Scotland is rich in animal life for its size. Herds of red deer graze in the corries and remote glens; although formerly woodland dwellers, they are now found mainly on higher ground, but roe deer still inhabit the woods, along with sika and fallow deer (both introduced species) in some areas. Foxes and badgers are widespread, and the number of wildcats may be increasing. Rabbits were once decimated by the disease myxomatosis but have largely recovered to earlier numbers. Pine marten, otters, and mountain and brown hares are among other wild mammals. A few ospreys nest in Scotland, and golden eagles, buzzards, peregrine falcons, and kestrels are the most notable of resident birds of prey. The red grouse, the Scottish subspecies of the willow grouse, has long been hunted for sport. Other species of grouse include the ptarmigan, found only at higher elevations, and the large capercaillie, which has been reintroduced into Scotland's pine woodlands. Large numbers of seabirds, such as gannets, fulmars, guillemots, and gulls breed on cliffs and on the stacks (isolated rocks) around the magnificent coasts. Almost half the world's Atlantic, or gray, seals breed in Scottish waters, especially around the Northern and Western Isles, as do numerous common seals; dolphins and porpoises are regularly seen and whales occasionally, especially on the west coast.