American Pika Distribution, Behavior, and Observer Variability

Moyer-Horner, Lucas

I conducted research in Glacier National Park (GNP), Montana, on the American pika (Ochotona princeps). The American pika is a potato-sized lagomorph that inhabits relatively cool climates of western North America, usually in mountainous regions, and typically in piles of large rocks (talus). Pikas are indicators of animal response to climate change because they are relatively easy to detect, poor dispersers, specific to discontinuous talus habitat, and physiologically intolerant to heat. I investigated observer variability among three groups: 1) bio-techs, 2) citizen scientists, and 3) between bio-techs and citizen scientists. Bio-techs found more pika signs than did the citizen scientists, with the exception of pika sightings. I suggest that surveys conducted by citizen scientists are sufficient for monitoring pika site occupancy. However, data on population dynamics of pikas (e.g., density) should be collected by bio-techs. I investigated talus distribution, pika density, and habitat. I identified 400 suitable habitat patches and surveyed 303 of them. GNP contains a relatively large pika population (2071 – 4052 individuals). AIC-based and adjusted R-squared-based habitat selection models revealed: 1) higher pika densities were predicted by higher elevations, more mosses, and taller grasses, 2) lower pika densities on North-facing slopes, 3) pika densities decreased during the three-year study, and 4) Julian date and time-of-day during which the survey occurred were among the strongest predictors of pika density.iv I observed pika behavior for 288 hours and characterized thermal characteristics of their habitat. Pikas were less active at higher temperatures and at lower elevations. I used a biophysical model, Niche Mapper™, to mechanistically model heat and water balance, activity hours, and foraging rates. Niche Mapper predicted pikas would be behaviorally constrained by the need to thermoregulate during the hottest times of day, and also by cold temperatures during morning and evening. Pikas will benefit energetically by maintaining summer pelage later into the fall, under a future warming scenario.

American Pika Distribution, Behavior, and Observer Variability

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