野水牛种

世界自然保护联盟将河水牛列为濒危物种，其总数量只有少于4000头，而成熟的数量则少于2500头，14年内估计会减少20%，21年内就会减少一半。

分类问题

一些学者会将河水牛分类在水牛之内，但以往水牛的学名是指家养的水牛，而河水牛这等野生的水牛则分类成独立的物种。

形态

成年家养的水牛只重300-600公斤，在野外的雌性河水牛重800公斤，雄牛重1200公斤。河水牛肩高1.8米，体长2.9米。在印度阿萨姆邦的种群栖息在喜玛拉雅山山脚的森林，体型且较为大，平均重900公斤，雄牛较雌牛大些许，肩高1.7米，可达2米高。最纯种的河水牛栖息在印度的加济兰加国家公园及不丹马纳斯国家公园。它们也分布在缅甸西北部。

基因污染

河水牛受到基因污染的威胁。家养的水牛日间在森林内放牧，与河水牛有所接触，发生种间繁殖。种间繁殖令河水牛的血统受到污染，相信是源自于南亚。除了在印度以外，纯种的河水牛就只有在泰国可以见到，但数量只有约50头，而在沿越南、老挝及柬埔寨边界的安南山脉也可以见到。现时在亚洲其他地方的河水牛都并非纯种的河水牛，且也有被引进到阿根廷及玻利维亚。

The wild water buffalo (Bubalus arnee), also called Asian buffalo, Asiatic buffalo and wild buffalo, is a large bovine native to the Indian subcontinent and Southeast Asia. It was first described in 1792.

The wild water buffalo is the most likely ancestor of the domestic water buffalo. It has been listed as endangered on the IUCN Red List since 1986, as the global population totals less than 4,000 mature individuals.

Taxonomy

Bos arnee was the scientific name proposed by Robert Kerr in 1792 who described a skull with horns of a buffalo zoological specimen from Bengal in northern India. Bubalus arnee was proposed by Charles Hamilton Smith in 1827 who introduced the generic name Bubalus for bovids with large heads, convex-shaped narrow foreheads, laterally bent flat horns, funnel-shaped ears, small dewlaps and slender tails.

Later authors subordinated the wild water buffalo under either Bos, Bubalus or Buffelus.

In 2003, the International Commission on Zoological Nomenclature placed Bubalus arnee on the Official List of Specific Names in Zoology, recognizing the validity of this name for a wild species.

Etymology

The specific name arnee is reminiscent of the classical Sanskrit word arnī meaning female wild buffalo.

Characteristics

The wild water buffalo has an ash-gray to black skin. The moderately long, coarse and sparse hair is directed forward from the haunches to the long and narrow head. There is a tuft on the forehead, and the ears are comparatively small. Its head-to-body-length is 240 to 300 cm (94 to 118 in) with a 60 to 100 cm (24 to 39 in) long tail and a shoulder height of 150 to 190 cm (59 to 75 in). Both sexes carry horns that are heavy at the base and widely spreading up to 2 m (6 ft 7 in) along the outer edges, exceeding in size the horns of any other living bovid. The tip of the tail is bushy; the hooves are large and splayed.

Distribution and habitat

The wild water buffalo occurs in India, Nepal, Bhutan, Thailand, and Cambodia, with an unconfirmed population in Myanmar. It has been extirpated in Bangladesh, Laos, Vietnam and Sri Lanka. It inhabits wet grasslands, swamps, flood plains and densely vegetated river valleys.

In India, it is largely restricted to in and around Kaziranga, Manas and Dibru-Saikhowa National Parks, Laokhowa Wildlife Sanctuary and Bura Chapori Wildlife Sanctuary and in a few scattered pockets in Assam, and in and around D'Ering Memorial Wildlife Sanctuary in Arunachal Pradesh. A small population survives in Balphakram National Park in Meghalaya, and in Chhattisgarh in Indravati National Park and Udanti Wildlife Sanctuary.

Ecology and behaviour

The wild water buffalo is both diurnal and nocturnal. Adult females and their young form stable clans of as many as 30 individuals, which have home ranges of 170 to 1,000 ha (420 to 2,470 acres) that include areas for resting, grazing, wallowing and drinking. Clans are led by old cows, even when bulls accompany the group. Several clans form a herd of 30 to 500 animals that gather at resting areas. Adult males form bachelor groups of up to 10 individuals, with older males often being solitary, and spend the dry season apart from the female clans. They are seasonal breeders in most of their range, typically in October and November. However, some populations breed year round.

Threats

A population reduction by at least 50% over the last three generations seems likely given the severity of the threats, especially hybridization; this population trend is projected to continue into the future. The most important threats are:

interbreeding with feral and domestic water buffaloes in and around protected areas;

hunting, especially in Thailand, Cambodia, and Myanmar;

habitat loss of floodplain areas due to conversion to agriculture and hydropower development;

degradation of wetlands due to invasive species such as stem twiners and lianas;

diseases and parasites transmitted by domestic livestock;

interspecific competition for food and water between wild water buffaloes and livestock.

Conservation

Bubalus arnee is included in CITES Appendix III, and is legally protected in Bhutan, India, Nepal, and Thailand.

In 2017, 15 wild water buffaloes were reintroduced into Chitwan National Park in Nepal to establish a second viable sub-population in the country.

In 2023, four wild buffalos were translocated to Udanti-Sitanadi Tiger Reserve to reverse its declining population in the state.