Willow Grous or Large Ptarmigan, Nuttall, Manual, part ii. p. 674.
Adult Male, in summer. Plate CXCI. Fig. 1.
Bill short, robust; upper mandible with the dorsal outline curved, the edges overlapping, the tip declinate and rounded, the basal part with a deep sinus on each side, lower mandible convex, broad, with the tip rounded. Nostrils basal, roundish, concealed by the feathers. Head small, neck rather long, body bulky. Feet of ordinary length; tarsus feathered, as are the toes, excepting towards the end, where they are covered with small scales and three terminal scutella; hind toe extremely short, two lateral equal; claws slightly arched, depressed, broad, with thin edges, and rounded.
Plumage compact, the feathers generally rounded, those of the head and upper neck narrow and proportionally short. The legs and toes covered with hair-like feathers. Wings short, the primaries strong, narrow, tapering, curved, third longest, second and fourth little shorter. Tail short, even, or very slightly rounded, of fourteen broad feathers, and four narrower central ones, which are superior.
Bill black. Iris brown. Toes and claws dark brown, the edges of the latter yellowish-grey. Head and neck bright chestnut, the feathers on the back part of the latter and crown of the head barred with black, and tipped with whitish. The back, some of the wing-coverts, the nearer secondary quills, the four upper tail-feathers, the anterior part of the breast, and part of the sides under the wings, variegated with brownish-black, chestnut and white, the feathers being of the first colour in the middle, and transversely barred with the second towards the end, while the terminal margin is of the last. Most of the coverts, all the primaries, and the greater number of the secondaries, with the whole under surface of the wings, the middle of the breast, the abdomen, legs and feet, pure white, the shafts of the primaries are more or less brown, excepting towards the ends, The fourteen tail-feathers are brownish-black, with the tips white, as is the basal portion of the outer web of the outermost. The superciliary membranes are vermilion.
Length 17 inches, extent of wings 26½; bill along the ridge ¾; tarsus 1½; middle toe with the nail 1 7⁄12; weight 1¼ lb.
Adult Female, in summer. Plate CXCI. Fig. 2.
In the female the superciliary membrane is much smaller, but of the same colour, as are the wings and tail. The head, neck, breast, abdomen, sides, as well as the upper parts, are variegated in a manner resembling the back of the male, but with the black spots larger, and the transverse bars of light brownish-red, broader and less numerous; the lower surface much lighter.
Length 16 inches, extent of wings 25; weight 1 lb.
Young a few days old. Plate CXCI. Fig. 3, 3.