Distress calls from a rare waterbird

Black-bellied tern (Sterna acuticauda) is a globally endangered bird species that belongs to the family Laridae and is locally known as “Utkroshi Phyalphyale” in Nepal. The species, once abundant throughout its distribution range, is vanishing silently. This calls for a heightened conservation attention from stakeholders.

Native to countries like Nepal, India, Bangladesh, Pakistan, Thailand, China and other Southeast Asian countries, this species is found near water bodies like rivers, ponds, lakes and marshes. Once found abundantly on the lowlands of Nepal at the elevation range of 75-730 meters, the species seems to have vanished, literally, these days.

Characterized by a distinctive black belly, deeply forked and long tail and slender orange bill, black-bellied tern is a small waterbird measuring 32-35 cm in length. Its diet includes fishes and insects. The bird is quick when diving for fish and skims over the surface of water and land to catch its prey. Nesting and breeding take place from February to April.

This bird is solitary during nesting, nests on sand and gravel islands in water bodies. It shares its habitat with other bird species, so conservation of one species helps other bird species as well. 

In the Bengali region, this bird is considered sacred and is associated with wealth and prosperity. The species is known for its unique appearance and a major ecological role, mainly as a predator to small fishes and insects. The conservation of this species is important to maintain a healthy ecosystem and biodiversity.

Globally, the population of this geographically-restricted species, like several other waterbird species, is declining, with an estimated population of less than 10,000 individuals at present, including merely 10-20 individuals in Nepal. 

Habitat loss and degradation, invasive species, overexploitation of resources and climate change are some of the threats facing the species. Anthropogenic activities such as hunting of the species for meat and foraging for eggs, and use of catapults have impacted the species directly. Invasive plant species in lakes and rivers, overfishing, sand and stone mining and extraction, dam and other water regulatory bodies, recreational activities (picnics near their habitats, boating, etc), agriculture and aquaculture have impacted the species indirectly.  

The threats to the species native to the Tarai region are multiplying, thanks to a number of factors like massive migration of people after the eradication of malaria from the region in 1950s’ and 60s’ in search of fertile farmlands and better infrastructure. Industrial development, rampant extraction of construction materials like sand, stones and boulders from riverbeds, ‘transformation’ of many wetlands turned into settlements and agricultural land, this species and several other flora and fauna are facing an increased threat. Combined, these threats can lead to local extinction of the species. 

What next?

As we have a limited understanding of the ecology of the species in Nepal, including information on its distribution, our first priority should be on addressing the knowledge void. 

What is shocking in this regard is a recent study that recorded just two individuals at the Koshi Tappu Region, considered a prime habitat for the species, pointing toward serious threats facing the species.

Deploying bird watching groups as citizen scientists can be fruitful in this matter. Conservation measures should be carried out side by side as we cannot wait till the ample evidence is collected for devising conservation measures. Raising awareness in local communities particularly those whose livelihood is directly dependent on the rivers and wetland is must.  Sensitization of other stakeholders, including local people, schoolchildren and government representatives are also essential.

Monitoring of the nesting sites to avoid egg collection, prohibition on collection of river bed materials during the breeding season and regulation of the use of heavy machinery in potential habitats are also equally necessary. Also important is the livelihood diversification of fishing communities to reduce their dependence on wetlands. Dams have drawn criticism for their negative impact on many species, but for this species, dams are a habitat. So, we might think of constructing dams in some areas as they provide a perfect habitat for this species and also protect its food habitat.

Conclusion

Black-bellied terns, whose population has suffered a drastic decline in Nepal, need serious conservation intervention. As we lack information on the ecology of the species, there’s a need to carry out research and conservation works side by side. Working together, we can create a better future for black-bellied terns and other waterbirds.

The author is a conservation associate at Environment Protection and Study Center (ENPROSC)