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Trophic cascades following the disease-induced decline of an apex predator, the Tasmanian Devil

Citation

Hollings, T and Jones, M and Mooney, N and McCallum, HI, Trophic cascades following the disease-induced decline of an apex predator, the Tasmanian Devil, Conservation Biology, 28, (1) pp. 63-75. ISSN 0888-8892 (2013) [Refereed Article]

Copyright Statement

Copyright 2013 Society for Conservation Biology

DOI: doi:10.1111/cobi.12152

Abstract

As apex predators disappear worldwide, there is escalating evidence of their importance in maintaining the integrity and diversity of the ecosystems they inhabit. The largest extant marsupial carnivore, the Tasmanian devil (Sarcophilus harrisii) is threatened with extinction from a transmissible cancer, devil facial tumor disease (DFTD). The disease, first observed in 1996, has led to apparent population declines in excess of 95% in some areas and has spread to more than 80% of their range. We analyzed a long-term Tasmania-wide data set derived from wildlife spotlighting surveys to assess the effects of DFTD-induced devil decline on populations of other mammals and to examine the relative strength of top–down and bottom–up control of mesopredators between 2 regions with different environmental conditions. Collection of the data began >10 years before DFTD was first observed. A decrease in devil populations was immediate across diseased regions following DFTD arrival, and there has been no indication of population recovery. Feral cats (Felis catus) increased in areas where the disease was present the longest, and feral cat occurrence was significantly and negatively associated with devils. The smallest mesopredator, the eastern quoll (Dasyurus viverrinus), declined rapidly following DFTD arrival. This result suggests the species was indirectly protected by devils through the suppression of larger predators. Rainfall deficiency was also a significant predictor of their decline. Environmental variables determined the relative importance of top–down control in the population regulation of mesopredators. In landscapes of low rainfall and relatively higher proportions of agriculture and human settlement, top–down forces were dampened and bottom–up forces had the most effect on mesopredators. For herbivore prey species, there was evidence of population differences after DFTD arrival, but undetected environmental factors had greater effects. The unique opportunity to assess population changes over extensive temporal and spatial scales following apex predator loss further demonstrated their role in structuring ecosystems and of productivity in determining the strength of top–down control.

Item Details

Item Type:Refereed Article
Keywords:apex predators, devil facial tumor disease, mesopredator release hypothesis, spotlighting, Tasmania
Research Division:Environmental Sciences
Research Group:Environmental Science and Management
Research Field:Conservation and Biodiversity
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Flora, Fauna and Biodiversity at Regional or Larger Scales
Author:Hollings, T (Miss Tracey Hollings)
Author:Jones, M (Associate Professor Menna Jones)
Author:McCallum, HI (Professor Hamish McCallum)
ID Code:89246
Year Published:2013
Funding Support:Australian Research Council (DP110103069)
Web of Science® Times Cited:23
Deposited By:Zoology
Deposited On:2014-02-27
Last Modified:2017-10-31
Downloads:0

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