Capercaillie ecology

The Capercaillie (Tetrao urogallus) is a magnificent turkey-sized bird whose habitat is restricted almost entirely to the mature Caledonian Pinewoods of the Highlands of Scotland. Capercaillies are a member of the grouse family, tetraonidae, and are the largest in the world. Males (cocks) can weigh up to four and a half kilos and are around three times larger than the female (hen). The UK population has decreased in size so rapidly that it is threatened yet again by extinction. There are now only an estimated 1000 breeding birds in the UK.

Habitat, Diet & Breeding

The Capercaillie’s ideal home is native pinewood with a good under storey of heather, Blueberry or Bilberry and Crowberry. They can also live quite well in forestry plantations of Scots Pine, Spruce and Larch but do not breed so well in this man-made habitat. During the summer months the adults eat the leaves, shoots and berries of blueberry along with the invertebrates that live on them. They may also eat the leaves of deciduous trees. Invertebrates are an extremely important part of the chick’s diet during the first few weeks after hatching. Throughout the winter months, when all the deciduous plants and trees have lots their leaves, the Capercaillie eat the needles and cones of Scots Pine and if nothing else available, Spruce and Douglas fir needles. Nests are constructed by the female by scraping a hollow at the base of a pine tree and lining it with feathers, moss and needles. She then lays between 7 and 11 creamy coloured eggs with red-brown speckles. Incubation lasts between 24 and 26 days and fledging occurs at 2 – 3 weeks.

Behaviour

One of the most notable characteristics of Capercaillie is their imposing breeding display. During April and May males congregate in a communal breeding ground (known as a Lek) to display and attract females. This flamboyant exhibition may well have contributed to the decline of the birds as hunters would take advantage of their oblivious state during lekking. Each cock performs a sort of song and dance that consists of pops and clicks and wheezes and the puffing out of their feathers and fanning of their large tail feathers. They may leap in to the air. It is a wonderful sight.

Threats to Capercaillie

One of the biggest threats to Capercaillie at present is habitat loss. Caledonian Pinewoods have declined dramatically over the last few centuries. Climate change in the past has had a major impact on these woodlands. A spell of wetter and windier weather around 2000 BC meant it was very difficult for trees to regenerate: Soils became waterlogged and peat started forming. The introduction of hill sheep meant large areas of native woodlands were cleared for grazing; trees were felled for fuel and also for timber. Since the introduction of sporting estates in the 1800’s, red deer have grazed heavily on tree seedlings. The removal of our pinewoods has left the Capercaillie with an extremely limited range of habitat.

Want to see Capercaillie in the wild? Join our brilliant spring birdwatching week!

Visit the Aigas Capercaillie breeding programme page.