PATTERNS OF CHANGE IN MICROCLIMATES IN AN ATYPICAL HABITAT FOR AMERICAN PIKAS

Johanna Varner; Colorado Mesa University; jvarner@coloradomesa.edu; Mallory Sandoval Lambert, Joshua J. Horns

Many species rely on microclimates (i.e., areas where temperature and weather differ from prevailing conditions) for protection against climatic extremes. American pikas (Ochotona princeps) are small, climate-sensitive lagomorphs that inhabit rocky habitats across western North America. While warming summers and reduced snowpack have driven population declines in parts of the pika’s range, the degree to which microclimate refugia are also changing remains poorly understood. We analyzed 14 years of temperature data (2011–2025) from four sites in the Columbia River Gorge, where cool, stable microclimates enable pikas to survive at their lowest elevation. We also evaluated the effects of the 2017 Eagle Creek Fire on microclimates at these sites. Since 2011, talus surface temperatures have increased by ~0.32°C per year, and while subsurface interstitial environments also warmed slightly, they remained consistently 6–11°C cooler than surface temperatures. Despite this buffering, the frequency of hot days (>25°C) rose by ~7% annually, both before and after the fire, increasing potential exposure to heat stress. These results underscore both the resilience and vulnerability of pika habitats: talus continues to mitigate extreme heat, yet climate warming and wildfire appear to be eroding this buffer, with potential consequences for persistence in this unique low-elevation habitat.

Ecology and Conservation of Pikas 2 - Occupancy & Climate 
Wednesday 4:30 PM