Pikas are roly-poly creatures with a distinctive high-pitched call that usually live in habitats above 8,200 feet in North America, Asia and Eastern Europe.
About 6 inches long and weighing 1/3 pound, they have a sphere-like shape and a thick coat that makes them perfectly adapted to cold temperatures but usually unable to survive more than two hours in temperatures above 78 degrees. Pikas have gone extinct in some parts of the West and moved to higher elevations in others as the climate grew warmer, but a petition to have the animal listed as an endangered species was denied in 2010.
Varner was surprised to hear a few years ago about pikas living in rockslides near sea level not far from Portland.
"I said, 'What do you mean the Columbia River Gorge? They shouldn't be there,'" said Varner, who observed 20 to 30 animals over two years with a team of undergraduates.
To her surprise, they discovered the pikas were subsisting largely on a diet of moss.
"They typically eat grasses and wildflowers," Varner said. "Very few mammals are able to eat large amounts of moss because it's really a nutritionally crappy food. It's sort of like eating paper."
In fact, the pikas in the study set a new record for moss in a mammal's diet at 60 percent, beating out even reindeer moss consumption.
Though it's not power food, moss is widely available on the rock slides, so the pikas don't have to work hard to find it. They process it by producing a special kind of feces, called caecal pellets, that they can eat again. It's a pretty common process for small mammals like rabbits, hares and mice, and allows them to take advantage of microbes that live in their guts.
"A lot of herbivores play this game of eating bacteria in order to increase the protein in their diet," said Denise Dearing, a U. biology professor and senior author on the study. "The bacteria is protein, and the bacteria are making more of themselves ... it's kind of a gross aspect, but it works for most small mammals."
Cows' digestive systems use a somewhat similar process, though it's contained within their stomachs.
Varner now plans to study how the pikas are able to survive in the low-elevation slides perhaps the moss also keeps temperatures cool and whether lessons in Oregon can be applied anywhere else.
In the meantime, she is asking hikers to record their observations of the pikas and encouraging people to avoid trampling the food source.