Date of Award

Spring 1-1-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology & Evolutionary Biology

First Advisor

Sharon Kay Collinge

Second Advisor

Chris Ray

Third Advisor

Christy McCain

Fourth Advisor

Rebecca Safran

Fifth Advisor

Mark Williams

Abstract

The American pika (Ochotona princeps) is considered a sentinel species for detecting ecological effects of climate change. Pikas are declining within a large portion of their range, but previous studies have focused only on local pika extirpation as a metric of change. This approach does not take into account the role of behavioral thermoregulation and the pika's use of microhabitats to ameliorate variations in climate. Without evidence of a direct climatic impact on pikas, studies correlating pika habitat occupancy with climate metrics provide relatively weak support for projecting effects of climate change on this species. This dissertation research focuses on the physiological stress response of pikas to differences in microhabitat and microclimate. First, I developed and validated bio-assays to measure physiological stress in pikas. Second, relationships were established between pika stress and habitat characteristics associated with sub-surface ice features, which are an important component of water resources. Third, I examined effects of local climate on stress, while accounting for the influence of environmental characteristics on a frequently used stress metric (fecal CORT). Lastly, annual individual survival was analyzed in relation to two different stress metrics (fecal and plasma CORT). Research efforts resulted in the establishment of non-invasive methods for estimating stress in pikas, and also emphasize the importance of considering environmental influences on stress measurements collected non-invasively across different eco-regions. Additional results suggest that pikas may serve as a sensitive bio-indicator of hydrological change in high elevation watershed areas. Finally, pikas appear to be experiencing chronic stress, and reduced survival, in some microhabitats regardless of behavioral adaptations.

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