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By Indra Acharja
Indra is chief of species conservation at the Royal Society for Protection of Nature in Bhutan. He can be contacted at email@example.com.
A new phase in the conservation and recovery of white-bellied heron (WBH), Ardea insignis, has begun in Bhutan with the establishment of the first pair of ex-situ breeding birds. In April 2021, researchers at the Royal Society for Protection of Nature (RSPN) collected a pair of pre-fledged juveniles from a wild nest and transferred them to the newly constructed Conservation Center in south-central Bhutan, where the birds will be raised and bred. The Center aims: to secure an ex-situ gene pool; to rear, raise, and breed herons; and to supplement the wild population by releasing them into safe habitats, where research indicates that herons should thrive. It will also serve as a center for research, a global information hub, and a place for coordinating conservation work in the region.
The collection of selective birds from the wild will continue until the population’s genetic diversity is expressed in several breeding pairs, as it is the only source of founders for the species. In the future, this tiny captive group will function as a breeding reserve and hopefully will be a safeguard from extinction and a source of birds for the introduction of herons into safe areas.
The WBH is critically endangered and one of the rarest heron species in the world. Today, fewer than 60 individuals survive over the extent of 165,000 km2 of Himalayan freshwater ecosystems, spanning the countries of Bhutan, India, Bangladesh, Myanmar, and China. It has been declared regionally extinct in Nepal and is possibly also extinct in Bangladesh. Bhutan is home to 45% of the global population, including between three and five active breeding pairs, which are vital for the survival and recovery of the species.
The RSPN, an environmental conservation charity in Bhutan, has been leading in the protection of species in the past two decades. In 2003, recognizing the bird’s plight, the RSPN began mapping and monitoring the WBH population and habitats. The first nest in Bhutan was discovered in 2003, after more than seven decades since the previous discovery anywhere in the world, in Myanmar in 1929. Owing to its small population, little was known about this heron’s ecology and biology.
Over the past two decades, the RSPN, in collaboration with the Department of Forests and Park Services, Local Conservation Support Groups and local communities, has monitored population trends, distribution and habitat use, nesting, and active breeding pairs, while also mapping major threats to the birds and their habitats. The annual population and nest surveys for the last nineteen consecutive years have recorded an average of 24 birds and three active breeding pairs, from which two chicks per nest have fledged, barely sustaining the extremely low population.
In 2011, with technical support from the San Diego Zoo, the RSPN conducted the first artificial incubation and captive rearing of the WBH with an egg lifted from the wild nest. The chick was reared and released back into the wild after being raised in captivity for 134 days. This experiment helped gain skills in captive management and build confidence to revive the population through a captive breeding program. It also allowed the understanding of the bird’s developmental processes, dietary preferences, and biology.
In Bhutan, we have also observed that the number of successful nesting pairs has declined from up to six active nests in 2012 to just three for the last four years. The number of nest failures is also increasing. In 2020, in one of the nests in Mangdechhu, we observed sexual conflict, parental infanticide, and nest failure, suggesting stressed breeding pairs, competition, and potential gender imbalance, or even inbreeding. Although we are still in the process of understanding the bird’s breeding biology and ecology, there is great concern that the population could decline to a state where it might not be possible to revive or to sustain a viable gene pool. Restricted distribution, small and fragmented population size, and poor recruitment are potential indicators of this species’ failure and impending extinction.
Three major challenges threaten the birds:
- Habitats are being lost to infrastructure development, agriculture expansion, hydropower dams, extractive industries, and climate change.
- Most of the few remaining habitats are increasingly under pressure owing to incautious eco-tourism and recreation, diminishing food resources, pollution, fragmentation, forest fires, and both man-made and natural calamities.
- The small population itself is a liability, with grave costs of increased mortality and declining breeding success.
The demand for natural resources, infrastructure, energy, transportation, and services has increased with the human population in Bhutan. Moreover, Bhutan has opted for hydropower as the primary energy source and revenue; increasingly, new dams are being built along the fast-flowing rivers. In the process, riverine habitats are being destroyed, fish populations are declining, and threatened wildlife species like the WBH are displaced.
The conservation and breeding center has been established to rescue this heron species from extinction risk. Approximately US$150,000 is needed annually to support the operational cost of the Center. Currently, only half of this cost is provided by the WBH Endowment Fund, supported by the Mava and Hans Wilsdorf Foundations.
We seek donations to fill the funding gap via the Bhutan Foundation, a partner based in the United States that helps us raise funds and manage donations. Over the next five years, we plan to build five additional aviaries and information amenities, to procure breeding and veterinary equipment, and to build the capacity to carry out conservation breeding work, which will cost around US$500,000.
Location of the WBH Conservation Center