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Presence-absence (detection/non-detection) data are routinely collected in wildlife studies where identification of individuals is impossible or impractical and where the detection method may be able to detect only the presence of an individual rather than a count (e.g., track or scat surveys). Estimating population density from presence-absence data usually is assumed to be difficult or impossible unless certain restrictive assumptions are made or supplementary information is collected. Recently, Chandler and Royle (2013) presented an extension of a spatially explicit capture-recapture model that estimates population density from spatially replicated counts in unmarked populations. We extended the model of Chandler and Royle (2013) to situations where only presence-absence data can be collected. The model assumes that individuals can be detected at multiple sample units, producing spatially correlated detections. A spatially explicit model of the detection process is then fit to the correlated detection data using Bayesian methods. We report on the performance of the model using simulation and illustrate its use with a practical example estimating the abundance and density of red foxes (Vulpes vulpes) from remote camera surveys in the Grampians National Park in southeastern Australia. Results from simulations suggest the model produces unbiased estimates of density if device spacing is less than the radial length of a typical home range and the number of encounter occasions is high (i.e., at least 10). Application of the model to camera detection data from foxes in the Grampians National Park resulted in an estimated density of 0.22 foxes/km 2 (95% CI: 0.16-0.53). For this dataset, precision of the density and detection parameter estimates were increased by the use of an informative prior distribution for the home-range-scale parameter. The current model should apply widely to a range of sampling situations that result in spatially correlated detection/non-detection data such as bait take, scat surveys, tracking stations, and chew cards, to name a few. Ó 2015 The Wildlife Society.

Dingoes/wild dogs (Canis dingo/familiaris) and red foxes (Vulpes vulpes) are widespread carnivores in southern Australia and are controlled to reduce predation on domestic livestock and native fauna. We used the occurrence of food items in 5875 dingo/wild dog scats and 11,569 fox scats to evaluate interspecific and geographic differences in the diets of these species within nine regions of Victoria, south-eastern Australia. The nine regions encompass a wide variety of ecosystems. Diet overlap between dingoes/wild dogs and foxes varied among regions, from low to near complete overlap. The diet of foxes was broader than dingoes/wild dogs in all but three regions, with the former usually containing more insects, reptiles and plant material. By contrast, dingoes/wild dogs more regularly consumed larger mammals, supporting the hypothesis that niche partitioning occurs on the basis of mammalian prey size. The key mammalian food items for dingoes/wild dogs across all regions were black wallaby (Wallabia bicolor), brushtail possum species (Trichosurus spp.), common wombat (Vombatus ursinus), sambar deer (Rusa unicolor), cattle (Bos taurus) and European rabbit (Oryctolagus cuniculus). The key mammalian food items for foxes across all regions were European rabbit, sheep (Ovis aries) and house mouse (Mus musculus). Foxes consumed 6.1 times the number of individuals of threatened Critical Weight Range native mammal species than did dingoes/wild dogs. The occurrence of intraguild predation was asymmetrical; dingoes/wild dogs consumed greater biomass of the smaller fox. The substantial geographic variation in diet indicates that dingoes/wild dogs and foxes alter their diet in accordance with changing food availability. We provide checklists of taxa recorded in the diets of dingoes/wild dogs and foxes as a resource for managers and researchers wishing to understand the potential impacts of policy and management decisions on dingoes/wild dogs, foxes and the food resources they interact with.

Foxes, wild dogs, feral cats, rabbits, feral pigs and feral goats are believed to have deleterious impacts on native biodiversity in Australia. However, although considerable resources have been expended controlling these six species, little is known about national patterns and costs of control and monitoring. We therefore conducted a survey of pest-control operations undertaken by conservation-focused organisations in Australia. A total of 1306 control operations were reported, with most conducted during 1998–2003: there was little information prior to 1990. Foxes and rabbits were the most, and feral cats the least, frequently controlled pest species. The total area on which control was undertaken in 2003, the year for which most information was available, ranged from ~0.4 × 104 km2 for feral cats to ~10.7 × 104 km2 for foxes. A wide range of techniques and intensities were used to control each of the six species. The estimated cost of labour expended on control in 2003 ranged from $0.4 × 106 for feral cats to $5.3 × 106 for foxes. Monitoring of the pest or biodiversity occurred in 50–56% of control actions in which foxes, wild dogs and feral cats were targeted, but only 22–26% of control actions in which rabbits, feral pigs and feral goats were targeted. Our results are discussed in relation to previous studies of pest animal control and monitoring in Australia.

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