Eur J Wildl Res (2011) 57:627–637 DOI 10.1007/s10344-010-0473-y

ORIGINAL PAPER

Prey preference of large carnivores in ,

Arumugam Kumaraguru & R. Saravanamuthu & K. Brinda & S. Asokan

Received: 3 July 2010 /Revised: 11 November 2010 /Accepted: 12 November 2010 /Published online: 26 November 2010 # Springer-Verlag 2010

Abstract Prey preferences of large carnivores (tiger (Panthera these carnivores. Sambar constitutes 35% of the overall diet of tigris), leopard (Panthera pardus) and (Cuon alpinus)) tiger, whereas it constitutes 17% and 25% in leopard and inthetropicalforestofAnamalaiTigerReserve(ATR)were dhole diets, respectively. was utilized less than sambar evaluated. This was the first study in ATR to estimate the in the range of about 7%, 11% and 15% by tiger, leopard and density of prey and the food habits of these large carnivores. dhole, respectively. Predator diet was estimated more accu- The 958-km2 intensive study area was found to have a high rately by scat analysis, which reveals 30% of smaller prey mammalian prey density (72.1 animals per square kilometre) species in leopard’s diet, which was not observed by kill data. with (20.61 animals per square kilometre) and chital This study reveals that ATR harbours high prey density, and (20.54 animals per square kilometre) being the most common these large carnivores seem mostly dependent on the wild species, followed by (13.6 animals per square prey rather than on domestic livestock as in some other areas kilometre). When the density figures were multiplied by the in the subcontinent. These factors make ATR a potential area average weight of each prey species, a high biomass density for long-term conservation of these endangered carnivores. of 14,204 kg km−2 was obtained for the intensive study area. Scat analysis and incidental kill observation were used to Keywords Prey preference . Food habits . Tiger . Leopard . determine the dietary composition of these predators. During Dhole . Anamalai Tiger Reserve (ATR) the study from the period of March 2001 to April 2004, 1,145 tiger scats, 595 leopard scats and 2,074 dhole scats were collected and analysed. Kill data were based on direct Introduction observation of 66 tiger kills and 39 leopard kills. Sambar, with a density of 6.54 kg km−2 was the preferred prey for Food habits of large carnivores are central to the ecological niche they occupy and play an important role in explaining their social systems, behaviour and factors affecting predator density. It may also have important implications in the life Communicated by C. Gortázar : : history of their prey. Knowledge of food selection is critical in A. Kumaraguru (*) R. Saravanamuthu S. Asokan understanding the life history strategies and developing sound PG Research and Development of Wildlife Biology, conservation recommendations (Miquelle et al. 1996). The Division of Zoology, AVC College, Mayiladuthurai 609001, India larger carnivores play a vital role as predators in regulating e-mail: [email protected] and perpetuating the ecological processes and maintaining the ecosystem as a whole (Sunquist and Sunquist 1989; K. Brinda Terborgh et al. 2002; Kumaraguru 2002). Predatory strate- Project Trainee, National Facility for Marine Cyanobacteria, Bharathidasan University, gies are shaped and refined by natural selection to maximize Tiruchirappalli 621 024, India nutrient intake within the bounds of a wide range of biologically relevant ecological constraints (Sunquist and Present Address: Sunquist 1989; Clutton-Brock and Harvey 1983). The A. Kumaraguru Centre for Cellular and Molecular Biology, scenario gets complicated when several predatory species Hyderabad 500 007, India hunt in the same area, resulting in a joint demand for a 628 Eur J Wildl Res (2011) 57:627–637 limited prey source. Ultimately, competition for a limited Study area prey resource leads to increased extinction risk of sympatric carnivores (Hayward and Kerley 2008). The present study was a long-term investigation (from Studies on food habits are of conservation significance in March 2001 to April 2004) planned to provide information two ways, i.e. primarily, competition can reduce the popula- on the large carnivores in ATR. This reserve was located in tion size of an endangered carnivore (Caro and Stoner 2003) the district of adjoining , (Hayward and Kerley 2008); secondarily, competition India (10° 12′ and 10° 54′ N and 76° 44′ and 77° 48′ E), between carnivores can affect the population of other species and was spread over 958 km2 (Fig. 1). Minimum and at lower tropic levels (Jedrzejewska and Jedrzejewski 2005). maximum temperature ranges from 10°C in December to For example, the absence of carnivore species may increase 37°C in April. Average annual precipitation varied between either herbivore population (Sinclair et al. 1990)orother 1,178 and 2,268 mm. The landscape was highly undulating, medium-sized carnivores (Sovada et al. 1995) or both and accordingly the rainfall varies from an annual average (Sinclair et al. 1990). Carnivores often regulate or limit the of 500 mm in the eastern part of the sanctuary to about numbers of their prey, thereby altering the structure and 3,000 mm in the Western Plateau and slopes. ATR has a function of entire ecosystems (Schaller 1972; Estes et al. heterogeneous nature of vegetation which ranges from 1998; Berger et al. 2001; Terborgh et al. 2002), and large evergreen to tropical scrub and thorn forest. These habitats carnivores themselves are limited by the abundance of their varied in their extent of cover and also experience two wet prey (Hayward et al. 2007). Prey selection of large carnivore seasons, a winter season and a dry season, in a year, each is a complex phenomenon (Bekoff et al. 1984;Kruuk1972; lasting for 3 months. The dominant vegetation types were Sunquist and Sunquist 1989). The hypotheses so far tropical evergreen forests, tropical semi-evergreen forests, proposed to explain that prey selection by predators indicate moist deciduous forests and forests, inter- that the energetic benefits for the predator and proximate spersed with patches of dry-deciduous forests, scrub forests mechanisms of selection shape their overall prey selection and grassland. The ATR was a home to teeming biodiver- (Griffiths 1975; Taylor 1976; Stephens and Krebs 1987; sity and supports a diverse assemblage of large mammal Temple 1987; Karanth and Sunquist 1995). prey species. Endemism was quite high, and the area was Studies of feeding ecology of large carnivores rely on one or the last stronghold of remnant populations of the nilgiri tahr a combination of many methods. There are varieties of (Hemitragus hylocrius) and the lion-tailed macaque techniques including fecal analysis (Johnsingh 1983; Karanth (Macaca silenus). Sympatric carnivore species include the and Sunquist 1995; Swaminathan et al. 2002; Kumaraguru tiger (Panthera tigris), leopard (Panthera pardus), stripped 2002) spoor tracking (Eloff 1984; Stander et al. 1997), radio hyena (Hyaena hyaena), (Melursus ursinus) and tracking (Seidensticker 1976) and direct observation of dhole (Cuon alpinus). The larger mammalian prey species animals hunting (Mills 1984). Scat analysis is non-invasive include (Bos frontalis), sambar (Cervus unicolor), and has been extensively applied in the studies of the nilgiri tahr (H. hylocrius), wild boar (Sus scrofa) and sloth carnivore food habits, either alone (Karanth and Sunquist bear (M. ursinus). Medium prey species like chital (Axis 1995; Hersteinsson and Macdonald 1996; Ranawana et al. axis), barking deer (Muntiacus muntjak), lion-tailed macaque 1998; Ramakrishnan et al. 1999; Khorozyan and Malkhasyan (M. silenus), common langur (Semnopithecus entellus), 2002) or in combination with data from predator kills (Presbytis johni), porcupine (Hystrix indica) (Sunquist 1981; Johnsingh 1983). The analysis of food habits and other mesopredatory species such as (Felis provides practical and immediately accessible information for chaus), (Felis bengalensis) and fishing cat (Felis the management of a particular species and occasionally aids viverrina) were found in the area. The smaller prey species law enforcement and management needs (Korschgen 1971). were mouse deer (Tragulus meminna), black-naped hare With the intention of collecting baseline information on (Lepus nigricollis), peafowl (Pavo cristatus), civets, mon- large carnivores and its prey species at ATR, the present study gooses, hedgehog (Paraechinus micropus) and honey badger was designed to estimate the density and biomass of major (Mellivora capensis). prey species of large carnivores in the study area and to study the food habits of large carnivores with reference to its prey availability and utilization pattern. This study was the first Methodology report in ATR to understand the ecological parameters, such as availability of prey, which support the survival of these Estimation of density, biomass and group size distribution endangered carnivores. Thus, increasing knowledge of prey of prey species preference and food habits of these carnivores will enable us to recognize the plasticity in the predator's ability to use the The line transect method (Eberhardt 1968; Burnham et al. available resources and conservation of these resources. 1980;Bucklandetal.1993) was used to estimate densities of Eur J Wildl Res (2011) 57:627–637 629

Fig. 1 Map showing the study area Anamalai tiger reserve along with grids for laying transects and carnivore scat collected roads prey species in the study area. This method had been survey of India’s toposheet. The maps were based on recent consistently and efficiently used as a standard method to satellite images and aerial photographs of the vegetation. A determine animal densities under similar tropical conditions total of 250 grids were drawn, out of which 64 were (Karanth and Sunquist 1992, 1995;VarmanandSukumar randomly selected (Fig. 1). The total number of grids 1995;Khanetal.1996; Biswas and Sankar 2002). The data (samples) selected for each habitat was in proportion to the were analysed using Gajah version 1.0 which was based on area of availability. In the selected grids, one transect was Fourier Series estimation. Forty two transects which varied in laid with a length of 2 km. Prey species populations were length between 2 and 5 km were laid randomly in the study estimated using direct sighting method. In the selected grid area. The total transect length of 127.4 km was monitored (s), transects were laid randomly with respect to the eight times in the early morning (0600–1000 hours) and in distribution of animals and topography of the area. Trans- the late afternoon (1500–1900 hours), resulting in 1,020 km ects of known distance were marked, keeping in view that of transect walked. The following sighting parameter such as changes in vegetation, if any, within the transect are kept sighting angle (with a field compass); sighting distance minimum in order to avoid attraction or repulsion of the (ocular estimated); and group size, sex and age class of animals (prey species). individuals (whenever it was possible to classify them) were recorded for each sighting in the transect. The major habitat Carnivore sample collection and microhabitat types were sampled in proportion to their availability in the study area. The sampling effort was Scat samples were collected from well-defined sampling uniform for different seasons of the year. areas along 18 different roads within the protected area of Stratified random sampling (Buckland et al. 1993) was the reserve. Attempts were made to select roads which used. The stratified vegetation map of the study area was represented a particular vegetation type. Generally, large divided into number of grids comprising 4 km2 in 1:50,000 carnivores have extensive home ranges; hence, roads 630 Eur J Wildl Res (2011) 57:627–637 located well within a particular habitat were considered for where Ei is Ivelv’s electivity measure of species i, ri is the this study, but not those which cut across two or more percentage of species i in the diet, and ni is the percentage of different types of habitats. species i in the environment.

Scat identification Kill study

Identification of dhole scat was fairly simple, as they tend The tiger, leopard and wild dog kills were studied in order to defecate in the middle of the roads and paths unlike the to assess their prey selection. Clues like odour, alarm calls large cats, which defecate along the edge of the road or of prey, carnivore signs and calls were useful to locate the path. Additionally, the entire pack of dhole defecates at the kill (Karanth and Sunquist 1995). Whenever the kill was same spot. Identification of tiger and leopard scats in the found relatively intact, the age and health of the killed areas where they co-exist has been largely based on size. individual were recorded on the basis of the size and colour For instance, tiger scat was differentiated from leopard scat, of the animal, sexual characters, etc. Whenever possible, as a full-grown leopard was about one fourth the size of a the colour and texture of femur marrow fat were examined full-grown tiger (Seidensticker 1976), thus producing in order to record the health condition of the kill as identifiably smaller scat. Though complete scat of large suggested by Schaller (1967). adult tigers can be easily differentiated from those of leopards, there can be mistakes in identification when shape Reconstruction of predator diets alone was taken into account. The scats were identified based on the shape as well as the associated signs such as Frequency occurrence of mammalian prey in carnivore scat pugmarks or the size of the scrape in the present study. This was commonly used as a parameter in predation studies. allowed greater accuracy as pug marks allowed more The frequency occurrence of different prey species in the accurate identification of the predator. scat of tiger was converted to the relative biomass (Floyd et al. 1978; Ackerman et al. 1984; Karanth and Sunquist Scat analysis 1995). The equation used is as follows:

A reference key was developed for the identification of prey Y ¼ 1:980 þ 0:035x ðÞTiger and Leopard species on the basis of hair structure/morphology. All scat Y ¼ 0:035 þ 0:020x ðÞDhole samples were sun-dried and preserved in tagged polythene bags for further analysis. Each scat was carefully broken and where Y is the kilogramme of prey consumed per field soaked in water to separate prey remains, such as hair, bones, collectible scat and x is the average weight of an individual hooves, teeth, feathers, etc. All these parts were observed and of a particular prey type (Ackerman et al. 1984). Multiply- analysed with a magnifying glass and under a light micro- ing each Y by the number of scats found to contain a scope. They were identified against the reference collection particular prey species gave the relative weight of each prey taken from captive animals by comparing features such as type consumed. These values were used to estimate per cent structure, colour and medullary configuration to identify prey biomass contribution of different prey species to the large species (Kopikar and Sabins 1976; Amerasinghe 1983; carnivore diet (Biswas and Sankar 2002). Karanth 1993;Kitsosetal.1995;Ranawanaetal.1998; Ramakrishnan et al. 1999). The remains of one prey species in one scat were scored as 1. If there were prey remains of Results two species in a scat, each prey species was scored as 1. Density of prey species Prey selectivity index Density estimation of individuals and groups of nine The most preferred prey of the these sympatric carnivores potential prey species present in the study area was estimated by Ivelv’s selectivity index (1961) was represented summarized in Table 1. The study area harboured high in Fig. 3. Selectivity index value, which ranges from +1 to −1, mammalian prey density of 72.1 animals per square denotes preference for a particular prey with a positive value kilometre with chital and wild boar constituting about and avoidance with a negative value. Electivity index was 50% of it. Among the different prey species, wild boar and calculated using the following formula. chital were the most abundant prey species with the highest density (20 km−2). Although the next predominant prey ðÞ − ¼ ri ni species was the nilgiri tahr (13.67 km 2), it was restricted in Ei ðÞþ ri ni its distribution to high-altitude grasslands, cliff areas of Eur J Wildl Res (2011) 57:627–637 631

Table 1 Individual density, group density and group size of different prey species in ATR

Species name Group density (km−2) Group size Individual density (D/km2) 95% Confidence interval

Dg SE GS SE Lower Upper

Wild boar 1.79 0.168 11.21 0.46 20.61 11.48 28.56 Chital 0.94 0.1 22.24 1.87 20.54 8.09 22.25 Nilgiri tahr 0.66 0.15 19.79 3.29 13.67 2.1 23.26 Gaur 1.26 0.11 10.02 0.72 12.34 5.6 16.43 Sambar 1.59 0.14 4.19 0.17 6.54 4.31 8.38 Elephant 0.43 0.07 6.38 0.5 2.79 1.49 3.42 Black-naped hare 0.78 0.13 1 0 0.78 0.69 0.88 Barking deer 0.28 0.05 1.04 0.2 0.28 0.23 0.34 Mouse deer 0.15 0.04 1.14 0.36 0.18 0.12 0.22

scrub forest and adjoining evergreen habitat. Whereas other tiger scats revealed the presence of eight prey species with a larger prey species such as gaur and sambar were found high preponderance of large-sized ungulates in the tiger’s with relatively lower density values of 12.34 and diet (Fig. 4). Sambar and gaur constituted 66% of the 6.54 km−2, respectively, with wide distribution all over overall diet composition of tiger followed by nilgiri tahr the sanctuary. Nilgiri tahr, barking deer and mouse deer and chital which constituted about 11% and 7%, respec- were present at relatively lower densities than chital. tively. Other prey species such as wild boar, porcupine and Wild boar showed the highest group density value of black-naped hare constituted less than 10% of the total diet 1.79±0.17 km−2. Certain prey species such as chital and composition of tiger. Comparison with the prey availability nilgiri tahr showed higher density value but with lower andtheconsumptionofpreybythesepredatorswas group density. The ecological density varied with group depicted in Fig. 6. Black-naped hare and porcupine size of different prey species. For example, prey species contributes 1.34% and 2.21% of tiger’s diet, which was such as chital and nilgiri tahr showed relatively lower group represented only in scat data. Analysis of 66 kills of tiger density than gaur and sambar. However, because of higher revealed the presence of seven prey species (Fig. 5). group size, they showed higher density value, which was Sambar and gaur constituted 22% and 21%, respectively. more than 13 km−2. Among the different prey species, Chital formed 12% of the diet by kill data which was high chital and nilgiri tahr showed the highest group size of 22± when compared to that by scat analysis. The per cent 1.87 and 19.79±3.29, respectively. The solitary prey occurrence of cattle by kill data was high for tiger with species such as hare, barking deer and mouse deer did not 21%, when compared to 5% by scat data. show any variation between the group density and actual density. The largest herbivore, calves of elephant (Elephas Prey preference and diet composition of leopard maximus), showed mean group size of 6.38±0.5 with density value of 2.79 km−2. The density figures of ungulates Black-naped hare and mouse deer were the most frequently when multiplied with the average weight of the respective taken prey of leopards, followed by sambar and nilgiri tahr. species gave a biomass density of 14,204 kg km−2 for the With an average prey size of 37 kg, leopard showed intensive study area which was compared with density of avoidance for wild boar, chital and gaur (Fig. 3). Analysis other tropical forest in Table 2. The estimate of the prey of 595 leopard scats reveals that approximately 40% biomass density showed that the bulk of prey biomass of composition of its diet was of medium-sized prey species gaur was 69% of the total standing prey biomass (Fig. 2). (Fig. 4). Sambar, wild boar and black-naped hare formed Four mammalian prey species, spotted deer, wild boar, nilgiri the major composition of leopard’s diet with 45%. The per tahr and sambar, together form 99.9% of standing biomass. cent occurrence of black-naped hare (15%), nilgiri langur (8%), mouse deer (3%) and mongoose (0.77%) as leopard’s Prey preference and diet composition of tiger prey was revealed only from scat data analysis. Leopard had a more varied diet and regularly consumed at least 12 The average prey size of tiger was 92 kg with sambar, different prey species. Similarly, chital, gaur, goat and nilgiri tahr and gaur as preferred prey. Based on Ivelv’s nilgiri langur contributed 37% of its overall diet. Analysis selectivity index, tiger showed avoidance for other medium of 39 kills of leopard revealed the presence of eight prey prey such as chital and wild boar (Fig. 3). Analysis of 1,145 species (Fig. 5). Sambar constituted 23% of its overall diet. 632 Eur J Wildl Res (2011) 57:627–637

Table 2 Comparison of wild biomass density of herbivores at tropical sites

Region Area Habitat type Biomass density (kg km−2) References

Asia Nagarhole Deciduous forest 14,744 Karanth and Sunquist (1992) Bandipur Dry forest–woodland 14,520 Johnsingh (1983) ATR Deciduous forest 14,204 Present study Kanha Moist forest-meadows 1,592 Schaller (1967) Pench Deciduous forest 6,013 Biswas and Sankar (2002) Wilpattu Dry forest-meadows 766 Eisenberg and Lockhart (1972) Bardia Moist forest-grasses 3,101 Dinerstein (1980) Chitwan Moist forest-grasses 2,581 Tamang (1982) Africa Rwenzori Swamps-savanna 21,373 Eltringham (1979) Manyara Dry savanna 19,259 Eltringham (1979) Serengeti Dry savanna 6,840 Eltringham (1979) Mara Dry savanna 19,200 Stelfox (1986) Nairobi Dry savanna 4,470 Eltringham (1979) Gabon Evergreen forest 1,020 Prins and Reitsma (1989) South America Masaguaral Dry forest-pasture 711 Eisenberg (1980) Barro Colorado Evergreen forest 3,553 Eisenberg (1980) Manu Evergreen forest 1,220 Terborgh (1986) Pantanal Moist forest pasture 295 Eisenberg (1980)

Chital and gaur constituted 21% and 5%, respectively. with an average prey size of 36 kg. The diet spectrum of Chital formed 12% of the diet by kill data which was high dhole included about 14 species (Fig. 4). Their specific then compared to that by scat analysis. The per cent territorial marking behavior combined with their use of occurrence of cattle by kill data was high for leopard with latrine site for defecation enabled us to collect large 23%, when compared to 6% by scat data. numbers of scats for this study. Two thousand and seventy four scats were collected and analysed to understand the Prey preference and diet composition of dhole food habits of dhole in ATR. Sambar (26%), chital (15%), black-naped hare (13%), gaur (12%) and wild boar (10%) Barking deer, sambar and mouse deer were the most together constituted more than 75% of prey composition of frequently taken prey of dhole. It showed avoidance for the dhole’s diet (Fig. 6). wild boar, chital, gaur, mouse deer and nilgiri tahr (Fig. 3)

Discussion

Over most of their range, tigers co-exist with other predatory carnivores such as leopards and . The densities of different predator species within such guilds appear to be greatly influenced by the relative abundance of different size classes of prey species in the assemblage (Karanth and Sunquist 1995; Karanth and Sunquist 2000; Karanth et al. 2004). We examine our results in an attempt to provide a more reliable measure of dietary patterns of these three sympatric carnivores in ATR. Prey densities estimated in the present study, when compared with that of other tropical forests from other species revealed that ATR harbours a high density of chital and nilgiri tahr. ATR is dominated by fairly open canopy with a heterogeneous habitat, ranging from evergreen to tropical Fig. 2 Proportion of the standing biomass of different prey species in ATR thorn forest. This condition of high habitat heterogeneity Eur J Wildl Res (2011) 57:627–637 633

Fig. 3 Overall prey preference index (Ivelv’s) of tiger, leopard and dhole for different prey species in ATR

probably favoured the high density of grazer (Eisenberg and where overall prey biomass densities were greater than Seidensticker 1976) such as chital. ATR also harbours large- 1,000 kg km−2, the tiger preferentially takes larger prey sized prey such as sambar and gaur. Contrary to intuition, (Karanth and Nichols 1998). The leopard was morpholog- three smaller species such as barking deer, mouse deer and ically adapted to kill large prey but may depend heavily on black-naped hare were lower in densities when compared to locally abundant small prey in difficult times (Hayward et that of chital and sambar. These prey species considered to al. 2006). Hence, the density and distribution of all the be selective feeders on rich but scarce food items such as three carnivores were often shaped by the dominant prey shoots and fruits might be a reason for their low density. species because dominant prey species provides the bulk of Their solitary nature and territorial spacing mechanism may available prey biomass (Kumaraguru 2002). Thus, identi- also contribute to their relatively low densities. fying the dominant prey was often the first step towards ATR ranks third when compared with other tropical understanding the carrying capacity for large carnivores in a sites, with a biomass density of 14,204 kg km−2. In places particular area. Based on the preferences of these three

Fig. 4 Proportion of prey occur- rence in scats (%) of tiger (n=1,145), leopard (n=595) and dhole (n=2,074) in ATR 634 Eur J Wildl Res (2011) 57:627–637

Fig. 5 Proportion of prey oc- currence in kills (%) of tiger (n=66) and leopard (n=39) in ATR

carnivores, was the critical prey species in which was based on the premise of a maximization of ATR. Whereas in most of the other tropical south Indian energy return to the predator for each prey encounter forest, chital was also a preferred prey species of leopards (Werner and Hall 1974; Krebs and Davies 1979). The mean (Hayward et al. 2006) and for these three large carnivores and range of prey size can increase with an increase in as reported from Bandipur (Johnsingh 1983), Nagarahole predator size (Wilson et al. 1995). Prey was categorized (Karanth and Sunquist 1995) and Mudumalai (Swaminathan into three size classes distinguishable in the field based on et al. 2002). This trend of chital was not only reported from species and weight. Black-naped hare, porcupine, nilgiri South India but also from neighbouring countries such as langur, mouse deer, mongoose and bird species were Chitwan, Nepal (McDougal 1977). Similarly, other species classified as small prey (5–30 kg). Chital, nilgiri tahr, wild such as red deer in Sikhote Alin, Russia (Miquelle et al. boar and goat were considered as medium-sized prey (31– 1996), and barking deer in Thailand (Rabinowitz and 100 kg). Sambar, gaur and cattle were categorized as large Nottingham 1986) were the dominant prey species for large (>100 kg) prey. In ATR, the average weight of a wild prey carnivores especially for tigers. species of tiger and leopard was 92 and 37 kg, respectively. The prey species was also selected based on the prey Similar to that of leopard, the prey size for dhole was also size which tend to support the concept of optimal foraging 36 kg. Our results showed that large-sized prey (sambar,

Fig. 6 Relation between per cent avilable and consumption of different prey species by tiger, leopard and dhole in ATR Eur J Wildl Res (2011) 57:627–637 635 gaur and cattle) comprised 70%, medium-sized prey (chital, arboreal prey such as langur in the scats of leopard could be nilgiri tahr, wild boar and goat) comprised 25% and small linked to the leopard’s greater arboreality and crypticity in prey (porcupine, black-naped hare, nilgiri langur, mouse comparison to the other two carnivores. The dietary prefer- deer and mongoose) provided only 3.5% of tiger’s diet ences of dhole are concluded based only on the scat analysis in based on scat analysis. On the other hand, medium-sized this study. Since prey such as chital and sambar are eaten prey dominated leopard diet, contributing to 37%. Large almost entirely, only the lower jaws remain, making detection prey and small prey provided about 31% and 27% based on of such kills unlikely (Venkataraman et al. 1995). The scat analysis. Dhole depend even more predominantly on presence of black-naped hare and bird species in the diet of medium-sized prey (~50% of overall diet). dhole could be due to pack hunting and the ability of the Sambar was the most important prey species for tigers, dholes to flush out and hunt the smaller and cryptic prey leopard and dhole in our study. In the site where predation on species. While being too small for the pack as a whole, such sambar was more, a correspondingly lower degree of chital prey was sufficient for an individual dog. Black-naped hare predation by tigers is recorded (Biswas and Sankar 2002). In when flushed out by the dogs was usually grabbed by the ATR, chital occurred in high densities, which might have nearest dog and eaten alone or shared with another dog while increased their predation rate, but their gregarious nature was the hunt continues for a larger prey more suitable for the supposed to be one of the factors that reduced the chance of entire pack. It was likely that risk of injury during prey predation by these large carnivores (Karanth and Sunquist capture may be the reason underlying the lower per cent 1995). Predation of wild boar in ATR suggests high overlap composition of large prey in the scats of leopard (Hayward et of habitat use between these large carnivores and wild boar al. 2006) and dhole. which might have facilitated a high level of predation on the In the present study, the data from scat analysis showed wild boar (Miquelle et al. 1996). The selectivity for wild that smaller prey species constituted more than 30% of the boar as prey suggests that these predators were making leopard’s diet, which was not clear from the kill observa- foraging decisions on the basis of energy gain and not on tions. This indicates that scat analysis give a more accurate injury risk (Sunquist and Sunquist 1989). estimate, whereas kill samples underestimated the propor- Tigers depend on concealment and ambush to capture tion of smaller prey in the carnivore’s diet. Hence in the prey. In ATR, grasslands were interspersed with islands of present investigation, the scat of predators and kill data which enables tigers to capture tahr and that could be were judiciously taken into consideration to determine the the reason for the higher proportion of tahr in tiger scat. prey composition of predator’s diet. The prime factor influencing the predation of gaur in the ATR was one of the areas that still harbour high prey study area was probably due to their high density density with predators mostly depending on wild prey (12 km−2). Presence of porcupine remains in the scats of rather than on domestic livestock for food as in many other tiger reflects the ability of tiger to hunt this aggressive prey areas of the Indian subcontinent. From the present study, it species. Similar observations have also been reported from can be concluded that ATR, because of its high wild prey Mudumalai on tiger which fed upon sloth bear (Swaminathan density, has the potential to accommodate a higher density et al. 2002). The restricted distribution of chital and nilgiri of predators (Hayward et al. 2007; Kumaraguru 2002), tahr in specific habitats may have compelled the tiger to go making it comparable to few of the best remaining tiger for different prey selection. habitats of the Indian subcontinent. Thus, protection of the The higher proportion of cattle in the diet of these large habitat along with regular monitoring of carnivores could be attributed to the considerable behavioural such as tigers, leopard and dhole along with their prey plasticity of these predators which could enable them to population using comparable scientific methods was essen- survive in diverse forest environments. Supplementary prey tial for ATR to emerge as one of the most important areas such as cattle become more important due to low prey for wildlife conservation in India. availability in specific size class and competition between co- predators for food and space. The role of livestock in the Acknowledgement We acknowledge PCCF and CCF, Tamil Nadu feeding habits of these large carnivores was relevant not only Forest Department (TNFD), for permitting us to enter and to carry out to the survival of these predators but also to understanding and research in protected areas of the forest. We extend our sincere thanks to the thus managing their conflict with farmers. TNFD for funding part of this project. We thank all forest rangers, foresters and field staff of ATR without whom the project could not be completed. In contrast to the preference of tiger, leopard and dhole We express our sincere thanks to principal, HOD and all staff members of showed preference for medium- and small-sized prey species. the Department of Wildlife Biology, AVC College, for providing us full Occurrence of smaller species such as black-naped hare, freedom to carry out the research. We thank Dr. J.C. Daniel, BNHS, and mouse deer, porcupine and mongoose in their diet might be Ajay A Desai., Asian Elephant Co-chair person, IUCN, for his valuable guidance to carry out this research and for useful suggestion during due the weight of these species that are within the preferred manuscript preparation. We express our sincere gratitude to the two prey weight range of leopard and dhole. The presence of anonymous authors for their valuable suggestions. 636 Eur J Wildl Res (2011) 57:627–637

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