Australian Mammalogy Australian Mammalogy Society
Journal of the Australian Mammal Society
RESEARCH ARTICLE

Differing mortality rates in two concurrently radio-tracked populations of koala (Phascolarctos cinereus)

Stephen Phillips
+ Author Affiliations
- Author Affiliations

Biolink Ecological Consultants, PO Box 3196, Uki, NSW 2484, Australia. Email: steve@biolink.com.au

Australian Mammalogy - https://doi.org/10.1071/AM16047
Submitted: 6 September 2016  Accepted: 25 July 2017   Published online: 24 August 2017

Abstract

Radio-tracking studies enable insights into factors that contribute to koala mortality. Two radio-tracking studies investigating the impacts of disturbance events on koalas were undertaken in different areas over the same period. Both studies employed similar techniques for koala capture, processing and monitoring. In one study, none of nine koalas died during a 5-month monitoring program following their translocation into a new habitat area, while in the second study 6 of 11 koalas died over the same period during an in situ impact-monitoring study. The two populations differed morphologically and genetically: that with the higher mortality rate notable for a smaller head and neck circumference and lower genetic diversity. Differing outcomes from the two studies lend support to a hypothesis that inbreeding and the loss of genetic information may predispose some individuals and/or populations of koalas to an elevated stress response and/or increased susceptibility to disease, the expression of which may become exacerbated in the presence of ongoing disturbance or novel stressors that can include research activities. If this is the case, the endocrinology and genetic structure of free-ranging koala populations needs to be afforded greater consideration in terms of predicting a given population’s immunological response to potential isolation and/or disturbance events.

Additional keywords: population fitness, genetic diversity, koala stress syndrome.


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