Roles for the Canidae in food webs reviewed: Where do they fit?

Eating smart: Free-ranging dogs follow an optimal foraging strategy while scavenging in groups

Foraging and acquiring of food is a delicate balance between managing the costs (both energy and social) and individual preferences. Previous research on solitarily foraging free-ranging dogs showed that they prioritise the nutritionally highest valued food, but do not ignore other less valuable food either, displaying typical scavenger behaviour. We conducted a similar experiment on 136 groups of dogs with the same set-up to see the change in foraging strategies, if any, under the influence of social cost like intra-group competition. We found multiple differences between the strategies of dogs foraging alone versus in groups with competition playing an implicit role in the dogs’ decision making when foraging in groups. Dogs continually assessed and evaluated the available resources in a “patch,” transitioning from random foraging to systematic foraging with time and more information. Dogs in groups used an, “eat first, sample afterwards” strategy whereas individual dogs sampled thoroughly before eating. Additionally, dogs in groups were quicker and more likely to respond to the experimental set-up and eat from it. The dogs adjusted their behaviour in terms of effort and time allocated according to the quality of the “patch.” Foraging in groups also provided benefits of reduced individual vigilance. The various decisions and choices made lend support to the optimal foraging theory wherein the dogs harvested the nutritionally richest patch possible with the least risk and cost involved but were willing to compromise if that was not possible. This underscores the cognitive, quick decision-making abilities and adaptable behaviour of these dogs, which is likely to have influenced the process of dog domestication.

Feeding ecology of the endangered Asiatic wild dogs (Cuon alpinus) across tropical forests of the Central Indian Landscape

Studies on resource utilisation by carnivores are essential as they aid in assessing their role in a community, by unravelling predator–prey relationships. Globally, prey depletion is one of the primary causes of declining Asiatic wild dog (dhole) populations. Therefore, it is essential to examine their diet across their range. Our study presents insights into dhole feeding ecology across multiple sites from the central Indian landscape of Maharashtra, India, for the first time. We conducted scat analysis using a subset of genetically identified scats and collected additional data from kills observed while tracking radio-collared dholes and other known packs from 2 study sites. We analysed 861 scats, and 191 dhole kills to identify species and age class of prey. We estimated the relative contribution of various prey, utilising non-linear biomass models of prey consumption. Overall, wild ungulates like sambar and chital were the principal prey in terms of biomass (sambar 61.08%; chital 19.08%) and number of prey consumed (sambar 39.28%; chital 13.83%). An analysis of kill data also suggested that dholes strongly preferred the two deer species; and differential selection of age classes was observed at the 2 study sites. Our study can potentially help manage and conserve this important population of an endangered carnivore.

Comparative craniometric measurements of two Canid species in Egypt: the Egyptian red fox and the Egyptian Baladi dog

The Egyptian red fox (Vulpes vulpes aegyptiaca) and Egyptian Baladi dog (Canis familiaris) are two members of the Family Canidae that are widely distributed in Egypt. The skulls of different Canid species vary greatly in their size and shape; therefore, they can be used as a tool to study the evolution and evolutionary history of these animals. The craniometric measurements are crucial for species identification and determination of the specific sites for nerve blocks. The present study compared the craniometric measurements of the red fox and Baladi dog skulls by measuring 47 parameters on each skull and calculation of 8 indices. The red fox skull had significantly lower values of 41 craniometric measurements (approximately 87% of the measurements done), including skull length, width, and height, cranial length and width, palatal and mandibular length, and dental measurements. In contrast, the red fox had significantly higher values of only 3 measurements (approximately 6% of the measurements done) including the tympanic bulla measurement. While only three skull measurements did not differ significantly between the red fox and dog. Statistics revealed that domestic dog had significantly higher values of foramen magnum and palatine indices, and significantly lower value of nasal index than those of red fox. The present work reported variations in the gross and craniometric measurements of skull between the red fox and dog. The measured cranial parameters of both adult animals provide valuable information that can be used in ecological studies, comparative anatomy, and clinical veterinary sciences.

Terrestrial mesopredators did not increase after top-predator removal in a large-scale experimental test of mesopredator release theory

Removal or loss of top-predators has been predicted to cause cascading negative effects for ecosystems, including mesopredator release. However, reliable evidence for these processes in terrestrial systems has been mixed and equivocal due, in large part, to the systemic and continued use of low-inference study designs to investigate this issue. Even previous large-scale manipulative experiments of strong inferential value have been limited by experimental design features (i.e. failure to prevent migration between treatments) that constrain possible inferences about the presence or absence of mesopredator release effects. Here, we build on these previous strong-inference experiments and report the outcomes of additional large-scale manipulative experiments to eradicate Australian dingoes from two fenced areas where dingo migration was restricted and where theory would predict an increase in extant European red foxes, feral cats and goannas. We demonstrate the removal and suppression of dingoes to undetectable levels over 4–5 years with no corresponding increases in mesopredator relative abundances, which remained low and stable throughout the experiment at both sites. We further demonstrate widespread absence of negative relationships between predators, indicating that the mechanism underpinning predicted mesopredator releases was not present. Our results are consistent with all previous large-scale manipulative experiments and long-term mensurative studies which collectively demonstrate that (1) dingoes do not suppress red foxes, feral cats or goannas at the population level, (2) repeated, temporary suppression of dingoes in open systems does not create mesopredator release effects, and (3) removal and sustained suppression of dingoes to undetectable levels in closed systems does not create mesopredator release effects either. Our experiments add to similar reports from North America, Asia, Europe and southern Africa which indicate that not only is there a widespread absence of reliable evidence for these processes, but there is also a large and continually growing body of experimental evidence of absence for these processes in many terrestrial systems. We conclude that although sympatric predators may interact negatively with each other on smaller spatiotemporal scales, that these negative interactions do not always scale-up to the population level, nor are they always strong enough to create mesopredator suppression or release effects.

Conserving an Endangered Canid: Assessing Distribution, Habitat Protection, and Connectivity for the Dhole (Cuon alpinus) in Bhutan

Most canids face population declines and range contractions worldwide. Although the dhole (Cuon alpinus) is widely distributed across 10 countries in South and Southeast Asia, limited studies exist on this species. Despite its globally “Endangered” status and ecological role as an apex predator, assessments on its distribution are limited to a few landscapes and countries. This explains the lack of a dhole-specific species conservation plan in most range countries, including Bhutan where no current population estimate exists. The species has also recovered from a country-wide poisoning campaign in the 1970s and 80s. In this study, we determine the dhole's distribution pattern and assess the protection and connectivity of dhole habitat in Bhutan. We anticipated dholes to be extant within their habitat well-represented in protected areas (PAs) and biological corridors (BCs). We used 721 georeferenced dhole occurrence records and eight environmental variables in MaxEnt software to model potential dhole distribution and habitat suitability. The model output was overlaid on the spatial layers of PAs and BCs to assess habitat protection and connectivity. As anticipated, we found the dhole widely distributed in all districts, PAs, and BCs in Bhutan. Dholes were recorded at the highest elevation range limit of 4,980 m above sea level, which overlapped with the “Vulnerable” snow leopard (Panthera uncia). Our model identified 72% (27,634 km2) of the country as suitable areas for dholes, of which, 31% (11,899 km2) was highly suitable and 41% (15,735 km2) was moderately suitable. Contrary to our expectation, PAs and BCs encompassed only 29% (8,046 km2) and 12% (3,185 km2) of suitable areas for dholes, respectively. A vast majority of the areas we deemed suitable for dholes currently remain unprotected, thus making dholes more vulnerable to human persecution and local extermination. We recommend adjusting PA boundaries to fully encompass suitable dhole habitat, and also advocate improved livestock husbandry to reduce dhole related livestock predation and minimize conflict, thereby ensuring its long-term survival in Bhutan.

A framework of integrated research for managing introduced predators in the Pilbara bioregion, Western Australia

The effective control of wild dogs, feral cats and foxes is of primary interest to land managers, both for biodiversity conservation and for the protection of livestock. Control programs primarily target single species within the context of biodiversity conservation or livestock practices, but their effectiveness in depressing predator densities is unclear because monitoring is limited or not conducted. Here, we review and discuss the outcomes of a workshop to identify research priorities for managing predation on native fauna by introduced predators in the Pilbara bioregion in Western Australia. We suggest that the control of introduced predators will be most effective if it is implemented at a landscape-scale comprising integrated predator management that considers interspecific (predator) interactions combined with standardised monitoring to measure the effectiveness and benefits of control. Four research themes were identified: (1) collation and collection of baseline data, (2) effective monitoring of introduced predators, (3) understanding functional (ecological) roles of introduced predators within the different ecosystem contexts, and (4) identifying novel complementary approaches to protect threatened species. These themes collectively include research areas that invest in foundational, ecological and alternative biological parameters in research to close knowledge gaps related to the functional roles of introduced predators in the landscape. Addressing these research themes will assist land managers to achieve outcomes that address the needs of both biodiversity conservation and pastoral production. This framework is timely given the ongoing investment in offset funding being mobilised in the region.

Individual and seasonal variation in contact rate, connectivity and centrality in red fox (Vulpes vulpes) social groups

Examining temporal variation in social connectivity and relating this to individual behaviour can help understand the role of individuals within social groups. Although red foxes are solitary foragers, they form social groups at higher population densities. To investigate the effects of season, sex and status on social connectivity in red fox social groups, we set camera traps for four consecutive seasons to record contact rates and social network metrics at food patches in seven fox territories. Higher food availability was associated with higher contact rates. Individual contact rates peaked in different seasons depending on sex and social status. Dominant foxes held central network positions in all seasons but there was no consistent pattern in social connections within territories, suggesting a greater influence of features such as group size and composition on network structure than seasonal behaviour. Increased extraterritorial movements by males during winter contributed to a significant reduction in local network connectivity. Female network strength did not vary with season, suggesting that females play an important role in maintaining year-round group cohesion. These data advance our understanding of canid social systems, the benefits of group-living in solitary foraging carnivores, and the impacts of management interventions for an ecologically important species.

Detection and genotyping of Toxoplasma gondii in wild canids in Serbia

To gain insight into the population structure of the protozoan parasite Toxoplasma gondii in wildlife in Serbia, multiplex nested PCR- RFLP was performed on T. gondii DNA positive samples of heart tissue of three wild canid species, including red foxes (Vulpes vulpes), golden jackals (Canis aureus) and grey wolves (Canis lupus). Out of 110 samples (28 red foxes, 72 golden jackals, 10 wolves), 30 (27.3%) were positive for T. gondii DNA, of which 24 were genotyped (nine red foxes, 13 golden jackals and two wolves). The results showed a large dominance of lineage II (n = 20, 83.4%) over lineage III (n = 4, 16.7%) strains. Lineage II comprised four archetypes, 14 variants and one which remained undetermined, while within lineage III there were three archetypes and one variant strain. However, a notable difference in diversity was observed among the examined canids, with eight (88.9%) of the nine strains detected in red foxes distinct, vs. six (46.1%) distinct strains of the 13 detected in golden jackals. Since anthropogenic food sources are a major reservoir of archetypal lineage II and III T. gondii strains, the results suggest that the golden jackal may be outcompeting the red fox, forcing it to hunt wild mammals and birds for sustenance, thereby increasing its chances of infection with variant strains. In addition to presenting the first data on the T. gondii population structure in wild canids in Serbia, this is the first report ever on T. gondii genotypes in golden jackals, a species with an increasing presence in Europe and another important reservoir of domestically circulating T. gondii strains.

Differences in persistence between dogs and wolves in an unsolvable task in the absence of humans

Despite being closely related, dogs perform worse than wolves in independent problem-solving tasks. These differences in problem-solving performance have been attributed to dogs’ greater reliance on humans, who are usually present when problem-solving tasks are presented. However, more fundamental motivational factors or behavioural traits such as persistence, motor diversity and neophobia may also be responsible for differences in task performance. Hence, to better understand what drives the differences between dogs’ and wolves’ problem-solving performance, it is essential to test them in the absence of humans. Here, we tested equally raised and kept dogs and wolves with two unsolvable tasks, a commonly used paradigm to study problem-solving behaviour in these species. Differently from previous studies, we ensured no humans were present in the testing situation. We also ensured that the task was unsolvable from the start, which eliminated the possibility that specific manipulative behaviours were reinforced. This allowed us to measure both persistence and motor diversity more accurately. In line with previous studies, we found wolves to be more persistent than dogs. We also found motor diversity to be linked to persistence and persistence to be linked to contact latency. Finally, subjects were consistent in their performance between the two tasks. These results suggest that fundamental differences in motivation to interact with objects drive the differences in the performance of dogs and wolves in problem-solving tasks. Since correlates of problem-solving success, that is persistence, neophobia, and motor diversity are influenced by a species’ ecology, our results support the socioecological hypothesis, which postulates that the different ecological niches of the two species (dogs have evolved to primarily be scavengers and thrive on and around human refuse, while wolves have evolved to primarily be group hunters and have a low hunting success rate) have, at least partly, shaped their behaviours.

Clever girl? An observation of innovative prey handling by a dingo (Canis dingo)

Predators often exhibit highly intelligent and adaptable hunting techniques to subdue large prey; however, these events are rarely captured. Here I report an infrequently seen occurrence of a dingo (Canis dingo) utilising waves on the eastern beach of K’gari (Fraser Island) to entrap, tire and deliberately drown an adult swamp wallaby (Wallabia bicolor). This behaviour highlights an adaptive technique for innovative prey handling by a single dingo to achieve an outcome that would usually take two or more animals under normal conditions.