White-tailed Ptarmigan: Rocky’s Elusive Alpine Dweller

Summer plumage ptarmigan camouflaged in the adjacent lichen covered rocks.

NPS/A Schonlau

Southern white-tailed ptarmigan (Lagopus leucura altipetens) are a memorable sighting in the alpine of Rocky Mountain National Park (RMNP). Last August, while working on a revegetation project with the Vegetation Crew, I was up on some rocks, scouting for native seed to collect for future alpine revegetation projects. Out of nowhere, or so it felt, there were three ptarmigan. It seemed I had walked right into their home, rock hoping, looking for ripe seed to collect, just as they were looking for ripe seeds to eat! I stayed put on my rock and observed them calling to each other as they waddled around me and over various rocks, foraging for food.

The reason why I didn’t see them at first is because they are expert at camouflaging into the landscape. They have grayish-brown mottled plumage in the summer and white plumage in the winter, which means they spends eight months of the year molting feathers! That is big energy output that they need to prepare for in the summer months. When hiking on trails in the tundra, these birds, which are the smallest of the grouse in North America, blend in so well that you may walk right by them, nestled in the rocks for protection, or foraging for plant material like stems, leaves, flowers and seeds.

Winter plumage ptarmigan sitting below a spruce.

NPS/K Daugherty

Trying to spot them in winter months? It may be even harder. Most of the time these birds don’t roost at the snow surface to be exposed to the harsh tundra elements. According to Michael A. Schroeder, a wildlife biologist at Washington Department of Fish and Wildlife, these birds can burrow deep into the snow, up to a foot deep, creating cozy caves called snow roosts. These roosts offer a warm, comfortable alternative to frigid overnight surface temperatures. In the winter days, they can be found on the snow surface, searching for bits of willow and other stems popping up through the snow. (Yuhas 2014)

CSU researchers work on affixing a band to track individuals in the population along Trail Ridge Road

NPS

Researchers at Colorado State University (CSU) and the U.S. Geological Survey (USGS) have been gathering demographic data for white-tailed ptarmigan in RMNP (Trail Ridge Road population). This population has been monitored yearly since 1966, with a 10-year break between 2000 and 2010. Since 2010, data has been collected through banding and band re-sight, to allow for estimation of survival and reproductive success. From 2013 through 2016, radio-telemetry tracking of hens took place to monitor nest success and chick survival and evaluate habitat requirements.

The Trail Ridge Road ptarmigan has had a tough go of it – between the mid-1970s and 2000, the population had declined by 66%. Ongoing studies are investigating changes in the seasonal timing (also called "phenology") of breeding and habitat use to learn what contributes to the decline. Spring snow depth and melt times can alter reproduction and laying of eggs, especially if the process is mistimed relative when food emerges (Wann 2017). If warming springs are reducing snowpack earlier in the year, yet ptarmigan are remaining white and haven’t started their molting phase, their survival may be affected due to predation (Wann et al. 2016). These alpine predators are coyotes, foxes, and raptors.

Alpine willows (Salix planifolia and S. brachycarpa) are important habitat indicators. Studies are looking at browsing levels on the willow by ungulates such as elk (Cervus canadensis) or moose (Alces alces). These large ungulates spend their summers in the high country to escape the heat of the lower valleys below, and willow is a primary food source for both moose and ptarmigan. Elk like to nibble on it too. Ptarmigan also rely on alpine willows for nest site selection and hens at RMNP are more likely to nest in areas with more willow cover. Changing habitat conditions and food competition, specifically the availability of alpine willow, limit suitable nesting habitat for ptarmigan, and could be additional factors contributing to population decline.

The southern white-tailed ptarmigan, as well as the Mt. Rainier white-tailed ptarmigan (L. l. rainierensis), are both "Under Review" for potential protection under the U.S. Endangered Species Act. They were petitioned to be listed as Threatened with Critical Habitat in 2012 by the U.S. Fish and Wildlife Service, and in March 2020, work began on a Species Status Assessment (SSA) to help determine if such protection is needed.

When wandering on the high alpine trails this summer, keep your eye out for these special birds, listen for their calls in the rocks, and you may just get to have your own special moment surrounded by Ptarmigan too!

To learn what the males and females sound like, along with their respective distress calls, use this resource. You can also search for any other bird species and learn their calls too! https://www.allaboutbirds.org/guide/White-tailed_Ptarmigan/sounds

References:
King S. and C. Turner. 2018. Resource Brief: Southern White-tailed Ptarmigan. Continental Divide Research Learning Center, Rocky Mountain National Park. https://irma.nps.gov/DataStore/Reference/Profile/2252846

Wann, G.T. 2017. Reproductive Ecology and Population Viability of Alpine Endemic Ptarmigan Populations in Colorado. Colorado State University, Dissertation.

Wann. G.T, C.L. Aldridge, and C.E. Braun. 2016. Effects of Seasonal Weather on Breeding Phenology and Reproductive Success of Alpine Ptarmigan in Colorado. PLoS ONE 11(7): e0158913. doi:10.1371/journal.pone.0158913

Yuhas. D. 2014. Ptarmigan May Be Tops in Adapting to Winter Weather. National Audubon Society. https://www.audubon.org/news/ptarmigan-may-be-tops-adapting-winter-weather

U.S. Fish & Wildlife Service. ECOS Environmental Conservation Online System. https://ecos.fws.gov/ecp0/profile/speciesProfile?spcode=B0H8

Camille Thorson, Learning Specialist

Continental Divide Research Learning Center

July 2020