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Sutherland D.R.,Phillip Island Nature Parks | Glen A.S.,Landcare Research | De Tores P.J.,Invasive Animals Co operative Research Center
Proceedings of the Royal Society B: Biological Sciences | Year: 2011

Emerging evidence increasingly illustrates the importance of a holistic, rather than taxon-specific, approach to the study of ecological communities. Considerable resources are expended to manage both introduced and native mammalian carnivores to improve conservation outcomes; however, management can result in unforeseen and sometimes catastrophic outcomes. Varanid lizards are likely to be apex- or mesopredators, but being reptiles are rarely considered by managers and researchers when investigating the impacts of mammalian carnivore management. Instances of mesopredator release have been described for Varanus gouldii as a result of fox and cat management in Australia, with cascading effects on faunal community structure. A meta-analysis showing extensive dietary niche overlap between varanids, foxes and cats plus a review of experimental and circumstantial evidence suggests mesopredator release of V. gouldii and about five other medium to large species of varanid lizard is likely in other regions. This highlights the need for managers to adopt a whole-of-community approach when attempting to manage predators for sustained fauna conservation, and that additional research is required to elucidate whether mesopredator release of varanids is a widespread consequence of carnivore management, altering the intended faunal responses. © 2010 The Royal Society. Source


Berry O.,University of Western Australia | Berry O.,CSIRO | Algar D.,Western Australian Wildlife Research Center | Angus J.,Western Australian Wildlife Research Center | And 3 more authors.
Journal of Wildlife Management | Year: 2012

Globally, invasive predators are major pests of agriculture and biodiversity and are the focus of comprehensive control programs. Because these species are typically elusive, wary of traps, and occur at low densities, their fundamental population dynamics are difficult to determine and quantitative evaluations of control programs are rarely conducted. Noninvasive DNA analysis has the potential to resolve this long-standing limitation to pest management. We carried out a landscape-scale experiment to quantify reduction in the abundance of a red fox (Vulpes vulpes) population when baited with sodium fluoroacetate (1080) poison (the most widely used method of fox control in Australia). We collected fox hairs with hair snares during 4 4-day sessions over the course of 6 months at a site in semi-arid Western Australia. The first session took place in late summer just prior to when juvenile foxes typically disperse, and the final session followed aerial baiting with 1080 poison. We obtained consensus microsatellite genotypes from 196 samples, and used them to conduct both spatially explicit and open model capture-recapture analysis. Twenty-eight percent of trap nights yielded hair samples suitable for identification of individual foxes, which is more than an order of magnitude greater than trapping rates reported with conventional techniques. Fox density changed little during 3 pre-baiting sessions and averaged 0.73 foxes/km 2 (±0.33 SE), which is less than most previous trap-based estimates for Australian foxes. Density dropped significantly in response to baiting to 0.004 foxes/km 2. Prior to baiting, the apparent survival of foxes remained static (0.72 ± 0.14 SE), but in response to baiting it dropped precipitously and was effectively zero. This experiment provides the first quantitative assessment of the effectiveness of 1080 poison baiting for reducing fox density, and in this case demonstrates it to be a highly effective method for culling foxes from a region. Further, it demonstrates that noninvasive DNA analysis will provide significantly more data than conventional trapping methods. This method is likely to provide greater precision and accuracy than conventional methods and therefore result in more robust evaluations of management strategies for the fox in Australia, and for cryptic species elsewhere. © 2011 The Wildlife Society. Source


Lawson J.,Lions Dryandra Woodland Village P. O. Box 118 | Lawson J.,Invasive Animals Co operative Research Center | Hitchen Y.,University of Western Australia | Hitchen Y.,Invasive Animals Co operative Research Center | Berry O.,CSIRO
Ecological Management and Restoration | Year: 2015

European Red Fox (Vulpes vulpes) baiting with 1080 poison (sodium fluoroacetate) is undertaken in many Australian sites to reduce fox abundance and to protect vulnerable native species from predation. The longest continuous use of fox baiting for fauna conservation commenced in south-west Western Australia in the 1980s and includes baiting Dryandra Woodland and Tutanning Nature Reserve. The trap success of the Woylie (Bettongia penicillata) in these two reserves initially increased more than 20-fold after the commencement of baiting and was maintained until 2000. Woylie captures then decreased rapidly, despite ongoing fox baiting, so the long-term efficacy of 1080 baiting was questioned. Here, fox density and probabilities of detection, re-detection and survival between replicated baited and unbaited sites were compared by modelling capture-recapture of individual foxes. These were identified from microsatellite DNA genotypes obtained non-invasively from hair, scat and saliva samples. The frequency and duration of fox residencies were also quantified. Remote cameras were used to determine the fate of baits but uptake by foxes was low, whereas nontarget species' bait uptake was high. Nevertheless, foxes inhabiting baited reserves had significantly higher mortality, shorter residency times, and 80% lower density than foxes inhabiting unbaited reserves. Baiting continues to significantly reduce fox abundance after more than 25 years of continuous use. This has positive implications for fox control programmes throughout Australia but reduced fox abundance may facilitate increased predation by feral Cats (Felis catus). © 2015 Ecological Society of Australia and Wiley Publishing Asia Pty Ltd. Source


Marlow N.J.,Invasive Animals Co operative Research Center | Thomas N.D.,Invasive Animals Co operative Research Center | Williams A.A.E.,Invasive Animals Co operative Research Center | MacMahon B.,Invasive Animals Co operative Research Center | And 7 more authors.
Australian Journal of Zoology | Year: 2015

The control of foxes (Vulpes vulpes) is a key component of many fauna recovery programs in Australia. A question crucial to the success of these programs is how fox control influences feral cat abundance and subsequently affects predation upon native fauna. Historically, this question has been difficult to address because invasive predators are typically challenging to monitor. Here, non-invasive DNA analysis was used to determine the fate of radio-collared woylies (Bettongia penicillata) in two reserves in a mesic environment where foxes had been controlled intensively for over two decades. Woylie trap success had increased more than 20-fold after fox baiting commenced in the 1980s but decreased precipitously in 2000. Ninety-eight monitored woylies were killed between 2006 and 2009. DNA analysis of swabs taken from radio-collars and carcasses of these woylies indicated that predation by cats (Felis catus) caused most mortalities (65%) and was three times the fox predation rate (21%). Also, indices of cat abundance were higher in fox-baited sites where foxes were less abundant. Predation on woylies by cats was greater than previously recognised and, by implication, may significantly reduce the effectiveness of fox control programs throughout Australia. Integrated fox and cat control is essential to ensure the success of fauna recovery programs. © CSIRO 2015. Source


Marlow N.J.,Invasive Animals Co operative Research Center | Williams A.A.E.,Invasive Animals Co operative Research Center | Thomas N.D.,Invasive Animals Co operative Research Center | MacMahon B.,Invasive Animals Co operative Research Center | Lawson J.,Invasive Animals Co operative Research Center
Conservation Science Western Australia | Year: 2015

The diet of foxes in two fragmented Wheatbelt reserves in south-west Western Australia, Dryandra Woodland (DW) and Tutanning Nature Reserve (TNR), was investigated. Fox baiting commenced in these reserves in the early 1980s and the trap success of woylies (Bettongia penicillata), a threatened species, increased significantly. Woylie capture rates were sustained in TNR until 1992 and in DW until 2000 but then decreased suddenly despite ongoing fox control. The diet of foxes was investigated as part of a larger study examining the reasons for the woylie decline. The contents of 283 fox scats from DW and TNR, and 167 scats from two unbaited sites, Quinns block (QB) and Highbury block (HB), were analysed volumetrically to determine the relative importance of each dietary item. The actual consumption of each item was calculated using digestibility estimates. In baited sites the foxes’ main dietary components were house mice (Mus domesticus, 28%), carrion (sheep, Ovis aries and western grey kangaroo, Macropus fuliginosus; 26%) and rabbits (Oryctolagus cuniculus, 17%). In unbaited sites the main components were carrion (predominately sheep, 60%) and some invertebrates (13%). Only one scat (from DW) contained any woylie remains. Approximately 10% of the foxes’ diet in all sites consisted of brush-tail possums (Trichosurus vulpecula). No remains from numbats (Myrmecobius fasciatus), bilbies (Macrotis lagotis), red-tailed phascogales (Phascogale calura), Antechinus sp., Sminthopsis sp. or echidnas (Tachyglossus aculeatus) were detected. Birds (<5%) and reptiles (<2%) were of little dietary importance at all sites. There was no significant seasonal variation in the foxes’ diet. The role of rabbits in the diet of foxes and the potential for the presence of this species to drive increases in fox abundance, and by deduction to increase predation on woylies and other similar prey species, is considered in relation to theoretical predator prey models and management options. © The Government of Western Australia, 2015. Source

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