Isotopic Niche Differentiation Among Mammals from a Rainforest in Peninsular Malaysia

We performed stable isotope analysis on eight mammalian species: pig-tailed macaque (Macaca nemestrina), long-tailed macaque (M. fascicularis), dusky leaf monkey (Trachypithecus obscurus), brush-tailed porcupine (Atherurus macrourus), wild boar (Sus scrofa), lesser mouse-deer (Tragulus javanicus), greater mouse-deer (T. napu), and barking deer (Muntiacus muntjac), to test the hypothesis that the differences in diet and habitat types among species, guilds and foraging strategies are reflected in the δ15N and δ13C signatures of their tissues. Whereas the isotopic ratios differed among taxa, the four major isotopic groups observed were: mouse-deer species, primate species, brush-tailed porcupine, and wild boar. The brush-tailed porcupine showed the most divergent isotopic signatures, depleted in both δ15N and δ13C, and the wild boar had isotopic signatures enriched in both δ15N and δ13C. Although results are only indicative, the three habitat types occupied by the species were reflected by differences in isotopic signatures, with the ground-dwelling species having the most divergent isotopic values from arboreal and semi-arboreal species. Likewise, among the four different types of dietary lifestyle groups tested, each group showed either significantly different δ15N or δ13C from other groups. Omnivores had the highest isotopic values, and bark-eater/frugivores had the lowest. By increasing the sample sizes both within the species and the number of species in future analyses, this isotopic technique provides opportunity to elucidate the diets of their putative predators in the rainforests of Peninsular Malaysia

Phylogeography and Genetic Ancestry of Tigers (Panthera tigris)

Eight traditional subspecies of tiger (Panthera tigris), of which three recently became extinct, are commonly recognized on the basis of geographic isolation and morphological characteristics. To investigate the species' evolutionary history and to establish objective methods for subspecies recognition, voucher specimens of blood, skin, hair, and/or skin biopsies from 134 tigers with verified geographic origins or heritage across the whole distribution range were examined for three molecular markers: (1) 4.0 kb of mitochondrial DNA (mtDNA) sequence; (2) allele variation in the nuclear major histocompatibility complex class II DRB gene; and (3) composite nuclear microsatellite genotypes based on 30 loci. Relatively low genetic variation with mtDNA, DRB, and microsatellite loci was found, but significant population subdivision was nonetheless apparent among five living subspecies. In addition, a distinct partition of the Indochinese subspecies P. t. corbetti into northern Indochinese and Malayan Peninsula populations was discovered. Population genetic structure would suggest recognition of six taxonomic units or subspecies: (1) Amur tiger P. t. altaica; (2) northern Indochinese tiger P. t. corbetti; (3) South China tiger P. t. amoyensis; (4) Malayan tiger P. t. jacksoni, named for the tiger conservationist Peter Jackson; (5) Sumatran tiger P. t. sumatrae; and (6) Bengal tiger P. t. tigris. The proposed South China tiger lineage is tentative due to limited sampling. The age of the most recent common ancestor for tiger mtDNA was estimated to be 72,000–108,000 y, relatively younger than some other Panthera species. A combination of population expansions, reduced gene flow, and genetic drift following the last genetic diminution, and the recent anthropogenic range contraction, have led to the distinct genetic partitions. These results provide an explicit basis for subspecies recognition and will lead to the improved management and conservation of these recently isolated but distinct geographic populations of tigers

prey selection by tiger, leopard and dhole in tropical forests

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 < 005) 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 prfeyed 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

Population structure, density and biomass of large herbivores in the tropical forests of Nagarahole, India

We studied the population structure, density and biomass of seven ungulate and two primate species in the tropical forests of Nagarahole, southern India, using line transect sampling and roadside/platform counts, during 1986-87. The estimated ecological densities of large herbivore species in the study area are: 4.2 muntjac km-2, 50.6 chital km-2, 5.5 sambar km-2, 0.8 four-horned antelope km-2, 9.6 gaur km-2, 4.2 wild pig km-2, 3.3 elephant km-2, 23.8 hanuman langur km-2 and 0.6 bonnet macaque km-2. Most ungulates have female-biased adult sex ratios. Among common ungulate species, yearlings and young of the year comprise about a third of the population, suggesting relatively high turn-over rates. Three species (muntjac, sambar and four-horned antelope) are solitary, while others form groups. The study area supports a wild herbivore biomass density of 14,744 kg km-2. Among the three habitat types within the study area, biomass is lower in dry deciduous forests when compared with moist deciduous or teak plantation dominant forests. Using our results, we have examined the factors that may contribute towards maintenance of high ungulate biomass in tropical forests

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

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

Patterns of Vertebrate Abundance in a Tropical Mosaic Landscape

Multi‐faceted field sampling in a mosaic landscape in Venezuela generated insights on how topographical characteristics, forest composition, degree of habitat interspersion, and paleoecology influenced the abundance and distribution of vertebrates. Physical heterogeneity resulted in distinct vegetation types and a very uneven distribution of medium to large‐sized vertebrates. Variations in forest composition resulted in dramatic contrasts in primate densities. White‐tailed deer densities varied an order of magnitude between vegetation types. Yellow‐knobbed curassow densities peaked in moist forest. Similar chachalaca densities were encountered in dry forest. Although there was spatial overlap between jaguars and pumas, from a large‐scale perspective pumas made more use of drier habitats. In select habitats the abundance and biomass of red‐footed tortoises exceeded that of multiple species of large native mammals combined. This variation in animal abundance highlights the significance of scale in the interpretation of ecological data

Isotopic Niche Differentiation Among Mammals from a Rainforest in Peninsular Malaysia

We performed stable isotope analysis on eight mammalian species: pig-tailed macaque (Macaca nemestrina), long-tailed macaque (M. fascicularis), dusky leaf monkey (Trachypithecus obscurus), brush-tailed porcupine (Atherurus macrourus), wild boar (Sus scrofa), lesser mouse-deer (Tragulus javanicus), greater mouse-deer (T. napu), and barking deer (Muntiacus muntjac), to test the hypothesis that the differences in diet and habitat types among species, guilds and foraging strategies are reflected in the δ15N and δ13C signatures of their tissues. Whereas the isotopic ratios differed among taxa, the four major isotopic groups observed were: mouse-deer species, primate species, brush-tailed porcupine, and wild boar. The brush-tailed porcupine showed the most divergent isotopic signatures, depleted in both δ15N and δ13C, and the wild boar had isotopic signatures enriched in both δ15N and δ13C. Although results are only indicative, the three habitat types occupied by the species were reflected by differences in isotopic signatures, with the ground-dwelling species having the most divergent isotopic values from arboreal and semi-arboreal species. Likewise, among the four different types of dietary lifestyle groups tested, each group showed either significantly different δ15N or δ13C from other groups. Omnivores had the highest isotopic values, and bark-eater/frugivores had the lowest. By increasing the sample sizes both within the species and the number of species in future analyses, this isotopic technique provides opportunity to elucidate the diets of their putative predators in the rainforests of Peninsular Malaysia

Survival, recruitment, and population growth rate of an important mesopredator: the northern raccoon.

Populations of mesopredators (mid-sized mammalian carnivores) are expanding in size and range amid declining apex predator populations and ever-growing human presence, leading to significant ecological impacts. Despite their obvious importance, population dynamics have scarcely been studied for most mesopredator species. Information on basic population parameters and processes under a range of conditions is necessary for managing these species. Here we investigate survival, recruitment, and population growth rate of a widely distributed and abundant mesopredator, the northern raccoon (Procyon lotor), using Pradel's temporal symmetry models and >6 years of monthly capture-mark-recapture data collected in a protected area. Monthly apparent survival probability was higher for females (0.949, 95% CI = 0.936-0.960) than for males (0.908, 95% CI = 0.893-0.920), while monthly recruitment rate was higher for males (0.091, 95% CI = 0.078-0.106) than for females (0.054, 95% CI = 0.042-0.067). Finally, monthly realized population growth rate was 1.000 (95% CI = 0.996-1.004), indicating that our study population has reached a stable equilibrium in this relatively undisturbed habitat. There was little evidence for substantial temporal variation in population growth rate or its components. Our study is one of the first to quantify survival, recruitment, and realized population growth rate of raccoons using long-term data and rigorous statistical models

Monthly recapture probability of northern raccoons (<i>Procyon lotor</i>) at the Ordway-Swisher Biological Station, Florida.

<p>Estimates and 95% confidence intervals are from model {φ(sex)<i>p</i>(month+sex)λ(season)}.</p