Seasonality in the use of heterogeneous terrain by a territorial habitat specialist, the American pika

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Climate change is likely to affect mountainous areas unevenly due to the complex interactions between topography, vegetation, and the accumulation of snow and ice. This heterogeneity will complicate relationships between species presence and large-scale drivers such as precipitation and make predicting habitat extent and connectivity much more difficult. We studied the potential for fine-scale variation in climate and habitat use throughout the year in the American pika (Ochotona princeps), a talus specialist of mountainous western North America known for strong microhabitat affiliation. Not all areas of talus are likely to be equally hospitable, which may reduce connectivity more than predicted by large-scale occupancy drivers. We used high resolution remotely sensed data to create metrics of the terrain and land cover in the Niwot Ridge (NWT) LTER site in Colorado. We hypothesized that pikas preferentially use heterogeneous terrain, as it might foster greater snow accumulation, and used radio telemetry to test this with radio-collared pikas and compare that data to summer trapping success records. We found that pikas use heterogeneous terrain during snow covered periods and less heterogeneous area during the summer. This suggests that not all areas of talus habitat are equally suitable as shelter from extreme conditions but that pikas need more than just shelter from winter cold. Because overall suitable habitat for pikas varies seasonally, future models must account for more than those factors that drive detection in summer surveys for pikas and other species. With increasing effects of climate change, this approach will be crucial to delineate true habitat extent, quantify habitat connectivity at both small and large scales, and to identify potential refugia for threatened or isolated species in areas of ecological concern.