1. Ecological factors influencing prey selection by tiger Panthera tigris, leopard Panthera pardus and dhole Cuon alpinus were investigated in an intact assemblage of large mammals in the tropical forests of Nagarahole, southern India, between 1986 and 1990. 2. Densities of large herbivores were estimated using line transects, and population structures from area counts. Carnivore diets were determined from analyses of scats (faeces) and kills. Selectivity for prey species was inferred from likelihood ratio tests comparing observed counts of scats to hypothesized scat frequencies generated from prey density estimates using parametric bootstrap simulations. Predator selectivity for size, age, sex and physical condition of prey was estimated using selection indices. 3. Ungulate and primate prey attained a density of 91 animals km -2 and comprised 89-98% of the biomass killed. Predators showed significant (P < 0.05) selectivity among prey species. Gaur Bos gaurus were preferred by tigers, whereas wild pig Sus scrofa were under-represented in leopard diet, and langur Presbytis entellus under-represented in dhole diet. 4. Tigers selected prey weighing more than 176 kg, whereas leopard and dhole focused on prey in the 30-175 kg size class. The average weights of principal prey killed by tiger, leopard and dhole were, respectively, 91.5 kg, 37.6 kg and 43.4 kg. Tiger predation was biased towards adult males in chital, sambar and wild pig, and towards young gaur. Dholes selectively preyed on adult male chital, whereas leopards did not. 5. These findings suggest that if there is choice, large carnivores selectively kill larger prey, and non-selective predation patterns reported from other tropical forests may be the result of scarcity of large prey. Because availability of prey in the appropriate size classes is not a limiting resource, selective predation may facilitate large carnivore coexistence in Nagarahole. Community structures of large carnivores in tropical forests may be highly sensitive to natural or human-induced variations in the relative densities of different size classes of prey.

https://www.jstor.org/stable/pdfplus/5647.pdf

Prey selection by tiger, leopard and dhole in tropical forests

Obtaining information on wild mammal populations has been a long-standing logistical problem. However, an array of non-invasive techniques is available, including recently developed molecular genetic techniques for the analysis of feces (molecular scatology). A battery of non-invasive, molecular approaches can be used on feces, which in conjunction with conventional analysis are potentially useful for assesing genetic structure, demography and life history of mammals. Several technical problems reman before large-scale studies of feces can be undertaken productively, but already studies are providing insight into population subdivision, food habits, reproduction, sex ratio and parasitology of free-ranging populations.

Facts from feces revisited

The diet of wild boar Sus scrofa in Western Europe is reviewed, paying particular attention to the consumption of agricultural crops and the implications of this from the point of view of crop damage. Data were taken mainly from 11 studies that provide quantitative informa- tion about the consumption of different food types, but we also list all the foods reported as being eaten by wild boar in a total of 21 studies. 2. Vegetable foods occurred more frequently in the diet than animal foods, and also consti- tuted the bulk of the food ingested. Overall, there were four major vegetable food categories: mast, roots, green plant matter and agricultural crops. Depending on the study area, wild boar always consumed at least one energy-rich plant food such as acorns, beechnuts, chest- nuts, pine seeds, olives, cereal grains or other crops. The number and types of agricultural crops consumed varied between study areas but crops represent an important component of wild boar diet throughout its Western European range. Among animal foods, insects, earthworms, birds and mammals were eaten most consistently but the diet also included amphibians, reptiles, gastropods and myriapods. 3. Seasonal, interannual and regional differences in the diet, together with its striking overall breadth, indicate that wild boar are opportunistic omnivores whose diet, in any particular instance, is largely determined by the relative availability of different food types. Dependence on energy-rich plant material as a major component of the diet, coupled with large body size and a propensity to trample crops as well as consume them, means that wild boar cause significant agricultural damage.

https://www.kora.ch/malme/05_library/5_1_publications/S/Schley_&_Roper_2003_Diet_of_wild_boar_in_Europe_with_reference_to_consumption_of_crops.pdf

Diet of wild boar Sus scrofa in Western Europe, with particular reference to consumption of agricultural crops

Behavioural factors that are likely to contribute to the coexistence of tiger Panthera tigris, leopard P. pardus and dhole Cuon alpinus, were investigated in the tropical forests of Nagarahole, southern India, during 1986–1992. Examination of predator scats and kills were combined with radiotracking of four tigers, three leopards, and visual observations of a pack of dhole. The three predators selectively killed different prey types in terms of species, size and age-sex classes, facilitating their coexistence through ecological separation. There was no temporal separation of predatory activities between tigers and leopards. Hunting activities of dholes were temporally separated from those of the two felids to some extent. Rate of movement per unit time was higher for leopards compared to tigers during day and night. In general, the activity patterns of predators appeared to be largely related to the activities of their principal prey, rather than to mutual avoidance. The three predator species used the same areas and hunted in similar habitats, although tigers attacked their prey in slightly denser cover than leopards. Both cats attacked their prey close to habitat features that attracted ungulates. There was no evidence for inter-specific spatial exclusion among predators, resulting either from habitat specificity or social dominance behaviours. Our results suggest that ecological factors, such as adequate availability of appropriate-sized prey, dense cover and high tree densities may be the primary factors in structuring the predator communities of tropical forests. Behavioural factors such as differential habitat selection or inter-specific social dominance, which are of crucial importance in savanna habitats, might play a relatively minor role in shaping the predator communities of tropical forests.

Behavioural correlates of predation by tiger (Panthera tigris), leopard (Panthera pardus) and dhole (Cuon alpinus) in Nagarahole, India

Summary 1. It is not always possible to track trophic interactions between predators and prey by direct observation. This is especially true when observing small or elusive animals with cryptic food-web ecology. Gut and/or faecal analysis can sometimes allow prey remains to be identified visually but is only possible when a component of the diet is resistant to digestion. In some cases there are no solid remains, and when there are it can lead to bias in interpretation of prey choice. 2. Numerous invasive and non-invasive methods have been developed to characterize predator‐prey interactions but two principal areas dominate ‘molecular’ research. These are reviewed under the headings of monoclonal antibodies and DNA-based techniques. 3. Early ‘molecular’ studies of predator‐prey food webs were dominated by the development of monoclonal antibodies. These methods continue to be used for mass-screening of field-collected arthropods for insect-specific proteins. 4. The application of species-specific primer design, polymerase chain reaction (PCR), restriction fragment length polymorphism analysis (RFLP), DNA cloning and sequencing, comparative sequence analysis (e.g. BLAST; basic local alignment search tool), high-resolution gel electrophoresis, Temperature/denaturing gradient gel electrophoresis (TGGE/DGGE) and automated fragment analysis with fluorescent probes is reviewed. The development of molecular techniques for use in predator‐prey studies is primarily limited by their cost and the development of new procedures and equipment that complement them.

/pdf/advances-in-molecular-ecology-tracking-trophic-links-through-39ectzru0w.pdf

Advances in molecular ecology: tracking trophic links through predator–prey food‐webs

For any frustrated field-mammalogists seeking observational data on their elusive study animals, dung may represent the most readily-available and easily-collected source of information upon which they may fall back in despair. Yet it is surprising how much ecological information may be deduced from an analysis of faecal depositions. This present article reviews some of the current methods available to the mammalogist for ecological detection from dung and some of the ecological areas in which it may offer information.

R. J. Putman

Papers

Facts from faeces