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Context Feral cats (Felis catus) are a threat to biodiversity globally, but their impacts upon continental reptile faunas have been poorly resolved. Aims To estimate the number of reptiles killed annually in Australia by cats and to list Australian reptile species known to be killed by cats. Methods We used (1) data from >80 Australian studies of cat diet (collectively >10 000 samples), and (2) estimates of the feral cat population size, to model and map the number of reptiles killed by feral cats. Key results Feral cats in Australia’s natural environments kill 466 million reptiles yr–1 (95% CI; 271–1006 million). The tally varies substantially among years, depending on changes in the cat population driven by rainfall in inland Australia. The number of reptiles killed by cats is highest in arid regions. On average, feral cats kill 61 reptiles km–2 year–1, and an individual feral cat kills 225 reptiles year–1. The take of reptiles per cat is higher than reported for other continents. Reptiles occur at a higher incidence in cat diet than in the diet of Australia’s other main introduced predator, the European red fox (Vulpes vulpes). Based on a smaller sample size, we estimate 130 million reptiles year–1 are killed by feral cats in highly modified landscapes, and 53 million reptiles year–1 by pet cats, summing to 649 million reptiles year–1 killed by all cats. Predation by cats is reported for 258 Australian reptile species (about one-quarter of described species), including 11 threatened species. Conclusions Cat predation exerts a considerable ongoing toll on Australian reptiles. However, it remains challenging to interpret the impact of this predation in terms of population viability or conservation concern for Australian reptiles, because population size is unknown for most Australian reptile species, mortality rates due to cats will vary across reptile species and because there is likely to be marked variation among reptile species in their capability to sustain any particular predation rate. Implications This study provides a well grounded estimate of the numbers of reptiles killed by cats, but intensive studies of individual reptile species are required to contextualise the conservation consequences of such predation.

Conserving large carnivores is controversial because they can threaten wildlife, human safety, and livestock production. Since large carnivores often have large ranges, effective management requires knowledge of how their ecology and functional roles vary biogeographically. We examine continental‐scale patterns in the diet of the dingo – Australia's largest terrestrial mammalian predator. We describe and quantify how dingo dietary composition and diversity vary with environmental productivity and across five bioclimatic zones: arid, semi‐arid, tropical, sub‐tropical, and temperate. Based on 73 published and unpublished data sets from throughout the continent, we used multivariate linear modelling to assess regional trends in the occurrence of nine food groups (arthropods, birds, reptiles, European rabbits Oryctolagus cuniculus, medium‐sized [25–125 kg] and large [169–825 kg] exotic ungulates [including livestock], and other small [<0.5 kg], medium‐sized [0.5–6.9 kg] and large [≥7 kg] mammals) in dingo diets. We also assessed regional patterns in the dietary occurrence of livestock and the relationship between dietary occurrence of rabbits and small, medium‐sized and large mammals. Dingoes eat at least 229 vertebrate species (66% mammals, 22% birds, 11% reptiles, and 1% other taxa). Dietary composition varied across bioclimatic zones, with dingo diets in the arid and semi‐arid zones (low‐productivity sites) having the highest occurrence of arthropods, reptiles, birds, and rabbits. Medium‐sized mammals occurred most frequently in temperate and sub‐tropical zone diets (high‐productivity sites), large mammals least in the arid and sub‐tropical zones, and livestock most in the arid and tropical zones. The frequency of rabbits in diets was negatively correlated with that of medium‐sized, but not small or large mammals. Dingoes have a flexible and generalist diet that differs among bioclimatic zones and with environmental productivity in Australia. Future research should focus on examining how dingo diets are affected by local prey availability and human‐induced changes to prey communities.

AimAn interaction between reduced habitat structural complexity and predation by feral cats (Felis catus) has been hypothesized as the primary driver of mammal decline in northern Australia. However, we have a limited understanding of the drivers of the distribution and abundance of feral cats at a landscape scale, including whether the occurrence of a top predator, the dingo (Canis familiaris [dingo]), limits feral cat populations. We modelled feral cat and dingo site occurrence, to provide the first broad‐scale assessment of their distributional patterns and co‐occurrence within monsoonal Australia.LocationAbout 370,000 km2 of monsoonal area in the Northern Territory.MethodsWe surveyed 376 sites using camera traps. We used single‐ and two‐species occupancy models to investigate feral cat and dingo site occurrence and the influence of dingoes on feral cat occupancy. We included predictor variables that relate to hypotheses of predator occurrence, including both environmental and disturbance‐related variables.ResultsFeral cat occurrence and dingo occurrence were best predicted by indices of habitat structural complexity; feral cat occurrence declined with increasing productivity, except in areas of relatively high fire activity (fire frequency and extent), and dingo occurrence declined with terrain ruggedness. We found no evidence that dingoes are spatially limiting feral cat occurrence.Main conclusionsOur findings suggest the protection and enhancement of habitat structural complexity at both the local and landscape scale could enable conservation managers to reduce the exposure of small‐ and medium‐sized mammals to feral cats and dingoes. This can most likely be achieved through improved fire and feral herbivore management, which is a more feasible management option than lethal predator control.

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Context. Feral cats are a major cause of mammal declines and extinctions in Australia. However, cats are elusive and obtaining reliable ecological data is challenging. Although camera traps are increasingly being used to study feral cats, their successful use in northern Australia has been limited.Aims. We evaluated the efficacy of camera-trap sampling designs for detecting cats in the tropical savanna of northern Australia. We aimed to develop a camera-trapping method that would yield detection probabilities adequate for precise occupancy estimates.Methods. First, we assessed the influence of two micro-habitat placements and three lure types on camera-trap detection rates of feral cats. Second, using multiple camera traps at each site, we examined the relationship between sampling effort and detection probability by using a multi-method occupancy model.Key results. We found no significant difference in detection rates of feral cats using a variety of lures and micro-habitat placement. The mean probability of detecting a cat on one camera during one week of sampling was very low (p = 0.15) and had high uncertainty. However, the probability of detecting a cat on at least one of five cameras deployed concurrently on a site was 48% higher (p = 0.22) and had a greater precision.Conclusions. The sampling effort required to achieve detection rates adequate to infer occupancy of feral cats by camera trap is considerably higher in northern Australia than has been observed elsewhere in Australia. Adequate detection of feral cats in the tropical savanna of northern Australia will necessitate inclusion of more camera traps and a longer survey duration.Implications. Sampling designs using camera traps need to be rigorously trialled and assessed to optimise detection of the target species for different Australian biomes. A standard approach is suggested for detecting feral cats in northern Australian savannas.