NORTH-AMERICAN PIKA (OCHOTONA-PRINCEPS) AS A LATE QUATERNARY BIOGEOGRAPHIC INDICATOR SPECIES

Reevaluation of Quaternary sites of fossil pika (Ochotona) lends no support for the inference that Nearctic pikas were not restricted to rocky habitat. The saxicolous nature of all widespread, isolated populations of extant Nearctic pikas and their closest Palearctic sister taxa support consideration of O. princeps, and perhaps all Nearctic Quaternary Ochotona, as indicators of cool, mesic, rocky situations. As indicators of rocky microhabitat, fossil remains of O. princeps do not require that the entire region was cool and mesic, but only that suitable rocky microhabitat existed in the vicinity. Use of fossil pika dung alone as indicative of pikas in the immediate community is suspect, as the small, round, and buoyant pellets may be transported downslope by hydraulic flushing of talus habitat. Current local elevational lower limits (E) of appropriate habitat for paleoecological reconstruction at extralimital fossil sites are predicted by the equation: E(m) = 14087 - (56.6)°N - (82.9)°W. © 1993 by Academic Press, Inc.