White-bellied Herons Declining in Bhutan

The first White Bellied Heron population survey was conducted in 2003, and it has been an annual event since then.( Pic : RSPN)

Sonam Penjor

Bhutan currently is home to 22 most critically endangered White-bellied Heron (WBH) which is decreasing over the years.

This is according to the 19th WBH annual population survey conducted from 27 February – 03 March this year. The survey confirmed 19 adults and three sub-adult individuals, which is five less than the previous year.

The extremely low and shrinking population of the WBH globally is attributed to human exploitation, disturbances, and loss of riverine habitat. And Bhutan is no exception.

According to the annual population survey, 2021 which was published by Royal Society for Protection of Nature (RSPN), the decrease in population was mainly observed in upper Punatsangchhu basin; Phochu, Mochhu, Adha and Harachhu which were the oldest and previously the most abundantly used habitats in Bhutan.

The survey covered all currently known and expected habitats along Punatsangchhu, Mangdechhu, Chamkharchhu, Drangmechhu, Kurichhu, Kholongchhu and other major tributaries.

For the survey, the survey report states that the habitats across the country were divided into 53 priority zones and surveyors were deployed to look for the WBH from 7:00 AM to 5:00 PM for five consecutive days within their designated zone. A total of 82 surveyors from the RSPN, Department of Forests and Park Services (DoFPS) and Local Conservation Support Groups (LCSG) were engaged in the survey.

The report further states that WBH sighted during the survey, observer, date, time, GPS location, count, age, and activity were recorded. In addition, all bird species sighted during the survey were also enumerated for record and to study the diversity and population trend of associated species within the area.

A total of 117 bird species; 59 water birds and 58 other species were recorded during the survey. The survey was conducted using Epicollect5 digital data collection platform.

All the data were recorded using the Epicollect5 mobile App and uploaded to the central WBH database and analyzed. Three live nests were also located during the survey of which two had three eggs each and one pair was found building a nest.

The first WBH population survey was conducted in 2003, and it has been an annual event since then. Today, the conservation of WBH is not only a flagship program but it is at the forefront of RSPN’s core mandate.

Meanwhile, the WBH is a large heron species of the family Ardeidae, order Pelecaniformes, found in freshwater ecosystems of the Himalayas.

It is categorized as critically endangered under the International Union for Conservation of Nature (IUCN) red list of threatened species and protected under the Schedule I of Forests and Nature Conservation Act 1995 of Bhutan. It was listed as threatened in 1988, up-listed to endangered in 1994, and to critically endangered since 2007.

The distribution of WBH to undisturbed freshwater river systems and its piscivorous feeding behavior can be easily associated with the health of the ecosystem and pristinely environment.

“They are the indicators of our freshwater river systems. Their presence in our rivers indicates the health of the rivers, the fish population, water quality, and the health of associated freshwater biodiversity, level of disturbances, pollution, and above all, intactness of our nature,” added the report.

They are predator, they are prey and they are player in a food chain. They are our natural wealth, our pride, and our heritage. By protecting them and their habitats, we protect our rivers, waters, landscapes, biodiversity, food, and the livelihoods of the local communities.

The bird is threatened by major challenges across the region which includes habitats are being lost to infrastructure development, agriculture expansion, hydropower projects, extractive industries, and climate change.

Most of the few remaining habitats are increasingly under pressure due to incautious eco-tourism and recreation, diminishing food resources, pollution, fragmentation, forest fires, and both man-made and natural calamities. The small population is under crises with increased mortality and declining breeding success.

“Therefore, it is easily foreseeable that such human-made and natural disturbances would lead to the extinction of this highly vulnerable bird if timely conservation interventions are not taken,” added the report.