This is a northern bird in the purest sense, a denizen of Arctic and alpine tundra during the summer, moving south to the forest only for winter. In their pure white winter plumage (they are brown in summer), ptarmigan stand out sharply on bare branches and against deep blue sky; and their low croaking (from which their onomatopoetic Koyukon name, dilbagga, derives) also helps to give them away. But when they land on the snow they mysteriously vanish. – Richard Nelson, Make Prayers to the Raven
The Willow Ptarmigan, the Alaska State Bird, is the largest and most numerous of North America's three species of ptarmigan. They are well-suited for life in the Arctic with feet that are feathered to the toenails, a tendency to spend most of a cold winter day in a snow burrow, and an annual replacement of feathers that keeps them in cryptic plumage year-round (white in the winter and brown in the summer). Willow Ptarmigan are considered architects of the tundra because they intensely browse willow shrubs in ways that influence the plant’s growth and reproduction. Clucking and calling ptarmigan are sure to get your attention but finding this cleverly camouflaged bird, if it is still and quiet, can be tricky.
Christie, K. S., Bryant, J. P., Gough, L., Ravolainen, V. T., Ruess, R. W., & Tape, K. D. (2015). The role of vertebrate herbivores in regulating shrub expansion in the Arctic: a synthesis. BioScience, 65(12), 1123-1133.
Hannon, S. J., P. K. Eason, and K. Martin (2020). Willow Ptarmigan (Lagopus lagopus), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi-org.arlis.idm.oclc.org/10.2173/bow.wilpta.01
Nelson, R. K. (1983). Make prayers to the raven: A Koyukon view of the northern forest. University of Chicago Press.