Undergraduate Honors Theses

Thesis Defended

Spring 2016

Document Type


Type of Thesis

Departmental Honors


Ecology and Evolutionary Biology

First Advisor

Chris Ray

Second Advisor

Pieter Johnson

Third Advisor

Mark Williams


Alpine and subalpine ecosystems are expected to experience a disproportionate amount of warming in the coming decades. Rising temperatures in these ecosystems threatens biodiversity and water resources globally. The American pika (Ochotona princeps) is a small mammal restricted to talus and rocky slopes often found above treeline. O. princeps has an acute sensitivity to high temperatures and utilizes microhabitats present in the talus to regulate body temperature. These attributes make pikas a bioindicator candidate for warming in the alpine. Monitoring and predicting pika persistence represents a potentially powerful tool to asses the current and future health of alpine ecosystems. Here, I analyze paired temperature and observational data collected across several years at five separate locations in Colorado and Montana. I explore the relationship between surface activity and two sets of predictor variables; physiological predictors (new) and climatic predictors (historic). Males pika were found to be more surface active than females. Additionally, ectoparasite abundance was found to be the best physiological predictor of surface activity. Analysis of historic predictors found wind speed and aspect to be important predictors of surface activity. Based on these findings, I suggest that temperature alone is likely not the best predictor of pika surface activity. Instead, surface activity is likely influenced by both climatic and physiological variables. A better understanding of these relationships can aid future studies at predicting pika behavior and accounting for some of the complexity we see in pika persistence.