The threat of hydropower project along the Punatshangchu river basin may lead to the extinction of the white bellied heronEfforts to save the critically endangered white bellied heron seem to be getting harder by the day.
A report by the Royal Society for Protection of Nature (RSPN) notes that “eight years of research on white bellied heron ecology has been driven down to drain due to development activities of Punatsangchu hydropower project.”
According to RSPN, chicks of the white bellied heron are already falling prey to predators like serpent eagle, pallas fish eagle, osprey, yellow throated martin and to some small cats.
“This is due to the growing competition for food as a result of displacement of birds and animals from their original feeding habitats along the Punatshangchu,” said ecologist with RSPN, Rebecca Pradhan.
Experts say that this is due to the chain effects of the hydropower project development activities along the Punatshangchu basin.
This chain effects of the development are driving away all the birds and animals from their usual habitat to inner valleys or along the small streams.
The feeding habitats decreased in size. Predation of the fishes increased and fish migration are disturbed by the development work.
According to Rebecca Pradhan, herons used to get two to three fishes in an hour but now it is difficult for the birds to catch one fish in about three hours. This means that the parent herons have to spend long hours looking for food which leaves the chicks without care for long hours exposing them to predators.
In the last two years, six eggs were lost to predators including two to climatic factors, six chicks to predators, one adult was killed by stoning, and another one electrocuted.
According to RSPN, the nesting sites are concentrated toward smaller tributaries like Digchu, Kisonachu, Haraongchu, Ada lake in western Bhutan and Bertichu in central Bhutan. Chirpine (Pinus roxburghii) forest is the key nesting and roosting habitat for the white bellied heron.
However, almost all the birds, with the exception of just one or two strays, are found only along the Punatshangchu developmental activities.
According to Rebecca Pradhan, the birds select the site to build the nest in very strategic places where the front view is open or clear.
“We might not be worried if the white bellied herons are found along rivers all over the country, but unfortunately maximum numbers are found only along the Punatshangchu,” said Rebecca Pradhan.
The fledging takes place in the monsoon when the small streams are full of fish and juveniles prefer to fish in smaller streams when the main river is flooded.
Protecting the birds is a major challenge and Rebecca Pradhan says that continuous awareness campaign to encourage the local people, hydropower project staff and workers to participate in the white bellied heron conservation effort is the only hope to save the birds.
As per the latest report, there are only 26 birds existing in Bhutan.
The white bellied heron is known from the eastern himalayan foothills in Bhutan and north-east India to the hills of Bangadesh, north Myanmar and, historically at least, across west and central Myanmar.