Critical snow density threshold for Dall’s sheep (Ovis dalli dalli)

Researchers identify a critical snow density threshold of 329 ± 18 kg/m³, above which the snowpack supports the mass of Dall’s sheep (Ovis dalli dalli), significantly influencing their winter movement and energetic costs. This finding suggests that changing snow conditions, potentially linked to recent population declines, could have profound implications for the species' survival in UNESCO World Heritage Sites like Wrangell–St. Elias National Park and Preserve. The study analyzed track sink depths in relation to top layer snow density (0–10 cm), sheep age class, and other snow properties, revealing that snow depth and hardness were poor predictors compared to density. This threshold provides a key insight for predicting the consequences of altering snowpack conditions on wildlife.

Sivy, K. J., Nolin, A. W., Cosgrove, C. L., & Prugh, L. R. (2018). Critical snow density threshold for Dall’s sheep (Ovis dalli dalli). Canadian Journal of Zoology, 96(10), 1170–1177. https://doi.org/10.1139/cjz-2017-0259