The Alpine Zone and White-Tailed Ptarmigan
By David Cronenwett
On a clear day from my desk window, I can see the limestone peaks of the Front nearly thirty miles distant. Though the prairies have begun to thaw, winter will hold tight in the high mountains for many weeks to come. I’ve never been to the Arctic, but have spent a great deal of time in the alpine zone of Montana’s backcountry, which shares many similarities with the barrens far to the North. For much of the year, the land above the trees is a frigid, wind-blasted and inhospitable realm. Deep snow and highly unpredictable weather add to the hardship inhabitants of this environment must regularly endure.
20,000 years ago in Montana, these kinds of conditions dominated the landscape. As the last ice age finally receded and the country warmed, a few species strongly adapted to the cold remained in, or retreated to, the high alpine zones while lower elevations transformed over time into grassland, deserts and other habitats. Species we know today as holdovers from the Pleistocene era are Canada lynx, woodland caribou, wolverine, snowshoe hare and the smallest member of the grouse family, the white-tailed Ptarmigan (Lagopus leucurus). The species can be found in from northern New Mexico up the spine of the Rockies to Alaska. Two other native ptarmigans, the willow and rock ptarmigan occupy different ranges and habitats. Neither occur south of Canada.
Like many arctic animals, the white-tailed varies its color as the seasons change; during the warmer months, it is a brown-gray dappled mix, perfect camouflage for a rock and tundra landscape. As winter approaches, its plumage transforms to entirely white…with the exception of black outer tail feathers, despite what the bird’s name suggests. The sexes are identical the male birds being slightly larger, a good-sized one weighing in at just over one pound. The white-tailed ptarmigan is the only Montana bird that spends its entire life cycle in the alpine-arctic zone. While it may venture into sparse subalpine forest on occasion, it is far more comfortable in the open. Predation by golden eagles and other raptors does occur but ptarmigans blend so seamlessly into their environment that mortality from predators is minimal.
Feathered feet and nostrils are specialized adaptations that provide protection from the deep cold. Like some other members of the grouse family, white-tailed ptarmigans will dig a temporary “snow nest” in frigid conditions; if, while traveling the alpine, you come across a pile of 50 or so grouse-like droppings in one spot, it may well have been a white-tailed ptarmigan’s snow shelter. During winter, ptarmigans consume a meager diet of leaf willow buds and conifer needles. This highly fibrous, woody material is impossible for most birds to consume in quantity but ptarmigan and other grouse have gut bacteria present in the cecum (part of the intestines) capable of digesting cellulose almost completely. This unusual adaptation is more often associated with beavers and porcupines than birds. In summer, ptarmigans transition to feed on alpine flowers, seeds, succulent leaves and berries.
In Montana, white-tailed ptarmigans are most commonly found in the Glacier-Bob Marshall-Mission Mountains high country, though populations could exist in other ranges with suitable habitat. If you have your heart set on viewing a white-tailed ptarmigan, head to Logan Pass in Glacier Park; a keen eye can pick them out negotiating the tundra and rock fields. Ptarmigans appears surprisingly absent from the largest swath of alpine tundra habitat in the state, the Beartooth plateau. Biologists suspect that a dearth of suitable willow-shrub habitat for breeding is to blame.
The most significant long-term threat to the bird’s presence south of Canada is climate change. Populations in northern New Mexico, the southernmost known extension of ptarmigans, are currently being studied to understand how the species might adapt to displacement of its alpine habitat…that is, if it is even possible to adapt. In 2012, responding to a legal petition, the US Fish and Wildlife Service agreed that certain subspecies of white-tailed ptarmigan may warrant protection under the Endangered Species Act because of immanent climate change concerns. Considered an indicator species for the health of its larger habitat, a potential Endangered listing is a sign that Fish and Wildlife recognizes the threat that global warming poses to the alpine ecosystem.
As I sit and gaze across miles of prairie to the snow clad peaks of the Front, it isn’t difficult to consider a future in which the alpine zone as we know it in Montana, largely disappears. At this point, even massive reductions in global emissions are unlikely to reverse projected warming and subsequent habitat conversion over the next century. While most of the alpine species we care about will probably continue to exist further north, the disappearance of creatures that have been present in this part of the world since the ice retreated, will be a great loss. The ptarmigan is an ambassador for the lofty world of flowers and tundra we still know today and what happens with this bird dubbed the “canary of the alpine” will likely foreshadow other transformations to its environment. Along with pursuing all conservation measures, it may also be our human responsibility to simply get out there and bear witness to the changes we are imposing on the landscape. Then at least, there may be a record in our collective memory of a time when wolverine, lynx and ptarmigan shared the high mountains with us.