Genetic degradation of Arna poses serious challenges

By Baburam Karki,Barahakshetra, Mar. 22: The wild water buffaloes (Arna) in the protected Koshi Tappu Wildlife Reserve are undergoing genetic degradation. 

Due to open grazing practices, interactions between Arnas and feral domestic buffalo bulls have increased, leading to a rise in ‘backcrossed’ offspring, which is causing the genetic deterioration of the rare Arna species.

According to Chief Conservation Officer Ramdev Chaudhary of Koshi Tappu Wildlife Reserve, around 1,500 to 1,600 feral cattle and buffaloes share the grazing grounds with Arnas. This has resulted in a rising number of backcrossed offspring born from these interactions, posing a serious challenge to conserving pure Arna populations.

While there is noticeable diversity among the Arna population in the reserve, no detailed qualitative study has been conducted. Chaudhary stressed the need for genetic-level research to safeguard the true Arna population from further genetic degradation.

Conservationist Bimal Timilsina said that simply placing Arnas in the protected areas is insufficient for their preservation. He warned, “If the government fails to promptly conduct research and adopt conservation measures, there is growing concern that Arnas may become extinct from Koshi Tappu.”

He highlighted that the uncontrolled presence of feral buffaloes is accelerating the genetic deterioration of Arnas, increasing the risk of their extinction.

Chaudhary said that calves born from interactions between feral buffaloes and Arnas may resemble true wild buffaloes but lack the distinct features of pure Arnas. Although the Arna population is increasing annually, the rising number of backcrossed offspring heightens the risk of losing the Arna's pure genetic traits, he added. 

The endangered Arna, which belongs to the Bovidae family, is the second-largest species in this group. Koshi Tappu's Arnas are believed to have ancestral roots in Assam's Kaziranga National Park in India. Preferring moist grasslands, marshy areas and dense forests on flat terrain, Arnas have permanently settled in Koshi Tappu after migrating from Kaziranga.

When the reserve was established in 1975, 63 Arnas were recorded. The latest census now shows their population at around 500. Koshi Tappu hosts the second-largest Arna population in the world after Kaziranga, Chaudhary said.

How to prevent genetic degradation?

Arnas are protected under Nepal's National Parks and Wildlife Conservation Act, 1973. They have distinct physical features compared to domestic buffaloes, such as taller, upward-pointing horns, dark grey to black skin and white markings around the throat, muzzle, eyes and knees.

However, a growing number of Arnas with mixed features resembling domestic buffaloes have been observed recently. Although they may appear similar at first glance, closer inspection reveals differences from pure Arnas.

Spanning 175 square kilometres, Koshi Tappu Wildlife Reserve is Nepal's key habitat for Arnas. Due to open borders, controlling the entry of local cattle and buffaloes for grazing has been challenging. Since much of the reserve lies along the floodplain of the Sapta Koshi River, fencing to separate domestic buffaloes from Arnas has proven difficult.

Conservationists recommend raising awareness among locals to control open grazing and stray livestock. Strict policies and regulations are necessary to manage open grazing practices.

The Koshi River's changing course during annual floods has further impacted the reserve's habitat, reducing the available grasslands and grazing areas for Arnas.

 Conservationist Timilsina suggested that improving grassland management could help minimise interactions between Arnas and feral buffaloes, thus preventing genetic degradation.

Why is Arna's conservation important?

The International Union for Conservation of Nature (IUCN) has listed Arnas as an endangered species on its Red List. Without immediate conservation efforts in Koshi Tappu, Nepal’s only Arna population may face extinction.

Efforts to establish Arna populations in various parts of Nepal have faced setbacks, as these areas lacked the suitable natural environment like in Koshi Tappu. Given Koshi Tappu's pivotal role in Arna conservation, the species symbolises the reserve's entire ecological identity.

If the rise in hybrid offspring continues, the pure Arna population may disappear from the reserve. Conservationists stress that Arnas play a vital role in maintaining ecological balance. Ensuring the right of every species to survive requires collective efforts from all sectors to protect biodiversity.

Recognised as one of the world's rarest species, Arnas is found in Nepal, India, Bhutan, Thailand and Cambodia. Without dedicated conservation efforts in Koshi Tappu Wildlife Reserve, future generations may never witness this magnificent species in its natural habitat. Protecting Arnas is crucial to preserving their legacy for years to come, said conservationists.