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

Abstract

The influence of season and weather on activity was examined for captive numbats, to separate the influence of weather from predation pressure and food availability, since these confound the interpretation of activity data for wild numbats. Unlike other Australian marsupials, numbats are exclusively diurnal, being active for an average of 21.2 % of the 24 h day. However, activity duration varied seasonally, with numbats being active for longer periods in summer (39-65 % of the available daylight) than winter (17-59 %). Captive numbats were active for shorter periods than wild numbats in winter (presumably as captive numbats don’t have to forage for food) but did not cease activity in the middle of the day in summer (suggesting that summer midday inactivity of wild numbats 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 on days of low light intensity and high relative humidity. The majority of numbat activity occurred at ambient temperatures below thermoneutrality (< 30 ºC). 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).