Vehicle collisions and dog attacks on Victorian koalas as evidenced by a retrospective analysis of sightings and admission records 1997 – 2011

Abstract

Koalas moving across open ground risk dog attacks and collisions with vehicles when crossings roads. Historical records from a resident survey, two regional wildlife carers and a state government department wildlife shelter returns database for Victoria, Australia, were examined to determine the importance of certain admission types. Koala Vehicle Collisions (KVCs) and dog attacks were important contributors to the overall intake of injured koalas. However, KVCs were the most numerous recorded cause of koalas entering a wildlife shelter, and the most frequently assigned cause of death. There were relatively high rates of admission into care, and of death, for male koalas. Furthermore, almost twice as many individuals were admitted during the breeding season; sex ratio was not a differentiating characteristic of road-kills between breeding and non-breeding seasons, or by individual months. Comprehensive, accurate and detailed data gathering are essential for effective evaluation of the success of rehabilitation and release, as well as post release survival rates. This, together with population studies would determine whether admission rates reflect the sex ratio of local populations, and whether the high number of injured or killed females has an impact on their viability. Analyses of wildlife carer databases have great potential for decision making in koala conservation.