Pikas and Permafrost: Post-Wisconsin Historical Zoogeography of Ochotona in the Southern Rocky Mountains, U.S.A.

Abstract

Occurrence of pikas (Ochotona princeps) in the southern Rocky Mountains is closely tied to past and present distribution of alpine permafrost conditions, which produce and maintain appropriate talus-slope habitat. Estimates of full-Wisconsin elevational depression of alpine permafrost and vegetation zones support the existence of glacial-maximum dispersal corridors between currently isolated populations of O. princeps. Altithermal warming accounts for 66.7% of apparent post-Wisconsin extinctions of insular populations of pikas in the region. Populations at sites with altithermal refugia >100 km2 enjoyed high survivorship (93.8%) compared to smaller refugia (6.1–15.2%). Extant populations are located within 5 km of current alpine permafrost and within 20 km of the estimated altithermal occurrence of permafrost, indicating minor subsequent dispersal from a more restricted distribution of 6000 yr ago. Recolonization of sites within 20 km has been rare (≤7.8%). Depending on the time scale considered, pikas ar...