A ‘predator’ is defined as ‘an animal that naturally preys on others’1. Wild boars Sus scrofa are generally not recorded as

natural predators of bonnet macaques, Macaca radiata. We report here an adult wild boar hunting and eating an adult

bonnet macaque in the Reception area of the Bandipur

National Park, Karnataka on 5 December 2013

Shreejata, Gupta

Sinha, Anindya

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SCIENTIFIC CORRESPONDENCE  CURRENT SCIENCE, VOL. 106, NO. 9, 10 MAY 2014 1186 A wild boar hunting: predation on a bonnet macaque by a wild boar in the Bandipur National Park, southern India  A ‘predator’ is defined as ‘an animal that naturally preys on others’1. Wild boars Sus scrofa are generally not recorded as natural predators of bonnet macaques, Macaca radiata. We report here an adult wild boar hunting and eating an adult bonnet macaque in the Reception area (11.67N, 76.63E) of the Bandipur  National Park, Karnataka on 5 December 2013.   Around 14:40 h, a bonnet macaque troop of around 40 individuals was for-aging in an open grassland, alongside a sounder of wild boars comprising an adult female and four juveniles. There were sudden alarm calls, which sounded typically like those given to leopards, from the bonnet macaques. The entire troop rushed towards the area where an adult female wild boar stood alertly,  approximately 5 m away from an adult female macaque, sitting on the ground. The macaque began to move slowly  towards an Eucalyptus tree, about 2 m away, dragging her left hindleg, which was bleeding profusely. A bystander, an employee of the Karnataka Forest  Department, reported the injury to have been due to an attack by the same boar a few minutes earlier. The boar attacked the monkey a second time, aiming at the already injured leg, and ripped it apart, holding down the struggling macaque steadily with one of her front hooves. It then began to feed on the still-alive  macaque and consumed her body, bar-ring the head, within a span of approxi-mately 20 min (Figure 1).   Although wild boars are known to feed on carcasses, reports of the species dis-playing typical predator-like behaviour, such as the one described here, are virtu-ally non-existent. There have, however, been several studies reporting feral pigs predating upon newborn lambs in Aus-tralia2–6. These feral pigs, representative of different breeds, had either been acci-dentally or intentionally introduced into the wild during periods of multiple colo-nizations by humans of diverse ethnic origin6,7. Thus, genetically, ecologically and behaviourally, the feral pigs of Aus-tralia with predatory behaviour could be considered distinct from their wild coun-terparts, represented by the wild boars of the Bandipur National Park. Moreover, the Australian feral pigs predated on newborn lambs in lambing enclosures in stark contrast to the free-ranging, wild, adult bonnet macaque, which was pre-dated upon in this case. In all respects, therefore, the unusual predator-like  behaviour of a wild boar in its natural habitat appears to be unique.   We propose several hypotheses, which need to be tested in the future, to explain the observed unusual behaviour of the boar.   The opportunistic predator hypothesis: We hypothesize that the prey individual was foraging away from the other troop members and thus, perhaps, increased its chances of being attacked opportunisti-cally by the predatory boar. Although opportunistic predators are not believed to necessarily prefer non-vigilant prey8, this possibility cannot be easily ruled out in this particular situation.   The habitat complexity hypothesis: This hypothesis argues that a greater structural complexity of the habitat would promote relatively less visibility of a prey species to its predator and vice versa9. The Reception area of the Park, where the hunting occurred, is character-ized by open, well-maintained grassland with sparsely spaced tall trees. The natu-ral habitat of wild boars in Bandipur, in contrast, is typically forested with fairly dense undergrowth and the contrasting open Reception area may thus have pro-vided better visibility to the boar and  induced an incipient predator-like behav-iour to express itself.   The intraguild predation hypothesis: A guild is defined as ‘a group of species that exploit the same class of environ-mental resources in similar way’10. Intra-guild predation refers to situations where two species, competing for shared re-sources, predate on one another11. In this particular case, one of the major food sources for both the bonnet macaques and the wild boars in the Reception area of the Park is provisioning of human-origin food by the visiting tourists. Such an anthropogenic foraging option could have potentially turned the two otherwise non-competing species into competitors and, as a result, a novel case of asym-metric intraguild predation could have emerged in this situation.   Our observation raises several crucial issues pertaining to the behaviour eco-logy of species that commonly occur  in anthropogenic landscapes. There has hardly been, for example, any systematic study on the behaviour of wild boars, which has the potential to uncover flexi-bility in behavioural traits such as the  reported switch from a more species-typical foraging strategy (carrion-feeding) to a more adaptive one (opportunistic predation). Moreover, the possibility of a wild boar predating on a non-traditional prey species such as a bonnet macaque as a result of competition over human-provided food resources, if tenable, has significant implications for their conser-vation in increasingly prevalent atypical ecological regimes.    1. Oxford English Dictionary; http:// www.oxforddictionaries.com/definition/ english/predator (accessed on 3 March 2014).  2. Plant, J. W., Marchant, R., Mitchell, T. D. and Giles, J. R., Aust. Vet. J., 1978, 54, 426–429.  3. Pavlov, P. M., Kilgour, R. J. and Peder-son, H., Aust. J. Exp. Agric. Anim. Husb., 1981, 21, 570–574. 4. Pavlov, P. M. and Hone, J., Aust. Wildl. Res., 1982, 9, 101–109. 5. Hone, J., Australian Meat Research Committee, Final Report, Department of Agriculture, New South Wales, Austra-lia, 1983.    Figure 1. The adult female wild boar feeding on the carcass of the adult female bonnet macaque after killing it.   SCIENTIFIC CORRESPONDENCE  CURRENT SCIENCE, VOL. 106, NO. 9, 10 MAY 2014 1187 6. Mc Gaw, C. C. and Mitchell, J., Pest Status Review Series – Land Protection, Department of Natural Resources and Mines, Queensland, Australia, 1998. 7. Pullar, E. M., Aust. Vet. J., 1950, 26, 99–109.  8. Cresswell, W., Lind, J., Kaby, U., Quinn, J. L. and Jakobsson, S., Anim. Behav., 2003, 66, 643–648. 9. Schmidt, J. M. and Rypstra, A. L., Oecologia, 2010, 164, 899–910.  10. Root, R., Ecol. Monogr., 1967, 37, 317–350.  11. Holt, R. D. and Polis, G. A., Am. Nat., 1997, 149, 745–764.  ACKNOWLEDGEMENTS. We thank the Cognitive Science Research Initiative of the Department of Science and Technology, New Delhi for providing financial support for our studies on primate cognitive networks in the Bandipur National Park. We also thank Mr  H. C. Kantharaju, Conservator of Forests and Director of Bandipur Tiger Reserve, for sup-port, and Mr Karthik Davey and Mr Sukanta Das of the Dhole’s Den Research Foundation for providing essential logistic facilities at the field site.   Received 6 March 2014; revised accepted 10 April 2014 SHREEJATA GUPTA1,* ANINDYA SINHA1,2,3   1National Institute of Advanced Studies, Indian Institute of Science Campus, Bangalore 560 012, India  2Nature Conservation Foundation,  Mysore 571 126, India  3Dhole’s Den Research Foundation, Bandipur National Park,  Chamarajnagar District, India  *For correspondence. e-mail: shreejata@gmail.com      Ant runners: an analysis of running speed of Leptogenys processionalis (Hymenoptera: Formicidae: Ponerinae)  Leptogenys processionalis are shiny and slender ants commonly found in India. They nest on ground and feed mainly on termites, cockroaches and other insects. They are nomadic and for these preda-tory ants, searching for food is an impor-tant activity. Coordination and speed could play a key role in hunting prey. Running speed in trail can affect flow of traffic, search distances and thus their foraging efficiency. These ants maximize their foraging efficiency by forming trails such that the area covered to dis-tance travelled ratio is maximum1. They actively clear obstacles to form physical paths, more often seen near the nest than away from it1. This may increase their foraging efficiency as the paths are used frequently. Like many other trail-forming ants, these ants deposit pheromones along their trail.   The literature on running speed of ants has focused mainly on how temperature, body mass or morphology affects speed2,3. What are the other main vari-ables that affect their speed signifi-cantly? Here I report the variations in running speed of L. processionalis under different natural conditions.  The study was carried out in Banga-lore (12.97N, 77.56E) during June and July 2013. Data were collected from four different colonies (two in IISc, one each in GKVK and NCBS campus). The dis-tance between the two colonies selected in IISc was at least 150 m apart, and thus they could be considered two distinct colonies. The study sites selected were reasonably faraway from buildings and thus had less human intervention. Time taken to travel 30 cm of a fixed position in the trail was measured for randomly chosen ants, for 30 min. A total of 16 such 30-min readings (16 replicates) were taken from the 4 colonies. For a given colony, the fixed positions of  observation in the trail were chosen at different distances from the nest to check whether distance from the nest affects running speed. The speed was not meas-ured where the hunting (for insects) takes place – at the terminal search field (TSF)1. TSF is the leading front of a trail where ants fan out from the trail result-ing in a triangular field of ants searching for prey1. Sometimes these ants form multiple lanes side by side, similar to roads with multiple traffic lanes. For simplicity in observation, all the readings were taken only in cases where the ants formed a single lane. Information about the other possible variables – tempera-ture, direction of ant (towards or away from nest), terrain, slope of the fixed  position, whether the ant is laden with food or not, and number of interactions made by the ant under observation with other ants running in opposite direction was collected. Terrain was classified into three categories: soil, leaf litter and grass lawn. Any brief antennal contact or head-on collision between the test ant and  another ant was considered to be an  interaction. Since there are no morpho-logical differences between foragers and soldiers in L. processionalis, the body weight and length of all individuals were assumed to be similar. If an ant was crippled with one or two amputated legs, a note was taken, to avoid any bias in measurements. All the observations were made between 10:00 and 17:00 h.   The data from different replicates were pooled and speed of the ants was calcu-lated for each variable separately. The analysis was done using trial version of StatistiXL and SPSS statistical package.   It was found that the mean  SD run-ning speed from pooled data (n = 913) was 4.24  1.90 cm/s (0.15  0.07 km/h) and median was 4.02 cm/s. Mean speed in the different categories is listed in  Table 1. The distribution of speed was non-normal and skewed to the right (2 = 46.98, df = 3, n = 913, P < 0.001). The mean running speed and median  after removing data points from crippled ants (38 out of 913) were 4.28  1.90 cm/s and 4.04 respectively.   According to the literature2, at 28C, desert ants like Cataglyphis bicolor (13.71 cm/s) and Ocymyrmex barbiger (8.81 cm/s) run faster than L. proces-sionalis (4.22 cm/s, from my data), whereas ants like Solenopsis invicta (1.67 cm/s) and Pogonomyrmex deserto-rum (1.62 cm/s) run slower. These inter-specific variations could arise mainly due to differences in body mass, leg  allometry, foraging temperature range and lifestyle (e.g. nomadic predatory ants run faster)2.  As reported in previous studies on dif-ferent species2,4, running speed increased 

A wild boar hunting: Predation on a bonnet macaque by a wild boar in the Bandipur National Park, southern India

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A wild boar hunting: Predation on a bonnet macaque by a wild boar in the Bandipur National Park, southern India

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