Colorado ptarmigan populations holding steady
Yet the southern white-tailed ptarmigan faces challenges from climate change, recreation pressures
Populations of southern white-tailed ptarmigan, an iconic yet well-camouflaged and easily overlooked bird of Colorado’s alpine regions, appear to be holding steady. But long-term concerns about its future remain in a warming world with growing numbers of people recreating in the state’s fragile alpine ecosystems.
The southern white-tailed ptarmigan is one of several subspecies of white-tailed ptarmigan, which is the smallest member of the grouse family. The southern subspecies is known only from Colorado and mountains in northern New Mexico, where it lives year-round in alpine environments at or above treeline. It is the only type of ptarmigan found in Colorado.
Colorado Parks and Wildlife undertook a multiple-year study of the alpine bird following an August 2010 petition by the Center for Biological Diversity to have the U.S. Fish and Wildlife Service list it as a threatened or endangered species.
The federal agency determined earlier this December that a listing and additional protections are not warranted. The agency is reportedly still considering a listing for the Mt. Rainier white-tailed ptarmigan, another subspecies found in the northern Cascades.
“This study took on a statewide focus and the report was peer reviewed to guarantee its integrity,” David Klute, species conservation unit coordinator for Colorado Parks and Wildlife, said in a news release. “The ‘not warranted’ decision by the U.S. Fish and Wildlife Service recognized the thoroughness of our work and the quality of the information it provided.”
The roughly seven-year study and its report, completed in 2018, found that populations and distribution of the southern white-tailed ptarmigan in Colorado have not changed much since the 1960s and 1970s, when it was last extensively studied, with the bird widely distributed in suitable alpine habitat across the state.
“We were thinking we wanted to reassess the bird, and then the petition came out. That kind of kickstarted our project,” said Amy Seglund, a conservation biologist at Colorado Parks and Wildlife who coordinated the study.
The bird, which is sometimes encountered on alpine hikes in Eagle County, is probably best known for its changing plumage. Birds are white in winter, to help them blend in with their snowy surroundings, and a mottled brown and gray other times of the year. The birds are uniquely adapted to their harsh, cold environment, with heavily-feathered feet that act as snowshoes.
Like other alpine species, the southern white-tailed ptarmigan is expected to face major challenges from a warming climate. Life on the alpine tundra is already hard for the birds, with less than one chick from ptarmigan nests that average roughly five and a half eggs surviving, according to Colorado Parks and Wildlife.
The birds burrow into soft snow during winter for warmth and insulation. That’s expected to be problematic if their alpine habitat sees more rain on snow events as part of a changing climate.
Snow arriving later or melting earlier than it historically has also makes the birds’ seasonal plumage less effective camouflage and makes them more vulnerable to predation.
“Like this year, people were taking pictures of white ptarmigan when there was no snow,” Seglund said.
Hotter, drier summers associated with climate change are expected to pose more challenges for the birds. And while Colorado has expansive alpine habitat, higher recreation pressures can also make trouble for the birds, making it difficult for them to nest in heavily trafficked areas.
During the course of the study, the ptarmigan disappeared from a narrow alpine meadow in the heavily-traveled Ice Lakes area near Silverton, and researchers have also found some birds killed by off-leash dogs. “People need to be responsible with their pets,” Seglund said.
Colorado generally had steady winter storms and consistent summer monsoon rains during the ptarmigan study, and that hasn’t necessarily been the case in the years since then, with varying winters and drier summers, Seglund said.
“We found they looked like they were doing OK when the study ended, but we definitely need to keep an eye on them,” Seglund said. “As an agency, just because it was good this last go-round, it’s our job to keep an eye on them and try to manage those threats we see and the ones we can actually manage.”
Tom Lotshaw can be reached at firstname.lastname@example.org.
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