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The impact of introduced predators on two threatened prey species: A case study from western New South Wales

Authors

  • Robert Wheeler,

  • David Priddel


  • Robert Wheeler and David Priddel are research scientists with the Department of Environment and Climate Change New South Wales (PO Box 1967, Hurstville BC, NSW 1481, Australia. Tel. 02 95856504. Fax: 02 95856606. Email: robert.wheeler@environment.nsw.gov.au). This project is part of a broader research programme aimed at developing new approaches and procedures for the recovery of Australia's threatened fauna.

Abstract

Summary  Since European settlement, many Australian mammals have become extinct; numerous others survive within substantially reduced ranges. Predation by the Red Fox (Vulpes vulpes) and House Cat (Felis catus) are two of the major drivers of this decline. The demise of Australia's native fauna continues, with ground-nesting birds such as the Malleefowl (Leipoa ocellata) now being at greatest risk of extinction. In regions of Western Australia, this situation has been partially reversed through the broadscale control of the Fox and the re-introduction of locally extinct species. In this paper, we review research undertaken on Yathong Nature Reserve (YNR) in western New South Wales to (i) evaluate current threats, and (ii) assess our ability to restore locally extinct species across this particular landscape. We conducted releases of both the Malleefowl and Brush-tailed Bettong (Bettongia penicillata), two species that were once common in the region. Despite the potential for food resources to have been diminished by exotic herbivores, we found no evidence that food shortage was a limiting factor for either of the two species we released. Predation by the Fox was the greatest single cause of Malleefowl mortality. Localized, intensive ground baiting of the Fox was essentially ineffective in mitigating this threat, whereas broadscale aerial baiting substantially enhanced Malleefowl survival, at least during the first few years. Accordingly, thrice-yearly aerial baiting for the Fox has been conducted on YNR since 1996. Despite this, and a long-term restocking programme, the size of the Malleefowl population has not increased since aerial baiting began. The release of the Brush-tailed Bettong into YNR in 2001 confirmed the effectiveness of the ongoing fox-control programme but demonstrated the detrimental impact of another introduced predator – the Cat. We conclude that, while current management actions continue, the Fox is no longer a threat to wildlife on YNR, and suggest that the Cat is now the major impediment to both the recovery of depleted faunal populations (including the Malleefowl) and the restoration of locally extinct species (such as bettongs) within this landscape.

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