Diets of sympatric native and introduced carnivores in the Barrington Tops,eastern Australia

Invasive predators have severe impacts on global biodiversity, and their effects in Australia have been more extreme than on any other continent. The spotted‐tailed quoll (Dasyurus maculatus), an endangered marsupial carnivore, coexists with three eutherian carnivores, the red fox (Vulpes vulpes), feral cat (Felis catus) and wild dog (Canis lupus ssp.) with which it did not coevolve. No previous study has investigated dietary overlap between quolls and the suite of three eutherian carnivores. By analysing scats, we aimed to quantify dietary overlap within this carnivore assemblage in eastern Australia, and to detect any differences that may facilitate coexistence. We also sought evidence of intraguild predation. Dietary overlap between predators was extensive, with the greatest similarity occurring between foxes and cats. However, some differences were apparent. For example, cats mainly consumed smaller prey, and wild dogs larger prey. Quolls showed greater dietary overlap with foxes and cats than with dogs. Intraguild predation was evident, with fox remains occurring in 3% of wild dog scats. Our results suggest wild dogs competitively dominate invasive foxes, which in turn are likely to compete with the endangered quoll.     

Rabies Virus and Canine Distemper Virus in Wild and Domestic Carnivores in Northern Kenya: Are Domestic Dogs the Reservoir?

Rabies virus (RV) and canine distemper virus (CDV) can cause significant mortality in wild carnivore populations, and RV threatens human lives. We investigated serological patterns of exposure to CDV and RV in domestic dogs (Canis familiaris), African wild dogs (Lycaon pictus), black-backed jackals (Canis mesomelas), spotted hyenas (Crocuta crocuta), striped hyenas (Hyaena hyaena) and African lions (Panthera leo), over a 10-year period, in a Kenyan rangeland to assess the role domestic dogs may play in the transmission dynamics of these two important canid pathogens. Observed patterns of RV exposure suggested that repeated introduction, rather than maintenance, occurred in the wild carnivore species studied. However, RV appeared to have been maintained in domestic dogs: exposure was more likely in domestic dogs than in the wild carnivores; was detected consistently over time without variation among years; and was detected in juveniles (≤1-year-old) as well as adults (>1-year-old). We conclude that this domestic dog population could be a RV reservoir. By contrast, the absence of evidence of CDV exposure for each carnivore species examined in the study area, for specific years, suggested repeated introduction, rather than maintenance, and that CDV may require a larger reservoir population than RV. This reservoir could be a larger domestic dog population; another wildlife species; or a “metareservoir” consisting of multiple interconnected carnivore populations. Our findings suggest that RV risks to people and wild carnivores might be controlled by domestic dog vaccination, but that CDV control, if required, would need to target the species of concern.     

The role of exotic mammals in the diet of native carnivores from South America

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Key factors and related principles in the conservation of large African carnivores

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Use of agroecosystem matrix habitats by mammalian carnivores (Carnivora): a global‐scale analysis

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Spatial and temporal avoidance of risk within a large carnivore guild

Within a large carnivore guild, subordinate competitors (African wild dog, Lycaon pictus, and cheetah, Acinonyx jubatus) might reduce the limiting effects of dominant competitors (lion, Panthera leo, and spotted hyena, Crocuta crocuta) by avoiding them in space, in time, or through patterns of prey selection. Understanding how these competitors cope with one other can inform strategies for their conservation. We tested how mechanisms of niche partitioning promote coexistence by quantifying patterns of prey selection and the use of space and time by all members of the large carnivore guild within Liuwa Plain National Park in western Zambia. Lions and hyenas specialized on wildebeest, whereas wild dogs and cheetahs selected broader diets including smaller and less abundant prey. Spatially, cheetahs showed no detectable avoidance of areas heavily used by dominant competitors, but wild dogs avoided areas heavily used by lions. Temporally, the proportion of kills by lions and hyenas did not detectably differ across four time periods (day, crepuscular, early night, and late night), but wild dogs and especially cheetahs concentrated on time windows that avoided nighttime hunting by lions and hyenas. Our results provide new insight into the conditions under which partitioning may not allow for coexistence for one subordinate species, the African wild dog, while it does for cheetah. Because of differences in responses to dominant competitors, African wild dogs may be more prone to competitive exclusion (local extirpation), particularly in open, uniform ecosystems with simple (often wildebeest dominated) prey communities, where spatial avoidance is difficult.     

Prey availability and intraguild competition regulate the spatiotemporal dynamics of a modified large carnivore guild

Effective conservation management requires an understanding of the spatiotemporal dynamics driving large carnivore density and resource partitioning. In African ecosystems, reduced prey populations and the loss of competing guild members, most notably lion (Panthera leo), are expected to increase the levels of competition between remaining carnivores. Consequently, intraguild relationships can be altered, potentially increasing the risk of further population decline. Kasungu National Park (KNP), Malawi, is an example of a conservation area that has experienced large‐scale reductions in both carnivore and prey populations, leaving a resident large carnivore guild consisting of only leopard (Panthera pardus) and spotted hyena (Crocuta crocuta). Here, we quantify the spatiotemporal dynamics of these two species and their degree of association, using a combination of co‐detection modeling, time‐to‐event analyses, and temporal activity patterns from camera trap data. The detection of leopard and spotted hyena was significantly associated with the detection of preferred prey and competing carnivores, increasing the likelihood of species interaction. Temporal analyses revealed sex‐specific differences in temporal activity, with female leopard activity patterns significantly different to those of spotted hyena and male conspecifics. Heightened risk of interaction with interspecific competitors and male conspecifics may have resulted in female leopards adopting temporal avoidance strategies to facilitate coexistence. Female leopard behavioral adaptations increased overall activity levels and diurnal activity rates, with potential consequences for overall fitness and exposure to sources of mortality. As both species are currently found at low densities in KNP, increased risk of competitive interactions, which infer a reduction in fitness, could have significant implications for large carnivore demographics. The protection of remaining prey populations is necessary to mitigate interspecific competition and avoid further alterations to the large carnivore guild.     

Tiger and leopard co-occurrence: intraguild interactions in response to human and livestock disturbance

Intraguild interactions have important implications for carnivore demography and conservation. Differences in how predators respond to different forms of disturbance might alter their interaction patterns. We sought to understand how human and livestock disturbance impact co-occurrence of sympatric large carnivores such as tiger (Panthera tigris) and leopard (P. pardus) and thereby mediate the intraguild interaction pattern to enable coexistence of the species in a human-dominated landscape. We surveyed 361 locations in Chitwan National Park, Nepal, to examine how prey abundance and disturbance factors such as human and livestock presence might influence habitat use by tigers and leopards independently and when co-occurring. Single-species single-season models and two-species single-season models were developed to examine hypotheses on unconditional detection and occupancy and species interaction respectively. Pervasive human use of the park had negative impacts on tiger occupancy while the abundance of prey had a positive influence. Despite significant prey overlap between tigers and leopards, none of the native prey species predicted leopard habitat occupancy. However, habitats used extensively by livestock were also used by leopards. Further, we found strong evidence of intraguild competition. For instance tiger occupancy was higher in prey-rich areas and leopard occupancy was low in the sites where tigers were present. These findings, and a species interaction factor of < 1 clearly indicate that leopards avoid tigers, but their use of areas of disturbance enables them to persist in fringe habitats. We provide empirical evidence of how intraguild interaction may result in habitat segregation between competing carnivores, while also showing that human and livestock use of the landscape create disturbance patterns that facilitate co-occurrence of the predators. Thus, because large carnivores compete, some disturbance may mediate coexistence in small protected areas. Understanding such interactions can help address important conservation challenges associated with maintaining diverse carnivore communities in small or disturbed landscapes.     

Seasonal variation in prey preference,diet partitioning and niche breadth in a rich large carnivore guild

Large carnivore community structure is affected by direct and indirect interactions between intra-guild members. Co-existence between different species within a carnivore guild may occur through diet, habitat or temporal partitioning. Since carnivore species are highly dependent on availability and accessibility of prey, diet partitioning is potentially one of the most important mechanisms in allowing carnivores to co-exist. Intra-guild interactions may vary over time as carnivore prey preference and diet overlap can change due to seasonal changes in resource availability. We conducted scat analysis to compare the seasonal changes in prey preference, diet partitioning and niche breadth of four large carnivore species, namely leopard Panthera pardus, spotted hyena Crocuta crocuta, brown hyena Parahyaena brunnea and wild dog Lycaon pictus in central Tuli, Botswana. Large carnivores in central Tuli display a high dietary overlap, with spotted hyena and brown hyena displaying almost complete dietary overlap and the other carnivore species displaying slightly lower but still significant dietary overlap. Dietary niche breadth for both hyena species was high possibly due to their flexible foraging strategies, including scavenging, while leopard and wild dog showed a relatively low niche breadth, suggesting a more specialised diet. High dietary overlap in central Tuli is possibly explained by the high abundance of prey species in the area thereby reducing competition pressure between carnivore species. Our research highlights the need to assess the influence of diet partitioning in structuring large carnivore communities across multiple study sites, by demonstrating that in prey rich environments, the need for diet partitioning by carnivores to avoid competition may be limited.     

Spatial interactions between sympatric carnivores: asymmetric avoidance of an intraguild predator

Interactions between intraguild species that act as both competitors and predator–prey can be especially complex. We studied patterns of space use by the black-footed ferret (Mustela nigripes), a prairie dog (Cynomys spp.) specialist, and the American badger (Taxidea taxus), a larger generalist carnivore that competes for prairie dogs and is known to kill ferrets. We expected that ferrets would spatially avoid badgers because of the risk of predation, that these patterns of avoidance might differ between sexes and age classes, and that the availability of food and space might influence these relationships. We used location data from 60 ferrets and 15 badgers to model the influence of extrinsic factors (prairie dog density and colony size) and intrinsic factors (sex, age) on patterns of space use by ferrets in relation to space use by different sex and age categories of badgers. We documented asymmetric patterns of avoidance of badgers by ferrets based on the sex of both species. Female ferrets avoided adult female badgers, but not male badgers, and male ferrets exhibited less avoidance than female ferrets. Additionally, avoidance decreased with increasing densities of prairie dogs. We suggest that intersexual differences in space use by badgers create varying distributions of predation risk that are perceived by the smaller carnivore (ferrets) and that females respond more sensitively than males to that risk. This work advances understanding about how competing species coexist and suggests that including information on both intrinsic and extrinsic factors might improve our understanding of behavioral interactions between sympatric species.     

Implications of African wild dog (Lycaon pictus) denning on the density and distribution of a key prey species: addressing myths and misperceptions

African wild dogs (Lycaon pictus) are often the least popular large carnivore among game ranchers because of their perceived impact on prey populations. Landowner perceptions include that wild dogs greatly deplete prey during their three-month denning period, take prey that could otherwise be sold for hunting and cause prey to move away from the vicinity of their den sites. Landowners’ tolerance towards African wild dogs could thus be improved with a more rigorous understanding of the actual impact of wild dogs on prey populations during the denning period. Using impala density data and wild dog denning records from Sango Ranch in the Savé Valley Conservancy, Zimbabwe, we compared impala densities between pre-denning, denning and post-denning season and between inside and outside the denning home range. Our results indicate that wild dog denning does not cause a significant local reduction in prey around the den and does not cause prey to move away from denning areas. However prey species did occur in lower density inside the denning home ranges than outside, in all seasons. This result indicates that wild dogs select dens in areas of lower prey density, perhaps as an avoidance mechanism for lions. Accordingly, contrary to what landowners believe, wild dogs do not have a significant impact on prey populations during their denning season.     

Topcats and underdogs: intraguild interactions among three apex carnivores across Asia's forestscapes

Intraguild interactions among carnivores have long held the fascination of ecologists. Ranging from competition to facilitation and coexistence, these interactions and their complex interplay influence everything from species persistence to ecosystem functioning. Yet, the patterns and pathways of such interactions are far from understood in tropical forest systems, particularly across countries in the Global South. Here, we examined the determinants and consequences of competitive interactions between dholes Cuon alpinus and the two large felids (leopards Panthera pardus and tigers Panthera tigris) with which they most commonly co-occur across Asia. Using a combination of traditional and novel data sources (N = 118), we integrate information from spatial, temporal, and dietary niche dimensions. These three species have faced catastrophic declines in their extent of co-occurrence over the past century; most of their source populations are now confined to Protected Areas. Analysis of dyadic interactions between species pairs showed a clear social hierarchy. Tigers were dominant over dholes, although pack strength in dholes helped ameliorate some of these effects; leopards were subordinate to dholes. Population-level spatio-temporal interactions assessed at 25 locations across Asia did not show a clear pattern of overlap or avoidance between species pairs. Diet-profile assessments indicated that wild ungulate biomass consumption by tigers was highest, while leopards consumed more primate and livestock prey as compared to their co-predators. In terms of prey offtake (ratio of wild prey biomass consumed to biomass available), the three species together harvested 0.4–30.2% of available prey, with the highest offtake recorded from the location where the carnivores reach very high densities. When re-examined in the context of prey availability and offtake, locations with low wild prey availability showed spatial avoidance and temporal overlap among the carnivore pairs, and locations with high wild prey availability showed spatial overlap and temporal segregation. Based on these observations, we make predictions for 40 Protected Areas in India where temporally synchronous estimates of predator and prey densities are available. We expect that low prey availability will lead to higher competition, and in extreme cases, to the complete exclusion of one or more species. In Protected Areas with high prey availability, we expect intraguild coexistence and conspecific competition among carnivores, with spill-over to forest-edge habitats and subsequent prey-switching to livestock. We stress that dhole–leopard–tiger co-occurrence across their range is facilitated through an intricate yet fragile balance between prey availability, and intraguild and conspecific competition. Data gaps and limitations notwithstanding, our study shows how insights from fundamental ecology can be of immense utility for applied aspects like large predator conservation and management of human–carnivore interactions. Our findings also highlight potential avenues for future research on tropical carnivores that can broaden current understanding of intraguild competition in forest systems of Asia and beyond.     

Phantoms of the forest: legacy risk effects of a regionally extinct large carnivore

The increased abundance of large carnivores in Europe is a conservation success, but the impact on the behavior and population dynamics of prey species is generally unknown. In Europe, the recolonization of large carnivores often occurs in areas where humans have greatly modified the landscape through forestry or agriculture. Currently, we poorly understand the effects of recolonizing large carnivores on extant prey species in anthropogenic landscapes. Here, we investigated if ungulate prey species showed innate responses to the scent of a regionally exterminated but native large carnivore, and whether the responses were affected by human‐induced habitat openness. We experimentally introduced brown bear Ursus arctos scent to artificial feeding sites and used camera traps to document the responses of three sympatric ungulate species. In addition to controls without scent, reindeer scent Rangifer tarandus was used as a noncarnivore, novel control scent. Fallow deer Dama dama strongly avoided areas with bear scent. In the presence of bear scent, all ungulate species generally used open sites more than closed sites, whereas the opposite was observed at sites with reindeer scent or without scent. The opening of forest habitat by human practices, such as forestry and agriculture, creates a larger gradient in habitat openness than available in relatively unaffected closed forest systems, which may create opportunities for prey to alter their habitat selection and reduce predation risk in human‐modified systems that do not exist in more natural forest systems. Increased knowledge about antipredator responses in areas subjected to anthropogenic change is important because these responses may affect prey population dynamics, lower trophic levels, and attitudes toward large carnivores. These aspects may be of particular relevance in the light of the increasing wildlife populations across much of Europe.     

Demographic and functional responses of wild dogs to poison baiting

Lethal control of wild dogs – that is Dingo (Canis lupus dingo) and Dingo/Dog (Canis lupus familiaris) hybrids – to reduce livestock predation in Australian rangelands is claimed to cause continental‐scale impacts on biodiversity. Although top predator populations may recover numerically after baiting, they are predicted to be functionally different and incapable of fulfilling critical ecological roles. This study reports the impact of baiting programmes on wild dog abundance, age structures and the prey of wild dogs during large‐scale manipulative experiments. Wild dog relative abundance almost always decreased after baiting, but reductions were variable and short‐lived unless the prior baiting programme was particularly effective or there were follow‐up baiting programmes within a few months. However, age structures of wild dogs in baited and nil‐treatment areas were demonstrably different, and prey populations did diverge relative to nil‐treatment areas. Re‐analysed observations of wild dogs preying on kangaroos from a separate study show that successful chases that result in attacks of kangaroos by wild dogs occurred when mean wild dog ages were higher and mean group size was larger. It is likely that the impact of lethal control on wild dog numbers, group sizes and age structures compromise their ability to handle large difficult‐to‐catch prey. Under certain circumstances, these changes sometimes lead to increased calf loss (Bos indicus/B. taurus genotypes) and kangaroo numbers. Rangeland beef producers could consider controlling wild dogs in high‐risk periods when predation is more likely and avoid baiting at other times.     

Impact of human disturbance on temporal partitioning within carnivore communities

1. Interspecific competition is an important evolutionary force, influencing interactions between species and shaping the composition of biological communities. In mammalian carnivores, to reduce the risks of negative encounters between competitors, species can employ a strategy of temporal partitioning, adapting activity patterns to limit synchronous activity. This strategy of non-human competitor avoidance, however, may be influenced by the expansion of human activities, which has driven wild mammals towards nocturnality.
2. We hypothesise that the disruption of temporal niche partitioning by humans and their activities could increase temporal overlap between carnivores, enhancing interspecific competition.
3. We reviewed the published literature systematically and employed generalised linear models to evaluate quantitatively the relative influence of a range of human, meteorological and ecological variables on coefficients of temporal overlap within mammalian terrestrial carnivore communities (orders Carnivora and Didelphimorphia) on a global scale.
4. None of the models investigated showed evidence of an impact of humans on temporal partitioning between carnivores on a global scale. This illustrates that temporal avoidance of humans and competitors does not always follow a consistent pattern and that its strength may be context-dependent and relative to other dimensions of niche partitioning (spatial and trophic).
5. Similarly, the regulation of activity patterns may be strongly site-specific and may be influenced by a combination of biotic and abiotic characteristics. Temporal avoidance of both humans and competitors by carnivores may take the form of short, reactive responses that do not impact activity patterns in the longer term.
6. Although we did not detect a global disruption of temporal partitioning due to human disturbance, carnivore communities may still experience an increase in interspecific competition in other niche dimensions. Further research would benefit from using controlled experimental designs and investigating multiple dimensions of niche partitioning simultaneously. Finally, we recommend complementing the coefficient of temporal overlap with other metrics of fine-scale spatiotemporal interactions.

     

Exposure of Free-Ranging Wild Carnivores and Domestic Dogs to Canine Distemper Virus and Parvovirus in the Cerrado of Central Brazil

Human population growth around protected areas increases the contact between wild and domestic animals, promoting disease transmission between them. This study investigates the exposure of free-ranging wild carnivores and domestic dogs to canine distemper virus (CDV) and parvovirus in Emas National Park (ENP) in the Cerrado savanna of central Brazil. Serum samples were collected from 169 wild carnivores, including the maned wolf (Chrysocyon brachyurus), crab-eating fox (Cerdocyon thous), hoary fox (Pseudalopex vetulus), puma (Puma concolor), ocelot (Leopardus pardalis), pampas cat (Leopardus colocolo), jaguarundi (Herpailurus yagouaroundi), striped hog-nosed skunk (Conepatus semistriatus) and coati (Nasua nasua), and from 35 domestic dogs living on rural properties bordering ENP. Serological tests showed that 10.6% of wild carnivores (maned wolves, crab-eating foxes and ocelots) and 71.4% of domestic dogs were exposed to CDV, and 56.8% of wild carnivores, including all species sampled except coatis, and 57.1% of domestic dogs were exposed to parvovirus. This report is the first to indicate that the free-ranging pampas cat, jaguarundi and striped hog-nosed skunk are exposed to parvovirus. CDV and parvovirus deserve attention in ENP, and it is extremely important to monitor the health of carnivore populations and perform molecular diagnosis of the viruses to determine the possible involvement of the domestic dog in their transmission.     

Interspecific and Geographic Variation in the Diets of Sympatric Carnivores: Dingoes/Wild Dogs and Red Foxes in South-Eastern Australia

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.     

Dietary preference of the Asiatic wild dog (Cuon alpinus)

The population of the Asiatic wild dog or dhole (Cuon alpinus) in the wild has been estimated to be less than 2500 mature individuals. This has led to the IUCN assessing the Asiatic wild dog as Endangered. The killing of Asiatic wild dogs in retaliation for livestock depredation is one of the major threat for the species across its geographic range. Understanding the prey preference of endangered large carnivores is imperative for making informed conservation decisions and devising management strategies. We studied the prey preference of the Asiatic wild dog by reviewing studies that have been conducted on the diet and prey abundance of the species across its distributional range. Nine available studies conducted in eight protected areas of three countries, in which 5265 scats were studied, were reviewed. Across studies, we tested whether prey consumption was based on prey availability or prey body mass. The value of Jacobs’ index was determined for each prey species and tested against the proportion of available prey and body mass. Sambar (Rusa unicolor) and chital (Axis axis) were found to be significantly preferred by the Asiatic wild dog, and the preferred prey body mass range was between 40 and 60 kg. The prey preference of the Asiatic wild dog was mainly influenced by the availability of prey.     

Differences in diet and trophic interactions of Patagonian carnivores between areas with mostly native or exotic prey

The prey base for Patagonian carnivores has been altered greatly over the past 150 years due to widespread overgrazing by livestock, invasions by exotic wildlife, and hunting. On ranches in northern Patagonia carnivores consume mostly exotic species, and native herbivores are ecologically extinct in their role as prey. In this study we compare diets of the culpeo (Lycalopex culpaeus), chilla (L. griseus), puma (Puma concolor), Geoffroy's cat (Leopardus geoffroyi), colocolo (L. colocolo), and hog-nosed skunks (Conepatus chinga and C. humboldtii) in a reserve with a mostly native prey base to their diets on the ranches, and evaluate how differences in prey bases affect trophic interactions among carnivores. Carnivores in the reserve consumed mostly native prey. Dietary overlap among carnivores was not significant on the reserve, but was highly significant on the ranches. This homogenization of diets where densities of native species are reduced could lead to stronger negative interactions among carnivores, altering the composition of the carnivore assemblage to the detriment of the more specialized species. Study of carnivore diets may be a relatively quick way to evaluate the conservation status and ecological functionality of prey assemblages in Patagonia and other areas where these have been altered.