Background
The authors write that American pikas (Ochotona princeps) "are habitat specialists in high-elevation talus (rockslides and boulder fields, generally above 2,500 m elevation) in western North America (Smith, 1974; Smith and Weston, 1990)," but they state that "they persist near sea level in the Columbia River Gorge, well outside their previously assumed climatic niche." Hence, their natural inclination was to attempt to discover what makes this situation possible.

What was done
Citing Tuomainen and Candolin (2011), who demonstrated that a "common response to rapid environmental changes is inclusion of new food resources into the diet," Varner and Dearing investigated the foraging behavior of pikas living in the atypical habitat of the Columbia River Gorge.

What was learned
The two researchers discovered that, in the Columbia River Gorge, moss comprised more than 60% of the pikas' diet at two different sites that they studied, which amount they say was more than had previously been observed for any mammalian herbivore in the wild. And with moss available year-round in this low-altitude habitat, the pikas did not have to construct large food caches to survive the winter.

What it means
In the words of Varner and Dearing, "these results suggest a larger degree of behavioral and dietary plasticity than previously assumed for this species." And they thus conclude that "understanding a species' capacity to adapt its foraging strategies to new resource landscapes will be essential to assessing its vulnerability to future climate change." But in the meantime, they have proof of the principle in their revealing study of the American pika.

References
Smith, A.T. 1974. The distribution and dispersal of pikas: influences of behavior and climate. Ecology 55: 1368-1376.

Smith, A.T. and Weston, M.L. 1990. Ochotona princeps. Mammalian Species 352: 1-8.

Tuomainen, U. and Candolin, U. 2011. Behavioral responses to human-induced environmental change. Biological Reviews 86: 640-657.