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An adult Mount Rainier white-tailed ptarmigan in brown summer plumage. Its feathers change seasonally—white in the winter, white and brown in the spring. Its tail remains white year-round. Photo Credit: Pete Plage/USFWS |
In July, the Mount Rainier white-tailed ptarmigan was officially listed as threatened by the U.S. Fish and Wildlife Service (FWS) under the Endangered Species Act (ESA), 14 years after the Center for Biological Diversity first petitioned for its listing. This designation is meant to help preserve the bird, whose survival depends on the glaciers of the Cascade Mountains of Washington State and British Columbia. It also reflects the complex challenges that alpine-adapted birds face in a warming world.
With its feathered, snowshoe-like feet that allow it to walk on high mountain terrain and its seasonal plumage that provides camouflage year-round, Mount Rainier white-tailed ptarmigans are adapted to high elevation regions above the treeline. They are frequently spotted in areas with mixed rock, snow and alpine plants. Their diet consists of twigs, leaves, buds and seeds of alpine tundra vegetation that only grow in treeless, cold and dry mountainous regions that receive critical moisture from spring snowmelt and summer glacier runoff.
Warming temperatures are accelerating glacier retreat and endangering the bird’s habitat: glaciers in the North Cascades shrunk 56 percent between 1900 and 2009. Mauri Pelto, director of the North Cascade Glacier Climate Project, told GlacierHub that ptarmigans are often spotted along the Shuksan and Ptarmigan Ridges near Mount Baker. In a study, Pelto found that seven of the 13 glaciers along those ridges have disappeared since the mid-1980s. Retreating glaciers risk reduced soil water availability for tundra vegetation and long-term habitat loss associated with warming temperatures.