Influences of forest type and disturbance on reproduction of the brushtail possum (Trichosurus vulpecula)

The effects of forest type and disturbance on specific reproductive traits are unknown for many forest-dwelling mammals. We assessed whether differences in forest type and disturbance influenced key reproductive traits of an arboreal marsupial, the common brushtail possum (Trichosurus vulpecula), in Tasmania, Australia. Trapping was conducted in spring-summer and autumn-winter during 2007-2008 at 6 dry Eucalyptus forest sites (3 regenerating and 3 relatively undisturbed) in southeast Tasmania and 4 wet Eucalyptus forest sites (2 regenerating and 2 relatively undisturbed) in the northeast. We aged pouch young and assessed the body condition of back young. We milked females captured during the late stage of lactation and compared the nutritional composition of milk among sites. Births occurred slightly earlier at the northern sites than at those in the south. Female body mass and offspring body condition and survival were similar across sites. Milk composition also was similar across sites, but possums in dry, undisturbed forest, primarily at 1 site, produced milk with significantly higher fat content; however, we found no evidence of a difference in body condition or survival of young that could be attributed to a difference in milk quality. Although forest type and disturbance influence demography and breeding frequency in the brushtail possum populations we studied, these population-level differences are not linked to variations in the reproductive traits examined here. We conclude that the brushtail possum is a physiologically resilient species, and the ability of individual females to reproduce successfully is relatively insensitive to forest type or habitat disturbance.