The Cairngorms provide a unique alpine semi-tundra moorland habitat, home to many rare plants, birds and animals. Speciality bird species on the plateaux include breeding ptarmigan, dotterel, snow bunting, golden eagle, ring ouzel and red grouse, with snowy owl, twite, purple sandpiper and Lapland bunting seen on occasion. Mammal species include red deer and mountain hare, as well as the only herd of reindeer in the British Isles. They now roam the high Cairngorms, after being re-introduced in 1952 by a Swedish herdsman. The herd is now stable at around 150 individuals, some born in Scotland and some introduced from Sweden.