Effect of ovariectomy on the social status of brushtail possums <i>(Trichosurus vulpecula)</i> in captivity

Abstract

Abstract Brushtail possums (Trichosurus vulpecula) are New Zealand's most important vertebrate pest. Options for the biological control of possums are being evaluated in the hope that bio‐control might provide a cost‐effective, long‐term solution not achievable by current technologies. Methods which inhibit possum reproduction may, however, affect sex steroid levels and result in changes in behaviour. In some species, loss of status by dominant animals allows subordinates to breed more successfully. This paper describes social heirarchies in captive groups of possums after ovariectomy of the dominant female. Seven groups consisting of two females and one male were established in pens and the dominance status of each animal was measured by recording the outcome of social interactions during monthly observations. In each pen, the dominant individual was a female. The dominant female in each pen was ovariectomised, and the subordinate female was given a sham operation. Social relationships remained unchanged in all pens for the duration of the experiment (5–12 months after ovariectomy). Their stability despite ovariectomy may be due to maintenance by adrenal steroids, or by force of habit. The findings of this study are encouraging because, if they are confirmed by similar observations of free‐living possums, biocontrol methods that disrupt steroid production could be considered for possum control.