摘要：Anticipating the response of small mammals to climate change requires knowledge of thermal conditions of their habitat during times of the day and year when individuals use them. We measured diurnal and seasonal temperatures of free air and of six habitat components for American pikas ( Ochotona princeps ) over five years at 37 sites in seven mountain ranges in the western Great Basin, United States. Talus matrices (subsurfaces) had low daily variances and, in the warm season, remained cool during the hottest times of the day relative to surfaces and free air. During winter, matrices were warmer than free air. Talus surfaces were warmer than free air in the warm and cold seasons, and had large daily variances. Summer forefield and dispersal environments were warmest of all habitat components. Talus surfaces in summer were highly responsive to solar radiation over the course of the day, warming quickly to high midday temperatures, and cooling rapidly in the evening. By contrast, matrices lagged the daily warm-up and remained warmer than free air at night. These differences afford diurnal and seasonal opportunities for pikas to adapt behaviorally to unfavorable temperatures and suggest that animals can accommodate a wider range of future climates than has been assumed, although warming of the dispersal environment may become limiting. Climate envelope models that use or model only surface air measures and do not include information on individual thermal components of pika habitat may lead to errant conclusions about the vulnerability of species under changing climates.
