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Dietary (scat) analysis is a key tool for assessing the potential effects of predators on prey and for comparing resource use between predators, information that is crucial for effective wildlife management. However, misidentification of the species from which scats originate could result in inaccurate conclusions regarding predator–prey interactions and their consequences for ecosystems, which may ultimately compromise conservation and management actions. To address this issue, we developed a framework for decision-making in the face of uncertain scat species origin by incorporating field, laboratory, and molecular identification techniques. We used the framework to examine the diets of two predators, a native apex predator (dingo, Canis lupus dingo) and an invasive mesopredator (feral cat, Felis catus), from 696 field-collected scats in the arid zone of Australia. We examined how uncertainty regarding scat species origin changed perceptions of the nature of the relationship between coexisting predators and their prey. The extent of dietary overlap between dingoes and cats varied with the method used to identify scat species origin. Dietary overlap assessed by laboratory identifications was twice as high as when uncertainty in scat species origin was resolved through our decision framework. If uncertainty in scat species origin is not resolved in dietary studies, practitioners and decision-makers relying on this information run the risk of making misinformed conclusions regarding the ecological function of predators (including potential impacts on threatened species), which could have perverse outcomes if the wrong predators are targeted for management. With uncertainty in scat species origin resolved through our decision framework, a low level of dietary overlap between the two predators was demonstrated, and medium-sized mammals most threatened with extinction were shown to be more at risk of impact from feral cat than from dingo depredations. [ABSTRACT FROM AUTHOR]

We investigated the hypothesis that trophic competition between a top predator and a smaller predator can create refuge from predation for small mammalian prey, using the dingo (Canis lupus dingo) and feral cat (Felis catus) in the MacDonnell Ranges of dryland Australia as a case study. We analyzed the diets of the 2 predator species for evidence of potential competition. There was no evidence of exploitation competition between the 2 carnivores—cats consumed mostly small mammals and particularly larger rodents, whereas the diet of dingoes was dominated by 1 species of large macropod. There was also no evidence of a shift in diet of cats, as their diets in refuges and non-refuges were highly overlapping. Consistent with interference competition, cats were the third most frequently consumed mammal species by dingoes. Although predation by dingoes could limit densities of cats across the MacDonnell Ranges, this alone does not explain why the most rugged habitats in the region are a refuge for rare mammals. We conclude that habitat complexity most likely underpins the refuge and that possible effects of dingo predation on the cat population would be of secondary importance. [ABSTRACT FROM AUTHOR]

Fire shapes biome distribution and community composition worldwide, and is extensively used as a management tool in flammable landscapes. There is growing concern, however, that fire could increase the vulnerability of native fauna to invasive predators. We developed a conceptual model of the ways in which fire could influence predator-prey dynamics. Using a before-after, control-impact experiment, we then investigated the short-term effects of a prescribed fire on 2 globally significant invasive mesopredators (red fox, Vulpes vulpes, and feral cat, Felis catus) and their native mammalian prey in a fire-prone forest of southeastern Australia. We deployed motion-sensing cameras to assess species occurrence, collected predator scats to quantify diet and prey choice, and measured vegetation cover before and after fire. We examined the effects of the fire at the scale of the burn block (1,190 ha), and compared burned forest to unburned refuges. Pre-fire, invasive predators and large native herbivores were more likely to occur at sites with an open understory, whereas the occurrence of most smalland medium-sized native mammals was positively associated with understory cover. Fire reduced understory cover by more than 80%, and resulted in a 5-fold increase in the occurrence of invasive predators. Concurrently, relative consumption of medium-sized native mammals by foxes doubled, and selection of long-nosed bandicoots (Perameles nasuta) and short-beaked echidnas (Tachyglossus aculeatus) by foxes increased. Occurrence of bush rats (Rattus fuscipes) declined. It was unclear if fire also affected the occurrence of bandicoots or echidnas, as changes coincided with normal seasonal variations. Overall, prescribed fire promoted invasive predators, while disadvantaging their medium-sized native mammalian prey. Further replication and longer-term experiments are needed before these findings can be generalized. Nonetheless, such interactions could pose a serious threat to vulnerable species such as critical weight range mammals. Integrated invasive predator and fire management are recommended to improve biodiversity conservation in flammable ecosystems. [ABSTRACT FROM AUTHOR]

Domestic cats ( Felis catus) have caused the extinction of many island species and are thought to kill many billions of birds and mammals in the continental United States each year. However, the spatial distribution and abundance of cats and their risk to our protected areas remains unknown. We worked with citizen scientists to survey the mammals at 2,117 sites in 32 protected areas and one urban area across 6 states in the eastern United States using camera traps. We found that most protected areas had high levels of coyote ( Canis latrans) activity, but few or no domestic cats. The relative abundance of domestic cats in residential yards, where coyotes were rare, was 300 times higher than in the protected areas. Our spatial models of cat distribution show the amount of coyote activity and housing density are the best predictors of cat activity, and that coyotes and cats overlap the most in small urban forests. Coyotes were nocturnal at all sites, while cats were nocturnal in protected areas, but significantly more diurnal in urban sites. We suggest that the ecological impact of free-ranging cats in the region is concentrated in urban areas or other sites, such as islands, with few coyotes. Our study also shows the value of citizen science for conducting broadscale mammal surveys using photo-vouchered locations that ensure high data quality. [ABSTRACT FROM AUTHOR]

Feral cats, Felis catus, inhabiting San Clemente Island, California, are both predators and competitors of multiple sympatric endemic species. To improve our understanding and management of these invasive predators, we used GPS-equipped radiocollars to track 11 (6F:5M) cats for a total of 3,108 days, resulting in 15,419 GPS locations. Average 100% minimum convex polygon, 95% kernel density, and 50% kernel density estimates were 229, 132, and 33 ha, respectively. The point estimate for average male home-range size was larger than the average for females, but there was substantial variation among individuals of both sexes. Overlap indices indicated similar usage areas during nocturnal and diurnal time periods. Sample size limited our ability to definitively detect habitat preference, but data suggested areas within 50 m of roads were avoided, and that thicker land cover was preferred over open grasslands. Three test collars deployed within active cat home ranges indicated GPS locations were precise, with 96% of locations having < 10-m error estimates, and that horizontal dilution of precision indices were not useful in screening data. Our results describe feral cat spatial ecology on a semiarid island and can be used to inform population estimation, control, and mitigation programs. [ABSTRACT FROM AUTHOR]

The diets of predators and their selection of prey often shape prey community dynamics. Understanding how different predators select their prey could enable ecologists to predict their impact on specific prey populations. Here, we investigate the diets of the feral cat ( Felis catus), red fox ( Vulpes vulpes), and dingo ( Canis dingo) in the Simpson Desert of central Australia, over a 1-year period between 2011 and 2012, and compare the selectivity of these predators for small mammalian prey. We found that cats showed the greatest consumption of small mammals, whereas dingoes consumed larger prey, thus indicating preferences for different prey sizes. High occurrence of small mammals in the diets of all predators probably reflected high abundances of small mammals in the environment; rodents declined after an irruption, but were still abundant at the time of sampling. The cat exercised greatest selectivity for small mammal species, whereas the dingo did not positively select for any species. Positive selection by predators for the long-haired rat ( Rattus villosissimus) and negative selection for the spinifex hopping-mouse ( Notomys alexis) may reflect inefficient and well-developed escape strategies by these 2 prey species, respectively. High selectivity by the cat for Forrest's mouse ( Leggadina forresti) suggests that conservation of this rare rodent may depend on effective cat management. [ABSTRACT FROM AUTHOR]

Domestic cats (Felis earns) have been introduced on many islands in the world and are responsible for much damage to native insular faunas. The worldwide success and spread of this opportunistic predator is generally associated with its trophic adaptability. We examined the diet of a long-established feral cat population on a small Mediterranean island through the analysis of 1,219 scats collected during a 4-year period. Our results confirm that feral cats are generalist predators, able to feed on a wide range of prey. However, only a few prey species formed the major part of its diet. Two introduced mammals and a Mediterranean endemic seabird provided 93% of the yearly biomass consumed by cats (ship rats, 70%: wild rabbits, 7%; and yelkouan shearwaters, 6%). Ship rats remained by far the staple prey for cats throughout the year, but the diet of feral cats was more diversified in spring and early summer, frequently including insects, reptiles, and migrant birds. Endemic yelknouan shearwaters were preyed upon most frequently in autumn and winter, that is, during the shearwaters' prelaying period. Because rats provide the majority of the food of cats, they could help to maintain or inflate this alien predator population with deleterious consequences to the endemic shearwater. A cat eradication campaign would help protect the population of shearwaters on this island. [ABSTRACT FROM AUTHOR]

Predation by feral cats (Felis catus) is recognized as a major threat to native fauna worldwide, but the competitive effects of cats on native species have not been extensively studied. Cats occur on San Clemente Island, California, in sympatry with endemic island foxes (Urocyon littoralis clementae). We examined diets of cats and island foxes between years, seasons, and habitats to assess the potential for resource competition between the 2 species, Analysis of 602 cat and 958 fox feces revealed a high level of dietary overlap (O = 0.93) and relatively narrow niche breadths for both species (Bstandard Fox = 0.37; B standard Cat = 0.49). Despite the overlap in diet, cats and foxes appear to partition prey resources. Cats consume approximately equal proportions of arthropod (47.9%) and vertebrate (44.2%) prey, the latter primarily rodents (29.2%) and lizards 112.9%). In contrast, foxes appear to rely more on arthropods (57.7%), with plants (20.5%) and vertebrates 121.6%) occurring in lower, but roughly equal frequencies. Season appeared to have little effect on diet; however, diet did vary between habitats and years for both species. Diets of cats on San Clemente Island are consistent with those from other studies. We found no evidence of a dietary shift by foxes that were in sympatry with cats. [ABSTRACT FROM AUTHOR]