Wild Water Buffalo

Bubalus arnee Linnaeus, 1758

Table of contents Taxonomy Distribution Description Ecology Conservation References

Wild buffalo are able to interbreed completely with domestic buffalo. The name Bubalus bubalis is applied to domestic populations, but some authors also use it for wild animals. Anatomical and behavioural traits have been suggested as a means of differentiating wild buffalo from backcrossed individuals (Heinen, 2002), but such discrimination is often difficult, and phenotypic characteristics alone are not sufficient to define pure wild animals. Some hybrid individuals retain wild characteristics and hence cannot be differentiated from purely wild individuals. Hybrid and wild buffaloes have extensive overlap in their supposedly discriminatory characteristics (Muley, 2001; Flamand et al., 2003).

The exact historical range of this species is uncertain due to at least 5,000 years of domestication in India and China. However, wild water buffalo have indisputably been extirpated from large parts of their former range. Relict and highly fragmented populations of wild Asian buffalo occur in southern Bhutan, south-eastern Nepal, east and central India (Assam, Arunachal Pradesh, Meghalaya, and Madhya Pradesh), northern Myanmar, western Thailand, eastern Cambodia and south-western Vietnam. Vietnamese individuals are mainly visitors from the nearby Mondulkiri region in Cambodia. The Indian population is by far the largest. The populations in Sri Lanka, Borneo and Java are strongly suspected to have a feral origin.

Body mass ranges from 700 to 1200 kg. Females are slightly smaller and weigh about 20% less than males. This species has the broadest horns of any living bovid and horns grow throughout their life. Adults can be sexed by their horn structure. Females tend to have longer horns, but males tend to have much thicker horns. Adult males also present a more massive musculature and they are larger than females of same age (Heinen, 2002). Supposed phenotypic differences from the domestic buffalo include broader horns and a wider distance between horns. Wild adult coloration is dark with one or two white chevron marks on the underside of the neck, white hocks, white tail tips and fine white markings around the eyes, nose and mouth. Young have a lighter coloration and become darker with age.

They are mainly grazers, inhabiting open forests, dry thornscrub, floodplains, tall grass area near swamp, stream and river banks. Species occurrence is strongly linked to the presence of grasslands and waterholes. Water buffaloes spend long periods wallowing in the mud. After leaving a wallow the leading buffalo rubs its body along a tree (Tulloch, 1979). An average density of 3.8 individuals per km² was reported in Sri Lanka, with a concentration of 14.55 per km² in very favourable habitats (de Silva et al., 1994). Densities of up to 34 feral buffalos per km² occurred in some localities of northern Australia when the population was at it highest. This species is normally active in day-time but human disturbance has tended to rend them more active at night. The peak of mating activity seems to occur in October-November in Nepal. Gestation period is from 312 to 334 days. Only 50% of the adult females appear to mate and calve in any single year. Calves can be left in the care of another adult of the herd while their mothers go to graze in open plains. If mothers die the calves can be adopted by other females which already have calves (Tulloch, 1979). Females reach maturity around two years of age and their life expectancy in the wild is about nine years in Sri Lanka. They are expected to produce not more than five calves in their life (de Silva et al., 1994). Calves are born at the end of the rainy season and start of the dry season when grasses are luxuriant and water is still abundant, to maximize the chances of survival. In the past this highly social species formed large herds of several hundred individuals (Tulloch, 1979), but now only a few scattered herds exist due to the collapse of populations all across its range. Males leave the herds as they mature and they tend to be solitary. The herd is composed of females and calves dominated by an old bull during the female oestrus period, which chases away other adult bulls. During most of the dry season both sexes live separately and the herd is led by the older females. Hybrid bulls resulting from a backcross with domestic buffaloes cannot dominate wild bulls and hence are not thought to be able to crossbred with wild females. However, hybrid females would be expected to breed with wild males (Flamand et al., 2003). Females are thought to stay within their natal herds for many years (Tulloch, 1970 & 1979). Prolonged periods of drought can severely impact the dynamics of water buffalo populations because they are quite exclusive grazers (Tulloch, 1970; de Silva et al., 1994). Water buffalo herds move seasonally in relation to depth of water and foraging availability. Main predators include the tiger (Panthera tigris), the leopard (Panthera pardus), the dhole (Cuon alpinus), the jackal (Canis aureus), and the crocodile (Crocodylus porosus, C. palustris, and C. siamensis). Wild herds of females are also extremely wary of any human approach. Solitary wild males are unpredictable and can charge (Heinen, 2002).

This species has experienced a severe decline due to poaching, habitat encroachment by agriculture, genetic introgression, competition and disease transmission from livestock and feral buffaloes. Rinderpest is a potentially severe risk for many populations, and it has already killed several hundred wild buffaloes in Assam and Sri Lanka (Choudhury, 1994; de Silva, 1994). The genetic integrity of some remnant populations is not clear, making conservation efforts complex. All populations are categorized as Endangered or Critically Endangered (Hedges, 1995; IUCN, 2006). The total world population is probably fewer than 4000 wild individuals. The main populations of wild water buffalo include Kaziranga National Park (1100 individuals) and Manas National Park (1200 individuals) in Assam, and Indravati Wildlife Sanctuary in Madya Pradesh. However their habitats are rapidly vanishing by conversion to agricultural lands (Choudhury, 1994). Another important population is found in Koshi Tappu Wildlife Reserve (165 km²) in south-eastern Nepal with about 159 wild individuals. This population is increasing at about 3.5% per year and translocation of some individual in another protected area has been recommended to secure a second population. However, genetic studies suggest that wild buffaloes have been cross breeding with domestic and feral buffaloes in Koshi Tappu for centuries. But the study also notes that despite such cross breeding, distinct populations of wild buffaloes remain and they are fully worthy of conservation efforts (Muley, 2001; Flamand et al., 2003). If a translocation programme is carried out in order to establish a second Nepalese population, it is important that only individuals assigned by genotyping to pure strain are selected (Flamand et al., 2003). The population of Ruhuna National Park (1,500 km² with its adjacent reserves) in South-Eastern Sri Lanka comprises about 2,000 individuals (de Silva, 1994), but its genetic integrity has still to be confirmed. Active management, including removal of individuals of domestic origin and translocation between protected areas is required to assure the survival of some populations (Heinen and Kandel, 2006). A feral population exists in northern Australia; it was established from 80 domestic individuals introduced first to Melville Island and Coburg Peninsula between 1825 and 1843 (Tulloch, 1970). There, feral buffalo numbers were so high that they were destroying wetlands before their dramatic decrease in the 1980s due to extensive culling.

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