| Description |
Contemporary climate change is occurring at an unprecedented rate and is already dramatically affecting biodiversity worldwide. However, despite many well-documented changes, relatively little is known about specific mechanisms by which climate affects species. Investigating survival and recruitment in sub-optimal habitat can be as illuminating as population declines or extinctions, in terms of identifying mechanisms by which climate impacts species distributions. This dissertation incorporates aspects of global change ecology, disturbance ecology, and animal behavior to understand mechanisms of survival and recruitment of a climate-sensitive small mammal, the American pika (Ochotona princeps), in atypical habitats. I first elucidate mechanisms underlying low-elevation pika survival in the Columbia River Gorge, Oregon. This region is characterized by a high degree of moss cover, which appears to promote pika survival in two ways. First, by consuming the moss, which is available year-round, pikas are released from constructing large food caches for winter, a hallmark of their behavior in typical habitats. Second, the moss mediates the microclimates relevant to the species, in some cases completely decoupling ambient temperatures from those measured in the pikas’ rocky habitat. Pikas in this habitat also exhibit a high degree of behavioral plasticity in foraging strategy and microhabitat selection. Finally, I had a unique opportunity to build upon these results by investigating how pikas recolonize habitat severely disturbed by wildfire. Pikas quickly recolonized seemingly barren habitat, but animal abundance did not increase until after a threshold in vegetation availability was reached. Defining these habitat thresholds will significantly advance our understanding of pikas’ resource requirements and their sensitivity to disturbance. These results will also inform practical conservation measures for this species and other small alpine animals. |
