Studying Large Mammals With Imperfect Detection: Status and Habitat Preferences of Wild Cattle and Large Carnivores in Eastern Cambodia

Studying large mammal species in tropical forests is a conservation challenge with species’ behavior and ecology often increasing the probability of non‐detection during surveys. Consequently, knowledge of the distribution, status, and natural history of many large mammal species in Southeast Asia is limited. I developed occupancy models from camera‐trapping data, thereby accounting for imperfect detection at sampling sites, to clarify the status and habitat requirements of four globally threatened or near threatened large mammals (banteng Bos javanicus, gaur Bos gaurus, dhole Cuon alpinus, and leopard Panthera pardus) in Mondulkiri Protected Forest, eastern Cambodia. Camera traps were operational for >3500 trap nights with 202 photographic encounters of the four study species. Model averaged occupancy estimates were between 5 percent (leopard) and 140 percent (gaur) higher than naive estimates (i.e., proportion of camera‐trap sites species recorded from) thus highlighting the importance of accounting for detectability during conservation surveys. I recommend the use of an occupancy framework when using camera‐trap data to study the status, ecology, and habitat preferences of poorly known and elusive species. The results highlight the importance of mixed deciduous and semi‐evergreen forest for wild cattle in eastern Cambodia and I emphasize that these habitats must be considered in conservation planning across the Lower Mekong Dry Forest Ecoregion.     

INDIVIDUALITY IN THE WHISTLE CALL OF THE ASIATIC WILD DOG CUON ALPINUS

ABSTRACT

The Asiatic wild dog or dhole Cuon alpinus is a threatened social canid that uses a repetitive whistle call to maintain group contact in dense habitats. Spectrographic analysis revealed significant differences between the whistles of captive dholes, allowing callers to be reliably identified. The most important discriminatory characteristics were the period from the start of one syllable to the next, the fundamental frequency, and the maximum frequency. The individual distinctiveness of the whistle is discussed in terms of its functional significance and possible survey applications.     

Diet and prey profiles of three sympatric large carnivores in Bandipur Tiger Reserve, India

We conducted a field study of diets of three sympatric large carnivores, the tiger Panthera tigris , the leopard Panthera pardus and the dhole Cuon alpinus in Bandipur Tiger Reserve, India, based on analyses of 381, 111 and 181 scats, respectively. The frequency of occurrence of prey items in scats was converted to relative biomass and number of prey consumed using regression equations based on earlier feeding trials. The results showed that although these predators kill ∼11–15 species of vertebrate prey, relatively abundant ungulate species provide 88–97% of biomass consumed by them. Although the dietary niche overlap among the three species was high (Pianka's index of 0.75–0.93), some specialized predation was observed. The largest ungulates, gaur Bos gaurus and sambar Cervus unicolor , provided 73% of biomass consumed by tigers, whereas medium-sized chital Axis axis and wild pig Sus scrofa formed 65 and 83% of the biomass intake of leopards and dholes, respectively. In terms of the relative numbers of prey animals killed by the three predators, chital, which is the most abundant prey species, dominated their diets (tiger=33%, leopard=39% and dhole=73%). The results of the study, in conjunction with earlier work, support the prediction that abundance of ungulate prey species, as well as their availability in different size classes, are both critical factors that facilitate sympatry among the three predators.     

BIPHONATION AS A PROMINENT FEATURE OF DHOLE CUON ALPINUS SOUNDS

ABSTRACT

Spectrographic analysis showed that dholes produce sounds with two fundamental frequencies (components): the high-frequency and the low-frequency, which may occur simultaneously or separately. The fundamental frequency of the low-frequency component varied from 0.52 to 1.44 kHz, and that of the high-frequency component from 5.51 to 10.77 kHz. In calls where both the frequencies occurred simultaneously, they were not integer multiples of each other. They also had different frequency modulations and had additional combinative frequency bands. These are features of biphonation. Our data showed biphonation occurs in a lot of dhole calls (20 to 92% of the calls, depending on the individual (n=14); average occurrence 44.3%, n=1317 sounds). The occurrence of biphonation did not differ between sexes and ages; however, occurrence of the high component only was significantly higher in subadult animals, whereas the occurrence of the low component only was significantly higher in adults. Based on the sound structures, we discuss probable mechanisms of sound production for both the components in the dhole. For the low component, the normal vocal folds oscillation mechanism is suggested. For the high component, four possible mechanisms of sound production are discussed. We conclude that the vortex-shedding mechanism is the most probable.     

Dhole pack size variation: Assessing the effect of Prey availability and Apex predator

In multipredator systems, group sizes of social carnivores are shaped by the asymmetric intraguild interactions. Subordinate social carnivores experience low recruitment rates as an outcome of predation pressure. In South and Southeast Asia, the Tiger (Panthera tigris), Dhole (Cuon alpinus), and Leopard (Panthera pardus) form a widely distributed sympatric guild of large carnivores, wherein tigers are the apex predators followed by dhole and leopard. In this study, we attempted to understand the variation in pack size of a social carnivore, the dhole, at two neighboring sites in the Central Indian landscape. We further evaluated local‐scale patterns of variation in pack size at a larger scale by doing a distribution‐wide assessment across the dhole ranging countries. At the local scale, we found an inverse relationship between the density of tiger and pack size of dhole while accounting for variability in resources and habitat heterogeneity. Larger dhole packs (16.8 ± 3.1) were observed at the site where the tiger density was low (0.46/100 km²), whereas a smaller pack size (6.4 ± 1.3) was observed in the site with high tiger density (5.36/100 km²). Our results for the distribution‐wide assessment were concordant with local‐scale results, showing a negative association of pack size with the tiger densities (effect size −0.77) and a positive association with the prey abundance (effect size 0.64). The study advances our understanding to answer the age‐old question of “what drives the pack size of social predators in a multipredator system?” This study also highlights the importance of understanding demographic responses of subordinate predator for varying competitor densities, often helpful in making informed decisions for conservation and management strategies such as population recovery and translocation of species.     

Case studies of the history and politics of wild canid restoration in Korea

Wild canids were historically abundant in Korea; however, the gray wolf, dhole, and red fox were extirpated during the twentieth century. The causes varied. “Pest control” during the Japanese occupation, ecological destruction during wars, disease epizootics, and “vermin control” after the Korean War contributed to the complete demise of wolves. The fox had succumbed to unregulated hunting, rodenticides, habitat loss, and disease epizootics. The dhole was naturally rare; its extirpation from northeastern Asia including Korea is not established. Although the wolf and fox are extirpated, the Korean government still lists both as endangered species to facilitate the recently implemented restoration programs. Restoration will face the challenges of importing genetically diverse populations and the critical loss, fragmentation, and alteration of peri‐urban habitats. The overall social support for these efforts is not clear: it may be low because of changes in social mores or simply an unintended consequence of land and water use choices and policies that people may not perceive in everyday life. In this critical analysis, we postulate that the current restoration programs are misdirected toward inappropriate species and likely employ outdated techniques. We propose that a reallocation of restoration efforts and resources to populations of existing rare or threatened species would be more ecologically beneficial with higher probabilities of success. We recognize that there can be good reason to restore the upper trophic levels, especially keystone species, but are concerned that the impetus is more about focusing on charismatic megafauna rather than pragmatic choices more likely to be effective.