Willow ptarmigan seeds and berries during the summer and largely subsisting on the buds and twigs of willow and other dwarf shrubs and trees during the winter. The willow ptarmigan is a medium to large ground-dwelling bird and is the most numerous of the three species of ptarmigan. Males and females are about the same size, the adult length varying between with a wingspan ranging from . The weight is . It is deep-chested and has a fairly long neck, a broad bill, short feathered legs and a moderately short rounded tail. In the summer, the male's plumage is marbled brown, with
White-tailed ptarmigan to hatch. Males remain in the vicinity of the nest until the eggs hatch, a period of about 23 days. The precocial young leave the nest six to twelve hours after hatching. They are at first covered with down but become fully fledged in seven to ten days. Ptarmigan chicks begin their lives eating insects. Once the chicks' digestive tracts and ceca are more fully developed, their diets shift to one of flowers and leaves. Hens choose foraging patches where plant species containing proteins are abundant. The hens call their chicks to these plants, which are critical for the growth