Hens usually lay six to ten eggs which are incubated for three weeks. Hatching takes place in late June and early July throughout Alaska. The male Willow Ptarmigan stays with the family and doesn t hesitate to defend the brood, but male White-tails and Rock Ptarmigan leave the care of chicks entirely to hens. The chicks grow with amazing speed. They can get off the ground only 9 to 10 days after hatching and fly well when they get their first full set of flight feathers at 8 to 10 weeks of age.
Autumn is a time of restlessness.
Flocks form and disperse and form again, and the birds move around into unfamiliar alpine areas. Ptarmigan are nomadic in winter, moving erratically from one sheltered slope or patch of food to another from November to March. The birds are quite sociable in winter and usually feed and roost in the snow close together. In April and early May, flocks of ptarmigan numbering several thousand sometimes appear in purposeful movement back to their breeding grounds. These huge flocks, perhaps created by the funneling effect of river valleys and narrow mountain passes, rapidly disintegrate when the summering areas are reached, as each cock demands his share of elbow room in the vast stretches of white and brown tundra.