Saturday, 3 November 2012

Galliformes 11: The Capercaillie

Male Western Capercaillie
One of the largest birds in Britain is also a close relative of the Black Grouse, the Capercaillie Tetrao urogallus. Among other distinctions, it was the first native species to be reintroduced to this country after having been exterminated by human activity (mostly deforestation and over-hunting). Although the reintroduction was at first highly successful, today the species is in trouble once more, and a good deal of intervention is underway to prevent it going extinct a second time.

Technically referred to in the guides as the Western Capercaillie, T.urogallus has a range centred on the Taiga forests of Scandinavia eastward into western Russia. In eastern Russia across into China it is replaced by the very similar Black-billed Capercaillie, T.parvirostris. The western species is also found in suitable habitat in the Alps and Pyrenees’, which points to a much wider range during the last glaciation. The original British population was basically another survivor from the last Ice Age, and by historical times was confined to Scotland and Ireland, although subfossil remains show it was once found to the south as well. Globally, both species are classed as Least Concern, although other populations of Western Capercaillie on the continent are also declining.
Male Black-billed Capercaillie
The habitat of the Capercaillie is highly specific as a result of its unique diet. All grouse feed on foliage to a large extent, but from October through to spring the diet of the Capercaillie is almost entirely composed of the buds and needles of Larch and Scots Pine, which practically nothing else in the world can digest. In the spring and summer they switch to more nutritious food in the form of the foliage and fruits of Bilberry Vaccinium myrtillus (also eaten by its relative the Black Grouse), and a variety of insects, especially Wood Ants. These food sources are found in old, fairly open coniferous forest both natural and modified by forestry. The birds can use conifer plantations temporarily but the habitat structure does not provide enough understory vegetation or suitable sites to perch, so they do not breed there.

Female Western Capercaillie
Capercaillies are highly dimorphic, with males reaching nearly 1m beak-to-tail and weighing over 4kg. Females are around 2/3 the size of the males and as with Black Grouse carry out all nest-building and chick-rearing alone. The males gather at leks like their smaller relatives the Black Grouse to show of their amazing display to each other and any visiting females. After mating, the hens will lay a clutch of up to 12 eggs (usually less) on the ground in a typical scrape and when the chicks hatch will lead them around her territory looking for food. At this stage they are very vulnerable to wet weather, and most of the reintroduced population is found in Eastern Scotland. The chicks grow rapidly and can fly a little by the time they are a month old. By the time they are around 3 months old they are fully independent and disperse to find their own territories to survive the winter. For a good video of a Capercaillie lek see here:

The extinction of the Capercaillie in Scotland was a combination of the extensive deforestation from the late medieval period onwards combined with additional hunting pressure following the development of modern firearms. The last record of the native form (which may have been a distinct subspecies) is a brief description on the back of a watercolour found in 1886 at Balmoral Castle in Aberdeenshire: “Two coileach-coille, capercailzie, shot on the occaision of a marriage rejoicing in 1785, and which Sir Robert is confident are the last of the native birds heard of in Scotland.” In Ireland, where the suitable habitat was always in short supply, deforestation had caused their extinction probably by 1750.

The first reintroduction attempts in Scotland began within 50 years of its extinction. Various Scottish aristocrats obtained live birds from the continent, mostly Sweden, and released them into their estates. The first success came in 1837 at Taymouth Castle, in Perthshire, where Lord Breadalbane released nearly 50 birds into the forests of his estate, followed the following year by another 16 hens. Eggs were laid, and as an additional measure some clutches were collected and placed in the nests of Black Grouse (then much commoner than today) to increase productivity. From there additional birds were translocated around the Highlands, furth extending their range. In western Scotland however the birds did not thrive, probably because of the wetter climate.

Unfortunately, in recent years the Capercaillie in Scotland has begun to decline. The series of wet summers has seriously reduced breeding success, and fences put up to keep deer out of young conifer plantations cause mortality from collisions. A lot of work has been done into removing redundant fencing, and this may help somewhat, but the great expansion of the deer population is potentially degrading the habitat and preventing natural forest regeneration.

One of the major issues with forest management in the UK, both in Scotland and in England, is the great increase in deer numbers in recent years. In the absence of apex predators like wolves, which died out in Scotland not long before the last native Capercaillie, deer populations have to be managed by shooting, and although demand for venison is growing at the moment, it is still not high enough to make much of an impact on deer numbers. In addition, the kind of people who become involved in conservation in urbanised societies like Britain are also the most likely to be opposed to hunting, which makes the whole issue even more complicated as there is a built in contradiction between their opinions on hunting wild animals and what needs to be done to maintain the habitat for wildlife in good condition. Personally, I have no objection to hunting as long as people make use of what they shoot or catch, and hunters know how to shoot straight, but I expect other readers of this blog may feel differently.

Next week, the only migrant gamebird in Britain, the Quail.

(images from wikipedia)

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