded to Bristol Zoo in three categories – best field conservation project for its white-clawed crayfish project; best education project for its spider phobia courses, and best new zoo enclosure for the zoo’s amphibian breeding facility, the AmphiPod.

Solar panels on roof of veterinary building

In December solar panels were installed on the veterinary and service department building. Heating and lighting enclosures and visitor facilities is one of the zoos’ main running costs, and the panels should cover their costs within seven years. The panels were provided by a company based in Backwell (near Bristol) company Solarsense. The 184-panel 46.92kW solar photovoltaic (PV) system covers an area roughly the size of a tennis court.

Baby Goeldi's marmoset on parent

The last zoo news for 2011 was the birth of another baby Goeldi’s marmoset on 21st December. This is the second baby for the year (marmosets usually have litters around every 6 months) and the fourth for this breeding pair. In the New year I will be doing a series on the various primates we have here at Bristol, so watch this space for more details1

That’s about it for this years’ news from Bristol. I have one more post for 2011, and then I hope to see you again in 2012! Any comments or requests would, as always, be much appreciated.

(images from Bristol zoo website)

Review of 2011 - part 1

2011-12-23T09:20:00.000-08:00

To round up this years posts I will review the year at Bristol. This has been a major anniversary for us, as Bristol is the fifth oldest zoo in the world in continuous operation, and the oldest outside a capital city. From the start Bristol has pioneered many exhibit styles, and has majored in zoo education, research, and public service, so even if a visitor may see larger versions in other zoos, there is a good chance we were at least early adopters if not originators. For example, we were among the first to have a reversed photoperiod nocturnal house and walk-though aquarium tunnel (admittedly the latter is very small compared to more recent versions as it was created before modern acrylics came into use).

The year got off to a very good start with the birth of two lion cubs, Jasleen and Kaylara, to our pair of Asiatic lions. The cubs were born on Christmas Eve 201, but did not go on show for a few weeks until they had had their vaccinations (lions are susceptible to the same diseases as domestic cats). The cubs are now a year old and Jasleen (the male) is already beginning to get his mane. The cubs will probably stay at Bristol next year, before being moved to other collections to become parents in their turn.

In February the new Meerkat exhibit opened. This has proved very popular with visitors and with the Meerkats themselves, who have already produced several offspring. Also in February another tapir calf was born. This was the seventh calf our female Tamang has produced, and as she has produced more than enough offspring the male Denzil has now been moved to another collection. At present we have the adult female Tamang, her previous calf ( also a female) and young Roger on show.

In March, the zoo released its illustrated history (on sale at the zoo shop) with photos from bygone years at Bristol Zoo, including the famous TV presenter Johny Morris. We also put up photos of bygone years at the zoo, of which the most moving I find is a photo of injured troops on leave attending a concert on the lawn outside the main central buildings.

In April, plaques for a Walk of Fame were installed around the zoo. Produced by the famous Bristol Blue Glass works in the city, they commemorate famous Bristolians, from the notorious pirate Blackbeard to the late actor Cary Grant and the equally famous street artist Banksy.

In May, children from Fair Furlong Primary school came to plant their edible garden they have designed. Mike Crook, Bristol in Bloom Chairman, said: “From 75 entries Fair Furlong Primary was picked as the winner due to their interesting and well laid out design.” Eddie Mole, Head of Horticulture Gardens, said:“Their chosen produce consists of strawberries, courgettes, sunflowers and green beans plus a host of herbs which are easy to harvest as well as being aesthetically pleasing and great food for the animals.”

He added: “The competition is now in its third year and this time, our on-site catering team specified the plant list so that some of the produce can be used in the kitchens. The chef’s will be able to pick fresh, seasonal herbs to use in their daily cooking.”

Also in May, a baby sloth was born to our old female Light Cap in Twilight world. Unfortunately, he has had to be hand reared, but has done very well and is now on solid food like his parents. Perhaps inevitably, he has been named Sid.

The big event in June was a second set of twins for our Golden Lion Tamarins. After several unsuccessful years, we now have a nice family group of these beautiful monkeys – I will be doing a full post on them in 2012.

Also in June a male Red Panda finally arrived to join our solitary female Jasmina. After having to wait for a suitable match, Sir Ed arrived all the way from New Zealand and has settled in well in good time for the 2012 breeding season. With luck, we will have cubs next year.

Next time – the second half of 2012!

(Images from the Bristol Zoo website)

In the pink

2011-12-17T08:19:00.000-08:00

Greater Flamingos, India

The first aviary a visitor encounters at Bristol is the Camargue aviary opposite the entrance. Although it contains several species, the most instantly recognised are our flock of Greater Flamingos, Phoenicopterus roseus, one of two living species found in the Old World, along with the Lesser Flamingo, Phoeniconais minor. There are another four species found in the Americas, of which the only one found naturally in North America is the American Flamingo Phoenicopterus ruber. The American Flamingo was formerly classed as a subspecies of Greater Flamingo but has now been split into a separate species. There other three species live in the Andes at high altitudes, and comprise the Chilean, Andean, and Puna or James’ Flamingoes. Very few Andean or Puna flamingos are in animal collections, but some can be seen at the Wildfowl and Wetland Trust collection at Slimbridge.The vast majority of flamingos to be seen in zoos or wildfowl collections are Greater, Chilean, or American flamingos.

Chilean flamingos

American flamingos

Today, flamingos can only be found naturally in the Old World in the Mediterranean, Africa, and North West India, but in the past they were more widespread. They were reported by early visitors to Mauritius, where they were probably wiped out with other endemic birds such as the Dodo, and further in the past they are known as fossils from Australia, where they were probably driven to extinction by increasing aridity during the Pleistocene. In the Americas they also occurred further north in the past – some fossil flamingos have been recorded from Oregon for example, though I am not sure of their date. The key feature controlling their distribution is not so much temperature as habitat – they need shallow, saline lakes with a fairly simplified ecosystem based on blue-green algae and brine shrimps, which provide their diet.

Lesser flamingo

Puna flamingo

Andean flamingo

Flamingos are filter feeders, extracting food particles from the water by using their thick, fleshy tongue as a piston to force water through fine plates on the roof of the mouth which trap the food particles. Depending on the gaps between the plates food items may be single-celled blue-green bacteria, or larger shrimps, baby fish, and small molluscs. Different species have different target food items, which is why two species of flamingo can often be found side by side. The Phoenicopterus species feed on larger prey items than the Phoeniconais forms.

Whatever there food preferences, the diet of flamingos will contain carotenoid pigments derived from blue-green algae, which are the source of the pink or red in their feathers and skin. Different species have different levels of pigment, and deposit them differently in their feathers, which is why different species may vary from almost white to deep red. Young flamingos have feathers which are white or brown, and take at least ay year for the feathers to turn fully pink. The bare parts, especially the legs, can take several years to colour up.

Flamingos are very long lived birds – they have been recorded as living in to their 50’s in captivity and probably often reach at least 30 in the wild. They need a long lifespan as they are not very productive – they only lay a single egg at a time and probably in the wild only raise a youngster to independence perhaps one year in three. They are of course famously social – colonies can reach many tens of thousands of birds in the Rift Valley. Even these vast flocks however may only be a shadow of the numbers that once existed – for example during the Messenian Crisis around 6 million years ago the temporary closure of the Straits of Gibraltar essentially caused the entire Mediterranean to dry out into one giant salt pan, which would have been prime flamingo habitat. The numbers living then must have been truly astronomical. We know that flamingos very similar if not identical to the modern forms were around then from fossils – modern-type flamingos go back at least 30 million years.

As a result of their specialised habitat, flamingos are at risk of human interference. Disturbance, drainage of lakes, and industrial pollution are probably the main threats. Having said that, around the Mediterranean flamingos will often breed and feed close to human activities, especially salt pans. There are major colonies in Spain and the Camargue, and they also winter on Cyprus.

Chilean flamingos, Norfolk, UK 2010

Flamingos have been kept in waterfowl collections for many years, and it is not unknown for them to escape. They may survive in the wild for many years, but a group of escaped Chilean flamingos in Germany some years ago actually began breeding in the wild, and still probably survive. These birds may have been the source of two birds which showed up at Cley in Norfolk in 2010. Some years ago a pair stayed with the swans at Abbotsbury in the South West UK, and even built a nest as I recall being told, but did not succeed in raising a chick. Given the number of other water birds which have colonised the UK in recent years, I wonder if flamingos will join the avocets of Norfolk? – flamingos and avocets after all favour very similar habitats. The main obstacle would be that they need to be in a large flock to encourage breeding, but it is not impossible.

At Bristol we had a good breeding season this year, raising seven chicks. This takes our flock to 38 birds, close to the minimum size for regular annual breeding. The youngster can be told by their white plumage and grey legs. Adult males are much taller than females. The captive diet is a specially prepared artificial diet which contains an artificial colour compound to replace the carotene in the wild diet. Flamingos are quite hardy birds, but in severe weather they are shut inside their house.

Well, that’s about all for this week. Next week part one of the review of the year, which has been a significant one for Bristol Zoo and for me.

(Images from wikipedia, Norfolk Wildlife trust website)

Part 6: And finally, the show scene

2011-12-10T08:40:00.000-08:00

Today the canary is one of the commonest pet birds in the world. Just about every pet shop in Europe or North America at least will have some, and a single bird or a pair is easy to accommodate. As with all birds however, larger accommodation in the form of an indoor or outdoor aviary allows them to keep fitter and more active. Anyone interested should consult any of the innumerable books, websites, or forums where information from other keepers is easily available.

As well as individual keepers of pets however this another level of keener keepers and breeders of canaries. These people have the aim not just of enjoying the company of an individual bird, but of producing the perfect specimen of the breed in question. As with dog breeders, whose star event in the UK is Crufts, there are specialist shows where these exhibitors, or rather their birds, compete for coveted rosettes. As with all competitive and obsessive activities, men feature much more commonly in this area than women.

Before a bird stands a chance of winning however, a vast amount of care must be taken by the prospective exhibitor. The first step is selection of the correct parents. Exhibition canaries of proven bloodlines can be quite expensive, and exhibitors have to be careful to pair up the correct birds. The general aim is to match the parents in the hope that their offspring will be as close as possible to the breed standard set by whichever national society is concerned with that particular breed.

Once the correct parents have been decided, they have to be brought into peak breeding condition. The correct seeds, supplementary foods, and supplements are provided, and the birds are kept in longer ‘flight cages’ where they can get more exercise. Once they are judges ready to breed, the pairs are placed in separate breeding cages supplied with a nest pan that the birds use to build their nest with materials provided.

When the birds begin to lay, the natural tendency is for the hen to begin incubating after the second or so eggs, whilst continuing to lay until the clutch is complete. In a wild bird this would result in a staggered hatching of the clutch, and if there was a food shortage the older and larger chicks would dominate their nestmates and survive whilst their younger brothers and sisters did not. This is not desirable in a domesticated situation, as the exhibitor wants all the clutch to fledge at the same size to increase the chance of a good bird being produced. To arrange that all the clutch hatches together, the eggs are removed as they are laid and replaced with dummy ceramic eggs until the clutch is complete, when all the eggs are returned to begin incubating.

When the eggs hatch, the young birds must be supplied with the correct food. This takes the form of proprietary or home made ‘egg food’ which is generally a powder or granulated mixture that is mexed with water and supplied separately to the parents food. In the wild canaries, like most seed eating birds, supply their young with unripe seeds or insects, and the egg food substitutes for this.

A few days after hatching, each bird is ringed by the breeder with a band that slips over the foot while the toes are still flexible. This ring has a unique identification number, and unlike the rings used by people who ring wild birds it is a closed metal band. The ring number identifies the individual and the year it was bred – a very important consideration when showing as there are different classes for current year and older birds.

Once the chicks fledge, they are fed by the parents for week or two before learning to feed themselves. Once they are independent, they spend some time in flight cages or aviaries, building up fitness before they are selected for potential showing. Surplus birds are usually sold to pets shops, which is where their stock tends to originate.

It is not enough for a bird to look good, it must also behave properly when at the show. Before the show season starts every bird will have time in the show cages, which are specified for each type of canary, so they do not panic when taken to the show.

The shows themselves are usually held in the autumn after the post-breeding moult and before the next breeding season starts. Judges are usually long-time keepers and exhibitors themselves, and they keenly examine each bird to select the best one. Generally birds are brought to the show bench for judging in the morning, and exhibitors are excluded, usually biting their fingernails, until the judging is complete.

That wraps up this series of posts – I hope people have been interested. If anyone is thinking of keeping a canary or other pet bird I highly recommend people visiting their local bird keepers club (there is usually one in your area) or one of the shows, either a local show or one of the national shows, where they can find a lot of very useful information.

Next week – Flamingos, and then the review of the year at Bristol, which has been an important one for us and has earned the zoo a lot of good coverage.

(images from Kentcages.com, petngarden.com etc)

Part 5: Down the mines

2011-12-02T13:52:00.000-08:00

Border canary

The canary in the coal mine is a familiar expression today, generally used either for some environmental change or for some ominous economic event, but how did it originate? And for that matter, what were canaries doing down the mines in the first place?

The story starts a long, in fact very long, time ago, with the evolution of the first dinosaurian ancestors of birds during the Triassic. Life on earth was still recovering from the greatest mass extinction event ever, the end-Permian event, when perhaps 95% of all the species of living things on earth died out. The survivors at first had little competition, but as new species evolved the evolutionary arms race intensified.

One of the areas of competition was in physiology. Active animals with a high metabolic rate could be up and about, finding food and catching prey, while less energetic animals were unable to escape or compete. To run an active metabolism however, an animal needs to be able to absorb oxygen efficiently from the air, and two methods eventually dominated.

The mammals evolved a muscular sheet, the diaphragm, inside their body cavities. This worked with the muscles of the thorax to improve the pumping of air in and out of the lungs, which themselves became more complex. The ancestors of dinosaurs used a different method. Air sacs extended from the lungs, at first only a few, but eventually more and more. These air sacs received air on inhalation, and on exhalation the air passed through thin tubes, the parabronchi, on its way out of the body.

Bird lungs - inhalation above, exhalation below

By the time birds evolved the system had become complex and highly efficient, with the air in the exchange surfaces being almost completely changed with each breathing cycle, while mammals changed only a small percentage. The result was that birds are far more efficient at absorbing oxygen from the air than mammals are. This is why geese for example can fly right over the top of Mount Everest, while the mountain climbers far below have to use supplementary oxygen tanks to survive.

The efficient avian lungs however have one drawback. They do not just absorb oxygen from the air, but inevitable accelerate the absorption of other gases. As a result, birds are highly susceptible to toxic gases. In many cases of the unexplained death of a pet bird, toxic fumes, often from an overheated non-stick pan, are the actual cause.

How birds came to be used as living gas detectors is down to one of the most famous scientists of the 19th Century, JS Haldane. A brilliant investigator, and dedicated Socialist, he devoted a great deal of time to the benefit of working men, especially miners. As part of his investigations of mining disasters and their causes, he analysed the various gases (mainly methane and carbon monoxide) which were so lethal , especially in coal mines. After experimenting on mice and birds, he suggested that each mine should have some canaries on hand in case of trouble. A canary could be taken down to the suspected trouble spot and if it showed signs of distress the miners would know to get out and improve the ventilation in a hurry. The scheme caught on, and even after mechanical devices began to take over, canaries were still kept on hand in case of emergencies.

With their lives depending on their birds, it is unsurprising that even today mining areas are strongholds of canary keeping g in the UK. For a round up of some of the clubs, shows, and other features of modern canary keeping, I will finish of this series of posts next week.

(images from wikipedia, sciencephoto, petinfospot)

Part 4: Rise of the red factor

2011-11-28T11:33:00.000-08:00

Red Siskin

Canaries are yellow. This is one of those ‘everybody knows’ facts that are in reality completely untrue. As you will have seen from images on previous posts, canaries come in all shapes and sizes, and are often greenish-brown rather than yellow. Up until the start of the 20th century however no one had succeeded in breeding a canary colour that was not a variation on the colours in the wild bird.

It was at this point that someone wondered if a new colour could be introduced from a different species altogether. It was already known that canaries would hybridize with other species of finch – in fact show schedules even today have a special section fro these hybrids, which are referred to as ‘mules’. Except for hybrids with the European Serin, which is involved with the origin of several continental breeds, practically all of these were believed to be sterile. This was in the early days of genetics, but the reason is probably differences in chromosome numbers.

Nonetheless, experiments were made with finches carrying various colours, especially red, and eventually it was discovered that male hybrids of the canary and the South American Red Siskin Cardualis cucullata retained some fertility. Further crosses back to canaries eventually resulted in a fully fertile canary whi9ch was capable of expressing red in its plumage.

Red Factor

The red in the feathers of a red factor canary is a lipochrome pigment related to the yellow in the normal bird. As with the yellow, the pigment is ultimately derived from the diet. For this reason birds entering the moult in particular must be fed a diet containing the chemical precursors, or the bird will develop feathers with insufficient depth of colour. This is supplied today by a commercial additive, but in the past it was supplied as far as possible by feeding a diet containing natural precursors.

It was soon discovered that not only the red factor had been incorporated into the red factor genome. Unlike wild canaries, Red Siskins are sexually dimorphic, and this dimorphism became established in one of the newly developed breeds. Called Dimorphics or Mosaics, these show colour points on the wings that differ in males and females.

Mosaic

With the new palette of colours available, an interest developed in a section of the hobby for breeding canaries for colour rather than type. Mutations in the concentration and distribution of eumelanin and phaomelanin have resulted in a variety of distinctly different colours.

Brown Isobel

Unfortunately, the original demand for Red Siskins to create these new colour canaries resulted in a ‘gold rush’ of trappers taking them from the wild. Although the species is now protected, a combination of illegal trapping and habitat destruction has put the species on the Endangered list. Although the pure species has been bred, the captive population is extremely low.

Next week: How the canary was sent down the coal mine.

(images from wikipedia, redbarnwings.com)

How canarys differ

2011-11-19T10:08:00.000-08:00

Lizard

Today a huge variety of recognisably different breeds of canary exist. As with the domestic dog, the difference from the wild ancestor can be extreme, and selective breeding is still altering them further from the wild type. So how do the different breeds differ?

Song

Timbrado

The original canaries were kept for their song, and all male canaries still sing of course. However, only a few of the canary breeds are actually specifically bred for song type and quality. In Europe, the three commonest types are the Roller, the Waterslager, and the Spanish Timbrado. Each of these has a different song type, a modification of the original wild song.

Song canaries compete at special shows. The birds compete on points awarded against various components , called ‘tours’ of their song. To hear some of these, this website allows you to hear them: http://www.germanroller.com/roller_canary_jukebox.html

One feature of the song varieties is that they are quick studies. It is important that the different breeds are not kept in earshot of each other, as they will imitate each others songs. As part of their training, they are placed where they can hear good examples of the breed type song from either a champion or (especially these days) a recording of one. The young birds hear these when they leave the nest and the song they hear becomes a model for their own.

Size

Yorkshire

The original wild Canary is a small bird, and some canary breeds are still tiny and active. Very popular in the UK at the moment is the Fife, which is minute. By contrast, the Yorkshire is a very large breed, almost 15cm long, and also has a distinctive upright stance. Most other varieties are somewhere in between.

Posture

Swiss Frill

Some canary breeds are bred for their distinctive body shape, especially as they sit on their perch. Not especially popular these days, and to me they do look rather strange, although they can all get around perfectly well. Several of these type canaries also have frilled body feathers, resulting in a very distinctive bird.

Colour

The original wild canary had four different pigments in its feathers. Three different forms of melanin (eumelanin black, eumelanin brown, and phaomelanin) contributed to various black and brown shades in the plumage. In addition, a yellow lipochrome pigment, containing carotenoids derived from the diet, was present in each feather.

In the development of the various breeds, variations in the distribution, presence, and concentration of each of these pigments causes the differences in the colour and markings of each bird. A lot of genetic understanding is required by breeders of exhibition birds, as the genes containing each of these traits may be dominant, co-dominant, or recessive. They may also sometimes be sex-linked, which means that the genes concerned appear on the chromosomes controlling gender. In birds, the male has an identical pair of Z chromosomes, whereas the females have a Z and a W chromosome. This means that a recessive gene on the Z chromosome will appear in all females, but the trait will only be manifest in a male if it is inherited from both parents.

The wild canary is a yellow-ground bird, but white canarys exist. These lack the ability to express the lipochrome pigment, giving a bird which is variously light brown, grey, bluish, or pure white depending on what melanins are expressed.

Feather

Gloster

As mentioned above, some canary breeds have frilled feathers, a result of changes in the orientation in the feather tracts as the feathers emerge from the skin. The other main breed difference is in the crested varieties, of which the commonest is the Gloster. In crested canaries the crest-bearing birds have the feathers on the top of the head radiating from a central point, rather than pointing backwards from the beak. The crested gene is an autosomal dominant, and if a bird carries the gene it is always expressed in the appearance of the bird. However, if two crested birds are bred together (the crest can appear in male or female), any eggs inheriting a double dose of the crested gene die before hatching. For this reason crested varieties come in two recognised forms, crested and non-crested.

The other feature of canaries is that in the course of domestication two distinct forms of body feather became established in all breeds. One type is called variously ‘buff’, ‘frosted’ or ‘non-intensive’. Birds carrying this body feather type appear larger and rounder, but also paler, than birds with the other type of feather (called ‘yellow’, ‘non-frosted’, or ‘non-intensive’), which is narrower, with no white edge, and has a higher pigment concentration. Similar variation exists in other domesticated cage birds, and I presume similar variation also exists in wild birds, at least the finches.

Feather types

The body feather types are present in most breeds, and the skill of an exhibitor lies in selecting pairings that combine the two types. Pairing two ‘yellow’ type canaries together eventually results in offspring with strong colour but which appear undersize and with a thin appearance, whereas pairing ‘buff’ type birds together results in birds which are large, pale, and loose-feathered.

All this was the state of play up to the 20th century. At this point, experimenters began trying to see if they could expand the palette of colours possible in the canary. The chosen additional colour was red, and how red canaries became possible is the subject of my next post.

Images from:

http://www.redbarnwings.com/
http://www.animalworld.com/

Part 2: Domestication

2011-11-12T08:53:00.000-08:00

One of the minor unexplained oddities of human beings is our fondness for keeping pets. Wherever you go, and in every society, you will generally find someone, often but by no means always a child, with a pet animal of some kind. Perhaps the world leaders in the variety of species kept are probably the native peoples of the Amazon – everything from parrots to tapirs has been reported as being kept in the villages. This happens even though the same animal may be hunted for food, or regarded as potentially dangerous (bears for example). True pets or companion animals are not the same as work animals such as hunting dogs, which may be quite badly treated. When people first started keeping them is not at all clear, but for some reason it is more common outside Africa. Given that we now know that non-African modern humans are at least part Neanderthal, I wonder – did the practise actually start with them? Contrary to what may be thought, hunter-gatherer societies are just as fond of keeping pets as settled agricultural ones, so there is no lifestyle objection to that idea.

However that may be, the first domesticated birds were raised for food. In Europe, these were the Rock Dove (whose squabs were a major delicacy into the Middle Ages) and the greylag Goose. Domestic chickens may have been domesticated earlier, probably in Thailand, but they did not reach Europe until around 400 BC. At first, chickens were kept not so much for food as for the ‘sport’ of cockfighting. The sight of rival males, resplendent in their finery, fighting furiously to show off appealed to Celtic aristocrats, who did much the same in real life, and they grew so obsessed that the Romans called them the Galli – the Chicken people. This was later worn down to Gaul, as any reader of Asterix knows.

Old English Game - probably the closest to the original Gallic chicken

There are many frescoes and other paintings from early times showing smaller birds being kept in cages, for their song for the most part. The Romans also imported parrots – probably the Indian Ring Necked Parrakeet – from India, and other birds from Africa. At that time though it is likely that they would have all been wild caught birds rather than true domesticated ones.

How the canary came to be domesticated is not at all clear. The first reference to canaries being kept for their song dates back to the 16th century, but at that time it is likely that most were wild caught. Allegedly a Spanish ship carrying some was shipwrecked near the Italian coast, and the escaped birds were the foundation stock from which all later canaries were bred. Whatever the truth of this, I wonder whether the actual techniques of breeding cage birds were obtained by the Spanish from their contacts with Asia, where cage birds were first bred by the Chinese and the skills then distributed along the Asian trade routes.

Another mystery is why they were domesticated and not other finches, as many more easily obtained small birds had been caught and kept since ancient times. I wonder whether, as an island endemic, it had weaker anti-predator instincts than continental relatives, and so was more likely to settle down to breed in the primitive conditions they would have been maintained in at first. Its adaptations to a fairly arid environment might also have helped, as animals from such environments tend to take the first opportunity to breed when food resources are at all available, even if inadequate. It is surprising how many of the world’s most common pets come from such habitats – the Syrian Hamster, Gerbil, Budgerigar, and Leopard Gecko are all commonly kept and all come from aridland environments.

As soon as birds were being bred in any numbers, a variety of mutations began to appear. The earliest forms were probably those with reduced or abnormal melanin production in their feathers, resulting in the familiar yellow canary of most books. However, a variety of other forms eventually appeared, and some of these I will cover next time.

Images from Wkipedia, www.fifecanary.org

The story of the canary

2011-11-07T11:14:00.000-08:00

Domesticated canary - the 'Gloster'

From ancient times, people have kept a variety of small birds as companion animals, usually for their song. Today a huge variety of species are kept, but probably the commonest is still the first to be truly domesticated, the canary. As they have been kept for so long, their story is entwined with the origins of genetics, conservation legislation, even health and safety. The ‘miners canary’ is still proverbial (at least in English) as a reference to some event which is a portent of far more serious disasters to come, and these days is most often heard referring to some environmental change heralding climate change induced catastrophes. This series of posts will investigate the natural and unnatural history of the canary, and some reflections along the way on its implications for the world as a whole.

Part 1: What is a canary, exactly?

Canaries are so familiar as cage birds that people forget that they actually occur in the wild. They are endemic to the Canary Islands, from which they take their name. The name of the islands, on the other hand, actually derived from the Latin Canis, ‘dog’ – apparently the Romans were impressed with the local breeds when they discovered the islands.

Juvenile wild Atlantic Canary

The wild canary is a member of a widespread, but primarily African, group of finches called the serins. The ‘official’ name of the wild birs is the Atlantic Canary, Serinus canaria. The 30 or more species seem to have fairly similar ecologies, with a habitat of open scrubland and grasses, and making nests in bushes and feeding on grass seeds in particular. The young are usually raised on unripe grass seeds and insect s. One species, the European Serin Serinus serinus, is widespread in Europe and most years at least one or two arrive in the UK. They have sometimes attempted to breed in this country, but there has been no real signs of a true colonisation, at least so far.

European Serin

The serins are a complicated group, and several sub-groups have been defined. Some at least may be closer to other Eurasian finches such as the European Goldfinch Carduelis than to other ‘official’ serins.

The wild bird is not especially colourful, being a greenish-brown bird with darker streaks, especially in the female. They tend to move around in flocks like many small birds, as this provides more protection against predators such as sparrow hawks. They nest in loose colonies as well, with each pair defending a territory in the immediate vicinity of the nest.

Whether the wild canary was originally confined to the Canary islands is unclear, but today it occurs on almost all of the main islands, and also on the Azores and on Madeira. The wild population is estimated at around 150-160,000 pairs, and is listed by the IUCN as Least Concern. They are often associated with human habitation, as are many other species of serin.

The serins tend to cope well in agricultural habitats, and almost all the species are listed as of Least Concern. One exception is the Yellow-Throated Serin, Serinus flavigula, which appears to be confines to a small area of eastern Ethiopia. Part of the reason for its status is that unlike many of its relatives it is intolerant of human disturbance. The population may be under 1,000 individuals – worryingly low for a small passerine, as the typical lifespan of such birds in the wild is probably only a few years at most.

Next time: how the canary was domesticated.

(images from wikipedia)

Halloween: Behold the Great Pumpkin

2011-10-29T02:12:00.000-07:00

For the last week the zoo has had its Halloween week, with among other special events some displays of pumpkins and squashes grown by the gardeners. Traditionally, the only members of the pumpkin family grown on any scale in the UK were marrows and their smaller relatives the courgette (zucchini), but with more varieties for sale in supermarkets more people are growing other varieties, such as butternut squash and, of course, pumpkins.

The Cucurbitaceae, the family to which pumpkins, gourds, and melons belong, has a worldwide distribution and various varieties were among the first food crops to be domesticated. As well as food, the hard rind of several forms are used to make containers, and one form, the Luffa gourd, is used to make vegetable sponges for cleaning. On the whole, they are warmth-loving plants, and only in recent years has the British climate been warm enough to grow the modern varieties outside.

The true Pumpkin, Cucurbita maxima, is the largest of the various forms that can be grown in the UK. Carving pumpkins for Halloween lanterns is fairly new in Britain (in the past turnips were used instead), but it is fairly common these days.

Of more interest is the pumpkins contribution to one of the more popular branches of gardening in Britain, the fine art of competitive vegetable growing. When the first giant vegetable show was held is lost in the mists of rural alcohol, but it seems to have been an outgrowth of the agricultural improvement movement, which became a major player in the increase of agricultural production from the mid-1750s onwards. At first only major landowners took part, but pretty soon everyone with an allotment or garden was joining in. As knowledge of how to selectively breed both plants and animals became widespread a passion for what was effectively amateur genetic engineering became part of the British worldview, and soon spread from agricultural crops and livestock to pets. Societies sprang up devoted to this species or other of animal or plant, and held shows where members could display their skill with breeding and husbandry. The most famous of these shows is probably Crufts, the most famous dog show in the world, but ornamental plants and garden shows are part of the same movement really. With vegetables the competition can be especially fierce, and by now some of the sizes of the vegetables shown are practically unbelievable. It is not unknown to see carrots approaching 2m long, or pumpkins weighing over 600kg.

Giant pumpkins are invariably specially selected strains of the variety ‘Atlantic Giant’, which was first produced in the US. To produce the largest fruits, growers restrict the number developing on every plant and watch the plants like hawks to ensure they do not suffer shortage of plant food (especially nitrogen) and suffer any checks to their growth from chilling. For more on this arcane art form, look here: http://www.veggiegardeningtips.com/in-pursuit-of-the-great-backyard-pumpkin/

Considering the amount of passion (and occasional skulduggery) that goes on behind these competitions they do not appear in art as often as you might expect. The best portrait I know of in recent years is Nick Park’s wonderful animated film The Curse of the Were-Rabbit (if you have not seen it, get a copy at once – I guarantee you will like it.

Today the cage bird society I belong to is having a show. Next week, I will tell you how I got on, and start a series on the natural and unnatural history of common pet birds. The story has more twists and turns than you might think.

By the light of the silvery Moon (Moth)

2011-10-22T08:10:00.000-07:00

A.selene male

Earlier this year we started showing a new species of silkmoth, in addition to the Giant Atlas Moths Attacus atlas and the Rothschild’s Atlas Moth Rothschildea jacobeae. These are the beautiful lime green Indian Moon Moth, Actias selene.Although we do not currently have adults on show, we have larvae growing off-show and should have the adults again in a few months.

I have a personal interest in these, as earlier this year I obtained some of the eggs of this species from a supplier and raised them myself at home. The larvae feed on many different plants, but I raised mine on hawthorn (Crataegus). They will also feed on the leaves of apple, evergreen oak, even rhododendron, and in their native habitat will feed on numerous forest trees.

A.luna female

Various species of moon moth can be found throughout Asia, and one species, Actias luna, the American Moon moth, has colonised North America from Quebec south to northern Mexico. They are usually fairly large moths, mostly green or yellow although the long tails on the hind wings are often pink. Males and females are often fairly distinct, with males having longer tails than the females.

Graellsia isabellae

There are perhaps over 20 different species of Actias described, and some species have several subspecies that should probably be treated as distinct. In addition, two other genera of moon moths exist, and seem to form a clade with Actias – the Spanish Moon Moth Graellsia isabellae, and the four species of African/Madagascan Argema. The latter genus contains one of the most magnificent of all moths, the Madagascan Moon Moth or Comet Moth Argema mittrei, which has a 20cm wingspan and tails 15cm long.

Argema mittrei

Although they will eat a variety of food plants in captivity, the moon moths in the wild often specialise in plants that protect themselves with resin against injury. American Moon Moths will feed on Liquidambar, Argema species feed on Eugenia, and Graellsia feeds on pine. Some Actias species will also feed on pine, such as the Chinese Moon Moth Actias dubernardii.

A.dubernardii male

As most of these moths are fairly easy to breed in captivity, and many species are subtropical or temperate zone moths rather than full rainforest species, they are widely bred on butterfly farms. Even the Madagascan moon moth can be bred in captivity, if with more difficulty than some others, as the larvae will take Eucalyptus as a substitute for the wild food plant. If you have access to the appropriate foodplants, anyone can raise the easier species such as A.selene or A.luna, so they make a fun project for children to try raising at home - the eggs are easily available mail order.

A. selene 5th instar larva

Most species will last out the winter or dry season as pupae inside fairly loosely woven cocoons. The “decision” to go into diapause rather than develop immediately depends on the larvae, especially the light regime and temperature as they develop. The adult moths emerge in early morning, and as with all Satuniids they do not feed, surviving on the fat reserves they built up as larvae. Depending on temperature, the adults live for around a week. They pair after dark, females attracting males with pheremones.

And what of the ones I raised I hear you ask? I only got one female emerge, but I had a successful pairing and the next generation of caterpillars hatched successfully. I have a thankful of second instar larvae now, feeding on raspberry and hawthorn. If I get these through to pupation, the next generation of moths should emerge in the spring.

(images from wikipedia)

Hot off the press

2011-10-18T01:57:00.000-07:00

C.annuum

How on earth did people come to decide that chilli peppers were a good addition to a meal? Here is a plant that comes from a family (the Solanaceae) which are often poisonous, and whose fruits contain a compound that specifically attacks mammalian pain receptors, causing a severe burning sensation. Nonetheless, about 8 or 9 thousand years ago, someone in Central or South America tried one and thought ”Hey, that’s great! I will put it in all my food!”

I ask the question because a few weeks ago Bristol had a festival of Chilli and Chocolate (heavy on the chilli) As part of the 175th anniversary celebrations the gardeners grew 175 different varieties, in all sizes, colours, and fieriness. Until I saw them all together I did not realise there were so many, but they could have grown more. The various plants were put on a tent on the lawn, and visitors were very interested. At the end the plants on show, plus some spares, were sold off to raise funds.

The multitude of chillis are actually derived from five different species of Capsicum, and this is reflected in their growth habit, fruit shape, and the concentration of Capsaicin (the active compound that gives “heat” to a pepper. The heat of a chilli is measured in Scoville units, which are calculated by measuring how dilute an extract of the fruit must be before the capsaicin is undetectable. The rating of various peppers varies from 0 for bell peppers, up to the current world record holder (actually grown in England!), the Dorset Naga, one of which was measured with a rating of 1,382,118 units, which is hotter than pepper spray.

The wild plants that gave rise to the cultivated peppers of today are basically weedy early successional shrubs of forest clearings. An individual plant can last perhaps five years if it does not fall prey to pests or diseases, and chillies can be kept overwinter in pots in a greenhouse or a windowsill if the weather is to cold outside.

The chilli became a worldwide item of diet as a result of Spanish and Portuguese monks spreading them around their countries empires once they found they could be used as a substitute for black pepper, which comes from an entirely different plant and was so expensive and hard to obtain that it was used a substitute currency – as the term “peppercorn rent” still shows. It was the search for pepper and other extremely valuable spices that drove early European explorers in the first place, so one could frame an entire history of the world around the accidental (by Europeans) discovery of the chilli pepper.

In Britain, chillis must be grown under glass to produce a good crop, although they will survive outside in the summer. In warmer climates they can be grown as ornamental as well as food crops – one visitor we had from Australia had planted chilli bushes along the driveway of her house.

The five species of chilli can be recognised by the shape of the fruits and the growth habit of the plant.

Capsicum annuum (which despite its name is a perennial) – Bell peppers, Sweet peppers, Jalapenos and similar.

C.annuum flower

The plants grow to 60cm tall and are densely branched. Fruits are large, usually red or yellow, and the flowers are off-white (sometimes tinged with purple). Some are grown for ornamental reasons, but the fruits of these are still edible.

C.frutescens – Birds Eye, Piri-piri, and Tabasco.

C.frutescens flower

Tabasco

These are usually much hotter than C.annuum, and the fruits are much smaller. The flowers are greenish white and the plants are usually shorter and more bushy.

C.chinense – Habanero, Scotch Bonnet, and the famous Naga peppers.

Dorset Naga

These are mostly extremely hot peppers, with a bushy growth habit. The Dorset Naga is a selected variety of plants originally grown in Bangladesh. At the exhibition at the zoo, I tried a 2mm cube of it and could still taste the heat ten minutes later. If you eat chillis regularly you become desensitized, so it does not taste quite so hot to someone used to Indian or Mexican cuisine, but even so it packs quite a punch. The flowers are usually yellowish and the plant can grow to over 1m.

C.pubescens – Rocoto or tree chilli.

C.pubescens flower

C.pubescens fruit

The specific name refers to the distinctive hairy leaves. Not often seen outside South America, they can grow to 4m tall, and sometimes have a climbing growth habit. They are also much longer lived, and can last 15 years.

C.baccatum – Amarillo or Aji peppers.

C.baccatum fruits

These are especially popular in Peruvian and Bolivian cooking, and have unusually shaped fruits. The plant is fairly large, and the fruits are not especially hot.

The key to growing chillis in the UK is to start the plants from seed early. They need a long growing season as the fruit ripens fairly late in the year. Any standard potting compost will do to grow them, but the flowers may require hand pollination with a brush if they are being grown inside.

(images from wikipedia)

Aquarium Tour: Mushroom polyps

2011-10-07T11:17:00.000-07:00

The last tank before you exit the aquarium is a marine tank housing a variety of small to medium-sized coral reef fish (incidentally, an informal count of visitors suggests the phrase “look –there’s Nemo Dad/Mum!” occurs at a frequency of around 10-15 times per hour in front of it). It is not the fish however I wish to close with, but some of the most colourful, and disregarded, animals in the tank, the extensive growth of soft corals of various species, particularly the mushroom polyps.

Ever since complex animal life appeared, the various species of Cnidarians (corals, see anemones, jellyfish etc) have been keystone species in the worlds oceans, and they remain so to this day. The coral reefs of this world are of course composed of stony corals, forms which extract calcium and other elements from sea water and use them to build their hard exoskeletons. There are probably even more “soft” corals on the reefs, which have either a hydrostatic or flexible skeleton to keep them upright. In aquaria, probably the commonest soft corals you will see are various forms of Actinodiscus or Discosoma. I say forms rather than species, as the taxonomy of the group is seriously complex. It is known from other Cnidarian groups that the same species can appear very different depending on circumstances, and also different species can appear practically identical. It is probable that the different forms have subtly different ecological niches, preferred food, or geographical range, but it is practically impossible to look at a captive specimen and identify it. The only certain way would be to do a DNA analysis, but the requisite reference work has itself not been done – it would make a good project for a university student I suspect to analyse as many different forms as possible and at least arrive at a ball park figure.

Mushroom polyps belong to a group called the Corrallimorpha. Some of this group can grow extremely large – over 50cm across- but Discosoma species usually average 5-6cm. The body form is as you would expect from the name, with a flat disk on top of a short stalk. The disk is usually held so as to receive maximum sublight, as mushroom polyps (like stony corals) harbour dinoflagellate algae in their tissues which supply much of the food requirements. They can also absorb particulate matter from the surrounding ocean, and probably directly absorb some chemical nutrients as well.

They often inhabit areas with a higher than average load of organic compounds compared to the main reefs, such as back-reef areas, and their fondness for shallow water means they are used to fairly large temperature variations as well. All this goes towards an animal which is much hardier in the aquarium than stony corals, which have more exacting requirements. It has not been studied as far as I am aware, but I wonder if the (presumably) more tolerant algae in Discosoma can swap host species with stony corals? Coral bleaching occurs when stressed stony corals eject non-functioning algae, but they sometimes recover when the algae are replaced. As these algae have to come from somewhere, and Corallimorphans and stony corals are closely related, I wonder if Discosoma colonies might act as reservoirs of suitable algae, hastening recovery?

Discosoma sp. Reproduce well in aquaria, usually by budding or division. They can build up their numbers quite quickly, and this can be a problem if they start to encroach on other corals in the tank. People often forget that corals are animals, and sometimes quite territorial ones. Some forms produce stinging tentacles to damage their opponents, other produce chemical toxins. As the battles often take place overnight, and often take weeks or months, aquarists may not notice what is happening until one or other is too damaged to survive. Any corals need to be well spaced out to avoid trouble.

As well as being aquarium animals, the various forms of Discosoma have recently acquired a new importance in biology. They are a source of a variety of fluorescent proteins, which can be used for tagging biological reagents or spliced genes in lab animals. Exposing the animal carrying the protein to ultraviolet light causes the fluorescence which shows how the gene has been taken up.

That concludes the aquarium tour. I hope you liked it. Next week, a few one-off posts will start.

(images from wikipedia, wetwebmedia.com)

Aquarium Tour: Lungfish

2011-10-03T13:32:00.000-07:00

The last large tank in the Aquarium contains a large variety of Malawi cichlids. While these are fascinating animals in their own right, I would like to write about one of the less commonly visible inhabitants of the tank, the African lungfish. There are actually four recognised species of Protopterus in Africa, with several divided into subspecies, and as they are very similar I am not sure if the two individuals we have are the same form, but they are probably P.aethiopicus. A third individual is in quarantine and will be going on show soon.

Lungfish are famous for their ability to breathe atmospheric air, in fact they will drown if prevented from reaching the water surface, but they have many other peculiarities as well. The air breathing habit is one they retain from their common ancestry with tetrapods, and indeed all fish except the sharks and rays have an internal organ which derives from an ancestral lung. In ray-finned fish the lung has been transformed into a flotation device called the swim bladder, and has lost its connection with the throat in many species. Some of these in turn have developed another air-exchange organ, but this is in addition to the swim bladder.

Lungfish are not often seen in the main lake at Malawi, although they are known from other Rift Valley lakes. This is because their preferred habitat is papyrus swamps and other areas where they can bury themselves in the mud, especially during the dry season. Malawi itself is too rocky for them.

Lungfish are fairly specialised predators, feeding mainly on snails, freshwater mussels and crustaceans, although they will prey on fish on occasion. They have specialised tooth plates, which act like nutcrackers to break shells, and have a powerful bite.

Lungfish have of course been around for a very long time. The earliest known date back well over 400 million years, and the split between them and their nearest living relatives (apart from terrestrial vertebrates), the coelacanths, must go back even further. The earliest lungfish may have been marine animals, perhaps using their lungs to survive in warm, oxygen-poor waters in back reef situations, but all the living forms are confined to freshwater. The habit of burying themselves in the mud to survive low water is also very ancient, and fossil lungfish burrows are common in the fossil record.

Lungfish breeding is keyed to their seasonal habitat. When the rains flood their burrows, they emerge, feed up quickly, then spawn in nest burrows constructed by the male, who guards the eggs fiercely. The larvae at first have gills, and remain in the nest for around 50-60 days. Once they reach around 25 mm the lungs begin to develop, and they disperse to live amongst the roots of swamp grasses. Their must be very high mortality, especially in the first year or so, before they have grown large enough to dig deep burrows to survive severe droughts. To compensate, they also appear to be extremely long lived – one in the Shedd aquarium in the US has apparently been there since the 1930’s, and was probably an adult when imported. A lifespan of 80-100 years does not seem unreasonable.

Although long lived in captivity – they are tough animals after all – as far as I am aware there has been no recorded captive breeding of this species or any other lungfish. As they grow very large – at least 1.5 m – and can be quite aggressive with each other, breeding would be a major operation. It would probably need a large, mud-bottomed, outside pool in a suitable climate which could be drained to encourage aestivation and then reflooded to replicate the habitat. As several thousand eggs can be produced, successful breeding would then also create the need to re-home vast numbers of baby lungfish – not something a responsible aquarist would like to face.

(image from wikipedia)

Special Delivery!!!!!

2011-09-27T11:07:00.000-07:00

Just born today:

Salome with baby

Repost from the BSG website:

Staff at Bristol Zoo Gardens are celebrating the birth of a baby western lowland gorilla.
The baby was born at lunchtime today (Tuesday September 27) by natural birth to Salome, and both mother and baby appear to be doing well.

The Gorilla House has been temporarily closed to allow the gorillas, including Dad Jock, time to bond with the new arrival.

The youngster, which is yet to be named, is the perfect gift for the Zoo, which this year celebrates its 175th birthday and is participating the European Zoo Association’s Ape Campaign, which aims to raise funds and awareness of the threats facing gorillas in the wild.

Senior Curator of Animals, John Partridge, said: “We are thrilled with the arrival of a baby gorilla. It is still very early days, but Salome is a great mother and has been cradling and cuddling her baby affectionately. We are pleased to say that both Salome and the baby are doing well.”

He added: “Salome keeps the baby very close and we are keen to give the gorillas space, therefore it is still too early to determine the sex of the baby. Naturally the gorilla keepers will keep a very close eye on mother and baby in these crucial first few days and weeks to ensure that they, along with the rest of the gorilla group, are healthy, content and bonding well.”

To see a video of the new baby visit www.youtube.com/watch?v=mgQepJ2il30

Aquarium Tour: Freshwater stingrays

2011-09-26T11:31:00.000-07:00

Opposite the piranha tank is another large tank containing a variety of Amazonian fish, of which the most spectacular are our group of freshwater stingrays, Potamotrygon motoro. Practically all rays, and their close cousins the sharks, are either confined to the sea or at best occasionally enter fresh or brackish water at estuaries, but the Amazon is home to several species of rays which are fully adapted to fresh water and can no longer enter the sea. It appears that this process began about 15 million years ago, when the rise of the Andes and other earth movements isolated a fairly standard coastal species. Today, around 23 species in three genera can be found across the Amazon basin. Most of these are in the same genus Potamotrygon as those at Bristol. Many are seldom seen in captivity, but P.motoro is perhaps the most widely kept.

All the rays have a fairly similar lifestyle. They spend much of the time, especially during the day, buried in the sediment with only their eyes and the spiracle through which they breathe showing. If disturbed or threatened, they can defend themselves by lashing out with their tails, which carry a barbed and venomous spine about half way along. The tail is very flexible, so the sting can be jabbed into whatever animal is threatening them, at least as long as it has a hide the barb can penetrate. As the barb is capable of penetrating bone, most animals will approach them cautiously, although large caiman are probably safe.

When active, rays will patrol the river bed on the search for their prey, which is basically any form of animal life that will fit in their capacious mouths. Invertebrates in the form of snails and freshwater shrimps are probably the main food items, but they are quite capable of eating small fish, especially if they catch them sleeping while on the prowl at night. Species which build a nest for their eggs and fry, such as most of the cichlids, need to have string defence behaviours against rays and other bottom feeders.

Rays are quite large, and the Motoro ray can grow to around 50cm across the disk. Some other species can grow much larger, to nearly 1 metre, with a nose to tail length of perhaps 1.5m or more.

Some marine rays are egg layers, but like many other sharks and rays the various Amazonian species are all live bearers. Adult males are easily distinguished by the claspers, modifications of the anal fin that are used in mating, and the female can produce up to 4 pups at a time. The new born rays, each about 15cm across, are independent from birth and immediately go about searching for food as soon as they have uncurled from the rolled up shape they are born in.

Bristol has bred Motoro rays in the past, and reports of captive breeding of this species are fairly common, but many others have not been bred at all and several others have only had already pregnant wild caught females give birth in captivity. As there is not a big demand for them in the aquarium trade, there is no motive to produce captive bred stock, and all rays seen for sale are wild caught. Mostly these are very young or new born rays, and there is a high mortality, especially if the water conditions they are kept in have even a slightly raised level of nitrate or nitrite.

For a good video of a stingray giving birth look here: http://www.youtube.com/watch?v=N_74GXQsfcM&feature=related

Rays are one of those species, like Pacu and other giant species, which most aquarists should not even try to keep. Even a very large home aquarium is inadequate to care for these species, and one with an unobstructed floor area of at least 4 square metres should be considered the absolute minimum. Basically, you are looking at a small heated swimming pool to keep them in. In a warm climate this is not too much of a problem, but the costs of heating and filtering a water body of this size in a temperate climate is simply too much for most hobbyists. There is also the issue of the venomous barb. Rays become quite tame and are not aggressive fish, but an unexpected startle response is always possible, so they should always be treated with respect.

Beside juvenile being caught for the aquarium trade, probably the main threat is over fishing. Rays take at least three years to reach maturity, and have a low birth rate, so they could easily be fished out, especially as they are considered a desirable food fish. As the range of many species is unclear, and there are probably several undescribed species as well, every effort should be made to study their requirements for breeding, in case replenishment of locally exterminatred stocks is required from farmed fish.

(Images from wikipedia)

Aquarium Tour: Supervillains need not apply

2011-09-20T11:34:00.000-07:00

P.nattereri

Exiting the walk through tank, on your left is a large aquarium containing what are certainly the most famous fish in South America, Red-bellied piranhas Pygocentrus nattereri. This is the species that is invariably seen on TV and in aquarium shops, as it is one of the commonest species, but actually, depending on how they are classified, there are at least 37, probably more, different forms of piranha throughout tropical South American rivers. How the different species are referred to locally varies, but species of Serrasalmus are often referred to as pirambebas. They are actually closely related to the Pacu I wrote about last week.

Different piranha species reach different sizes and probably have very different feeding strategies, which may also change as they grow. Small species and young are mostly schooling fish, sometimes in mixed-species schools, but some of the larger species especially become solitary as adults, and probably have a feeding strategy similar to pike or perch. Most forms grow 20-30cm long, but large S.rhombeus approach 50cm.

Piranhas are not strict carnivores, and several forms feed heavily on seeds or plants at some seasons, but on the whole they feed on animal prey, ranging from aquatic crustaceans when small to larger animals, especially injured ones. At least one species, the Wimple Piranha Catoprion, is a specialist feeder on fins and scales, and lurks in weeds by itself waiting for larger fish to swim by. For the other species, favourite prey are fish that have been caught on hook and line, even if they are other piranhas, and when a large shoal attacks they could be dangerous. Despite that, actual fatal attacks on humans are vanishingly rare (although I suspect more than one murder has been passed off as a piranha attack) and in fact they are considered good eating throughout their range. It is not just humans who eat piranha however, giant otters, river dolphins, larger fish, and caiman all target piranhas as prey. The large schools they go around in when young are actually for self-defence, not hunger. Even so, they have formidable jaws, although ecept when feeding the teeth are not especially obvious. In prepared or dried specimens, the soft tissue cover is removed and their armoury is revealed.

S.nattereri jaw

Piranhas, at least the species that have been studied, breed during the rainy season. The male will dig out a nest to attract a female, and both parents will guard the 600 or so eggs until they hatch. After that, very little if any parental care is shown, and the young disperse to look after themselves, often joining with other young piranha, or the related Metynnis and Myleus species (which are vegetarian).

The fearsome reputation of piranha is mostly down to the late Theodore Roosevelt, not a man to allow the facts to get in the way of a good story. In his book, Through the Brazilian Wilderness (1914) he gave a graphic description:

“The piranhas habitually attack things much larger than themselves. They will snap a finger off a hand incautiously trailed in the water; they mutilate swimmers—in every river town in Paraguay there are men who have been thus mutilated; they will rend and devour alive any wounded man or beast; for blood in the water excites them to madness. They will tear wounded wild fowl to pieces; and bite off the tails of big fish as they grow exhausted when fighting after being hooked. But the piranha is a short, deep-bodied fish, with a blunt face and a heavily undershot or projecting lower jaw which gapes widely. The razor-edged teeth are wedge-shaped like a shark’s, and the jaw muscles possess great power. The rabid, furious snaps drive the teeth through flesh and bone. The head with its short muzzle, staring malignant eyes, and gaping, cruelly armed jaws, is the embodiment of evil ferocity; and the actions of the fish exactly match its looks. I never witnessed an exhibition of such impotent, savage fury as was shown by the piranhas as they flapped on deck.”

Keeping a fish like that attracts a cetain kind of aquarist. Unfortunately, in the confines of an aquarium piranha have a tendency to attack and kill each other, and without a large aquarium for a school big enough to disperse aggression you tend to end up keeping only a single survivor. Worse, in warm climates it is not unknown for them to be dumped, with obvious risks if they started to breed in the wild. For this reason in many US states keeping them is illegal. As far as I am aware, so far at least this has worked and there are no introduced populations anywhere in the world (so far).

Next week, freshwater stingrays.

(Images from wikipedia)

Aquarium tour: It came from the Amazon

2011-09-10T08:50:00.000-07:00

In the centre of the aquarium is our walk-through tank. One of the first in the world, though now outclassed by many newer buildings, it was actually created from an old 19th century bear pit. That in turn was a modification of the original building, one of two lime kilns that were on the site before it was acquired by the zoo back in 1835. A great deal of the buildings in Clifton and the surrounding area were built with cement made on the Bristol Zoo site.

There are various species of Amazonian fish in the walk-through tank, but the largest are our Pacu, Colossoma macropomum. As you might guess from the name, they are very large fish, about 1m long and probably weighing around 30kg. They are actually fairly closely related to their smaller, but more famous, cousins, the various species of predatory piranha, but unlike them are omnivorous, with a strong preference for vegetation and fruits of trees.

The name Pacu is in a native Brazilian language, but incorrectly applied to Colossoma sp, in English. The correct local name for the fish is tambaqui. Pacu is the name given to smaller, but related, species such as Metynnis.

Pacu are one of those species which really should not even be considered for home aquaria. In the UK, fish stores typically do not even stock them, but in the US it is more frequent for them to be sold, usually at a length of 5cm or so. The inevitable result is that they rapidly outgrow their accommodation, and either die young or are dumped. In warmer parts of the US they could probably survive in the wild, so there are stringent laws against this. Even though the trade in this species in the UK has now mainly ceased, occasional youngsters turn up mixed with other species, and there are still some in private hands, so the result is that any public aquarium in the UK is contacted at least once and often several times a month by people wanting to rehome overgrown fish of this or other species. Part of the problem is a persistent myth that fish grow to fit the size of their accommodation – this is simply not true. What does happen is that fish in improper accommodation suffer stunted (but still massive) growth and die young, which is not the same thing at all. I am unaware of any estimates of the potential lifespan of a Pacu, but 20 years+ is probably quite possible, so if you are unprepared to provide a heated pool for this length of time do not buy them.

In the wild, pacu are solitary except when breeding. When the forest floods they disperse widely, feeding on fruit falling from the trees and helping to disperse the seeds. As the seeds take longer to pass through their guts than more well-studied dispersers such as birds and primates, the seeds can travel long distances – probably several kilometres, whereas mammals and birds typically only spread seeds a few tens of metres. In the dry season they are confined to the main river channels, and survive lean periods by relying on their extensive fat reserves.

The pacu’s vegetarian diet and high fat content makes for a highly edible fish, and they are extensively wild-caught and these days also aquacultured. Overfishing is a potential threat, and in heavily fished areas large individuals are becoming rare. As an aquaculture subject they have great potential, as unlike most such fish, which are fed a diet of animal protein (salmon for example are fed fishmeal), the pacu can be raised on an all-vegetable diet, which is much less wasteful. Unfortunately, they are also now being raised outside their native range, such as in India and other parts of South East Asia, and this raises the possibility of escapes establishing themselves in the wild, to the detriment of native species. This has only taken off in the last 5-10 years, so much still remains to be learned about best practice. In the meantime, if anyone reading knows what they taste like, please leave a comment.

(image from wikipedia)

Aquarium tour: The Picasso Triggerfish

2011-09-02T02:07:00.000-07:00

One of the most colourful marine fish we have on show is or Picasso Triggerfish, Rhinecanthus aculeatus. Triggerfish belong to the same order as the pufferfish, the Tetraodontiformes, but have a different means of self defence. Their skin is covered with very tough scales, and in the dorsdal and anal fins there are locking spines. When erected, these spines make the fish hard to swallow, and they are also used for wedging the fish into crevices in the reef rock, which is where they spend the night.

Different species of triggerfish are found in tropical and subtropical waters all over thw orld. One species, the Grey triggerfish Balistes capriscus, even reaches as far north as southern England and Ireland, at least in the summer, although whether they actually breed in British waters is unlikely. Most triggers grow to a fair size, although at around 20cm the Picasso Trigger is one of the smaller species. Picasso Triggers (they get their name from their colour pattern resembling a Cubist painting) live on reef slopes and lagoons, usually retreating to deeper water at low tide. As lagoon waters vary in salinity, temperature, and dissolved organics more than the open sea, triggers of this species tend to be less stressed by the varying conditions of a home aquarium than some other species, especially those from deeper waters, which means they are fairly popular with home aquarists.

In the wild, some Picasso triggers have been known to live and maintain a territory for eight years, and their maximum lifespan is probably in the 10-15 year range. Very few captive individuals live that long, and the capture of wild marine fish for the aquarium trade is a serious animal welfare issue. Most freshwater tropical fish today are bred on fish farms, and are mostly small species with a 1-2 year life expectancy anyway, but most of the marine fish for sale are wild caught. Some species are now being captive bred, notably clownfish, but with breeding other species aquaculture is still in its infancy. The key problem is raising the newly hatched fry, which spend anything from days to months in the plankton until they metamorphose into the adult form and settle on a reef. For example, although closely related to clownfish, few if any of the damselfish are captive bred, because unlike clownfish their larvae appear to be specialist predators on the larvae of marine copepods (according to one species account anyway), and culturing the correct species of prey is proving difficult.

Having said all that, at least one species of trigger fish has been successfully raised in captivity, so other species may also be in the near future. This raises another issue though, the actual environment a captive fish is kept in, and this is where I am somewhat concerned with trigger fish and similar large species. Whereas a clownfish in the wild has a home anemone and never moves more than a meter from it at the most, a trigger fish is a very wide ranging animal.

The exact social structure in most species has not been studied, but in Picasso triggers they appear to have a large home range of perhaps a hectare of reef, with a male’s territory overlapping with that of several females. When they spawn, the female will viciously defend the nest site for the few hours it takes for the eggs to hatch against all other intruders, even divers (divers rate trigger fish as among the more dangerous species on a reef because of this). While roaming the reef, they search for crustaceans, sea urchins, and similar hard-shelled prey, which they can easily crunch up with their strong bony beaks. They will often manipulate their environment to get at the prey, blowing strong water jets to blow away rocks or covering sediment.

Triggerfish on reef

In view of their natural behaviour, I think that despite their general hardiness and beauty they are not good subjects for a home aquarium as the captive environment, unless in a truly gigantic tank, is simply not roomy enough for them to fully express their natural behaviour. They are often inclined to take bites out of other fish in the aquarium, so many species are hard to keep with other fish in the tank, and although their diet of crustaceans and shellfish is easy enough to provide, their unique hunting strategy is not exercised when food is simply dropped in the tank by the owner.

I wonder whether puzzle toys could be created to allow them to use their natural behaviour to obtain food. They certainly seem to be intelligent animals, and this would be a useful means of exercising their minds. That might make an interesting study project – puzzles have been used in studies of octopus behaviour and a toy that released food when a suitably directed jet of water from the fish was applied should be fairly straightforward to design – perhaps an ecology student could design one?

(images from wikipedia)

Aquarium tour: Arrowhead Pufferfish

2011-08-27T09:07:00.000-07:00

Next to the brackish water display is a tank that most of the public walk past, as it appears at first glance to be empty. This is their loss, as it actually contains two of the oddest fish we have, the Arrowhead Puffer fish Tetraodon suvattii.

Pufferfish belong to the order Tetraodontiformes, a group which contains some of the oddest fish on earth today. They are characterised by odd body shapes, slow and precise movement, and often some form of bony beak. The order includes (besides the puffer fish) the trigger fish, box fish, and the giant ocean sunfishes. Aside from some puffer fish, almost all are marine. Most are reasonably sized to large fish, but some are quite small and one or two (such as the sunfish) are gigantic.

Puffer fish get their name of course from their habit of swallowing water (or air if they are fished out with a net) to make themselves look bigger. This may be to make them appear too large for a predator to swallow, or it may be used as a display in threat or courtship. Their other claim to fame is their sequestering of toxins in their liver. This is tetrodotoxin, and despite its lethality it is eaten as the famous Japanese dish fugu, which is prepared from some marine species found near Japan. Apparently the minute amounts in a properly prepared dish impart a pleasant tingling sensation on the lips as it is eaten. If it improperly prepared the only hope is to support the patient on a heart-lung machine until the patient recovers. There is usually at least one death every year or so apparently. My favourite description of this meal comes from one of Sir Terry Pratchett’s books – “fish and chips – for men!”

From their odd appearance one might think that all puffer fish are much the same. In fact, they have radiated into a variety of ecological niches, varying from coral reefs to acidic freshwaters all over the tropics, although they shun colder waters. Most species are marine to brackish water specialists, and they tend to avoid open water, where they are exposed to predators. Many species are found in mangrove swamps where the salinity varies. The Mekong river, where our Arrowhead puffers originate, has at least five endemic species, with habitats ranging from muddy shallows to weedy river margins to rapids.

Almost all are specialist predators of molluscs and crustaceans, and to help them in that they have a continuously growing bony beak. This may cause problems if they are fed softer food in an aquarium than they would obtain in the wild, as the beaks can overgrow, requiring specialist dental care to grind down the beak.

Our Arrowhead puffers exploit a slightly different niche. Instead of searching plants or rocks for aquatic snails, they are sit-and-wait predators of small fish. In the mud of the Mekong where they originate, they half bury themselves and wait, sometimes for days, until a smaller fish swims overhead, Then they suddenly dart up and either swallow the fish whole or bite it in two . The whole strategy is rather reminiscent of the marine angler fishes, without the lure.

T.suvattii in lurking mode

In our aquarium, the tank is furnished with a deep layer of fine sand and some river cobbles about the size of the puffers (ours are about adult size at 15cm). They can be quite aggressive with each other – they are in a large tank but are always at opposite ends. This territoriality is one of the reasons most puffers in the aquarium trade are wild caught – tank breeding of some species has occurred, but the low demand for such fish and the difficulty of breeding them means that there are no commercial fish farms producing them.

Having said that, T.suvattii is one of the few species that has been bred. What the exact trigger for breeding is not clear – lowering barometric pressure in summer may simulate the start of the monsoon, when many South East Asian species breed. Most of the reports of breeding seem to occur in August or late summer in any event. The eggs are laid (after a leisurely courtship) on a smooth hard surface and are guarded by the female. The newly hatched fry feed on microorganisms and small crustaceans. Once adult, they only feed about once per week – this is important in an aquarium as overfeeding is easy but can result in water pollution, which is rapidly fatal to all puffer fish.

With their predatory lifestyle, one can see that this is definitely not a fish for the standard mixed home aquarium. It demands (and deserves) a tank by itself and a fair amount of attention. As a group, all the Tetraodontiformes including puffer fish, trigger fish, and box fish seem to have an intelligent and curious personality, and definitely get to know their keepers. This raises the question of aspects of aquarium fish care that are often overlooked – the psychology of the fish themselves and how a captive environment may affect it. That discussion I will take forward next week. In the meantime, here are a couple of links you might like:

Video of T.suvattii spawning: http://www.youtube.com/watch?v=9X9l99oHbWY
An account of a T.suvattii spawning:
http://www.thepufferforum.com/forum/library/puffers-in-focus/suvattibreeding/

(Images from seriouslyfish.com)

Aquarium Tour: Archer Fish

2011-08-19T11:36:00.000-07:00

T.jaculatrix

The next tank along contains a selection of species from mangrove or estuarine habitats. The most distinctive of these are the Archer fish, Toxotes sp. There are at least seven different species of Toxotes, but the fish we have are probably T.jaculatrix or T.chatareus, which are the species most commonly seen in the aquarium trade.

Archer fish have a unique way of catching the insects which make up most of their diet. By flicking their tongues, they can eject water as much as 1m into the air (more in large individuals). They use this to shoot down flies, small land crabs, and similar prey so that they can grab them. The technique is especially effective when several fire at the same time, which often happens because they tend to live in loose schools.

Clearly, the habits of these fish make specialised aquaria essential for their proper care. As well as shooting prey into the water, they will readily jump to catch food, so the ideal aquarium is a deep tank that is only half full. Depth of water is not essential, as they spend almost all their time at the water surface. In the wild they tend to lurk amongst mangrove roots and under overhanging vegetation, only occasionally venturing into open water. They are quite large fish, some species growing to 20cm, so a fairly large aquarium is required. They can be mixed with other species, but will prey on surface-dwelling fish, and they can tackle fairly large prey. Ours share their tank with scats, Scatophagus sp, and Monos, Monodactylus sp.

Although Archer fish will take food from the water surface, they much prefer to hunt live prey, and here at Bristol we have a feeder rigged for them. This is a plastic pot with some holes drilled in the side and some artificial plants attached. Live crickets are placed inside, and every so often one will crawl out into view of the Archers and be shot down. This keeps them occupied in feeding throughout the day, just as they would in the wild. This is an example of an issue that is rarely considered in aquarium fish keeping, what is referred to as “enrichment” activities. For land animals, especially mammals and parrots, a lot of keepers time is spent on ensuring they spend as much of their day as possible exercising skills they would need in the wild, but as soon as other groups are considered very little, if anything, tends to be done. Partly this is because it is assumed that non-endothermic, especially aquatic, animals are too stupid to need anything, and partly because no one is sure how to provide it. Scatter feeds are useful for animals that spend a lot of time searching for small food items, and in an aquarium live food has a similar effect, but it would be a great help if home aquarists would spend some time in considering the natural behaviour and habitat of their pets and see what they can do about it. If you have any ideas, do leave a comment.

One other point that would repay research is reproduction of Archer fish. Some Toxotes sp are purely fresh water animals, living hundreds of kilometres inland, but the species commonly seen in the aquarium trade are believed to breed out on the reef rather than in the mangroves. Very few aquarium spawnings are reported, probably because they tend to be kept singly, and a breeding tank for Archer fish would need to be very large. They are probably seasonal spawners as well, timing reproduction to the monsoon, possibly also with the phase of the moon or tide levels. The eggs themselves are apparently scattered at the water surface, and hatch in about 12 hours, but this may not be the case for all species.

For a video of Archer fish feeding, see here: http://www.youtube.com/watch?v=YGgNc2TMhZU&feature=related

(images from Wikipedia)

Aquarium Tour: Here be Dragons

2011-08-13T01:37:00.000-07:00

Gold form S.formosus

Next door to the paddlefish aquarium is another large tank containing large fish from Asia. One of the most important species in the tank is some young Asian Dragon Fish, Scleropages formosus. They are especially significant because they are the results of what we believe to be the first breeding of this species in a public aquarium anywhere. Previous captive breeding has been in outside ponds, mostly in Asia.

Dragon fish belong to a very ancient group of fish, commonly referred to as the ‘bonytongues’, as their tongues are ossified and bear teeth. The group as a whole has representatives or close relatives in fresh waters on every continent, but the closes relatives of Scleropages are all in the southern hemisphere, suggesting that they originated in the supercontinent of Gondwana. How they got north of the equator into south east Asia is unclear – it is suggested they were carried on the Indian subcontinent as it moved north after the break up of Gondwana, but there are no Scleropages in India today, although there are several species of the similar knife fish Notopterus. Outside Asia, there are two species of Scleropages in Australia, but there has always been a sea barrier between Australia and Asia which these obligate freshwater fish cannot cross, so the phylogeography of Scleropages is still obscure. Given that the Australian species are almost identical to the Asian forms, the genus itself probably dates back to the late Cretaceous or even earlier.

The taxonomy of the Dragon fish is somewhat debatable. They certainly vary in colour over their vast range, with some forms being deep red, but mostly silver, sometimes with red fins. It is quite possible that these represent different species, or at least subspecies, which raises problems for their conservation.

Dragon fish and their relatives have numerous peculiarities. As with many fish that live in warm, oxygen-poor waters they can breath atmospheric air, using a vascularised swim bladder as a lung. They are mouth brooders, the males retaining the large eggs in their throats, and providing shelter to the young for some time after hatching.

S.formosus fry December 2008

Dragon fish and their relatives are all surface-feeding predators, taking insects from the surface, small fish, and anything flying over the surface. Mostly these would be dragonflies and similar, but given their size it would not surprise me for them to take swallows and martins as they fly over the surface as well. The South American Arowanas can leap 2 metres out of the water to take insects off overhanging branches, and Dragon fish can probably do the same.

Unfortunately, the Dragon fish is listed by the IUCN as Endangered. In the past they were greatly over-collected for the aquarium trade (the red form being especially prized). As a slow-growing fish with a low reproductive rate, it is susceptible to loss from fishing and habitat destruction. Although now listed on CITES Appendix 1, captive bred fish are available from licensed fish farms in Singapore and a few other countries. Each individual fish is microchipped and accompanied by appropriate liceneces and paperwork before being sold.

Given their large size (over 1m) and somewhat aggressive nature, at least with fish small enough to eat, most Dragon fish are kept singly. Our original parent fish actually originated as a customs confiscation, and lived for many years with us before any breeding behaviour was observed. After several occasions when eggs were laid but either not picked up by the male or did not hatch, improvements in the water in the tank and raising the temperature slightly resulted in successful breeding. Some of the eggs were removed from the male and hatched artificially, and some were left for the male to raise. Unfortunately, the parent-rearing did not succeed, but the artificial rearing resulted in 15 young in December 2008.

Now over 2 years old, nine youngsters are on show. They are still only around half grown, and will probably take at least another 3 or 4 years before they are adult size.

Large fish like these can be a problem for public aquaria. There are far to many juveniles of large fish sold in aquarium shops, and when they grow out they become a problem for their owners. There is a persistent belief that fish grow to the size of their aquarium – this is just not true. What does happen is that they suffer poor health, stunted growth, and die young, which is not the same thing at all. If anyone wants to keep one of these large fish, please think again unless you have a lot of spare cash – proper care for most of these would involve something the size of a Koi pond, with an added heating bill.

Next week – fish of the mangroves

(images from Wikipedia, Bristol Zoo)

A Tour through the Aquarium: American Paddlefish

2011-08-06T02:36:00.000-07:00

The first large tank in the Aquarium is dedicated to a variety of ‘primitive’ fishes, whose ancestors split from the ancestors of more modern fish such as perch and carp in the distant past. Still surviving today, the Chondrostean fish are characterised by a great reduction in bone and a skeleton that is mostly cartilage. They also often have a shark-like heterocercal tail, and were at one time thought to be close to the sharks. It is now plain that they are modified ray-finned fish, and the surviving forms are not necessarily even closely related to each other. We have two species at Bristol, the Sterlet (a small European species of sturgeon) and the subject of this article, the American Paddlefish Polyodon spathula.

Until 2003 there were two species of paddlefish, the American and the Chinese. No Chinese paddlefish (which grew much larger than the American species) have been seen for several years now and the species is sadly almost certainly extinct. The cause of its demise is probably water pollution and the dams on the Yangtze, the only place it lived.

The American paddlefish is in slightly better shape, as re-stocking of some areas has been started. It is extinct in Lake Erie however, and overfishing of this very slow-growing fish has severely restricted the population in many areas

The natural home of the paddlefish is the Mississippi river drainage system, where it lives in slow moving, deeper waters. They breed towards the heads of rivers, often migrating hundreds of miles. They lay their eggs in midwater over rock or shingle, and when the adhesive eggs hatch they young are swept down river to mature. They probably take at least eight years to reach adult size of over 1.5m, and may live as long as 50 years – possibly more.

The most distinctive feature of the paddlefish is its enlarged rostrum. This has several functions, mostly associated with feeding. Paddlefish are primarily filter feeders, although they will also feed on larger food items at times, and swim with their mouths open using their gill rakers to trap zooplankton. It is thought the rostrum acts as a stabilizer while they do this, helping to keep the head in the right position for most efficient feeding. The rostrum also contains electoreceptors, which may be used for finding large concentrations of plankton, or navigation in murky water.

Commercially, paddlefish caviar, similar to that from sturgeon, has been a prized delicacy. As a result, the paddlefish is now CITES Appendix 2 listed, which means that a licence is required for trade to occur. They can grow quite fast in the appropriate circumstances, and an arrangement has been reached in the US where a single licensed producer commercially raises paddlefish to a suitable size then leases them to owners of reservoirs and similar water bodies to be grown on. When the fish reach a suitable size for harvest, either for meat or caviar, the owner of the reservoir receives some commercial benefit. As the paddlefish feed on the natural zooplankton in the reservoir, they need no additional feeding. Paddlefish caviar retails at around $67 for a 1.5oz jar, so producing it is a profitable business.

Unfortunately, people in other parts of the world have also experimented with paddlefish farming. In recent years, many have been caught in the lower Danube in Europe, and reportedly from rivers in Russia. It is not yet clear whether these are recent escapes from fish farms, or if they are a self-sustaining introduced population. As they do not take bait, removing them if it becomes necessary could prove extremely difficult, depending on whether they are spawning in a single site or not.

(images from wikipedia, USGS)

A Tour through the Aquarium: The livebearers

2011-07-31T02:06:00.000-07:00

Ameca splendens male

The next tank to the Potosi pupfish contains several species of its fairly close relatives, the Goodeids. Unlike the egg-laying pupfish, Goodeids are livebearers. In any aquarium shop you will find for sale many species and colour varieties of livebearers, such as guppies, platies, and swordtails, which have been the target for selective breeding by aquarists for many years. These belong to another related group, the Poeciliids.

As a group the Cyprinodontiformes (the killifish group) is characterised by producing small numbers of large eggs that have long incubation times, and often some degree of internal fertilization. Retaining eggs within the body of the female until the point of hatching, then producing live young, is the commonest way in which live birth is evolved throughout the animal kingdom, and in the killifish it has evolved at least three times, in the Poeciliids, the Goodeids, and the strange four-eyed fish Anableps which lives in South America and along the coast.

Species which evolve an ecology based around production of comparatively small numbers of young tend to have limited dispersal ability, and as a result the killifish, both the egg-laying and live-bearing forms, tend to develop many endemic species. In the highlands of Mexico, where mountains have resulted in numerous small watercourses, this has resulted in large numbers of species with limited ranges. Unfortunately, agricultural development, deforestation, and introduced species such as trout can have a devastating effect on these small water bodies and their unique inhabitants, so many species of Goodeid are classed as threatened or worse.

Many species however breed very well in aquaria, and in most cases any home hobbyist could play a key role in preserving them. Some can be kept with other species in a typical mixed species home aquarium, but for breeding they deserve a tank of their own. For most species a temperature range around 22 degrees Celsius is best, and for most the diet is a standard aquarium flake food supplemented with vegetable matter.

Not all the species we have are on show, but among those in the display tank (which are producing young regularly), are these:

Ameca Splendens Butterfly Goodeid

A.splendens female

This is one of the larger species – females can grow to 12 cm. Males are usually much smaller, and can be distinguished by the vertical black and yellow stripe in the tail. This is a very common feature in male Goodeids. It originates from the Ameca river drainage, and today is known in the wild only from a single pond closed to Ameca town, which apparently is used by the locals for washing cars, so the risk of a pollution incident wiping out the last wild population must be extremely high. They can be a little aggressive in an ordinary home aquarium, so a species tank is best for them. They are however easy to keep and breed providing their needs for space is met – unlike some other livebearers they seldom feed on the fry, which are quite large at birth.

Ataenobius toweri: Bluetail goodea

A.toweri

Originating from the Rio Verde, this likes a similar set up to Ameca splendens, except slightly warmer. It is classed as Endangered on the IUCN red list. The generic name relates to the apparent lack of trophotaenia, outgrowth of the lower intestine in the unborn young that absorb nutrients from the parent in the same way as a mammalian placenta, which are universal in Goodeids. It now appears that these are merely smaller than usual and regress completely before birth. It is likely that it will be transferred to the related genus Goodea at some point.

Characodon lateralis Rainbow characodon

C.lateralis

Endemic to the state of Durango, this species may be extinct in the wild. A subtropical species, it lives in streams and is very sensitive to water pollution, which is a probable cause of its disappearance. It needs frequent water changes and good filtration in an aquarium, and like other Goodeids a large vegetable component in the diet. It seems to benefit from cooling down in the winter months, and is probably a seasonal breeder. The young can be quite large and are not especially bothered by the parents.

Zoogoneticus tequila Crescent Zoe

Z.tequila (male)

Critically Endangered, and possibly extinct in the wild, the Crescent Zoe was only described in 1998. It formerly inhabited the Rio teuchitlan in the Ameca river drainage system, and was believed extinct in the wild until a tiny population (only about 500 in total including fry) was found in one small pool. They are difficult to breed, being shy and slow growing. It appears to prefer less stony substrates than the stream dwelling Goodeids, but this may be a result of the destruction of preferred habitat, as several of the source streams of the river have been converted into spas.. Several aquarists are maintaining this species in aquaria in both the US and in Europe.

That covers the livebearers we currently keep at Bristol. Given the vast size of the aquarium market, there is considerable scope for home aquarists to provide vital space to maintain the smaller species of threatened fish, but working out administration of any breeding programme is proving problematic. Anyone interested in helping should contact one of the specialist aquarist societies such as the British Livebearer Association (http://www.britishlivebearerassociation.co.uk ) or the American Livebearer Association (http://livebearers.org ). For the egg-laying killifish, contact the British Killifish Association (http://www.bka.org.uk ) or the American Killifish Association (http://www.aka.org/aka/ )

A tour through the aquarium: The Potosi Pupfish

2011-07-23T01:36:00.000-07:00

As you enter the Aquarium at Bristol the first tank you meet is a display tank containing a few rather pretty little blue fish. These are male Potosi pupfish, a species of killifish sadly extinct in the wild. Originating in Mexico, from El Potosi in Nuevo Leon, they are examples of a group of species found all over the south west of North America, from Nevada down into Mexico, which are relicts of a very different environment to that experienced today. The group we have at Bristol were originally from London Zoo, and we and London are the only zoos on ISIS to have these species, with a total population of around 400 fish, although there are a few private breeders in Spain, Mexico and the US who also keep them.

During glacial periods, the interior of North America experienced much higher rainfall, and melting ice from further north also raised water levels. As a result, vast wetlands developed in areas which are now grassland or desert, and the common ancestor of the Potosi pupfish (and its relatives) was widespread. With the end of the last glaciation water levels dropped, and where small ponds survived (even in Death Valley), so did the pupfish. Isolation is a potent generator of new species, and today every pool will have its own unique local variety.

Unfortunately, what 10,000 years of climate change has done can easily be destroyed by modern agriculture. Water abstraction across the south west has lowered water tables, drying out the ponds, and fertilizer and pesticide pollution has affected water quality. Pupfish are pretty tough, surviving where no other species can, but several forms have already become extinct, and a species that only lives in a pond 10 metres across is perpetually vulnerable to any passing accident in any event.

Many species of pupfish have already been bred in aquaria, and they are for the most part quite easy. They mostly like quite alkaline, even saline, water, and are adapted to the extreme temperature changes in their shallow desert pools. In the winter months the fish are cooled down to around 150, and in the spring when they are warmed up the males will encourage the females to spawn on the mats of algae that cover the floors of the pools. The eggs are quite large and tough, as is standard with the killifish, and are at least partially drought resistant, which has enabled them on occasion to be transported between ponds on the feet of waterfowl. When the eggs hatch they feed on mosquito larvae and other small invertebrates, along with a fair amount of algae as well. In an aquarium it is best to have only a single male in a breeding tank, as they are very territorial.

A small fish which is straightforward to breed would not seem to present many problems for a conservation breeding programme, but there is a particular problem with many rapidly breeding, short lived species, which is that they are very plastic in their physical form (the phenotype) depending on their environment, and genetic changes can happen very quickly as well. The result is that after a few generations in a captive environment, with a different diet, different water composition, different temperatures and temperature ranges, amongst other variables, you may well wind up with a species that no longer resembles its ancestor in significant ways. With more longer-lived species the process takes longer, but it still occurs. The challenge for the forthcoming century is not merely how you preserve a species in captivity, but how you ensure that the multitude of adaptations, not merely in physical appearance, but in physiology, reproductive ecology, psychology and so forth are also conserved.

In the case of the pupfish, those species in the US have often been maintained in outdoor concrete ponds close to their original springs. This can be quite successful, but there is an inevitable change in the environment all the same, and the rescued species may still appear at least slightly different from their ancestors after a few years. I believe that consideration of details of the habitat, diet, and even risk of predators is going to be the next major step forward in captive husbandry in zoos, especially for smaller vertebrates and invertebrates where the risk of ‘unnatural selection’ is probably most severe. I would be interested in what the readers think.

Next week: livebearers.

175 years and 1 week today!

2011-07-18T11:57:00.000-07:00

Utila Iguana

Last Monday the zoo celebrated its 175th birthday with an evening picnic and hog roast, with a variety of stalls for the visitors. Fortunately we had great weather, so a great time was had by all. Bristol is actually the fifth oldest modern zoo in the world, and the oldest outside a capital city. The older ones run like this:

Vienna zoo – 1752

Madrid – 1775

Paris - 1795

London Zoo – 1828, but only opened to the public in 1843

In fact, Bristol could claim to be the oldest “zoo” – the first recorded use of the word in print refers to Bristol Zoo (in 1847). Of course, collections of exotic animals are far older – the oldest known is a menagerie at Hieronkopolis in Egypt dating to 2500 BC. For most of human history, rulers have collected exotic wildlife, and swapped their own native wildlife as diplomatic gifts a custom that still survives with China’s panda diplomacy.In the UK the Tower of London had a menagerie from the 13th century. Mostly these did not live long, and the last animals in the Tower menagerie were transferred to London Zoo in 1835 (that the Duke of Wellington had an interest in the zoo may have had some relevance to this). With the growth of public transport, especially the railways, the newly affluent and mobile public wanted something to do on an afternoon, and from the 1860’s on zoos were opened to the public in many countries, with Philadelphia being the oldest in the US.

From the beginning, Bristol was heavily involved with both entertainment and education, and for only a 12 acre site it manages to punch well above its weight in innovation in animal husbandry and education. Notable firsts at the zoo include:

• World’s first nocturnal house in 1953

• First chimpanzee to be conceived and born in Europe in 1934

Aye-Aye 'Kintana' the first to be raised at Bristol

• First black rhino to be born in the UK in 1958

Bristol was also one of the first zoos in the world to breed Okapi, and currently is one of the few zoos to hold Aye-Aye, Livingstones’ Fruit Bat, Utila Spiny-Tail Iguana, and the only surviving colony of the Raiatea tree snail Partula faba (all 112 of them).

One of the main focuses of current conservation work at Bristol is in situ projects all over the world, often in conjunction with other conservation bodies or local groups.

Current projects include:

Africa:

• Cameroon – Ape Action Africa, currently caring for 250 orphaned primates from the bushmeat trade

• Comoro Islands – protecting rainforest and biodiversity

• Madagascar – Lemur conservation on the Sahamalaza peninsula

• South Africa – African penguin conservation with SANCCOB

Asia:

• Vietnam – working with the Asian Turtle Network to educate locals and preserve threatened Asian chelonians

• Philippines – Forest preservation on Cebu and conservation breeding programme for the Negros Bleeding Heart Dove

South America:

• Columbia – Silvery Brown Tamarin

Oceania:

• Tahiti and Moorea Partula snail programme

Partula faba. Bristol has the last of their species

• White clawed crayfish conservation

• Water Vole reintroduction

• Avon Gorge and Downs Wildlife Project

For more on these projects check out the downloads from the Bristol Conservation and Science Foundation website at http://www.bcsf.org.uk/conservation-research-worldwide

The other main activity at Bristol is the constantly busy Education Centre, built a few years ago and handling many thousands of school pupil visits a year. Catering for all years, the Centre also does spider phobia courses in conjunction with a local clinic

Future plans for the zoo at our main site are a 10 year programme of new exhibits, hopefully to be started on next year. These are aimed at increasing visitor use of some of the less popular corners of the zoo, and also will enable the zoo to exhibit and become involved in the conservation of more species. At present, four are planned, but the exact order has not yet been decided on – much depends on funding. They are currently

• Mountain habitat for Barbary Macaque, Giant Salamander, Rock wallabies and others

• New rainforest exhibit to include a permanent butterfly house (the current version is a polytunnel with about 5 years life left in it)

• Enlarged gorilla house

• River display, possibly with large crocodiles amongst others

The history of Bristol Zoo has always been entwined with all the other historical events that have so transformed the world since the start of the Industrial Revolution. In a world facing multiple political, economic, and above all ecological challenges it will undoubtedly continue to be a major player. Hopefully, for the bicentennial in 2036 none of the species we currently care for will have become extinct – I wish I could say for those we do not have room for.

Next week - the aquarium

Something different: the Sundews

2011-07-09T12:04:00.000-07:00

D.madagascariensis

This week I thought I would take a break from talking about animals and instead write about one of their more unusual predators. I grow a small collection of carnivorous plants and last week at Chester Zoo there was an international meeting of growers from all over Europe. As well as plants for sale, there were also great displays, including from the national collections of Sarracenia and Drosera, and I came away with three of the latter for my collection.

Sundews have figured in folklore from early times, as it was recognised that instead of dew disappearing with sunshine, on these plants it actually increased, which was thought to be magical. Of course, what people were seeing was not dew drops but sticky mucilage on short tentacles that cover the leaves, and which trap insects, usually small ones. These are digested by enzymes secreted by the plant, giving it a boost of nitrogen lyand phosphorous that cannot be obtained from the soil it grows in, typically sphagnum bogs and other nutrient-poor soils. Mostly these habitats are constantly wet, but some Australian sundews live in areas where the swamp dries out, and these survive the dry season as small tubers deep in the sandy soil.

The insect-eating habit is plainly very ancient, as most insectivorous plants can be placed in a clade closely related to Drosera, even if they have totally different trapping mechanisms, such as the Southeast Asian Nepenthes species. Drosera species can be found in their characteristic swamps all over the world, but the largest diversity of species is in Australia, with South Africa close behind.

As flowering plants, carnivorous plants have an obvious problem – how do they avoid killing the insects that pollinate their flowers? The answer lies in the specialised targeting of their trapping leaves, which usually focus on a small range of flying insects, especially mosquitoes. The flowers, which are usually pink or white and quite attractive, are carried on tall stalks and are pollinated by different insects. If no suitable pollinators arrive, the flowers are usually also self fertile. The tiny black seeds are dispersed by the wind and can germinate wherever suitable habitat can be found, although this is usually close to the parent plant.

Unfortunately, although Bristol Zoo has quite a good carnivorous plant collection, they do not currently have a suitable display area, so the plants mostly stay in off-show greenhouses. As a group, many carnivorous plants are much easier to grow than people think, as long as their key requirements are met. The most important of these is water, which must be mineral-free, preferable rainwater or reverse osmosis water. The plants should stand in this constantly in the summer, but in the winter when growth slows the pots should be kept damp only. The growing medium needs to be acidic – a standard mix is of peat+perlite, but sand may also be added. If a peat substitute is used, it is important that the PH of the medium be tested and should be kept acidic. The final need is light – most Droseras, and other carnivorous plants, are exposed to full sun in the wild and do not tolerate shade, so they do best in a greenhouse although a sunny windowsill will be adequate for most of the small forms, likely the widely available D.capensis which can be found in most garden centres.

Finally, here is some brief information about three species I got up at Chester:

D.madagascariensis

This species is widespread in South Africa and Madagascar, and can grow up to 25cm tall. It tends to die back in the winter, but will regrow in the spring. As with most of the South African sundews, it is easy to grow, in the same was as D.capensis.

D.filiformis traceyi

This is a hardy North American species with a range from Canada all down the eastern sea board to Louisiana, and I currently have this outside in a water tray. As with many Droseras from temperate climates, it dies back to a resting bud called a hibernaculum in the autumn, sprouting again in the spring. There are two forms of this, one with red tentacles on the leaves and the form I have, var traceyi, which has white ones. The leaf form is very distinctive – 10cm or more long thread-like leaves, which unfurl from the base like a fern.

D.spathulata

Originating from Australia, across to New Zealand and South East Asia, D.spathulata is as one might expect from so wide-ranging a plant quite variable. It generally forms rosettes about 4cm across, with a flower stalk about 6cm high. It can be a weed in carnivorous plant collections, as it produces large amounts of seed.

One final though for anyone interested – be careful about growing any carnivorous plant from seed bought in a seed store. The seeds of most carnivorous plants lose viability quickly, and the best way is to buy live plants or join a society like the UK Carnivorous Plants Society, as members receive as part of the membership an annual seed list of many unusual species produced by members, and which is therefore still fresh and viable.

For more information, check out the CPS forum at http://www.cpukforum.com/

(images from wikipedia)

Zoo Review: Exmoor

2011-07-01T06:39:00.000-07:00

Tamandua tetradactyla

Last weekend was the Severn Counties annual summer coach trip. We often visit zoos, and this year we decided to try Exmoor Zoo in north Devon. A fairly small zoo, only set up in its current incarnation 8 years ago, it is situated down one of the typical narrow Devon lanes. An accident on the main road forced our coach to take a longer way round than usual, so the trip down took longer than expected.

Tayra Eira barbara

That however was the only downside of the day. The weather was excellent and although Exmoor zoo is fairly small, I was very impressed with the collection. Often these small private zoos (it is not a charitable foundation) have a fairly standard animal collection with no real surprises, but Exmoor has made a USP out of having animals and birds you are very unlikely to see elsewhere. The reptile and invertebrate collection is a token really, although they do have Rhinoceros Iguanas (some of the youngsters Bristol bred I think), but the mammal and bird collection is outstanding.

Sri Lanka Giant squirrel Ratufa sp.

Among mammals on show are the first Tayra I had ever seen, a splendid Tamandua, Hairy Armadillo, and what I believe are the only Sri Lankan Giant Squirrels in the country. There is not much in the way of larger mammals, but they have 2 Sitatunga (both males according to ISIS) which I presume are spare males from the coordinated breeding programme. Primates include Lar Gibbon and Diana monkey, and Ring tail and Black lemurs (the latter with a small baby). There are at least 6 different callitrichids, and most of the groups appeared to have young either being carried or independent.

Silvery marmoset Mico argentatus

Birds include Bare-Faced Curassow (which they have bred) and White-browed Coucal (for which they had the first UK breeding). There is a major collection of cranes, including Florida Sandhill and Sarus. There is also a breeding group of Yellow-Billed storks and (a new addition) three Striated Herons currently moulting into adult plumage. There are also several pigeon species, including Wonga and Crested, which I have not often seen at other collections.

Bare-faced Currasow Crax faciolata

The zoo itself is situated in a valley, which makes for steep paths in places. The only road access is at the top, so all lavatories and the cafeteria are by the entrance, but the size of the zoo makes getting their not too onerous.. The cafeteria is very reasonably priced and the food was good.

Striated Heron Butorides striata

All zoos run on a shoestring, and Exmoor does not have many sources of funds outside gate receipts at present. Nonetheless, they have a commitment to education, and the keeper talks were well designed and informative. Some of the exhibits and their interior furnishings looked as if they were made by local builders compared to the (overdone?) designs at some other zoos, but were well designed from the animals point of view – for example the squirrels had access to a wire mesh run threaded through the branches of a tree, giving them cover while protecting the tree from being gnawed to death. They have a small group of Humboldt penguins in a freshwater lake in the center of the zoo. Generally sea birds do not do very well in this sort of situation, as they are often prone to water borne diseases if the water has a high bacterial count, but the lake is fed direct from a spring, giving a constant supply of chilled, clean water through their exhibit. There was some waterfowl on the lake, but even these were not the usual ones – Comb Duck and Andean Goose were present and posed well for visitors.

Comb Duck Sarkidiornis melanotos

My only real criticism is the zoos website, which badly needs updating with current news and information. If any web designer wants to assist, I suspect they would be gratefully received.

To sum up, this is a zoo that is the animal equivalent of those specialist nurseries that keen gardeners visit instead of garden centres, and is one I will certainly visit again. If anyone in that part of the world has animal-mad kids or an interest in zoology, they should certainly go.

Bristol Waterfowl 8: And finally

2011-06-25T10:00:00.000-07:00

In 2009 Bristol added a new species to our waterfowl collection, the Marbled duck Marmaronetta angustirostris. We succeeded in breeding them last year, and a small flock can now be seen in the Camargue exhibit by the zoo entrance.

Marbled Duck are a very small species, and although they resemble small teal seem to be slightly more closely related to the diving ducks. They are birds of brackish waters, especially with extensive reeds, and feed heavily on seeds rather than on invertebrates. They disperse when the often temporary pools dry up, and as a result of this habit have an extensive range, from Spain to Afghanistan and south to the pools of sub-Saharan Africa. The clutch is around 8-10 eggs, and both parents assist with rearing the young, with the male tending to take more of a guarding role while the female broods the ducklings.

Unfortunately, the Marbled Duck is currently classed by the IUCN as Vulnerable, because the population has suffered serious declines as a result of loss of habitat. One of the most serious losses were the near total destruction of the Iraq marshes as part of Saddam Hussein’s genocidal campaign against the Marsh Arab’s, which included the construction of major canals in southern Iraq and forcing people away from the marshes into towns.

With fall of Saddam one of the first actions taken by the locals was the breaching of the dikes and sluices, thus reflooding much of the area. This work was done piecemeal, and it took some time for proper water flow to re-establish. The problem was compounded by a serious lack of rainfall in th years up to 2010, plus water abstraction in the headwaters of the Euphrates and Tigris. Improved rainfall in the past winter has greatly relieved the pressure on both the marsh wildlife and the hard-pressed farmers in Iraq, and to date bird surveys by local conservationst have recorded 337 species, including first breeding records for Glossy Ibis , Upcher’s Warbler and Eastern Orphean Warbler. Most importantly, a count in the southern marshes recorded no less than 41,000 Marbled Duck. Until that point, the entire world population was estimated at 20,000 at most. Marbled Duck seem able to recover numbers quite quickly, as a result of their adaptation to ephemeral waters, but this is an amazing population boom, and will hopefully continue. For more on conservation in Iraq, see the Nature Iraq link in the Useful links section – the English language newsletters are very informative and well written.

That brings this series to a close – next week a change of topic, but I have not decided what yet.

(image from wikipedia)

Bristol Waterfowl 7: Meller's Duck

2011-06-18T02:36:00.000-07:00

Meller's Duck

On view in a couple of Bristol’s aviaries are pairs of one of the rarest ducks in the world, the Endangered Meller’s duck, Anas melleri. Originating from Madagascar, where it lives in wetlands in the east of the country and the central plateau, Meller’s ducks superficially resemble a large female mallard, with both the male and female having almost the same plumage. There are several species of ducks, especially in the tropics, which do not have the widely variant plumages familiar from temperate zone species, and this is reflected in their breeding behaviour.

The natural habitat of Meller’s duck is freshwater wetlands, especially Lac Alaotra, with rainforest streams and backwaters being important breeding areas. The deforestation in Madagascar, combined with extensive hunting, has caused a rapid decline, and today the world population is probably well under 5,000 individuals. There was a small introduced population on Mauritius, but this is probably now extinct for the same reason. Although they congregate outside the breeding season, when breeding they are highly territorial, and must be housed separately from other waterfowl in captivity. The diet of Meller's duck is typical for a surface-feeding bird – water plants, seeds, and aquatic invertebrates are the main components.

Although the male does not incubate, he is very protective of the female and his territory, and when the 8-10 eggs hatch he will help guard the ducklings, which are very similar to those of a mallard. Especially if the pair is successful the pair bond may last several breeding seasons, although as with many species it might be more accurate to say that both partners remain in the same breeding territory – anthropomorphism in this kind of long-term pairing is a permanent feature of reporting on apparently monogamous species. The young fledge at around 11 weeks, and can breed the following year. The lifespan is around 10-15 years in captivity, much less in the wild.

Unfortunately, because Meller’s duck is not particularly colourful, there has been comparatively interest in collections holding them. They will mingle happily with non-waterfowl species, but will attack and even kill other duck species in their enclosure. The ducklings are not hard to rear, and can be parent-reared fairly readily, but should be removed on fledging. They are slightly susceptible to Duck Virus Enteritis (DVE), so need isolation from wild birds in covered aviaries or annual vaccinations.

As one of the only three surviving species of endemic waterfowl on Madagascar, the others being the Bernier’s teal and Madagascar Pochard, Meller’s ducks should have a higher profile than they currently do. The current captive population on ISIS numbers only 124, with Louisville zoo being the only US collection to hold them. They are sometimes held in mixed exhibits – the Masaola rainforest exhibit at Zurich zoo has them with lemurs – but much might depend on the other species. It would be an interesting experiment to have them in a suitable-sized enclosure though.

Next week is the last in this series, a duck with its stronghold in Iraq, the Marbled teal.

(Images from mangoverde.com, DWCT)

Bristol Waterfowl 6: Wild Goose chase

2011-06-12T09:25:00.000-07:00

One of the most beautiful geese in the world is unfortunately also one of the rarest. The Red-breasted Goose Branta ruficollis is currently estimated to have a population of around 35,000 in the wild; perhaps half what it was only 10 years ago, when it was already the rarest in the genus aside from the far more famous Nene Branta sandvicensis.

As with most of its relatives, the Red-breasted Goose breeds in the Arctic, with the main breeding areas on the Tamyr peninsula in Siberia and neighbouring parts of the tundra. They winter much further south, and in the past enough seem to have reached the Nile delta for them to feature on ancient Egyptian wall paintings. Today they winter mainly on a few small areas on the Black Sea coast, mainly in Bulgaria and Romania. Unfortunately agricultural development and hunting, both by locals and increasing numbers of visiting hunting tourists, have an impact on the populations.

The other problem they face is on their breeding grounds. As a very small goose (mallard-size or even less) they are prime prey when nesting, especially to Arctic Foxes. As a precaution against this, they have an unusual relationship with birds of prey, often nesting within 20m of Snowy Owl or Peregrine Falcon nests. This is not as odd as it seems – raptors tend not to hunt close to their nests but vigorously defend their young, so the goose gets a free security guard. While some goslings may fall prey to raptors, especially in good lemming years the owls and falcons will tend to focus on those, enabling a large family of goslings (the usual clutch is 6-7 eggs) to be raised. A decline in peregrines on the Tamyr peninsula has been matched by a similar decline in goose numbers, probably as a result of reduced fledging success.

As with other geese, Red-breasted Geese are grazers, feeding mainly on land on grasses and herbs. In the winter they may frequent farmland, especially winter wheat, often in the company of other geese. Although they are a protected species, it is in this situation that they are most vulnerable to hunting – they can look very similar to Brent geese in the distance, especially in poor light, and Brent are a legal quarry species.

In the UK, Red-breasted Geese are a very rare winter visitor, and probably always have been, although there is a report of a sub-fossil specimen dated at around 130,000 b.p. from a site in Essex in south-east England. It is most likely, as the site is a warm interglacial one, that this too represents a wintering rather than a breeding bird.

Red-breasted geese are not very prolific in captivity, although some are bred every year, and the reason for this may well be day length. As an extreme high-Arctic specialist, Red-breasted Geese will usually conduct their breeding season in continuous daylight, and the longer nights at most of the zoos and wildfowl collections where they are kept at lower latitudes may disrupt their breeding rhythm. Feeding and care is as for other geese – essentially a suitable shallow pool and an area for grazing that is predator-free. They seem to nest in loose colonies, so having several pairs in the same enclosure may also be an advantage.

For more on the conservation of Red-breasted geese, check out the Wildfowl and Wetland Trust website here: http://www.wwt.org.uk/latest-news/redbreasted-geese-tagged-for-the-first-time

At Bristol, we currently have only a solitary male, which can be seen in the Camargue exhibit by the entrance. Although they do not currently winter as far west as the Camargue, the wintering habitat is somewhat similar. The zoo does not have any current plans to expand the breeding of Red-breasted Geese, concentrating instead on two other species of waterfowl, Mellers’ Duck and Marbled Teal.

Next week: the ferocious Anas melleri!

(images from wikipedia)

Bristol Waterfowl 5: The Holy Duck of Northumbria

2011-06-05T13:52:00.000-07:00

Drake Common Eider

Sharing a pool with the African penguins in the Seal and penguin Coast Exhibit are three pairs of Common Eider, Somateria mollissima. Along with the other two Somateria species, S.fischeri (Spectacled Eider) and S.spectabilis (King Eider), plus the slightly more distantly related Steller’s Eider, Polysticta stelleri, they are a readily recognised group of Arctic to temperate zone marine ducks which specialise on shellfish (which are usually swallowed whole), plus some other marine invertebrates. They spend almost their entire lives in salt water, except when storm-driven inland, and are among the heaviest ducks in the world.

Economically, Common Eiders have been important since earliest times, as a food item (they are still heavily hunted, especially in Canada), as a potential pest of oyster and mussel fisheries and farms, but most importantly as the source of eiderdown.

Eider down is used by the birds to insulate their nests, which are usually in as sheltered a location as the female can find, against the Arctic weather. She plucks the down from her breast and uses it to line and insulate the nest, covering the eggs with more down when she leaves to feed. At a very early stage people began harvesting this down, and in Iceland today eider ‘farmers’ still collect it. The farmers provide special nest sites which provide above average protection, and this enables them to collect a handful or so of down from each nest without damaging nest performance. The eiders feed themselves on the mussels and clams around the coast where they breed, and so for minimal effort the eider farmers gain an important source of income – the value of the eider down industry is worth several million dollars annually, even though only around 2.5 tonnes are harvested each year. Most of the ‘eiderdown’ in stores uses synthetics or down from domestic ducks or geese, and is consequently much cheaper – an authentic eider down duvet can easily cost $1500 or more.

In Britain unfortunately eiders are less well regarded, as the oyster and mussel beds which are important in many places around the coasts are a major food source for eiders, especially during the winter when they move south away from the storms. As the locals do not benefit from the eiders, which breed further north, they are not popular.

Despite this, eiders have the distinction of being the beneficiaries of some of the earliest bird protection legislation in the world, and the instigator was, somewhat improbably, a 7th century English monk called Cuthbert (later canonised). Cuthbert lived at a time when the political boundaries that would define post-Roman Britain were still being decided, and entities that could be labelled ‘England’, Scotland’ or ‘Wales’ simply did not exist. Most of what is now southern Scotland and northern England were instead part of the large and powerful kingdom of Northumbria, bordered to the south by the equally powerful Mercia, and to the north by the Gaelic-speaking kingdom of Dalriata in the north west and the kingdoms of the Picts in the east.

12th Century portrait of St Cuthbert in Durham Cathedral

Christianity had been reintroduced to England from Ireland, via monks from Iona, and Cuthbert entered a monastery, eventually becoming prior of Old Melrose Abbey. He carried out considerable missionary work throughout Northumbria, and was an important political figure as well – it was at his recommendation that his second cousin Aldfrith, whose mother was an Irish princess, became king of Northumbria after a disputed succession.

In 676 he followed the pattern of many monks in the Celtic tradition, and adopted a solitary life, building his ‘cell’(a small stone hut) on the Farne Islands, which are exposed the ferocious storms of the North Sea in winter. It was the custom at that time for holy men to act like this, and while modern western Christians might find it hard to understand, these kind of ascetic practises and techniques are far more prevalent in other branches of Christianity and other religions. It might be better to picture Cuthbert as having more in common with a Hindu Sadhu rather than with the well-fed monks of a Robin Hood movie. It was while he was resident there that he came to love the resident-breeding Eiders, perhaps because he felt their power to ride through the harshest storms of the northern winter was a good metaphor for a properly-conducted life, and he forbade them to be harmed. He died in AD 687.After several moves and reburials, his body was eventually laid to rest in Durham, where some of his vestments (he was made a bishop in 684 over his protests) can still be seen. To this day, his beloved Eiders are often called Cuddy ducks (Cuddy is a diminutive of Cuthbert) in the North East.

The fate or Northumbria was less happy. After a golden age of learning under Aldfrith and his successors, which produced the greatest art work of Anglo-Saxon Britain, the Lindisfarne Gospels, the kingdom was shattered by the Viking raids. The northern part was incorporated into the new Scottish kingdom of Alba, itself a product of the joining of Dalriata and the Pictish confederacy, and the south became part of the Danelaw, and later England.

Today the various Eiders are currently classed as of Least Concern, except for the Steller’s Eider which is classed Vulnerable. One cloud on the horizon though is their habit of wintering in vast flocks, which makes them vulnerable to extreme weather events and oil spills.

(images from wikipedia)

Next time, the Red-Breasted Goose – a species in trouble.

Bristol Waterfowl 4: Shelducks

2011-05-28T08:36:00.000-07:00

A common sight on wetlands in the Old World, from northern Europe across as far as New Zealand, are the various species of large, colourful ducks generally referred to as shelducks. They tend to prefer water in the middle of open country, or on the coast, and their diet tends to be biased towards aquatic invertebrates, although some plant material is also taken.

Common Shelduck

Shelducks are not especially gregarious, and tend to be seen singly or in pairs in large flocks of other species, but when moulting they may gather in large groups at traditional lakes or estuaries.

Shelducks tend to nest in holes or tree hollows, and in Britain and much of the rest of Europe they often use rabbit burrows. They will also take to nest boxes of a suitable size, especially if they have an entrance tunnel. The clutch is 6-12 eggs, and both parents look after the young.

Ruddy Shelduck

Crested Shelduck

Most species of shelduck have stable or increasing populations, so they are listed by the IUCN as of Least Concern. One species however, the Crested Shelduck, is either extremely rare or possibly extinct (no confirmed sightings since 1964). If the Crested Shelduck survives, it will be as a very small population in north east China or North Korea, so going looking for it may be a bit risky for even the most intrepid birder.

In Europe two species of shelduck are found, the Common Shelduck Tadorna tadorna, and the Ruddy Shelduck T. ferruginea. Common Shelducks are mostly coastal birds, whereas Ruddy Shelducks tend to frequent saline lakes inland, and have a range extending further east into Central Asia and India. There are some records of Ruddy Shelduck from previous glacial and interglacial periods in the UK, and they also turn up as vagrants from Eastern Europe, causing much anguish amongst birders as they try to decide if they are genuine vagrants or escapes (various shelduck species are common in waterfowl collections).

At present, Bristol has 3 shelducks in the collection. However, they may confuse people as to their correct identification, as they are hybrids of Ruddy and Common Shelducks. Originally we had both the parent species, and eggs from a female Ruddy Shelduck were raised believing they were purebred birds, as the ducklings of Ruddy and Common Shelduck are extremely similar. As they matured it became plain that they were a mixture, so they are just display birds now and are not bred from. Oddly, they seem in many ways to resemble the Cape Shelduck T. cana of South Africa. For hybrids to resemble a completely different species to either of the parents is not uncommon in waterfowl, which as a group are prone to hybridise in both captivity and the wild.

Cape Shelduck

Next week: how a 7th century saint instituted one of the world’s earliest bird protection laws – and how the beneficiaries became the foundation of a multi-million dollar business.

(images from wikipedia)

Bristol Waterfowl 3: Diving Ducks

2011-05-21T02:15:00.000-07:00

Common Pochard

As part of the legacy of earlier days when Bristol’s collection of waterfowl was focused on ornamental ducks we still have a couple of species of diving ducks in the collection – Tufted Duck Aythya fuligula and Pochard A. farina. When these last individuals pass away they will probably be replaced with more endangered waterfowl species. On the whole, the various Aythya species are common ducks around the northern hemisphere, with a few species south of or near to the equator. One of these, the Critically endangered Madagascar Pochard, was believed extinct and is now the focus of an intensive conservation programme with the aid of DWCT and the WWT. Not in quite as bad a position, but still declining to a worrying extent, the East Asian Baer’s Pochard A. baeri is believed to number less than 20,000 adults, possibly under 10,000, and is classed as Endangered by the IUCN.

Madagascar Pochard

Diving ducks get their name from their habit of feeding in deep water – often diving several metres down to feed on water plants, freshwater mussels, and other aquatic life. Mallard and Wigeon by contrast are called dabbling ducks – they feed at the water surface or on land. The various ecological specialisations of waterfowl are what enable a single lake to be home to a multiplicity of species.

Diving ducks as part of their adaptation to a more aquatic lifestyle have their legs set further back on their bodies than dabbling ducks. This gives them more manoeuvrability on water but makes them ungainly on land, and as a result when nesting they often prefer to build their nests at the edge of the water, often in reeds or other dense vegetation. The usual clutch is 6-8 eggs. When they hatch, the ducklings immediately enter the water and will dive deep from a few hours old. This means if rearing them away from the parents they need a deep tank, otherwise they are liable to bang their heads on the bottom if startled!

A small duckling is a tasty meal for large predatory fish, and the introduction of tilapia to Lake Alaotra, combined with habitat loss, is probably the cause of the near-extinction of the Madagacar Pochard. Even other species experience high losses during the fledging period.

Tufted Duck

Outside the breeding season, most diving ducks are migrants, often over long distances. In the UK, the wintering population of Tufted Ducks and Pochard is increased by large numbers of migrants from Scandinavia and Siberia. Among these, some rarer species such as Scaup and Ferruginous Duck can be found, causing much excitement among birders. Unfortunately, diving ducks readily hybridise, even in the wild, and the resultant hybrids can resemble the vagrant species, so duck ID is one of the trickier aspects of birding.

In a mixed waterfowl collection diving ducks need to have their food provided either at the water edge or preferably in the water. They often have a higher protein requirement than dabbling ducks, but keeping other birds from getting their first can be a problem. I have seen at the Wildfowl and Wetland Trust at Slimbridge one way round this – an open-bottomed chicken-wire cage on the water which the diving ducks will enter from below, while keeping off the dabbling ducks on the same lake.

(images from Wikipedia)

Bristol Waterfowl 2: Wood Duck

2011-05-14T08:53:00.000-07:00

A.sponsa male

One of the commonest non-domestic ducks to be seen in any waterfowl collection is the American Wood Duck or Carolina Duck, Aix sponsa. With its small size, ease of care, and free reproduction in captivity it is popular with both beginner and experienced amateur keepers as well. The only rival it has is with the very closely related east Asian Mandarin, Aix galericulata.

A.sponsa female

Both of these species have rather unusual habitats and breeding behaviour for ducks. They are specialists in deciduous woodland pools and slow-moving rivers, especially those with dense cover close to the waters edge. Their diet is mainly seeds of waterside plants, but they are also fond of acorns and beech mast in the autumn, and will also feed on aquatic invertebrates, especially females in lay and growing ducklings, which need more protein.

A.sponsa duckling

The Wood Duck and Mandarin are both classed in a separate tribe to the mallard and similar dabbling ducks, the Cairini or perching ducks, This is a reference to their fondness for trees, both for perching when out of the water (they have sharp claws on their toes and can climb well), and also as a nest site for their eggs. Hollow trees, woodpecker holes, and similar sites are all used, often at a considerable distance from the ground – up to 90m have been recorded – although 10-15m is more usual. Whatever the height, the ducklings climb to the nest entrance in response to the female’s call and then jump to the ground or water if the nest hole overhangs the pool. Unusually for ducks, especially where there is a great difference in colour between the sexes, the male stays with the female and helps guard the brood, although he does not help with incubation.

In the past, deforestation and overhunting brought the Wood Duck to the verge of extinction, but protection measures, nest box schemes (they take readily to nest boxes), and a reduction in deforestation have improved their prospects considerably.

As one might expect from such a widely kept bird, Wood Ducks have escaped and bred in the wild in the UK, but the population is apparently not self sustaining. This is in contrast with the Mandarin, which has an estimated UK population of perhaps 7,000, mostly in southern England. The reason for the difference is not clear, but may be because the Mandarin fledges at around 8 weeks, whereas Wood Duck take nearer to 10. This makes them more vulnerable to predators and the vagaries of the British climate than their Asian relatives.

Although there are now no European species of Aix, there is a report of Mandarin, or possibly a related and now extinct species, from around 500,000 bp in one site in the UK at West Runton. If this is not a later contaminant, it would suggest that Aix species were once resident in Europe but later became extinct during one of the intervening glacial periods. As a specialist in deciduous woodland they would be very vulnerable to loss of habitat, for example during the height of the last glacial maximum the nearest extensive oak woodland to western Europe was apparently along the southern shores of the Black Sea, with deciduous woods even in Spain and Italy reduced to isolated small copses in sheltered and damper areas. This raises a point about the surviving fauna of modern Western Europe – it is extremely impoverished in species compared to comparable forests in America and Asia. This is because the main geographic barriers in Europe, mainly the Alps and the Mediterranean, run east-west, and block southward dispersal of birds, reptiles, and mammals and their return north in response to climate change. The high percentage of invasive or naturalised species in Europe, as well as the spread more recently of eastern birds such as the Collared Dive, may be a reflection of the lack of competition in Europe compared to other regions.

Next week – the Pochard

References:

The History of British Birds DW Yalden & U.Albarella

The Naturalised Animals of the British Isles C.Lever

(Images from wikipedia)

A.galericulata male

Bristol Waterfowl 1: Chiloe Wigeon

2011-05-09T10:15:00.000-07:00

A.sibilatrix

When Bristol Zoo was opened 175 years ago the centrepiece was a large lake on which a variety of waterfowl were kept. Although the species have changed over the years we still have waterfowl on the lake as display birds and also more important species in various aviaries where they can be better protected from the ever-present urban fox and also receive special care. This series of posts will be about the various ducks (and one goose) held at Bristol.

A.penelope

Often these days preferring the moat around the Gorilla Island is a small group of Chiloe Wigeon, Anas sibilatrix. These belong to a small clade within the huge genus of dabbling ducks, whose most famous member is the Mallard. Other members of the clade are the European Wigeon, A.penelope and the American Wigeon, A.americana. More distantly related are the Falcated Duck A.falcata and the Gadwall, A.strepera.

A.strepera

The true wigeons are distinguished by a short bill, which they mainly use on land to graze on grasses and sedges. Just north of Bristol at the Wildfowl and Wetlands Trust site at Slimbridge thousands of European Wigeon arrive from further north to spend the winter, and are constantly marching across the fields feeding up for the spring return migration and nesting season. Other dietary items are seeds, other plant parts, and (especially as ducklings) insects and crustaceans.

In the wild, Chiloe Wigeon have a vast range in the southern part of South America, where they frequent marshes, pools, and slow-moving rivers in the breeding season. As a result of their large distribution, they are currently classed as of least Concern by the IUCN

After breeding, they disperse to the coast and migrate north as far as Brazil for the southern winter. As with most ducks, they can travel far and fast at times, and have reached South Georgia and other sub-Antarctic islands, and also breed on the Falkland Islands.

Breeding in Chiloe wigeons is similar to most ducks. The nest is a scrape concealed in waterside vegetation, and 6-10 eggs are the usual clutch. Although the male does not incubate, he guards the nest area (and probably the female) against predators and rival males. The ducklings fledge at around 6 -8 weeks, but will probably not breed until they are at least one year old and more usually two. In captivity at least they can live to be 20 years old.

A.americana

The first Chiloe wigeons to be seen in Europe alive arrived in 1873, and they soon proved easy to breed and care for. For this reason they are popular beginner’s birds with private keepers, as they will live and breed happily in even fairly modest sized water bodies. With waterfowl, as with poultry, a key issue is protecting birds from predators, especially when they are nesting. It is vital that back garden birds are surrounded with a fox-proof fence (raccoon-proof as well in the US). Obviously they also need a pond, but the depth of this for dabbling ducks does not need to be very great. More important is that the pond be able to be emptied, cleaned, and refilled easily, as ducks produce a lot of waste and are mostly large birds – Chiloe Wigeon can weigh 2 kg as an adult.

A.falcata

For more on waterfowl, see the British Waterfowl Association website at http://www.bwa.org.uk/

For a video of live Chiloe Wigeons, see here: http://www.youtube.com/watch?v=xKLO8jX7134

(image from wikipedia)

Nest week, the other ornamental we have – the American Wood Duck

New arrival: Pallas' Long-tongued bat

2011-04-30T01:03:00.000-07:00

Just gone on show in Twilight World is a group of Pallas’ Long-tongued bats, Glossophaga soricina. These are quite a significant addition to Bristol’s species list, as according to ISIS this makes us the only zoo in the UK, and one of only 10 institutions worldwide, to have them on display.

Bat taxonomy has undergone a lot of revision in recent years, and the old split between the Old World fruit bats (like our Livingstone’s) and all other bats has been abandoned. Instead, bats are still split into two groups, the Yinpterochiroptera, which includes both Old World fruit bats and the horseshoe bats, and the Yangochiroptera, which includes almost all the others. Glossophaga belongs here as a member of the family Phyllostomidae, a New World group of bats found in Central and South America.

Phyllostomid bats are extremely diverse in their ecology, and although many still feed on insects others are predators (the largest of these, the False Vampire Bat, can take birds the size of pigeons), fruit feeders, or like the Long-tongued bat, feed on nectar. The true vampire bats Desmodus also belong in this group. The fruit feeders are important in the distribution of seeds of forest plants, and the nectar feeders are important pollinators.

There are about five species described of Glossophaga bats, but they cover a huge range and it is very possible that there are several cryptic species involved. Because bats identify each other by call, they have no need to develop physical differences to aid species recognition, and any group of bats that are studied so far have revealed numerous species which are almost identical except for their ”call-sign”. This is true even in Europe – only in the last few years was the commonest British bat, the Pipistrelle, realised to be two different species, now called the Soprano and the Common Pipistrelles. Our own species as it stands is found from Argentina north to Mexico

Long-tongued bats have huge energy demands, using up 50% of their stored fat in a day, so they must feed constantly during their activity period to stay alive. They must move constantly from flower to flower, and this of course means they also transfer pollen. As a favourite food source are the flowers of Agave, the source of tequila, it is in the interest of many that they thrive, and as long as their roost sites are safe (these can be anything from a hollow tree to an abandoned mine) they can make use of agricultural landscapes. Aside from nectar, they will also feed on fruit and insects.

P.mucronata

As they are found in Costa Rica, where our butterflies come from, they are also important in the ecology of Heliconius butterflies – several important Passiflora species (the foodplant of Heliconius larvae) have white, night-blooming flowers that are pollinated by bats. Examples would be Passiflora mucronata, P.trisecta, and P. penduliflora amongst others. Typical bat-pollinated flowers can be identified as fairly large, usually white, and often strongly scented – these bats seem to use their sense of smell as much as echolocation to find their food, although they presumably echolocate when hunting insects, the other main component of their diet

The societies of different bat species are only just being understood, but it appears that female Long-tongued bats form maternity roosts when raising young and live in mixed-sex colonies the rest of the year. How males compete for females is not yet fully understood – in some other species they perform song flights, sing from perches, or take part in a mass display similar to the leks of some birds. They produce only one baby at a time, as with most bats, and the maximum recorded lifespan is 11 years.

Our bats are housed in a room-sized enclosure in Twilight World, illuminated with green light (which they cannot see). The room is filled with live plants and has the sides decorated with branches to provide perches when not flying. A couple of upside down 30cm plastic flower pots provide a roost area during the day. Feeders are hung round the enclosure so that several can feed at the same time if they wish – the diet is an artificial nectar similar to what is fed to our lorikeets.

It is estimated that perhaps a quarter of all mammal species are bats, and their conservation has in many cases been sadly neglected, as their habits make it very difficult for people to enter their world. Even the small insectivorous bats found in the UK are extremely diverse (17 confirmed breeding species plus some vagrants from mainland Europe), so a good start would be for people to stop using phrases like ‘there’s a bat’ – that is about as meaningful as saying ‘there’s a bird’ when you could be referring to anything from a wren to an eagle. For information on native British bats check out the Bat Conservation Trust website at www.bats.org.uk

(images from the net)

New Butterflies at Bristol

2011-04-25T01:05:00.000-07:00

C.atreus

For the April instalment, a few new species have been added to the collection to be seen in the Butterfly House in addition to the regular species. El Bosque Nuevo, the Costa rica butterfly farm that supplies us, has at least 70 species available, so the collection manager likes to ring the changes occasionally to keep things interesting for the annual members who visit regularly.

C.atreus upperside

First, off, we have two new species of Owl butterfly. Largest and most richly coloured of the owls is the Yellow-Edged Giant Owl, Caligo atreus. Like the Pale Owl we have had from the beginning, it has a cryptically coloured underside enlivened by a single large eye spot. I presume that the difference in underside colour means it rests in different locations by preference in the wild to the rather greyer Pale owl, but I have not found any studies to confirm this – one of the many considerations that need researching. Most knowledge of butterflies is extremely superficial beyond bare descriptions and location data, and this is a subject that could well repay studies in the wild or in butterfly houses. My impression from Bristol is that they like to rest closer to the ground than Pale Owls, but this may be a constraint of their surroundings. Like their relatives, Yellow-Edged Giant Owls are long lived as adults – some at least seem to reach close to 50 days. The foodplant is various Banana and Heliconia species.

O.tamarindi

The other Owl butterfly we have has only just emerged, so I am not sure of the lifespan. The Tamarind Owl Opsiphanes tamarindi is a half-sized version of a Giant owl with a more plainly patterned underside. It seems to fly differently to Giant Owls, being much more active and a faster flyer. Caligo species prefer to fly at dawn or dusk, but the activity period of Tamarind owls may be different. The foodplant is as for the Caliogo species.

P.anchisaides

We have also added two new species of Swallowtail butterfly. The Red-spotted Swallowtail Papilio anchisaides feeds on Citrus, so the red spots (usually a sign of a distasteful species) may be mimicry of a more toxic species. Mimicry rings, especially in the tropics, can involve numerous species, including butterflies, moths, wasps, flies, beetles and other groups, all mimicking each other and some of which are toxic and others just pretending to be, so disentangling the network of imitation can be very difficult. Almost certainly toxic is the Green-celled Cattleheart, Parides childrenae, which feeds as a larva on Aristolochia. This plant contains numerous toxins which are retained into the adult butterfly, and most Aristolochia-feeders worldwide have various warning patterns. Unlike the owl butterflies, which feed on fruit juices as adults, the swallowtails visit flowers.

P.childrenae

Finally, we have a new species of Pierid, the Orange-barred Sulphur Phoebis philea. Another flower-feeder, it seems to like to rest well off the ground if possible here at the Butterfly house. The foodplant of the larva is Cassia.

P.philea

Coming up, a new species in Twilight World and then a survey of the waterfowl we have here at Bristol.

(images from wikipedia, bugguide, encyclopedia of life)

Frogs of Bristol 6: Handle with care

2011-04-16T08:54:00.000-07:00

D.azureus

To wrap up this series on Bristol Zoo’s frog collection, there are the three poison arrow or poison dart frogs we currently have on show. Belonging to the Dendrobatidae, almost all the species of dendrobatid are highly colourful, day active frogs which tend to be fairly bold and therefore make good exhibits, unlike the tiny Mannophryne species I talked about last week. They can of course afford to be conspicuous, as their skin secretions are unusually toxic, although of the ones we have only the Golden Poison Frog, Phyllobates terribilis, is toxic enough to kill humans, with a single frog estimated on average having enough toxin to kill ten adult human beings or 22,000 mice. Fortunately, captive bred individuals never acquire the toxicity they have in the wild, as the wild diet appears essential for the production of the multiple toxins found naturally.

P.terribilis

The other two species of dendrobatid we have on show, the Yellow-banded poison dart frog Dendrobates leucomelas and the Blue poison dart frog D. azureus are not sufficiently toxic to be used by local peoples in poison darts, being merely distasteful to predators. Despite all their defences however, there is at least one snake that specialises in poison dart frogs and other toxic amphibians, the 50cm Leimadophis epinephelus, which is so resistant it can even prey on Phyllobates species. Since it is so small however, it may only feed on juveniles of the more toxic amphibians it encounters.

D.leucomelas

The dendrobatid frogs all undertake various forms of parental care, with the species we keep all having egg clutches guarded by the male. When the tadpoles hatch after about 2 weeks they climb onto the male’s back and are transported from the nest site to small pools, bromeliads, or other tiny water bodies, where they mature in about 2 months.

The diet of dendrobatid frogs is composed of vast numbers of small insects, especially termites and ants. Some of the larger species will feed on woodlice, small millipedes, and insects up to the size of a small cricket, even small earthworms. The captive diet is mainly hatchling crickets and fruit flies, supplemented with wild caught small insects such as aphids and some wax moth larvae – although these last are very fattening and should not be fed frequently.

With their low reproductive rate and limited power of dispersal, dendrobatid frogs are very likely to produce unique local varieties. Wide ranging species usually are found in multiple morphs, all with restricted ranges. All of these are prone to extinction in the event of deforestation or chytrid fungus outbreaks, so there is considerable work being done on their preservation. They are widely kept by hobbyists, even the Phyllobates species (which is actually one of the easier to maintain forms). Naturally, anyone planning on keeping such a frog should do their research first, and this includes being able to produce sufficient food to maintain them – cultivating fruit flies is a vital skill for dendrobatid keepers. Hobbyists will often produce spectacular planted vivaria to house their animals, especially including ferns and miniature orchid species which do well in a dendrobatid vivarium – if the plants are growing and flowering well it is a good sign that the environment is correct for the frogs as well.

If the frogs do produce eggs, standard practise at Bristol is to remove the egg clutch and incubate them separately. Tadpoles must be reared singly, as many species are cannibalistic as larvae. At Bristol plastic drinking cups are used, with the water changed daily. The other important factor is exposure to UV light, which is vital to larval development. While the requirement for UV of reptiles is well known, amphibian requirements are less well studied, and probably vary greatly depending on the lifestyle of the species, with adults and larvae quite probably having different requirements.

This concludes this series on Bristol’s frogs. Next week, some new arrivals in the butterfly house and then a new series on our waterfowl.

(images from wikipedia)

Frogs of Bristol 5: Noisy but secretive

2011-04-09T10:47:00.000-07:00

One of the least conspicuous, but noisiest, of all the frogs we have at Bristol are our Trinidad Stream Frogs, Mannophryne trinitatis. Originally thought to be found on Trinidad in the Caribbean and part of the mainland of Venezuala, the mainland population is now classed as a separate species, M.venezuelensis. This is only to be expected, as any interchange between Caribbean islands and South America must be very infrequent at best. Our species is part of a group of very similar species mostly found in montane forests of Caribbean islands and Venezuela. Several are listed by the IUCN as declining, near threatened, critically endangered, or at best data deficient, with the Trinidad Stream Frog classed as Vulnerable. At present, they are still reasonably common in suitable habitat.

Part of the reason for the lack of knowledge of the various forms is their small size. Trinidad Stream frogs are at best under 2cm long, usually smaller, and are cryptically coloured, unlike their better known and more colourful relatives the poison dart frogs. They are animals of leaf litter, where they lay their eggs. As with poison dart frogs, the eggs are guarded by the male, and the newly hatched tadpoles are carried by the male to small pools, chosen for their lack of predators.

The best way to locate these frogs is by ear. The males are amazingly loud for their size, presumably so they can be heard above the noise of the streams and waterfalls they live beside. The effectiveness of this can easily be discovered in the reptile house, where we have a group living free in the house. The reptile house has a 12m high waterfall falling onto rocks over the pools housing our turtles and dwarf crocodiles, and the splash zone creates a perfect replica of the streams and waterfalls they live beside in the wild. Males tend to call from prominent rocks near the waterfall, but visitors are only likely to see them if they move, as they are the same colour as the rocks. This is doubtless very useful camouflage, as they do not have the same level of toxins as the poison dart frogs and could be eaten by practically anything. Aside from being inconspicuous, their only defence is that they are amazing jumpers, hence their other English name of Rocket Frog.

Their own diet is what one would expect – minute insects and other leaf litter invertebrates. At Bristol the ones kept in vivaria are fed pinhead crickets, fruit flies, and springtails, with tadpoles fed on flaked fish food and some other artificial diets. As with all amphibians, they are prone to heat stress, so it is important that they are not kept too warm. Lighting requires a low level UV bulb – too much UV can be a cause of cataracts in animals not used to living in full sunlight, and these frogs favour shady streams.

Unlike the poison dart frogs, which are very colourful and showy animals and make for a good display in a collection, Trinidad Stream Frogs are rarely seen in zoos. At present ISIS only lists 99 individuals, all in the UK. This kind of bias is a major problem for conservation – zoos need animals which are visually interesting fro visitors to want to come and see, whereas a lot of vulnerable or endangered creatures are frankly dull to look at unless you are a specialist in the group they belong to, so they tend not to get the attention and conservation funding they need. The IUCN red list has 9 species of Mannophryne which are classed as Endangered or Critically Endangered, but only one organization is involved in their conservation, the Laboratorio de Biogeografía/ Biogeographic Laboratory, Universidad de los Andes in Venezuala. I am not aware of any projects targeted directly on the Caribbean species.

Next week, some true poison dart frogs – colourful character with complicated lifecycles.

(image from Amphibiaweb. Picture by Dr Joanna M Smith)

Frogs of Bristol 4: Splendid Leaf Frog

2011-04-02T10:15:00.000-07:00

One of the more spectacular frogs we have at Bristol is the Splendid Leaf Frog, Cruziohyla calcarifer. Unfortunately, visitors usually do not get to appreciate their full colour, as like many frogs they are nocturnal and during the day they spend their time fixed to a large leaf, where their camouflage green makes them hard to spot.

In the wild of course it is much harder, as they are a thinly distributed species that spends its entire life in the rainforest canopy. Only when they are active are their bright flank colours visible, and these are usually only seen briefly in daylight, as they act as a warning flash as a disturbed frog leaps to another resting place. At present we only have males on show, but hopefully we will get a few females soon and be able to breed some of these impressive frogs ourselves.

Originating from Costa Rica and Panama, it is a specialist in lowland primary rainforest, avoiding disturbed areas. This is probably a reflection of their breeding behaviour, as they need hollows in fallen trees to breed in. As with most of the phyllomedusine tree frogs, they lay their eggs out of water, above the water-filled depressions in the logs where their tadpoles develop. The tadpoles are probably omnivorous, but are certainly capable of taking some animal protein if it is available.

The pools they develop in are small, so there would usually only be a few successful metamorphs from each site. This is probably one of the reasons it appears scarce – it is adapted to make use of small, widely scattered breeding sites rather than large population concentrations. This may also make it vulnerable to deforestation – in any one area the numbers are probably quite low, so connected areas of forest are needed to sustain a viable population.

As with most tree frogs, the diet is mainly insects of various types in the wild. In captivity they will take crickets and small locusts. These are ‘gut loaded’ – a term for ensuring the insects have fed on a high quality diet before being eaten by the frog. This is very important for all captive animals – wild insects will have fed on a variety of leaves and fruits, which provides essential vitamins and minerals.

The trick of encouraging breeding in many amphibians involves the use of a ‘rain chamber’. This is basically a container with several inches of water in the bottom containing a water pump that circulates water through a spray bar at the top. When the pump is on, a continuous spray of water falls on the inhabitants. This mimics the rainy season, which is when most rainforest frogs in particular will breed.

For a video of a breeding set up for this species, see here:
http://www.youtube.com/watch?v=9KcW__YWmu0

(image from wikipedia)
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Frogs of Bristol 3: Tastes like?

2011-03-25T13:30:00.000-07:00

Pity the poor Mountain Chicken frog. As if being eaten to extinction on several Caribbean islands by both humans and introduced mongooses is not bad enough, it then had its last stronghold on a volcano in Montserrat blow up and finally the survivors were hit with chytridiomycosis. A frantic effort was initiated by DWCT on Jersey – if you are at all interested in any conservation work check out the Dodo blog on their site – and a few European zoos now hold and breed Leptodactylus fallax. With a wild population on the last two islands where it lives (Dominica and Montserrat) having a combined population of under 8,000 (probably much less) this species is in dire need of help.

There are many species grouped under the Leptodactylus, and the genus should probably be split up into smaller genera. There is a considerable range in size, behaviour, and distribution, with Mountain Chicken frogs being among the larger of the worlds’ frogs – bigger than an American Bull frog for example. Mountain Chicken frogs are terrestrial, as one would expect from their size, and are quite secretive, preferring to spend most of the daylight hours hidden away in burrows. The diet in the wild is large insects, and probably any smaller frogs as well, and here at Bristol our adults get adult locusts and Blaberus cockroaches, all vitamin supplemented.

Breeding Mountain Chicken frogs is a tricky business. They exhibit a great deal of parental care, as the females lay their eggs in a foam nest in their burrows. The tadpoles remain in the nest, developing into miniatures of the adult. The developing tadpoles are fed by the female, who lays infertile eggs into the foam nest for them. Breeding has been made possible by manipulating temperature, day length, and humidity, combinations of which are the usual triggers fro reproduction in amphibians.

After holding Mountain Chicken frogs for several years, in 2010 Bristol had its first successful breeding of these magnificent frogs, raising 19 from one nest. These are being raised off show, but the adults can be seen in the Reptile house. If you are visiting, try and look inside the rolls of cork bark we have as shelters – they will often be found hiding inside. With these and other successful breeding, the captive population now stands at over 500. Most of these are in Europe, but a few US zoos now have them as well – check out on ISIS for your nearest collection to hold them.

For great video of these frogs see here:

http://www.youtube.com/watch?v=06huqK6yql0

Next week – a truly splendid tree frog

(images from wikipedia)

Frogs of Bristol 2: The Lemur Leaf Frog

2011-03-19T12:02:00.000-07:00

The other species we are currently breeding in the Amphipod, although in somewhat smaller numbers, is the Lemur Leaf Frog Hylomantis lemur. Originating from Costa Rica and Panama, this tiny (3cm) tree frog has undergone massive declines in recent years, almost certainly due to chytridiomycosis, although it is apparently slightly more resistant than some other species. It was assessed as Critically Endangered in 2008.

There are several other species in Hylomantis, but they are currently classed as Data Deficient or Least Concern – although this last may be in part due to lack of study rather than any actual difference in their status. The ‘lemur’ part of its scientific name come from the Latin word ‘lemures’, which means spirit or ghost, and presumably refers to its nocturnal habits and bulging eyes. The same word was of course also given to the Lemurs of Madagascar, which are of course primates.

As well as being small, Lemur Leaf frogs are spindly animals, with long legs and slender bodies. They climb rather than jump mostly, hauling themselves up vine tendrils hand over hand. Green during the day, at night they change colour, becoming reddish brown. The diet is various small invertebrates, including small snails – an often overlooked part of the diet of many insectivorous animals.

As with many frogs, they have unusual breeding habits. The eggs – up to 35 in a clutch have been recorded – are laid on the end of a leaf overhanging water, and the tadpoles are washed into the pool or slow moving river when they hatch after about a week. The tadpoles are vegetarian, and grow quite large before they metamorphose.

Lemur Leaf Frogs were first bred at the Atlanta Botanical garden in 2001, and the captive population in zoos currently stands at 242. In the last year Bristol, the only zoo in Europe which has them on show, has bred 63, which is a pretty respectable number although we still need to boost productivity. Identifying the correct trigger for breeding in amphibians is a large part of the secret of breeding them, and research in this area is ongoing. They are kept in 40cm x 40 cm x 60 cm tall glass vivaria, with a potted plant in each for them to rest on. feeding is on small crickets and similar small insects.

One of the key institutions in the breeding and study of the phyllomedusine tree frogs, the group to which the Lemur Leraf Frog belongs, is the Manchester Museum. For a video about the Lemur Leaf Frogs at the Manchester Museum, see here: http://www.youtube.com/watch?v=0NF9hlbgRxE The herpetologist in charge also produces a good blog, which I have added to the links section = please check it out!

Next week, from small frogs to gigantic ones – the Mountain Chicken Frog of Montserrat (sounds like something from a horror story doesn’t it)

Frogs of Bristol 1: The Golden Mantella

2011-03-12T08:42:00.000-08:00

A recent piece of research into which animals visitors to zoos pay most attention to rated amphibians as next after mammals (especially primates) in popularity. Just over a year ago, Bristol opened its ‘Amphipod’ – a climate controlled timber exhibit with two modest sized rooms for breeding endangered amphibians. Most people reading this blog will be aware of the global amphibian crisis caused by chytrid fungus, so I will not repeat that. I would like to talk instead about the various amphibians we have at Bristol and their current situation in the wild.

The Amphipod was designed to provide biosecure breeding facilities for at-risk amphibians, and few are more so than the Critically Endangered, tiny (2cm) Golden Mantella, Mantella aurantiaca. One of at least 16 species of Mantella (there are probably several more undescribed forms), it is confined in the wild to perhaps as little as 10km2 of primary and secondary rainforest in east central Madagascar at a fairly high altitude. The habitat is basically a collection of forest fragments, all threatened by logging for firewood and forest fires, although their preference for marshy areas provides a little protection from those.

Amphibians as a group have some of the greatest diversity in reproductive strategies of any vertebrate, and this makes breeding them in captivity a challenge until their breeding behaviour is understood. Mantellas are terrestrial breeders, laying eggs in wet moss at the edge of water and allowing rain to wash tadpoles into the water where they develop. For Golden Mantellas at least, their breeding is opportunistic, and breeding takes place whenever the conditions are right. Some other amphibians have far more complicated triggers to breeding - I have heard of one Caribbean species that reproduces only on one or two nights a year, triggered by the first full moon of the rainy season.

In the Amphipod, conditions can be modified so that they can be bred at will, and from a starting group of 38 adults we have produced over 500 tadpoles and froglets in 12 months. Most of these have since been distributed to other collections in Europe. The tadpoles develop in the same way as for more familiar species, but the newly metamorphosed froglets are only a few millimetres long, so feeding them is a problem. Adults will take fruit flies and pinhead crickets, but the new froglets require even smaller prey, so they are fed on springtails. It takes several months before they develop the bright orange warning colours of the adults.

The adult frogs are kept in all glass vivaria for ease of cleaning. A sloping glass land surface, covered with live sphagnum moss, with a potted plant for climbing is all they require. A plumbed-in mister allows the adults to be sprayed with chemical-free water daily, and the lighting is a full spectrum fluorescent lamp. It is important that amphibians receive UV lighting, as infertility or disease results if they do not, but it is vital they do not overheat. Amphibians are extremely prone to heat stress, and before the Amphipod was built we had no luck breeding Mantellas during the summer, even in the UK, as it became too warm for them.

In the post I made a short while ago on Asiatic Lions (our cubs are doing nicely by the way), I mentioned the problems of maintaining captive populations of sufficient size to be viable. With animals the size of most amphibians, this is less of an issue, as the vast majority are extremely small. To maintain a viable population of say 2000 mantellas, you would require about twice the space of the average sized living room, which is at least theoretically manageable. Even the largest of the frogs and toads could easily be saved, so long as sufficient space for their often peculiar lifestyles was available.

For a video of Golden Mantellas in the wild, see here:
http://www.youtube.com/watch?v=QimakmiWQYY&feature=related

Next week, Lemur Leaf Frogs – the other inhabitants of the Amphipod

New Arrivals - Black Hornbills

2011-03-05T09:41:00.000-08:00

Male

A new species that arrived at Bristol earlier this year is a pair of Malayan Black Hornbills, Anthracoceros malayanus. One of 54 recognised species of hornbill (plus the closely related Ground Hornbills of Africa) they originate from South East Asia, which is a center of diversity for the Bucerotiformes. Among the close relatives of hornbills are the hoopoes, kingfishers, rollers, and woodpeckers. Most of these were originally grouped together in the Coraciiformes, but these have now been split into separate orders.

Female

Our pair are two of only 49 of this species listed on ISIS. Most are in Europe, with only 6 in the US. In the last year 5 pairs bred worldwide, producing 8 chicks between them. This is typical for hornbills even in the wild – many will not breed every year as the strain of raising even the typically small clutch of 1 or 2 is too much, and adults will take a break between years. As is also typical of animals with a low reproductive rate, hornbills are long lived birds, especially the larger species. The oldest on record is a female Great Hornbill Buceros bicornis who was believed to be over 50 when she died. Several others have been known to breed when in their 30’s.

Except for the aberrant Ground Hornbills, hornbills are canopy birds, feeding omnivorously on fruit, insects, reptiles and eggs of other birds, although the percentage of animal prey varies between species. Fruits are picked delicately, and then thrown in the air to be caught and swallowed. Hornbills typically choose smooth-skinned fruits (often red or purple ones) and swallow them whole, later regurgitating the stones for large-seeded fruits, or passing small seeds out in their faeces. In either case, they are important seed dispersal agents.

As birds of (mostly) primary rainforest, they are threatened by deforestation. This not only removes their food supply, but as often very large hole-nesting birds they are dependent on large emergent trees which are the only ones suitable for nesting.

The large bills of hornbills require special treatment in aviary birds. It is important the birds have appropriate forked sticks or ropes which they can use to clean their bills. If a birds bill is damaged vets have been successful in using dental acrylic or fibreglass to prepare prosthetic bills – although getting these to stay on considering the amount of use they get can be difficult.

The other big husbandry problem with hornbills is one shared by many other rainforest birds – a susceptibility to hemochromatosis or iron retention disease. Believed to be due to excess iron in the diet, this causes sudden death from liver failure, often in birds showing little signs of illness. The main reason for this disease is that rainforests often grow on soils extremely poor in minerals, with a corresponding lack of iron in the vegetation that grows on it. In addition the birds will ordinarily drink pure rainwater or water from tree hollows which is full of tannins which block iron absorption.. The tannins in the wild diet may be replaced by adding supplements to their water in captive birds – in this case in the form of cold tea!

Replacing the fruits eaten in the wild can also be problematic, for all fruit-eating animals, not just hornbills. Domestic fruits have all been bred over many thousands of years to appeal to human taste buds, and are typically much higher in water and sugar, and lower in fibre and protein, than wild fruits. Different wild fruits have very different nutrient compositions, with some producing fruits rich in fats, others rich in carbohydrates. Now the cause of hemochromatosis is understood, diets of captive birds are designed around low-iron pelleted foods, and citrus fruits are rarely fed. This last is because Vitamin C promotes iron uptake and so can be a health risk.

The most famous aspect of hornbill ecology is their strange breeding behaviour. At the start of the nesting season, the female is walled up in the chosen nest cavity by the male using mud, until only a narrow slit that the female can get her beak thjrough remains. This protects the female from predators, but means she is utterly dependent on the male for food for the several months it takes before the chicks are large enough to require two parents to feed them. In some species the female leaves before the chicks fledge and the chicks then re-seal the entrance behind her. When supplying hornbills with nestboxes, it is important that this behaviour is borne in mind and the right type of nestbox is supplied so this behaviour can occur, or the birds will not breed successfully.

For more on hornbills, see here: http://www.coraciiformestag.com/Research/Research.htm

(pictures from wikipedia)

A good start to our 175th anniversary year

2011-02-27T14:06:00.000-08:00

Finally, after many disappointing years, Bristol has two lion cubs. The proud parents are two (a male and a female) of the around three hundred Asiatic Lion, Panthera leo persica, in captivity. The wild population as of April 2010, comprised 411 individuals, including 150 cubs, all located in the Gir forest and a few neighbouring areas in Gujarat, India.

In prehistory, lions were the most widely distributed of large mammals, with a range extending from South Africa to Peru, and as far north as Britain. In that range various subspecies have been recognised, with the American form sometimes being treated as a separate species P.atrox, but aside from being unusually large the American lion was a typical lion.

One feature of the extinct cold-climate lions, at least as shown on cave paintings, is that the males were maneless or nearly so. This makes sense considering the conditions they survived in – a mane would rapidly weigh the animal down with ice crystals in the winter and make hunting impossible. As they seem to have derived from these cold-adapted forms, the American lion was probably also maneless, although no paintings survive from that period as confirmation.

The collapse of the lion population began about 10,000 years ago with the mass extinction of the Americas, where lions probably succumbed to loss of their main prey species. By around 2,500 years ago, they had gone from most of Europe but still survived in the Balkans and throughout the Middle East. Wherever large concentrations of people, especially livestock farmers, developed, lions were wiped out as a direct or indirect threat to humans. The last known Asiatic lion seen alive outside India was in Iran in 1941.

The Gir forest reserve is now the only place lions survive outside Sub-Saharan Africa. The reserve itself is 1412 km² of dry teak forest and some surrounding grassland, and is probably at maximum carrying capacity for lions. The reserve needs to be large enough to maintain viable populations of the lions prey – chiefly wild boar and deer although they will also take wild cattle and gazelles.

Clearly, the population in both the wild and captivity is far too small. The calculations are complicated, and depend among other things on reproductive rates and lifespan, but in general for a mammalian species to have reasonable long-term survival prospects without human intervention there needs to be around 5,000 breeding adults in a continuous population. Below this number, natural disasters, inbreeding, and diseases increase the risk of extinction dramatically.

This brings us back to our cubs. The Asiatic lions in Europe’s zoos are managed centrally, as with most of the species that can be seen in zoos today. There is a separate studbook for those in American zoos for reasons of ease of management, and currently the Asiatic lion studbook is managed from Twycross Zoo. Our male, Kamal, came from Twycross while our female, Siva, came to us from Besancon in France. The cubs were born on 24th December and their existence has been kept under wraps until we were sure they were going to be Ok (first litters in lions and other animals often do not survive due to maternal inexperience) and also they could not be put on show until the cubs had been vaccinated – lions are vulnerable to many diseases spread by domestic cats such as Feline Immunodeficiency Virus (FIV). Canine distemper, present in Bristol’s extensive urban fox population, is also a risk.

The cubs will remain with the mother until they are at least 2 years old, when in the wild the male at least would disperse to find a pride of his own. Where the cubs go to will be determined by the studbook holder, depending on where new pairs are to be created to maintain genetic diversity in the captive population.

At present reintroducing zoo-bred lions to the wild is a very distant prospect - although given their prehistoric range there are plenty of possible areas. Reintroducing carnivores, especially ones capable of attacking humans, is universally difficult or impossible. The creation of some large fenced areas where they could live at least a semi-natural existence is a far more likely scenario, but given the state of conservation awareness and political will in possible countries (including South East Europe) there is very unlikely to be any such attempt for several decades at least.
For more on the lions of the Gir forest, see here: http://www.asiaticlion.org/

For a video of the birth of our cubs, see here: http://www.youtube.com/watch?v=ZLPgKsfyIiM

Next week; hornbills

(images from Bristol Zoo website, Asiatic Lion.org)

Society show last week

2011-02-20T10:12:00.000-08:00

Last weekend the cage bird society I belong to, Severn Counties Foreign and British Bird Society, held its annual members Show. The club has two shows a year, with the autumn one open to non-members which results in a higher number of entries from hobbyists from all over, especially the west of England and Wales. Unfortunately, owing to the sad loss of a couple of enthusiastic exhibitors this year, the number of entries was down, but there was still an impressive range of species kept and bred by club members on show.

Severn Counties was founded in 1972 and has for many years had a stand down at the Bath & West show each year. The club has a monthly meeting , usually a slide show and talk, and also does charitable events and helps at the annual Winterbourne carnival over the May Day weekend. There are also various club outings to various walks, zoos etc.

I joined the club a few years ago and am currently the librarian – the club has a quite impressive collection of literature on various natural history topics, though the main function of the library is to act as a reference source for knowledge about various species.

Severn Counties is actually a fairly recently founded club – some of the oldest in the UK were founded as part of the Victorian explosion of leisure-centred clubs and societies. The oldest tended to focus on the breeding of various varieties of canaries, with later budgerigars, zebra finches, and other species having dedicated nationwide societies being set up.

The history of the various species now kept is a complicated one, involving among other things exploitation of wildlife, the process of domestication, social history, and attempts at genetic engineering by both amateur hobbyists and professional scientists. It is far too complicated to go into in a single post, but later in the year I hope to blog about some of this.

In the meantime, here are some species kept, bred, and shown by club members - how many species can you identify?

Next week, some new arrivals at Bristol.