Metabolism and Thermoregulation of a Fossorial Rodent, the Northern Pocket Gopher (Thomomys Talpoides)

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Abstract
Body temperature, O2 consumption and evaporative water loss were measured in the northern pocket gopher at various ambient temperatures between 1 and 38.degree. C. Body temperature was maintained at 36.9.degree. C at ambient temperatures from 1 to 30.degree. C. Above 30.degree. C, the ability to dissipate heat was reduced and body temperature rose. Several animals died following 1 h exposures to ambient temperatures above 38.degree. C. The zone of thermal neutrality for T. talpoides extended from approximately 26 to 32.degree. C. Within this zone, O2 consumption averaged 1.33 cm3 O2/g.cntdot.h) in resting animals. Thermal conductance, determined from the slope O2/(g.cntdot.h) of the relation between O2 consumption and ambient temperature below 26.degree. C, was 0.08 cm3 O2/(g.cntdot.h.cntdot.C). O2 consumption rates were higher (124%) than predicted on the basis of body weight alone. Thermal conductance values were 84% of predicted. A reevaluation of data from the literature on the metabolism of fossorial rodents revealed that most of the species which were studied are also probably characterized by reduced rates of thermal conductance. It was previously considered that thermal conductance rates were greater than expected on the basis of body weight. Evaporative water loss increased curvilinearly from 8 to approximately 38.degree. C. A maximum of 21% of the metabolic heat production could be dissipated by evaporative mechanisms.