Altitudinal Zonation of Chipmunks (Eutamias): Adaptations to Aridity and High Temperature
Heller HC and Poulson T. 1972. Altitudinal Zonation of Chipmunks (Eutamias): Adaptations to Aridity and High Temperature. The American Midland Naturalist. 87(2):296-313
Fecal, urinary and evaporative water losses were measured at 15 C, 50-75% humidity for four species of western chipmunks (Eutamias) which are contiguously allopatric and altitudinally zoned on the eastern slope of the Sierra Nevada, California. Evaporative loss and hyperthermia were also studied for acute exposures to 25, 35, and 40 C. Differences in total water budgets, calculated for 35 C and 11% humidity are not important in determining the lines of contact, starting from the alpine and descending toward the desert, between E. alpinus and E. speciousus or between E. Speciousus and E. amoenus. But they may play a role in preventing E. amoenus from colonizing the desert sagebrush habitat occupied by E. minimus. E. minimus can be active in the open areas of the hot, arid sagebrush desert by minimizing evaporative water loss and tolerating increased body heat content; this species frequently retreats to its burrows to unload excess body heat. When large patches of shade are available from pinon pines, the aggressively dominant E. amoenus can occupy the sagebrush habitat. Hence, in the field area of this study the line of contact between E. amoenus and E. minimus coincides with the lower limits of the pinon pine.
- Type
- Journal Article
- Authors
- Heller, H; Poulson, Thomas
- Units
- YOSE
- Keywords
- Air Temperature, alpine chipmunk (Tamias alpinus), Animal Studies, Elevation, Habitats, least chipmunk (Tamias minimus), lodgepole chipmunk (Tamias speciosus), yellow-pine chipmunk (Tamias amoenus)