With roughly 200 White-Bellied Herons (Ardea Insignis) in the world today, herons are among the 50 rarest bird species on earth and Bhutan alone shelters about 28 herons in their prime habitat at Punatsangchu valley in Punakha.
The Royal Society for the Protection of Nature (RSPN) has established two important White-Bellied Herons (WBH) habitat places, like Punatsangchu basin, Wangduephodrang dzongkhag and Berthi in Zhemgang, in efforts to conserve the habitat of the critically endangered bird species.
Despite numerous initiatives taken up by RSPN, the mortality rate of the bird has always remained high due to manmade and natural causes.
As per a recent report released by RSPN, the endangered bird is found dead every year and RSPN has recorded causalities of 12 individuals since 2003 to 2015 at different locations.
The report stated that in 2011 alone Bhutan lost three WBH roosting in the Phochu vicinity to predators and another two in 2014 in its Harrarongchu habitat where the cause of death was unable to be ascertained.
According to the report, forest fires, electrocution, wild animals preying on the bird and other reasons like chick felling out of the nest, drowning in the river and injuries sustained by the bird are some of the causes of death among WBH.
From among the 12 WBH, three individuals have died due to electrocution, three were predated on by predators, two individuals were died with unknown reasons, and similarly other four individuals died either by falling from the nest, drowning in the river, injured in the wings and killed during the forest fire.
A research found out that since 2003 the population of WBH has remained constant, in contradiction to the regular population survey and nest monitoring activities which found out that around 10-12 juveniles are produced annually.
“There is no clear understanding about why there is no significant increase in WBH population in the country,” the report stated.
As per the 2015 population census conducted by RSPN from February 27 to March 3, Bhutan has 14 percent of the world’s total WBH population.
RSPN has been carrying out WBH population census regularly for last 13 years and their census has revealed that atleast12 WBH juveniles are produced every year. Hence, the number of WBH in the country has, on an average, remained constant during the entire survey period.
During the census survey, RSPN has counted 14 individuals in their maiden survey in 2003, and since then the WBH population has seen a steady rise in the country until 2009 where RSPN recorded the highest of 30 herons in 2008 and 2009.
However, the number has declined for next 4 years after the survey, and in the 2013 survey, RSPN was able to count only 20, which was a drastic decline from the 10 less highest records of 30.
Yet last year, in a survey conducted from February 24 to 28, it recorded a rise in WBH number from the previous year, with the sighting of two more individuals.
Although the mortality rate of the critically endangered bird has been significant over the years, Bhutan still has a good number of WBH, owed in part to the aggressive conservation effort pursued by RSPN in collaboration with Department of Forest and Park Services (DoFPS).
RSPN has also completed assessment of mitochondrial genetic diversity of the endangered bird and a WBH chick in captivity has reared for the first time.
Apart from the existing conservation effort, RSPN is also carrying out various activities which include community awareness, long-term conservation strategies and “White-bellied Heron Recovery Plan” project.