Presentation at ICCB, Montpellier: "Trophic cascades following disease induced decline of the T

Prof. McCallum recently gave a presentation highlighting the great work of one of his students, Tracey Hollings, at the 27th International Congress for Conservation Biology, in Montpellier, France, held on 2-6th August 2015.

Abstract and link to slides below.

Hollings, T., McCallum, H., Jones, M. and Mooney, N. (2015) Trophic cascades following disease induced decline of the Tasmanian devil. Conference Proceedings: ICCB 27th International Congress for Conservation Biology, Montpellier, France (link).

Abstract:

TROPHIC CASCADES FOLLOWING DISEASE INDUCED DECLINE OF THE TASMANIAN DEVIL

Tracey Hollings, University of Melbourne Hamish McCallum, Griffith University

Menna Jones, University of Tasmania

Nick Mooney, Environmental Consultant

Infectious diseases of wildlife can have consequences beyond the species they infect. Tasmanian devil facial tumour disease is a host specific infectious cancer that continues to spread across Tasmania, with population declines of up to 90% in affected populations. The Tasmanian devil is the apex mammalian predator in Tasmanian ecosystems and its decline has the potential to cause trophic cascades, including mesopredator release and impacts on prey populations. Two independent lines of evidence, a spotlighting time series and surveys comparing sites with different extents of disease induced devil decline, provide strong evidence that introduced feral cat numbers have increased concomitant with devil decline. There is evidence that mammal communities are increasingly dominated by invasive species, cascading effects of mesopredator release of cats on prey and decline of the native eastern quoll, a predator smaller than the cat. Further, toxoplasmosis, a parasite for which cats are the obligate definitive host, occurs in wallabies at higher prevalence where devils have declined. Effects on devil prey species are less obvious, likely because of the influence of bottom-up factors such as food supply, but giving up density experiments show brushtail possums become bolder following devil decline. Tasmania maintains populations of at least four mammal species that are extinct on the Australian mainland because of feral cat and European red fox predation. Foxes were illegally introduced to Tasmania a decade ago, but remain at very low numbers. Disease induced devil decline in Tasmania threatens to cause increases in both cat and fox numbers, leading to declines or extinctions in native species. Tasmanian devils were widespread on the Australian mainland until about 5000 years BP. Our work suggests that reintroduction of disease free devils to the Australian mainland may produce biodiversity benefits beyond those to the devil itself, by suppressing introduced feral predators.