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Saturday, September 13, 2014
High Country Birding: White-tailed ptarmigan, the chameleon bird
Bob Bowers | Special to the Daily
Colorado and Summit County’s High Country provide a year-round home to a seldom-seen bird more commonly found in the alpine tundra of Alaska and northwest Canada, the white-tailed ptarmigan. Related to 21 species of other upland game birds, from grouse to quail, the white-tailed ptarmigan is the smallest bird in the grouse family and the only ptarmigan regularly found south of Canada. In the lower 48 states, the largest white-tailed ptarmigan territory is in Colorado, where it lives year-round at or above timberline.
This is a fairly good-sized bird for being difficult to find, at about a foot in length, weighing a pound and with nearly 2 feet of wingspan. At that size, and as a permanent resident of the state, the bird would be easy to find, one might think, if not on the treeless summer slopes at least in the pure white of snow-swept winter High Country. However, this is a bird prized by high-mountain predators and, consequently, has evolved cryptic plumage as camouflage that fits every mountain season.
The white-tailed ptarmigan’s plumage turns mottled and barred in spring, with brown feathers on its head, back and breast and white on its belly, tail and wings. This camouflage blends perfectly with the rocky tundra, making it extremely difficult to find a ptarmigan at rest, whether you are a golden eagle or a High Country birder. Likewise, as winter arrives and snow covers the alpine rocks, all of the white-tailed ptarmigan’s brown feathers are replaced with white, leaving only two small black eyes and a small black bill to locate the bird in the snow banks where it roosts, making winter spotting even more difficult than summer.
Nevertheless, predators are as patient as they are hungry, and ptarmigan mortality rates, especially for newly fledged birds, are high. Like quail and other family members, ptarmigans are hatched as precocial, meaning they are out of the nest and foraging less than a day after hatching. Also like other family members, they are hatched in numbers, typically up to eight, which is important for survival when more than 50 percent of the young are lost to predation. Those that survive, however, can live up to 15 years or more, perfecting their habitat-blending skills along the way.
The downy young start life by eating insects but soon switch to a vegetarian diet consisting of flowers, buds, leaves, seeds and twigs. Willow is their preferred food source, but they are happy with needles in the dead of winter, when they move down closer to timberline. The bitter cold of winter doesn’t seem to be much more than a seasonal inconvenience to the ptarmigan, either. They conserve their energy in winter by avoiding flight and seeking out warmer snow banks for long roosts.
They’ve also developed feathers around their nostrils to mitigate breathing icy air and even grow feathers on their feet to give them snowshoe-like insulation against snow. Those feathered feet gave them their genus name, Lagopus (foot of the hare), and their full scientific name, Lagopus leucurus, means “white-tailed hare-feet.” Not the most complimentary of names, maybe, but at least it’s accurate.