The Small Mammals of Little Nourlangie Rock, N.T II. Ecology of Antechinus bilarni, the Sandstone Antechinus (Marsupialia: Dasyuridae)

Abstract

In a capture-mark-release program on Antechinus bilarni at Little Nourlangie Rock, N.T., from February 1977 to June 1979, 34,800 trap nights were set, for a total catch of 174 males and 162 females. Breeding is strictly seasonal, with mating around late June. Pouch young are carried in August and September. Lactation continues until December, when free-living young are first trapped. Males show a seasonal increase in testes size, with a decrease after mating. There is no die-off of males; both males and females may survive for a second breeding season. Males undergo a second cycle of increase in testes size, and histological sampling revealed spermatogenesis during their second breeding season. Individual males and females were trapped for up to 24 and 25 months respectively; KTBA estimates are similar for both sexes. Both sexes continue to increase in body weight throughout life. although males lose weight substantially after each breeding season. Sex ratios dropped during October of each year because the activity and trappability of males dropped. Males were recaptured with the onset of the wet season. The preferred habitat was scree slope, at an altitude of around 40-55 m. Some seasonal shifts in habitat were probably related to food availability.