Abstract
Collared pikas (Ochotona collaris) are cold adapted alpine lagomorphs of western Canada and Alaska that are vulnerable to direct and indirect effects of climate change.
However, we do not yet know to what extent they can adapt to these changing climates.
Collared pikas do not hibernate, so they spend the entire summer season foraging and
caching vegetation within rock dens to survive winter. Our objectives were to 1) determine
whether territory-specific microclimate and microhabitat characteristics influence occupancy
of individual collared pika dens across years, and 2) characterize daily and seasonal foraging
patterns of collared pikas to identify thermal limitations and understand how warmer
conditions may affect food acquisition. We recorded den occupancy and territory
characteristics, and placed temperature loggers within pika dens across 3 study areas with
contrasting climate gradients in southcentral and interior Alaska, USA, during 2017-2022.
We also conducted behavioral observations of collared pikas in these study areas across
varying weather conditions and times of day to determine when pikas were foraging during
July and August 2020-2021. We evaluated climatic conditions and habitat features to test
hypotheses on den occurrence and used these data to estimate territory persistence with a
Bayesian dynamic occupancy model. We tested hypotheses on proportional daily foraging
activity as a function of both temporal and thermal explanatory variables through linear
mixed-effects models. Daily maximum temperature during summer and winter best predicted
collared pika occupancy rates, and dens with larger rocks remained cooler during summer.
Foraging patterns of collared pikas were dependent on temperature, wind, and time of day,
and caching behavior was dependent on a narrower range of conditions compared to grazing.
These results demonstrate that specific microclimate requirements within collared pika
territories, during both summer and winter, can influence territory occupancy and foraging
behavior, and habitat characteristics can buffer temperature extremes. This information can
advance understanding about the mechanistic links between climate and population
persistence for collared pikas under the rapidly changing arctic climate.