Trophic niche overlap between coyotes and gray foxes in a temperate forest in Durango, Mexico

Resource partitioning, and especially dietary partitioning, is a mechanism that has been studied for several canid species as a means to understand competitive relationships and the ability of these species to coexist. Coyotes (Canis latrans) and gray foxes (Urocyon cinereoargenteus) are two canid species that are widely distributed, in Mexico, and they are sympatric throughout most of their distribution range. However, trophic dynamic and overlap between them have not been thoroughly studied. In order to better understand their ecological relationship and potential competitive interactions, we studied the trophic niche overlap between both canids in a temperate forest of Durango, Mexico. The results are based on the analysis of 540 coyote and 307 gray fox feces collected in 2018. Both species consumed a similar range of food items, but the coyote consumed large species while the gray fox did not. For both species, the most frequently consumed food categories throughout the year and seasonally were fruit and wild mammals (mainly rodents and lagomorphs). Coyotes had higher trophic diversity in their annual diet (H’ = 2.33) than gray foxes (H’ = 1.80). When analyzing diets by season, trophic diversity of both species was higher in winter and spring and tended to decrease in summer and autumn. When comparing between species, this parameter differed significantly during all seasons except for summer. Trophic overlap throughout the year was high (R0 = 0.934), with seasonal variation between R0 = 0.821 (autumn) and R0 = 0.945 (spring). Both species based their diet on the most available food items throughout each season of the year, having high dietary overlap which likely can lead to intense exploitative competition processes. However, differences in trophic diversity caused by differential prey use can mitigate competitive interactions, allowing these different sized canid species to coexist in the study area.

A comparative test of inequity aversion in domestic dogs (Canis familiaris) and dingoes (Canis dingo)

Despite much recent empirical work on inequity aversion in nonhuman species, many questions remain about its distribution across taxa and the factors that shape its evolution and expression. Past work suggests that domestic dogs (Canis familiaris) and wolves (Canis lupus) are averse to inequitable resource distributions in contexts that call upon some degree of training such as ‘give paw’ and ‘buzzer press’ tasks. However, it is unclear whether inequity aversion appears in other canid species and in other experimental contexts. Using a novel inequity aversion task that does not require specific training, this study helps address these gaps by investigating inequity aversion in domestic dogs and a closely related but non-domesticated canid, the dingo (Canis dingo). Subjects were presented with equal and unequal reward distributions and given the opportunity to approach or refuse to approach allocations. Measures of interest were (1) subjects’ refusal to approach when getting no food; (2) approach latency; and (3) social referencing. None of these measures differed systematically across the inequity condition and control conditions in either dogs or dingoes. These findings add to the growing literature on inequity aversion in canids, providing data from a new species and a new experimental context. Additionally, they raise questions about the experimental features that must be in place for inequity aversion to appear in canids.

Combining cameras and citizen science to define the distribution and behaviour of dingoes and foxes in New South Wales

ABSTRACT We used two survey methods - citizen science for private land and cameras for protected areas - to map the distribution of dingoes/wild dogs and foxes in NSW. Dingo/wild dog records were mostly confined to the east coast and ranges, with scattered locations in western NSW. This contrasts to the distribution of foxes, in which occupancy was high across most of the state. Data from 200 WildCount camera sites within protected areas also showed marked differences in the distribution of the two canid species. At the scale of the state, dingoes/wild dogs are uncommon, with the greatest concentration being in the north-east of the state, as well as a marked presence in the south-east. Foxes are common and widespread within protected areas, but less common in the north-east of the state. The camera data also indicated that feral cats are widespread within protected areas. The second aim of our study was to examine the WildCount data for behavioural patterns of the canid species. Foxes and dingoes/wild dogs significantly separated within two sub-formations of dry sclerophyll forest based on the Keith (2004) classification of NSW vegetation. From species pairwise interactions at sites, we found only limited evidence for significant interactions, and then only for the co-occurrence of fox-rabbit and fox-swamp wallaby, but no avoidance for any of the predators with each other. Camera records of the time of day of being active showed little effect of the presence of dingoes/wild dogs on the times of activity of foxes, but foxes curtailed the activity times of dingoes/wild dogs. From the analysis of inter-animal times at sites where both canids were recorded, there was little difference between the time since the other species was present. Thus, there was no evidence that dingoes/wild dogs or foxes inhibit the other from being at a site. We concluded that at the landscape level, both vegetation type and land tenure play a role in the interactions between dingoes/wild dogs and foxes. We also concluded that citizen science and cameras are complementary, not alternative techniques, especially as they sample different land tenures, and that cameras in protected areas and occupancy from citizen science have produced higher resolution maps and behaviour patterns than have been previously available. We can confirm that foxes are a ubiquitous threat throughout NSW, whereas dingoes/wild dogs are concentrated into a much smaller area of eastern, particularly north-eastern, NSW.

Little brainiacs and big dummies: Are we selecting for stupid, stout, or small dogs?

Background: Brain size has been associated with intelligence of various orders and families of animals, leading to the concept of encephalization. Brain size scales with body weight between species within mammals to approximately the 0.67 power. However, within species, this scaling exponent appears to be much smaller (approximately 0.27 power). Aim: We examined whether this relationship has persisted in dogs over the 120 years since this was originally observed. Methods: Comparative cross-sectional study of magnetic resonance imaging (MRI) data obtained from 127 dogs, compared to historical data from 157 dogs and 24 non-dog canid species. Results: Brain size in dogs measured by MRI had a scaling exponent virtually identical to that observed previously (0.24 vs. 0.26). However, the proportionality constant was smaller, suggesting that dogs in the study cohort had relatively smaller brains than the historical cohort. Absolute brain size appeared to have both a lower and upper limit in dogs. When compared to non-dogs canids, the most appropriate “representative” size for a “typical dog” when examining allometric scaling across Canidae appeared to be approximately 10–15 kg. Conclusions: We interpreted the slight reduction in relative brain size to be a function of increased obesity in the study cohort compared to dogs examined 120 years ago. Further, we suggest that dog brains have a finite lower size limit. Finally, concepts of encephalization should not be applied to dogs.

Genomic analyses of the extinct Sardinian dhole (Cynotherium sardous) reveal its evolutionary history

SummaryThe Sardinian dhole (Cynotherium sardous)1 was an iconic and unique canid species of canid that was endemic of Sardinia and Corsica until it became extinct at the end of the Late Pleistocene2–5. Given its peculiar dental morphology, small body size and high level of endemism, several canids have been proposed as possible ancestors of the Sardinian dhole, including the Asian dhole and African hunting dog ancestor 3,6–9. Morphometric analyses3,6,8–12 have failed to clarify the evolutionary relationship with other canids.We sequenced the genome of a ca 21,100 year old Sardinian dhole in order to understand its genomic history and clarify its phylogenetic position. We found it represents a separate taxon from all other living canids from Eurasia, Africa and North America, and that the Sardinian and Asian dhole lineages diverged ca 885 ka. We additionally detected historical gene flow between the Sardinian and Asian dhole lineages, that ended approximately 500-300 ka, when the landbridge between Sardinia and mainland Italy was broken, severing their population connectivity. Our sample showed low genome-wide diversity compared to other extant canids - probably a result of the long-term isolation - that could have contributed to the subsequent extinction of the Sardinian dhole.

Ancient DNA from the Asiatic Wild Dog (Cuon alpinus) from Europe

The Asiatic wild dog (Cuon alpinus), restricted today largely to South and Southeast Asia, was widespread throughout Eurasia and even reached North America during the Pleistocene. Like many other species, it suffered from a huge range loss towards the end of the Pleistocene and went extinct in most of its former distribution. The fossil record of the dhole is scattered and the identification of fossils can be complicated by an overlap in size and a high morphological similarity between dholes and other canid species. We generated almost complete mitochondrial genomes for six putative dhole fossils from Europe. By using three lines of evidence, i.e., the number of reads mapping to various canid mitochondrial genomes, the evaluation and quantification of the mapping evenness along the reference genomes and phylogenetic analysis, we were able to identify two out of six samples as dhole, whereas four samples represent wolf fossils. This highlights the contribution genetic data can make when trying to identify the species affiliation of fossil specimens. The ancient dhole sequences are highly divergent when compared to modern dhole sequences, but the scarcity of dhole data for comparison impedes a more extensive analysis.

Introgression does not influence the positive ecological and functional role of dingo populations

ABSTRACT The impact of hybridisation between dingoes and domestic dogs, and the subsequent introgression of domestic dog genes into dingo populations, remains a topic of significant impact. It has been claimed, but with little evidence or logical argumentation, that dingoes with significant dog introgression have different effects on agriculture and ecosystems than dingoes with no dog introgression. Introgression is a natural process in evolution, occurring in many species, although this is sometimes human assisted. Canid species in particular show high levels of introgression, due to their genetic and phylogenetic similarities, and human persecution creates scenarios encouraging hybridisation. Dingoes are no exception and demonstrate high levels of introgression of domestic dog genes, particularly in the temperate areas of south-eastern Australia. The available evidence shows that this introgression has minimal effects on the functional morphology of the dingo skull. There is also some preliminary evidence that introgression has not had a major impact on dingo reproductive biology. Studies on the impacts of dingoes on arid, tropical and temperate ecosystems, where levels of introgression vary greatly, all show consistent positive impacts of dingoes, regardless of the amount of domestic dog genes within the dingo population, on these ecosystems. Hence, hybridisation and resultant introgression from domestic dog genes appear to have little effect on aspects of the functional morphology or ecological role of the dingo. Accordingly, introgression does not diminish the conservation status of the dingo.

Demographic expansion of an African opportunistic carnivore during the Neolithic revolution

The diffusion of Neolithic technology together with the Holocene Climatic Optimum fostered the spread of human settlements and pastoral activities in North Africa, resulting in profound and enduring consequences for the dynamics of species, communities and landscapes. Here, we investigate the demographic history of the African wolf ( Canis lupaster ), a recently recognized canid species, to understand if demographic trends of this generalist and opportunistic carnivore reflect the increase in food availability that emerged after the arrival of the Neolithic economy in North Africa. We screened nuclear and mitochondrial DNA in samples collected throughout Algeria and Tunisia, and implemented coalescent approaches to estimate the variation of effective population sizes from present to ancestral time. We have found consistent evidence supporting the hypothesis that the African wolf population experienced a meaningful expansion concurring with a period of rapid population expansion of domesticates linked to the advent of agricultural practices.

Predation by Himalayan Wolves: Understanding conflict, culture and co-existence amongst Indo-Tibetan community and large carnivores in High Himalaya

The wolves in the Hindukush-Himalayan region belong to one the most basal lineages within Canis lupus, yet little is known about its ecology, distribution, and behavior. To understand ecological aspects of wolves in this landscape, we predict wolf distribution, diet patterns and conflict perception in Spiti, India using field and remotely sensed information. We collected scats (n = 283) of canid species namely, Wolves, and other predators over a period of 3 years (2014-17) [66]. Wolf diet constituted mostly of domestic prey (79.02 %) while wild prey constituted to 17.80% of wolf diet over the three years. Village surveys recorded only 4% of the respondents confirmed wolf presence and perceived them as a possible threat to various livestock. Over, 98% of the respondents claimed that wolves were not safe for livestock and were averse to its presence. Marginal response curves depicted the model to have positive responses to animal location, LULC, village population, village density and wolf depredation. We found perceived presence/threat distribution wolves in the area significantly differed from actual ecological presence and distribution of wolves. The Himalayan wolf is an apex flagship predator in this fragile high altitude system, whose role is intricately linked with the ecology of the region. The use of such methods can aid in understanding such aspects as well as designing effective long-term conservation strategies for the species.

Some ecological aspects of dhole (Cuon alpinus) in the Huai Kha Khaeng Wildlife Sanctuary, Uthai Thani Province, Thailand

The dhole (Cuon alpinus) is one of the least frequent studied endangered canid species and many aspects of ecological knowledge about this species are lacking. The objectives of this study were to investigate the spatial movement of dholes, prey abundance, prey selection, and prey overlaps with other large carnivorous species in the Huai Kha Khaeng Wildlife Sanctuary, Thailand, during November, 2017 and October, 2018. Two adult female dholes were captured and fitted with GPS collars. Twenty camera trap sets were systematically used to survey the area. Scat collection was conducted along forest roads and trails. The home range sizes and activity radii of the two dholes were 3,151.63 ha. and 1,442.84 m, and 33.39 ha and 331.56 m, respectively. The sambar deer (Rusa unicolor) was the most abundant prey species (30.93%). However, dhole fecal analysis showed that the monitored dholes preferred red muntjac (Muntiacus muntjak) (57.1%). There was a high degree of prey overlap between dholes and leopards (98%), indicating very high prey competition. The dholes in this study represent movement patterns in richly abundant prey habitats, but with the presence of other predators that can affect prey selection and movement patterns of the dhole in the area.