As the first hints of winter blow across North America, many birds begin their migration to southern climes. Those dependent on insects or nectar are the first to leave, staying ahead of the freeze line as it gradually dips across the Continent. More hardy species, capable of surviving on seeds, berries and hibernating insects, do not migrate or merely move from the North Woods to the Temperate Zone. Some, such as great gray owls, snowy owls and snow buntings are irruptive species, moving south only if forced to do so by heavy snows or dwindling food supplies.
Like the flatlanders, mountain birds escape the stress of winter by heading to milder climes; in many cases, this is limited to vertical migration, a descent to elevations with warmer temperatures and less snow. Along the Colorado Front Range, a variety of mountain birds visit the urban corridor during the winter months; these include mountain chickadees, red crossbills, Cassin's finches, Townsend's solitaires and gray-headed juncos, among others.
But there is one bird that defies this pattern, moving to higher elevations for the winter. The blue grouse, common throughout the western mountains, from northwest Canada to New Mexico, summers and breeds in the open, ponderosa pine woodlands of the lower mountains and foothills; there they feed on insects, seeds, berries, buds and pine needles. Come winter, they ascend to the Subalpine Zone, surviving on the foliage of conifers (pine, spruce and fir). There must be a good reason for this behavior......but it escapes me!
