Factors affecting the prey preferences of jackals (Canidae)

Prey selection by carnivores can be affected by top-down and bottom-up factors. For example, large carnivores may facilitate food resources for mesocarnivores by providing carcasses to scavenge, however mesocarnivores may hunt large prey themselves, and their diets might be affected by prey size and behaviour. We reviewed jackal diet studies and determined how the presence of large carnivores and various bottom-up factors affected jackal prey selection. We found 20 studies of black-backed jackals (Canis mesomelas) from 43 different times or places, and 13 studies of Eurasian golden jackals (Canis aureus) from 23 different times or places reporting on 3900 and 2440 dietary records (i.e. scats or stomach contents), respectively. Black-backed jackals significantly preferred small ( 120 kg) hider species and follower species of any body size. They had a preferred and accessible prey weight range of 14-26 kg, and a predator to ideal prey mass ratio of 1:3.1. Eurasian golden jackal significantly prefer to prey on brown hare (Lepus europaeus; 4 kg), yielding a predator to preferred prey mass ratio of 1:0.6, and a preferred and accessible prey weight range of 0 – 4 kg and 0 – 15 kg, respectively. Prey preferences of jackals differed significantly in the presence of apex predators, but it was not entirely due to carrion availability of larger prey species. Our results show that jackal diets are affected by both top-down and bottom-up factors, because apex predators as well as prey size and birthing behaviour affected prey preferences of jackals. A better understanding of the factors affecting jackal prey preferences, as presented here, could lead to greater acceptance of mesocarnivores and reduced human-wildlife conflict

The Role of the Proteinase Inhibitor Ovorubin in Apple Snail Eggs Resembles Plant Embryo Defense against Predation

BACKGROUND: Fieldwork has thoroughly established that most eggs are intensely predated. Among the few exceptions are the aerial egg clutches from the aquatic snail Pomacea canaliculata which have virtually no predators. Its defenses are advertised by the pigmented ovorubin perivitellin providing a conspicuous reddish coloration. The nature of the defense however, was not clear, except for a screening for defenses that identified a neurotoxic perivitellin with lethal effect on rodents. Ovorubin is a proteinase inhibitor (PI) whose role to protect against pathogens was taken for granted, according to the prevailing assumption. Through biochemical, biophysical and feeding experiments we studied the proteinase inhibitor function of ovorubin in egg defenses. METHODOLOGY/PRINCIPAL FINDINGS: Mass spectrometry sequencing indicated ovorubin belongs to the Kunitz-type serine proteinase inhibitor family. It specifically binds trypsin as determined by small angle X-ray scattering (SAXS) and cross-linking studies but, in contrast to the classical assumption, it does not prevent bacterial growth. Ovorubin was found extremely resistant to in vitro gastrointestinal proteolysis. Moreover feeding studies showed that ovorubin ingestion diminishes growth rate in rats indicating that this highly stable PI is capable of surviving passage through the gastrointestinal tract in a biologically active form. CONCLUSIONS: To our knowledge, this is the first direct evidence of the interaction of an egg PI with a digestive protease of potential predators, limiting predator's ability to digest egg nutrients. This role has not been reported in the animal kingdom but it is similar to plant defenses against herbivory. Further, this would be the only defense model with no trade-offs between conspicuousness and noxiousness by encoding into the same molecule both the aposematic warning signal and an antinutritive/antidigestive defense. These defenses, combined with a neurotoxin and probably unpalatable factors would explain the near absence of predators, opening new perspectives in the study of the evolution and ecology of egg defensive strategies

The Nature of Knowledge in Composition and Literary Understanding: The Question of Specificity

↵PETER SMAGORINSKY is Assistant Professor, College of Education, University of Oklahoma, 820 Van Vleet Oval, Norman, OK 73019-0. He specializes in classroom literacy.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Seed dispersal potential of jackals and foxes in semi-arid habitats of South Africa

We determined the consumption of fruits and estimated potential seed dispersal of a canid community in semi-arid ecosystems of South Africa by comparing diets, defecation sites, densities and potential seed shadows of cape foxes (Vulpes chama), bat-eared foxes (Otocyon megalotis) and black-backed jackals (Canis mesomelas) on Benfontein and Rooipoort nature reserves. On Benfontein, all canid species consumed the fruit of Diospyros lycioides throughout the year. Jackals, but neither fox species, consumed relatively large amounts of Prosopis spp. (mesquite), an alien invasive. On Rooipoort, jackals had relatively high consumption of Ziziphus mucronata, followed by Grewia flava and D. lycioides. Bat-eared foxes had high consumption of fruit per area, although their seed dispersal potential was low due to their small potential seed shadow and poor germination sites. Cape foxes had the largest potential seed shadow, but their seed dispersal potential was low because of low fruit consumption, low density, and poor germination sites. Jackals had the highest seed dispersal potential because they consumed the most fruit species, had moderate densities, a relatively large potential seed shadow, and mostly good germination sites. We conclude that seed dispersal potential of South African canids, especially jackals, is more significant than previously known

Documenting the demise of tiger and leopard, and the status of other carnivores and prey, in Lao PDR's most prized protected area: Nam Et - Phou Louey

The Nam Et - Phou Louey National Protected Area (NEPL) is known for its diverse community of carnivores, and a decade ago was identified as an important source site for tiger conservation in Southeast Asia. However, there are reasons for concern that the status of this high priority diverse community has deteriorated, making the need for updated information urgent. This study assesses the current diversity of mammals and birds in NEPL, based on camera trap surveys from 2013 to 2017, facilitating an assessment of protected area management to date. We implemented a dynamic multispecies occupancy model fit in a Bayesian framework to reveal community and species occupancy and diversity. We detected 43 different mammal and bird species, but failed to detect leopard Panthera pardus and only detected two individual tigers Panthera tigris, both in 2013, suggesting that both large felids are now extirpated from NEPL, and presumably also more widely throughout Lao PDR. Mainland clouded leopard Neofelis nebulosa had the highest estimates of probability of initial occupancy, persistence and colonization, and appeared to be the most widely distributed large carnivore, followed by dhole Cuon alpinus. Both of these species emerge as a priority for further monitoring and conservation in the NEPL landscape. This study provides the most recent assessment of animal diversity and status in the NEPL. Our analytical approach provides a robust and flexible framework to include sparse and inconsistent data sets of multiple species to assess their status via occupancy as a state process, which can often provide insights into population dynamics

Social organization, home ranges, and extraterritorial forays of black‐backed jackals

We radio‐tracked 15 black‐backed jackals(Canis mesomelas)from 8 adjacent family groups onBenfontein Game Farm(i.e., Benfontein)in South Africa to investigate their movement patterns and socialorganization. Jackal family groups consisted of mated pairs(alphas),0–3 nonbreeding adults(betas), andpups, depending on the season. Mean(±SE)home‐range size of alphas(9.4±1.2 km2,n=6)did not differ(P=0.766)from betas(9.8±0.7 km2,n=8). Most beta jackals(8of10)remained philopatric on Ben-fontein, apparently because of the high density of springbok(Antidorcas marsupialis), their preferred prey.Three of 5 alphas and all 8 betas went on extraterritorial forays(i.e., forays). Generally, betas spent more oftheir active time on forays(2–20% of time)than alphas(0–3%;P=0.048), and betas went farther on forays(2–8km)than alphas(2–3 km;P=0.003). The number of forays differed(P<0.001)among seasons; mostforays occurred during summer(64%)when jackals visited neighboring livestock farms, apparently topredate on domestic sheep. Overall, our results indicate forays by jackals are affected by social status,seasonal availability of preferred prey, and the reproductive cycle of jackals. To reduce jackal predation onlivestock farms near reserves, we recommend that preventative measures(e.g., use of herders, jackal controlactivities)be increased during summer when jackals are most likely to travel outside reserves. © 2019 TheWildlife Society

Documenting the demise of tiger and leopard, and the status of other carnivores and prey, in Lao PDR's most prized protected area: Nam Et - Phou Louey

The Nam Et - Phou Louey National Protected Area (NEPL) is known for its diverse community of carnivores, and a decade ago was identified as an important source site for tiger conservation in Southeast Asia. However, there are reasons for concern that the status of this high priority diverse community has deteriorated, making the need for updated information urgent. This study assesses the current diversity of mammals and birds in NEPL, based on camera trap surveys from 2013 to 2017, facilitating an assessment of protected area management to date. We implemented a dynamic multispecies occupancy model fit in a Bayesian framework to reveal community and species occupancy and diversity. We detected 43 different mammal and bird species, but failed to detect leopard Panthera pardus and only detected two individual tigers Panthera tigris, both in 2013, suggesting that both large felids are now extirpated from NEPL, and presumably also more widely throughout Lao PDR. Mainland clouded leopard Neofelis nebulosa had the highest estimates of probability of initial occupancy, persistence and colonization, and appeared to be the most widely distributed large carnivore, followed by dhole Cuon alpinus. Both of these species emerge as a priority for further monitoring and conservation in the NEPL landscape. This study provides the most recent assessment of animal diversity and status in the NEPL. Our analytical approach provides a robust and flexible framework to include sparse and inconsistent data sets of multiple species to assess their status via occupancy as a state process, which can often provide insights into population dynamics

Density trends of wild felids in northern Laos

Determining the density trends of a guild of species can help illuminate their interactions, and the impacts that humans might have on them. We estimated the density trends from 2013 to 2017 of the clouded leopard Neofelis nebulosa, leopard cat Prionailurus bengalensis and marbled cat Pardofelis marmorata in Nam Et—Phou Louey National Park (NEPL), Laos, using camera trap data and spatial capture-recapture models. Mean (± SD) density estimates (individuals/100 km ) for all years were 1.77 ± 0.30 for clouded leopard, 1.50 ± 0.30 for leopard cat, and 3.80 ± 0.70 for marbled cat. There was a declining trend in density across the study years for all three species, with a ≥ 90% probability of decline for clouded leopard and leopard cat and an 83% probability of decline for marbled cat. There was no evidence that mesopredator release occurred as a result of tiger (Panthera tigris) and leopard (P. pardus) extirpations. We believe that snaring, the factor that led to the extirpation of tiger and leopard in NEPL, is now contributing to the decline of smaller felids, to an extent that over-rides any potential effects of mesopredator release on their densities and interactions. We recommend that the NEPL managers implement a more systematic and intensified snare removal program, in concert with extensive community outreach and engagement of local people to prevent the setting of snares. These actions might be the only hope for saving the remaining members of the felid community in NEPL