Natal dispersal and range establishment behaviour of the brushtail possum (Trichosurus vulpecula) characterised with advanced satellite telemetry

Abstract

In New Zealand, the introduced brushtail possum (Trichosurus vulpecula) damages natural forest ecosystems and threatens the dairy industry, as a vector of bovine tuberculosis (TB). Detailed information on the spatial ecology of this noctumal marsupial pest is therefore vital for establishing efficient, cost-effective control strategies. The objective of this research was to characterise aspects of natal dispersal and range establishment behaviour of juvenile brushtail possums through the deployment of lightweight global positioning system (GPS) collars. Juvenile possums play a crucially important role in maintaining the possum problem in New Zealand, acting as vectors of TB and re-colonising areas following control. However, the spatial-temporal behaviour of juveniles has not previously been well researched or understood. The findings obtained in this research demonstrate the small home-range sizes of juvenile possums, and reveal how current ground control operations are likely to insufficiently target this population cohort. The detailed data collected from GPS collars provided new insights into juvenile possum dispersal behaviour, including the non-uniform orientation of dispersal trajectories, the precise timing of dispersal events and the movement paths taken. Analysis of spatial-temporal data from mother-offspring pairs revealed a high degree of range overlap and den sharing, continuing past the onset of maturity in daughters. The experimental removal of mothers of known independent juveniles resulted in significant changes in offspring space use, suggesting that young possums may expand their ranges following control operations and providing insights into the potential role which mature conspecifics may play as drivers of mammalian dispersal. This research also included a comparison of the performance of three brands of lightweight GPS collars deployed on brushtail possums, providing important information for wildlife researchers considering using GPS collars to monitor the movements of smaller vertebrate species. Recommendations are made as to how the new findings obtained here can be applied to improve brushtail possum management practices in New Zealand. The results are also discussed in terms of their contribution to the wider field of mammalian spatial ecology and dispersal.

Moved 1/10/20 LT