Changes in Australian brushtail possum (Trichosurus vulpecula) den site use following density reduction

The den use of possums (Trichosurus vulpecula) may be density dependent, meaning that individuals change their denning behaviour in response to changes in population density. Increases in den use due to changes in density may result in increases in bovine tuberculosis (Mycobacterium bovis; bTB) transmission among possums, as infection has previously been correlated with den use. In this study, the den use of a possum population was monitored in 2011 before and after a density reduction event. Females increased their den use following density reduction, but males did not. However, den use was more dependent on the sex of the individual than density reduction, with males having greater den use than females. A second site of different habitat where density reduction was not carried out was also monitored for den use, in 2012. In contrast to the manipulated site, den use did not differ between monitoring events or possum sex at this site. Possums at this site also had greater den use than possums at the manipulated site. This research suggests that bTB transmission risk may not be uniform among habitats. In addition, to prevent potential increases in transmission risk from bTB-infected possums surviving control, pest control operations should aim to remove the majority of possums in a population.