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A proposed dam in Arunachal Pradesh threatens Black-necked Cranes’ habitat

Read time: 4 mins
7 Jan 2021
A proposed dam in Arunachal Pradesh threatens Black-necked Cranes’ habitat

Black-necked cranes in Ladakh [Image credits: Dibyendu Ash, CC BY-SA 3.0, via Wikimedia Commons]

One of the only fifteen crane species in the world, the Black-necked Crane is now classified a Vulnerable species on the IUCN Red List. This enormous bird lives in the high-altitude Himalayas of India, China, and Bhutan. Every year, these cranes move to lower altitudes of the Himalayas to escape the harsh winter and breed. Shallow open marshes, river valleys, and agricultural fields, which used to be their preferred habitats, are now threatened by construction of dams and clearing of land. Can we still build dams and protect the homes of these now-dwindling cranes? Perhaps, says a new study, if we understood these cranes and their homes better.

The study, by researchers at the Wildlife Institute of India, investigates how the proposed construction of a hydropower dam in Arunachal Pradesh would change the habitat of the Black-necked Cranes. The study was published in the journal River Research and Applications and was funded by the Ministry of Environment, Forestry and Climate Change, Government of India.

The proposed hydropower dam is located in the Zemithang Valley, on the Nyamjang Chu River, which is one of the river valleys visited by the Black-necked Cranes, besides those in Ladakh and Sikkim, between November and February. Every year, about twenty breeding pairs are spotted in the region. This year, however, the researchers found none during the winter, and had to rely on records from the previous five years for the study.

It is well-known that dams are double-edged swords. While they provide livelihoods to people, they also cause irreversible changes on the biodiversity of the region. The proposed dam in the biodiversity-rich Arunachal Pradesh is no different. But, how it affects the mystique cranes is what the researchers wanted to understand. Hence, they evaluated the flow of the river water and its effect on the riverbed during winter, where these cranes forage and nest. Using mathematical models, they simulated the physical habitats of a species and found out what would be needed at the Nyamjang Chu River to make it suitable for the visiting cranes.

The study found that the cranes used the dry parts of the riverbed for resting and the shallow parts for foraging. A maximum depth of 30 cm of water on the river bed would be ideal for the cranes to continue to use this region. Any deeper, and it is likely that the cranes would move away and this might disturb the delicate biodiversity balance in the region. The construction of the dam would result in the water level of the riverbed exceeding the ideal 30 cm depth during the winter months.

Although the researchers are not aware of the current status of the proposed hydropower dam, they found that the local communities are opposed to the construction. These communities have religious associations with the Black-necked crane and the dam’s construction would likely submerge the habitat and drive away the birds.

The researchers have compiled their findings to bring it to the attention of the concerned. “The Wildlife Institute of India has submitted the final report of the project, where we clearly explained the adverse impact of the proposed project on Black-necked Crane habitat and have recommended that the proposed dam not be constructed,” says Dr. J.A. Johnson, the lead author of the study from WII.

While the dam may be one of the bottlenecks in the conservation of the Black-necked Cranes, other steps are also needed to protect them.

“Identifying and monitoring their wintering sites, mapping key wetlands in the region, studying their movement ecology and securing the wintering habitats as community reserves are some steps in the right direction,” says Dr. Johnson, adding that it is also necessary to involve local communities in such efforts. 

This article has been run past the researchers, whose work is covered, to ensure accuracy.