Influence of season and weather on activity patterns of the numbat (Myrmecobius fasciatus) in captivity

Abstract

To separate the influence of weather from predation pressure and food availability, and to aid in the interpretation of activity data for wild numbats, we examined the influence of season and weather on the activity of captive numbats. Unlike other Australian marsupials, numbats are exclusively diurnal, being active for an average of 21.2% of the 24 h day. However, in the present study, activity duration varied seasonally, with numbats being active for longer periods in summer (39–65% of the available daylight) than winter (17–59%). During winter, captive numbats were active for shorter periods than wild numbats (presumably because captive numbats don't have to forage for food); however, they did not cease activity in the middle of the day during summer (suggesting that the inactivity of wild numbats at midday during summer is a response to food availability rather than a thermoregulatory response). Captive numbats were more active in summer than in winter, which may reflect their summer breeding season. Environmental conditions significantly affected daily activity, with low levels of activity recorded on days of low light intensity and high relative humidity. The majority of numbat activity occurred at ambient temperatures below thermoneutrality (<30°C). The associated costs of thermoregulation for active numbats were calculated, from activity time, to be higher in winter (0.586 mL O₂ g^–1 h^–1) than in summer (0.274 mL O₂ g^–1 h^–1).