Fasting metabolism and thermoregulatory competence of the star-nosed mole, Condylura cristata (Talpidae: Condylurinae)

Abstract

Metabolic and body temperature ( T b) responses of star-nosed moles ( Condylura cristata) exposed to air temperatures ranging from 0 to 33°C were investigated. The thermoneutral zone of this semi-aquatic mole extended from 24.5 to 33°C, over which its basal rate of metabolism averaged 2.25 ml O 2 g −1 h −1 (45.16 J g −1 h −1). This rate of metabolism is higher than predicted for terrestrial forms, and substantially higher than for other moles examined to date. Minimum thermal conductance was nearly identical to that predicted for similar-sized eutherians and may represent a compromise between the need to dissipate heat while digging and foraging in subterranean burrows, and the need to conserve heat and avoid hypothermia during exposure to cold. C. cristata precisely regulated T b (mean ±SE=37.7±0.05°C) over the entire range of test temperatures. Over three separate 24-h periods, T b of a radio-implanted mole varied from 36.6 to 38.8°C, and generally tracked level of activity. No obvious circadian variation in T b and activity was apparent, although cyclic 2–4 h intervals of activity punctuated by periods of inactivity lasting 3–5 h were routinely observed. We suggest that the elevated basal metabolic rate and relatively high T b of star-nosed moles may reflect the semi-aquatic habits of this unique talpid.