Rapid assessment of site occupancy by collared pika (Ochotona collaris) at the leading edge of their range

Abstract

Global climate change is a threat to the persistence of many species, particularly those that may experience climate-induced habitat loss, have limited dispersal ability, and a narrow ecological breadth. The collared pika (Ochotona collaris) is a small, cold-adapted mammal that meets these criteria. For species that are particularly vulnerable to climate warming, such as collared pika, conservation efforts may be most effective at the leading—rather than trailing—edge of their range because their distribution is predicted to shift northward. Using a rapid assessment protocol, we determined site occupancy rates for collared pika near the northern (leading) edge of their range. We used repeated, time-based searches to survey 55 sites for pika occupancy. Detection probability was high (p = 0.917), and our modelled occupancy rate was moderate (Ψ = 0.238). Sites surveyed were categorized with a habitat quality rank (1–4), which was a strong predictor of pika occupancy. Sites within the best habitat quality rank had a probability of pika occupancy of about 76%. Our results suggest that the most suitable habitat is largely already occupied. As pika distribution shifts northward in response to climate change, population growth at the leading edge of their range may be inhibited by a lack of available habitat. Given limited monitoring of collared pika trends, we recommend establishment of a series of areas throughout the species’ range, where occupancy-based surveys are periodically conducted, particularly at the leading and trailing edges. For cold-adapted species like collared pika, range edges should be prioritized to monitor for climate-induced changes in occupancy rates and distribution.