Abstract

The breeding biology of Trichosurus vulpecula has been studied in some detail for temperate populations but not for the northern brushtail possum (T. v. arnhemensis), the tropical form of this species. Data for the distribution of births and sex ratio of the young, growth and development of the young and reproductive cycles of both males and females were obtained. Most data were collected from a captive breeding colony of northern brushtails and supplemented with data from wild populations. The reproduction, growth and development of T. v. arnhemensis are very similar to those already described for other populations of T vulpecula. The observed differences can be explained by variation in the size of the animals and the absence of a restricted breeding season. Neither males nor females showed any periodicity in their reproductive strategy. This continuous breeding cycle can be attributed directly to their tropical environment. These tropical possums occupy a stable habitat, mature early and have a higher reproductive effort than populations in more seasonal and unpredictable environments. This suggests that the northern brushtail has a stochastic or 'bet-hedging' reproductive strategy.