Forced to live in isolation, white-bellied heron inches closer to extinction

Loss of habitat is forcing the white-bellied heron to lead an isolated lifestyle deep inside forests, which in turn is pushing this critically endangered bird more towards extinction, scientists have found in a new study.

It is estimated that less than 10 of these water birds are presently living in Arunachal Pradesh, which is its only habitat in India, while around there could be 70 – 400 in the world. The population is critically endangered, meaning that it is just one step away from going extinct.

“Due to loss of habitat, primarily wetlands, this bird seems to have changed its lifestyle over years. Unlike most other water birds, which are usually group foragers, the white-bellied heron has been living in remote jungles without much interaction with other water birds. This is pushing it further towards extinction. It is like a viscous trap,” said G Maheshwaran, a scientist from the Zoological Survey of India who led the study.

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The isolation prevented these birds from gaining experience from fellow foragers about new sites and food sources which could have enhanced their survival.

“Earlier studies have shown that water birds, which are mostly colonial foragers, enhance their survival skills by sharing experiences and information about food and suitable habitats. But as these herons lost their original habitats and got isolated inside undisturbed forests inside the Namdhapa Tiger Reserve, they depended on fishes found in fast flowing streams and rivers, which hardly support any water bird community. With no interaction with other foraging birds, they failed to gather experience about new habitats and food sources and are now facing extinction threat,” said Himadri Sekhar Mondol, an expert with the Bombay Natural History Society, who was also a part of the study team.

The scientists said that this is the first such study on the white–bellied heron to find out the reasons behind its depleting population. The findings have been published in the peer-reviewed journal Ecological Informatics published by Elsevier.

Scientists of the ZSI in Kolkata and BNHS unless efforts are made to conserve the population in northeast India, the birds may move to Myanmar and Bhutan.

“There is a need to enhance protection measures in the existing protected areas where the birds are found. More extensive Environment Impact Assessments should be undertaken before large scale developmental activities, including constructing a dam, are given permission in the area. Models have projected that the birds may also prefer riverine habitats along the Kamlang and Lohit rivers. If human activities like mining, garbage dumping and dams impact these ecosystems then it may threaten long term viability of the species,” said Lalit Sharma, a wildlife ecologist with the ZSI specialising in geospatial modelling.

Experts said that just like the great Indian bustard has a species recovery plan prepared by the centre for its conservation, such plans should also be made for the white-bellied heron.

“It is very shy and critically endangered. We do not have a proper survey for these birds in the river basin where they are found in Arunachal Pradesh and there are no detailed studies as they are rarely spotted. If proper conservation measures are not adopted, they might go extinct. We have such long-term dedicated monitoring programs such as the GIB. Ecologically and evolutionarily, they have adapted to such ecosystems along fast flowing rivers in deep forests. If the river’s flow is disrupted it may take an effect of the toll on the bird’s population,” said GV Gopi, a senior scientist at WII working on water birds.