Development of thermoregulation in the sugar glider Petaurus breviceps (Marsupialia: Petauridae)

Abstract

Young, relatively undeveloped sugar gliders Petaurus breviceps have been observed to be left alone in the nest while the mother forages and may be subject to considerable thermal or energetic stress. As no information is available on the development of thermoregulation in this species, which begins reproduction in winter, we measured resting metabolic rate (RMR), body temperature (T_b) and thermal conductance over a range of ambient temperatures (T_a) in 10 sugar gliders from c. 55 days of age until they had grown to adult size. Sugar gliders were unable to maintain a stable T_b over a T_a range of 30–15 °C until the age of 95–100 days, although they raised RMR somewhat as T_a decreased. Further growth resulted in a steady decrease in mass-specific RMR, an increase in T_b and a substantial decrease in thermal conductance. Our study shows that young gliders below the age of 100 days rely largely on heat produced by adults to maintain a high T_b, but are well able to cope with regular falls in T_b of > 10 °C and a concomitant decrease of RMR. This thermal tolerance and reduction in energy expenditure should allow the mother to forage and replenish her own body fuels while her offspring are left alone in the nest.