Watching pikas on Mount Rainier: 900 talus sites surveyed since 2007

A small mammal that cannot take much heat lives on the slopes of a mountain that shrinks as you climb it. That is the American pika's problem at Mount Rainier National Park, where staff and volunteers have identified 900 pika sites since 2007. This summary follows a park science brief by Michael Hansen, Anna Mangan and Tara Chestnut.

American pika. NPS photo.

A mammal built for cold

The American pika (Ochotona princeps) is a small herbivore related to rabbits and hares, living in mountains of western North America, mostly in talus, patches of fragmented rock and boulder fields. It does not hibernate. In summer it gathers ferns, grasses, herbs, bits of shrub and conifer twigs into "haypiles" to eat through winter. A thick coat and a high metabolism keep it warm, but also make it prone to overheating: the brief, citing research, says as little as two hours above 28°C (82.4°F) can be fatal. Talus keeps a fairly steady temperature, cool in summer and warm in winter.

Pikas are declining or disappearing in some parts of their range in response to human-caused climate change. Warmer, drier talus may be pushing them uphill, but a mountain's land area narrows with elevation and suitable rock and plants thin out, leaving few places to go. Populations respond differently from region to region, so detailed monitoring across the range is needed to see how each is doing and how to manage them.

Counting pikas at Mount Rainier

The park started monitoring in 2007, at first to check the effects of road maintenance and construction on nearby pikas. Each site is a separate patch of talus holding one or more pika territories. The park's goals are to learn where pikas live and what habitat they choose, watch for impacts from road building and other disturbance, and track their status over time.

American pika sites at Mount Rainier National Park, in roadway project areas (light blue) and wilderness areas (dark blue). NPS image.

Surveyors search talus patches by looking and listening for pikas and by finding haypiles and scat, which tell them how many territories a patch holds and the minimum number of animals. As many as 35 pikas have been seen in one patch. They also record each site's slope and aspect, patch size, average rock size, the quality and abundance of the plants pikas gather, and the surrounding habitat, such as forest or meadow.

Fresh pika scat, one sign surveyors look for, is the size and shape of peppercorns. NPS/A. Mangan photo.

A large haypile made mostly of ferns. Haypiles range from a few stems to several cubic feet of vegetation. NPS/A. Mangan photo.

What is known so far

Pikas are widespread in the park and use talus of every size, from a few boulders to areas bigger than a soccer field. The data have not yet been analyzed to say whether their numbers are stable, rising or falling.

Three pika sites near Chutla Peak. Small sites can be just a few boulders; large ones can cover whole hillsides. NPS/A. Mangan photo.

Sources

• National Park Service, Mount Rainier Science Brief "American Pika at Mount Rainier National Park" by Michael Hansen, Anna Mangan and Tara Chestnut (https://www.nps.gov/articles/american-pika-at-mount-rainier.htm), which cites research including Beever and colleagues (2010, 2011) and MacArthur and Wang; rewritten in hubnx's own words.