Summer surface activity of a sub-surface microhabitat specialist (Ochotona princeps)

In response to climate change, heat-sensitive species might shift certain activities to cooler times of day. The American Pika (Ochotona princeps), which sheds heat by accessing subsurface microclimates, could be a good model for temporal shifts in behavior as a response to increased heat stress. At the Niwot Ridge Long-Term Ecological Research (LTER) site in the Front Range of Colorado, logistical constraints often limit behavioral observations to midday hours. To extend inference to crepuscular activity, we conducted paired dawn and dusk observations of n=11 unique pikas at two sites on Niwot Ridge, for a total of 60, 45-minute observations during the summer of 2016. No significant difference was found in the average percent of time pikas were surface-active at dawn (38%), dusk (53%) or midday (33%). Preening activity was more prevalent at one site at dusk; all other activity frequencies did not differ significantly between dawn and dusk, and were consistent with previous data for midday behavior. Sub-surface temperatures, recorded during each observation, were significantly cooler at dawn than at dusk at both sites. Together, these results suggest that summer temperatures on Niwot Ridge currently do not disrupt the consistency of pika surface activity from dawn through dusk. However, when the effects of individual pika, location, and time were accounted for in logistic regression models, a relationship emerged between subsurface temperatures and surface activity.