Population recovery of common brushtail possums after local depopulation
Weihong Ji A D , Stephen D. Sarre B , Piran C. L. White C and Mick N. Clout AA School of Biological Sciences, The University of Auckland, PO Box 92019, Auckland, New Zealand.
B Applied Ecology Research Group, University of Canberra, ACT 2601, Australia.
C Environment Department, University of York, Heslington, York YO10 5DD, UK.
D Corresponding author. Present address: Environment Department, University of York, Heslington, York YO10 5DD, UK. Email: wj2@york.ac.uk
Wildlife Research 31(5) 543-550 https://doi.org/10.1071/WR02048
Submitted: 17 June 2002 Accepted: 8 June 2004 Published: 13 December 2004
Abstract
Brushtail possums (Trichosurus vulpecula) were live-trapped for two years prior to and following depopulation in two ~6-ha areas of native forest in New Zealand. The populations had recovered to 55% of the original density at one site and 40% of the original density at the other site, two years after the depopulation. The post-removal populations responded to reduced density with a higher proportion of females breeding, higher survival rate of young, and less seasonal fluctuation in body condition. The initial recolonisation was probably mainly due to surrounding animals shifting their ranges into the depopulated area, rather than long-range dispersal, which resulted in an even sex ratio in the recovering populations. The greater proportion of adult males in the post-removal populations is likely to increase sexual contact rates for females. This would enhance the dissemination of a viral-vectored biological control agent through the population, when used as part of an integrated control program.
Acknowledgments
This study was funded by Auckland University, the Auckland Regional Council and New Zealand Foundation for Research, Science and Technology. We thank Yidong Ran, Sandra Anderson, Du Chunhua and Richard Hendra for their help with the fieldwork and Dianne Brunton for her advice on statistical tests. We thank two anonymous referees for their comments on the earlier draft.
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