Captive breeding, growth, and development of thermoregulation in the eastern pygmy-possum 'Cercartetus nanus'

Abstract

Information regarding captive breeding of 'Cercartetus nanus' is not available in the literature and little is known about the development of this species. We were able to breed a litter of four 'C. nanus' in captivity by maintaining two females and one male in a large aviary under natural photoperiod and temperatures. Growth and development of thermoregulation were quantified in one captive-bred and two wild-caught litters. Crown-rump length of young increased rapidly until weaning (60-65 days). Body mass rose steeply until 100 days and after a further period of slow growth, adult body mass was attained at approximately 150 days. At 40- 43 days (body mass 4.4 ± 0.4 g), young could not maintain body temperature (Tb) when exposed to ambient temperatures (T a) below 30°C, as they were unable to raise metabolic rate. However, by 62-65 days (body mass 12.3 ± 1.8 g), shortly before weaning, they could increase metabolic rate proportionally to compensate for heat loss and maintain Tb over a Ta range of 5-34°C. Our study shows that 'C. nanus' can be bred in captivity when maintained in large enclosures under natural conditions. The slow growth and development of thermoregulation in 'C.nanus' should require only a small increase in energy expenditure of females as they need only expend a little on extra foraging and processing of food. This may allow them to produce offspring even when food supply is limited.