Land of the Dodo 13: Bulbuls

Scattered from Asia to Madagascar, the Black Bulbuls of the genus Hypsipetes comprise nine surviving species, of which two survive in the Mascarenes, on reunion and Mauritius. An additional species, not yet formally named, is known from fossil remains on Rodrigues and died out either before or shortly after first contact – there are no surviving accounts of it known.

Bulbuls are medium sized, largely fruit-eating birds, supplementing their diet with insects, especially when breeding. The nest is an open cup, built in a bush or tree, and in general they can be thought of as the Asian equivalent of common European and American thrushes.

The Hypsipetes bulbuls of the Mascarenes seem to have originated from Asia, initially via the Seychelles. From the DNA evidence it appears that the Mascarene birds then went on to colonise Madagascar, which in turn then spread out again to the Comoros, where two species now occur – one originating from the wave that colonised the Mascarenes, and a second derived from the Madagascar Black Bulbul Hypsipetes madagascariensis.

The Reunion Bulbul H.borbonicus (called a Merle there) is still common, but the birds are more easily heard than seen. I was unable to locate any decent photos of either of the Mascarene species, so the picture at the head of this post is the common Indian Black Bulbul Hypsipetes leucocephalus.

Unfortunately the Mauritius Merle H.olivaceus is in a far worse state. The current population is under 300 pairs, which is far too low to be secure, but at least at present the population appears stable. The probable reason for its decline is habitat destruction, and it is hoped that the restoration projects currently under way will help to foster an increase.

Unfortunately, one obstacle to this is an introduced species, the Red-whiskered bulbul Pycnonotus jocosus. This is a fairly common cage bird, and has been introduced to both Mauritius and (more recently), Reunion. This has the potential to compete with the Merles, especially in human-modified habitats, and possibly act as a reservoir of disease. In addition, introduced predators such as rats may predate on nests.

Aside from habitat restoration, there is currently no specific conservation interventions aimed at benefiting the Mauritius bulbul. Some related species are however kept, and sometimes bred, in a few zoos, which provides a baseline of avicultural knowledge if a captive breeding programme for any of the Mascarene species is required, or possibly a re-introduction of a related species to Rodrigues.

Picture at top: Black Bulbul from Wikipedia
Picture at bottom: Red-Whiskered Bulbul from Wikipedia

Research colloquium

Each month Bristol Zoo invites a speaker to present a talk on various research projects of interest to zoo staff and students. Yesterday the talk was from Dr Vincent Nijman, of Oxford Brookes University, on “Welfare Atrocities: Keeping conditions of captive primates in Indonesia”. As you might guess from the title, it made for a pretty shocking evening.

The basic issue is that the attitude to wildlife in Indonesia can best be described as medieval. Animals are simply commodities, and concern for their welfare, except at one or two places, is basically nonexistent. If an animal dies it is simply replaced, usually by one bought from the local market. The talk focussed on gibbons, but by all accounts other taxa are treated no better. The typical cage is only one or two cubic metres, with no interior furniture or frequently any cover from the sun. Feeding is usually inadequate, and often provided by members of the public buying sweets, sugar cane, or other inadequate foods from stalls in the grounds. Water is often polluted, where it is present at all.

What is particularly distressing is that the vast amount of animal suffering could be avoided by only a few simple measures. Simply cleaning the cages would be a start (many are only cleaned when the animal dies and is thrown out), and provision of ropes, branches, or just better food would be a big start. Both food and labour are cheap, so cost is not really a factor.

The general tenor of the lecture was that some of the best help western zoos could give would be simple information and advice. I have to say that Bristol is ahead of the game hear – via our links to Ape Action Africa and Yaoundé Zoo in Cameroon we are providing training to zoo staff and local education outreach to schoolchildren, but plainly there is far more to be done everywhere.

One of the more overlooked elements in conservation education is the total lack of contact with nature amongst the poor of the developing world, and the inevitable lack of interest. If you are living in a slum – and with the urbanization of the last 50 years that is where vast numbers of people in the developing world live – then even learning what is living in your own country is not going to be at all easy. I would expect that more people in London have seen a lion or giraffe than citizens of Nairobi have for example.

I would be interested if any readers could let me know what their local zoo does about education overseas – do they have any partner zoos abroad for example?

On another note, the colloquia I mentioned above are open to the public. The programme for the rest of the year runs as follows:

7th October: Summer and Winter vitamin D3 levels in platyrrhines and lemurs housed at Bristol Zoo with outdoor access

4th November: Effects of habitat alteration on the ecology and behaviour of Sahamalaza Sportive Lemur (Lepilemur sahamalazensis)

3rd December: Nutrition research at Paignton Zoo: Myth and reality in the kitchen

Finally, there is an important symposium coming up on Thursday 29th October - following our 2008 symposium on evidence-based conservation, the Bristol Conservation and Science Foundation has for this year’s symposium invited primatologists, both from the in situ (field) and ex situ (zoo) sector, to discuss success stories and challenges in primate conservation programmes. We aim to bring together evidence on how well we are doing to date in saving primates from extinction, and to suggest ways forward to ensure the survival of our closest relatives beyond the 21st century. Special emphasis will be given to the role of zoos in primate conservation.Invited speakers include:

· Prof. John F. Oates
· Ian Redmond OBE
· Dr Anthony Rylands
· Dr Anna Nekaris
· Dr Jean-Marc Lernould

The one-day symposium will be held in the Clifton Pavilion at Bristol Zoo Gardens, starting at 10.00 am and finishing at 5.30 pm. Registration fees are £75 per person and include a buffet-style lunch as well as coffee/tea breaks between the sessions and entry to Bristol Zoo Gardens. Registration forms are available from the Bristol Zoo website.

A spiky problem

On view in Twilight World here at Bristol we have a group of interesting small rodents, the Turkish Spiny Mice Acomys cilicicus. Several UK zoos hold this species – Bristol has 75 (at last count!) and there are over 600 in UK zoos in all. The reason there are so many being kept is that the species is believed to be rare and possibly endangered in its homeland – at present it is only known from the type locality.

Spiny mice are an interesting group of rodents, with 20 or more species, mainly in Africa but some extending to the Greek islands, and, of course, Turkey. They are chiefly desert, or savannah woodland animals, and get their name from the bristly coat. It is believed this helps with heat regulation – the bristles would certainly not be an effective defence against predators.

Although long believed to be related to the murine rodents (house mice, brown rats and their allies) it now seems that the spiny mice belong to a separate group more closely related to gerbils, along with a few other African genera of rodents. Their reproductive biology is certainly different – instead of large litters of naked young, spiny mice produce small litters (2 – 3 in the case of A.cilicicus) of young after a fairly long gestation period of 5 – 6 weeks. The young are precocial, being born fully furred and with eyes open, and leave the nest when only a few days old. The life span is fairly long – up to 5 years although 3 – 4 is more usual.

As with most small desert rodents, spiny mice are omnivorous, feeding on seeds, flowers, plus some insects. The natural enemies would be cats, weasels or other small mammalian carnivores, birds of prey, and reptiles, especially snakes, although they are extremely alert and fast moving animals and I suspect from their fairly low reproductive rate that mortality in the wild is less than for similar rodents. They are good climbers, and will frequent bushes and rocky slopes as well as feeding on the ground. They do not seem to make nests – in the hot climates they prefer insulation is not really needed, and their habit of sleeping in groups (they are very sociable) means that even a cold night will pose few threats.

In captivity they need to be kept in groups – given sufficient space even multiple male groups work – with plenty of opportunity to climb. They need to be kept at least at room temperature – lower temperatures (below 15C) can stress them severely. In captivity the diet is a standard rodent mix with some added animal protein in the form of mealworms.

Some species of spiny mice are in the pet trade. The one usually seen is the Egyptian Spiny Mouse A.cahirinus, although the Golden Spiny Mouse A.russatus is also sometimes seen. They do not make especially good children’s pets though – they are a little inclined to nip and they move like lightening, which makes catching one when they get out a bit tricky. They are also good at chewing through plastic hamster cages – a large glass aquarium design is best.

Aside from the Turkish spiny mice most species from the mainland are not considered endangered, but the situation is different on the Greek islands. The Cyprus spiny mouse A.nesiotes has not been seen for many years and is believed extinct, and the Cretan spiny mouse A.minous is considered threatened. The reasons for the decline is probably an increase bin the human population, and even more cats, plus changes in land use reducing suitable habitat. One issue yet to be resolved however is the status of these endemic species – they are very similar to the widespread A.cahirinus and in view of the known tendency for rodents to hitch hike on ships from the earliest times, their must be a possibility that they reached the islands quite recently, possibly as a result of Greek or Roman shipping.

(Picture from Wikipedia)

Banana scoffers of Africa

Living in African rainforests, and with a few species in more open country, is a group of mostly highly colourful, fairly large, arboreal birds, the turacos. Despite their African origins, several species occur at fairly high altitudes, and they are less susceptible to cold in captivity than one might think. They appear to be alert and curious, and I have seen several used in flying displays.

They are fairly widespread in captivity, both in zoos and private breeders, and a few species, such as the White-Cheeked, are semi-domesticated, with a few colour mutations being bred. However, other species are far more difficult to breed and are rarely if ever seen. Most species are not threatened, although some forms are localised and may be at risk from deforestation.

Turacos are currently classified in over 38 distinct taxa, currently grouped into 22 species in 6 genera, with the majority in the large Green Turaco genus Tauraco. They are a fairly distinct group, but appear to be closest to a group of “near passerine” birds including the cuckoos.

There is a very odd feature of turaco colour – whereas in almost all birds green colour is a structural effect, resulting from the structure of the keratin in the feathers, in turacos the colour is due to a green pigment. This can be extracted from the feather with a weak alkali solution.

Most turacos are week fliers, preferring to run or hop through the branches with only short glides, although they are capable of powered flight. More open country species, such as the Go-Away birds Corythaixoides, are stronger fliers. As such, turacos are an interesting model for early birds, as these are also believed to have been week fliers with similar means of getting around in the trees, although turacos themselves are fairly advanced birds.

Turacos are mainly fruit eaters, although some species also eat surprising amounts of foliage, and a few species take at least some insects, especially when rearing chicks. They will also eat flowers. They seem to have a fondness for banana – in fact one genus, Musphaga, actually means “banana-eater”.

In captivity they are fed chopped fruit, an artificial diet for softbills (“softbill” is an avicultural term for non-seed-eating birds), plus some leafy vegetables such as broccoli and lettuce. Many keepers also provide seasonal wild fruits such as blackberries.

They are fairly territorial, although territory size in the wild is unknown, and in captivity are usually kept either singly or in pairs. Flock behaviour in the wild does not appear to occur.

Turacos make an open, cup-shaped nest with two eggs. In captivity they readily take to nesting baskets, which may mean that in the wild they also re-use other birds’ nests. The chicks hatch after approximately 22 days and grow rapidly, leaving the nest at two weeks, although at this point they cannot fly.

Bristol Zoo currently has one paid of Red-Crested Turacos (picture at top from Wikipedia) on show. Unfortunately the aviary is not a walk-through, as you need to see the birds in good light to appreciate their beauty. They are in the aviary just before you enter our Butterfly House – if a reader is visiting Bristol Zoo please check them out. There has recently been a stud book set up, managed by Cotswold Wildlife Park, which has several species of Turaco on show, including the largest species, the Great Blue Turaco, which is Toucan-sized.

For more information on turacos, see the International Turaco Society website http://www.turacos.org/

Land of the Dodo 12: The White-eyes

Scattered on most of the islands of the Indian Ocean, Australasia, and the pacific, as well as the mainland of Africa, and Asia is a huge group of small passerine birds, the White-Eyes, Zosterops. There are currently over a hundred species, with more being described each year. One would think that such diversity is a sign of a long history, but in fact the genus seems to have originated only a few million years ago. This makes Zosterops one of the fastest evolving vertebrate groups, about as fast as the well known cichlids of the African Rift Valley.

The reason for this rapid expansion is not altogether clear – separate species have evolved even on islands separated by only a few kilometres. This would suggest a species that does not move far, which is contradicted by the rapid spread of the genus as a whole. It appears that part of the reason is the short generation time and the tendency of the species to move around in flocks, which means that either large numbers of colonists arrive at a new location, or none – there is no steady “drip” of genes travelling from the source to the founder population.

White-eyes are fairly generalist small passerines, behaving in many ways like the leaf warblers Phylloscopus found across temperate Asia. The plumage is usually yellow-green, with a distinctive white eye-ring, which is where the name comes from.The main diet is insects, supplemented by fruits and nectar. The nest is an open cup made of grasses and moss, and the clutch is usually 2- 4 eggs.

There are three or four species surviving on the Mascarenes, living on Mauritius and Reunion. None are known from Rodrigues, but this may mean that they died out before being recorded. It appears that they are closest to the Asian White-eyes, although other Indian ocean islands have been colonised from Africa.
The Grey White-Eye is found on both Reunion and Mauritius. Depending on the taxonomist, the two islands are either home to a species each (Zosterops borbonicus and Zosterops mauritianus), or they are united as subspecies of the Reunion Grey White-eye shown here. Both forms are fairly distinctive, having lost the yellow in their plumage and also the white eye-ring, but in their behaviour they are typical white eyes. Both species are still common, probably because they are adapted to disturbed habitats such as man-made clearings.

Far more distinctive, and in more trouble, are the two species of Olive White-Eye. The Reunion species, Z.olivaceus, is allegedly still common, at least at higher elevations, but the Mauritius Olive White Eye Z.chloronothus (shown at top) is critically endangered, and is restricted to only 25 square kilometres on the mainland, with perhaps only 100 pairs. With a species with such a short lifespan this means that only 2 bad breeding seasons could result in its extinction, so strenuous efforts are being made to enable its survival, in the form of regeneration of native forest and captive breeding attempts. Some have been released on isle Aux Aigrettes, but until recently there had been no successful nesting. However, in October 2008 for the first time 2 young were fledged on the island.

The problem the Olive White-Eyes have is that they have become specialists. Unlike their adaptable ancestors, they have become specialist nectivores, feeding mainly on the nectar of native plants. With the widespread habitat destruction this has resulted in a loss of their food source, with inevitable results. Experiments are being made with supplemental feeding – as many in America who feed hummingbirds know, nectar feeding birds will often take to artificial feeding stations. The main problem is that nectar feeders tend to be territorial around food sources, so any feeding stations have to be widely scattered, which takes a lot of upkeep in difficult terrain.

Images- Mauritius Olive white-eye from Durrell Wildlife Conservation Trust
Reunion Grey White-eye from Wikipedia