Conservationists are worried by the increasing disturbance of prime habitat in Bhutan.
White-bellied Heron, the world's second-largest heron, is one of the world's rarest birds and is classified as Critically Endangered. It is feared that fewer than 60 individuals remain, with an estimated 24 of these (plus five juveniles) in Bhutan, where it is patchily distributed. Elsewhere, it is found in northern Myanmar. It favours fast-moving mountain rivers.
The area of Phochhu was declared an Important Bird Area in 2014. However, researchers from the Royal Society for the Protection of Nature (RSPN), birders and rafting operators have all suggested that the heron's population at Phochhu and nearby Mochhu has declined over the years.
Hishey Tshering, a local birder, said that he saw up to five individuals in the area in 2001. "Now it is very rare to see even a single [White-bellied Heron] along the Mochhu. In 2016, there were three along the Phochhu. Today, we can see only one and that is also being continually disturbed."
Chief of communications and membership division with RSPN, Tashi Phuntsho, said that the heron was a secretive species that is generally intolerant of humans. "Disturbance from humans and loss of habitat undoubtedly attributed to their extirpation over much of their former range. Threats to these birds are further intensified by the growing tourism activities like rafting and kayaking along the important habitats. There are more than three rafting companies operating along Phochhu and Mochhu rivers in Punakha."