Eroding grasslands, sandbars along Brahmaputra threaten Arunachal sanctuary, home to endangered bird

On a humid, overcast afternoon in June, Namash Pasar spotted something adrift in the rising floodwaters while surveying deluge on the outskirts of Jonai town in upper Assam’s Dhemaji district. As it drew closer, he realised it was a live animal. Along with two other bystanders, he managed to rescue it from the waters that were threatening to sweep it away. Pasar drove it to local forest officials to provide initial care and to aid its recovery and rehabilitation. It was later identified as a Bengal florican bird (Houbaropsis bengalensis) or as it is locally called, ulumora.

“It was an adult ulumora desperately trying to stay afloat, presumably come from one of the chaporis (river islands) of the nearby Daying Ering Memorial Wildlife Sanctuary,” said Pasar, who is an office bearer of the Jonai sub-divisional unit of Takam Mising Porin Kebang, a tribal student body and social organisation led by the Mising community. “The bird sustained injuries on its wings and legs. We carefully pulled it out of the water and promptly drove it to the forest office.”

Heavy spells of monsoon had arrived and by late June, waters of the surrounding rivers flooded the grassland habitats of the Bengal florican, a critically endangered bird according to the IUCN Red List data, with fewer than 1,000 individuals left in the wild.

A refuge for endemics

In Arunachal Pradesh, Daying Ering Memorial Wildlife Sanctuary is the only protected area where this rare bustard is found. The 190 sq km sanctuary is a patchwork of grasslands, wetlands, marshes and a small fragment of rainforest in the district of East Siang. It has a cluster of chaporis on the river Siang and its tributary Sibia near Pasighat, where it joins the Brahmaputra.

Named after an administrative and political pioneer from the local Adi community, the sanctuary is an Important Bird Area. A majority of the sanctuary – about 80% – is covered in reeds and grasslands, making it an ideal habitat for Bengal floricans. This large, terrestrial bird is endemic to the sub-Himalayan grassland ecosystem in the country. In the sub-continent, its population has severely declined owing to expansion of agricultural lands. It once roamed riparian habitats in Bangladesh, but vanished following decades of anthropogenic activities that have decimated its habitats.

Only a few studies have been conducted on avifauna in Daying Ering, leaving data scant. Daniel Mize, a zoologist from Rajiv Gandhi University in Arunachal Pradesh and author of a 2014 study on avifaunal diversity in the sanctuary, recorded 55 species, of which nine were threatened and three were on the brink of extinction.

A survey carried out in 2016 found 29 territorial male Bengal floricans in Daying Ering, with an estimation that 60-70 adult territorial males could be present in the sanctuary, making it one of the most important conservation sites in India for the species.

The swamp grass-babbler (Laticilla cinerascens) is another endemic bird found in the sanctuary. The elusive avian species, categorised by IUCN as endangered, is now confined to the hyperlocal habitats in the Brahmaputra and Gangetic plains. Bird Life International attributes the very rapid decline of the species to “excessive” habitat loss and fragmentation. A 2019 study on swamp grass-babblers in Daying Ering, found that the species requires the ecosystem health of the sanctuary’s grasslands to be maintained for its survival.

Losing grasslands

The sandbars and wetlands within the protected area also host Asian elephants and the once ubiquitous and culturally significant wild water buffaloes (Bubalus arnee), a species that is currently facing a host of threats to its population, as well as tigers and leopards.

The rainforest patches of the sanctuary also shelter a small number of hoolock gibbons , an arboreal species highly susceptible to changes in forest canopies.

A 2023 study published in Journal of Applied and Natural Science has found that 55.91 sq km of native grasslands have been cleared in Daying Ering over the period of ten years (2012-2022), for widening Siang and Sibia rivers.

Grasslands which formerly covered an area of 84.50 sq km in the sanctuary have been reduced to 28.59 sq km in 2022. The study also reveals that accelerated accretion has resulted in the expansion of sandbars from 25.25 sq km to 65.19 sq km, in turn increasing the risk of floods.

The upper Brahmaputra plains have been witnessing a significant loss of grasslands according to a 2015 study. Nabajit Hazarika, one of the co-authors of the study and assistant professor of Environmental Biology and Wildlife Sciences at Cotton University in Assam, says that the primary factors triggering land cover change in the region are “flood, erosion, and silt deposition, as well as expansion of agriculture and other human activities.”

“With the population growing in the region, floodplain usage for human activities is expected to continue to increase in the near future,” Hazarika told Mongabay-India. “The increased human interventions are a potential agent of altering an already endangered ecosystem.”

Erosion and floods

Nabin Bori, a 43-year-old farmer told Mongabay-India that he lost his homestead on a river island close to the sanctuary to erosion a few years ago. The turbulent waters of the Brahmaputra had eroded more than five bighas (1.3 acres) of his land.

The northeast Indian region, especially Arunachal Pradesh, has been witnessing an infrastructure boom in the past few years, aimed at connectivity, hydropower production. This, along with the expansion of agriculture, has resulted in rapid deforestation.

Further, experts point out that extreme weather events such as cloudbursts and flash floods, as well as hydropower dam-induced floods might adversely impact the long-term survival of endemic species in sanctuaries like Daying Ering, which are situated in the downstream reaches of the Yarlung Tsangpo, as the Brahmaputra is called in China.

What further jeopardises wild species found in reclusive habitats is that they are less likely to adapt to changes, says Titash Choudhury, who studied the rare black-necked crane (Grus nigricollis) habitat sites in Arunachal Pradesh and was formerly with the World Wildlife Fund. “A crow in the city will be highly adaptive to changes whereas it is very unlikely that a rare Bengal florican will be able to adapt to sudden changes in its habitat,” she explained.

Gazing towards one of the river islands threatened by erosion, Pasar, a 40-year-old Takam Mising Porin Kebang activist from Jonai, recalls a different reality from his childhood, when the ulumora, as the Bengal florican is known in Assamese, could be sighted more frequently.

“We have conducted awareness programmes on the importance of conserving wild animals and birds which are rapidly vanishing,” he told Mongabay-India. “This is the least we can do to help protect these iconic wildlife species.”

This article was first published on Mongabay.