Thermoregulatory responses in the plains pocket gopher, Geomys bursarius

Abstract

Abstract 1. Thermoregulation was studied in the Plains pocket gopher, Geomys bursarius . 2. The thermoneutral zone, TNZ, for G. bursarius extends from 30 to 33°C with a resting V O 2 of 0·70 ml O 2 /g per hr. 3. Below the lower critical temperature V O 2 increased but was variable due to labile and reduced rectal temperature, T re . Above the upper critical temperature V O 2 increased approximately 27%. 4. Calculated thermal conductance expressed in ml O 2 /g per hr. C decreased progressively as ambient temperature, T a , was reduced. 5. The pulmo-cutaneous water loss increased with increasing T a . 6. The T re of animals in TNZ averaged 35°C. As T a decreased T re progressively declined reaching an average of 26·5°C at a T a of 10°C. Above TNZ, T re increased to a high of 39°C at T a of 38°C. 7. Data on G. bursarius was compared with other pocket gophers studied. These comparisons suggest that pocket gophers in general deviate from strict homiothermy and utilize labile T re in varying degrees as an adaptive mechanism for survival in stressful environments.