Oral presentation- Open Session 12th International Mammalogical Congress

Monitoring population size and structure by individual recognition in brush-tailed rock wallabies (Petrogale penicillata) (#375)

Gerhard Koertner 1 , Stuart Green 1 , Karl Vernes 1
  1. University of New England, Armidale, New South Wales, Australia

Population size is one of the fundamental measures in conservation biology and many different methods have been devised to measure it. For rock wallabies, these encompass scat counts, trapping, observations and scat DNA analysis. As colonies are usually small, the precision of the chosen method is of utmost importance. In this study we attempted individual identification from high quality photographs relying on fur colouration and facial scarring. Six colonies of brush-tailed rock wallabies were sampled yearly in northern New South Wales from 2010 to 2016. Only individuals that had permanently left the pouch were counted. Colony size ranged from 1 to 21 individuals, but for any given colony size remained relative stable over the years. Overall, 116 wallabies were identified and the sex ratio appeared to be close to parity, with a quarter of all individuals being subadults. Although rock wallabies generally exhibit high site fidelity, about half of all individuals were photographed during only one survey and only five were known to be alive during all seven years, implying that few individuals realize their greater than ten year lifespan. There was a trend for females to persist longer in colonies than males. Overall, the high turnover in these colonies indicates dispersal, particularly of young animals, but probably also predation. The poor body condition of some wallabies further suggests that parasites or disease are prevalent. Nevertheless, currently recruitment appears to be sufficient to compensate for these losses as we observed little fluctuations in population size.