Genus LAGOPUS, Vieillot.
Lagopus, Vieillot, Analyse, 1816. (Type, Tetrao lagopus, L.)
Gen. Char. Nasal groove densely clothed with feathers. Tail of sixteen or eighteen feathers. Legs closely feathered to the claws. The northern species snow white in winter.
The Ptarmigans inhabit the northern regions of both hemispheres, and with the Arctic fox and hares, the lemmings, and a few other species, characterize the Arctic zone. They are of rare occurrence within the limits of the United States, though farther north they become abundant. The species all change to white in winter, except L. scoticus, which appears to be merely a permanently dark, southern, insular form of L. albus. (See Alfred Newton in Proceedings of the Philadelphia Academy, July, 1871, pp. 96, 97.)
Species and Varieties.
A. Tail-feathers always with more or less black.
1. L. mutus. Bill small, slender, the length from the nasal groove to the tip decidedly more than the height through the base. Male in winter with a black stripe on the lores.
♂ in summer with uniform black feathers on the breast; autumnal plumage bluish-gray, mottled. Hab. Northern Europe … var. mutus.
♂ in summer without uniform black feathers on the breast. Autumnal plumage orange-rufous. Hab. Northern North America; Greenland; Iceland … var. rupestris.
2. L. albus. Bill large, stout; the length from the nasal groove less, or not more, than the height through the base. Male in winter without black stripe on lores. Hab. Northern Europe and northern North America.