- Vulnerable lesser adjutant storks are successfully breeding at higher numbers than expected in Nepal, a new study of the species across the country’s southern plains indicates.
- Among 206 nests studied, researchers found 280 chicks had fledged, exceeding the expected rate for larger storks of about one fledged chick per nest.
- Lesser adjutant colonies are threatened with habitat loss, as they nest in tall trees that are often cut in farmlands and areas of road construction or home building.
- Previously, the species had not been studied in detail, but this new research raises hopes among conservationists who say local governments need to help raise awareness of the birds’ importance.
KATHMANDU — They have a bare yellow neck and a head connected to a long pointed beak, and they can be easily spotted in Nepal’s agriculture fields when the rice plants turn green a few weeks after planting. Perching on tall trees, lesser adjutant storks scan the fields for prey such as fish, frogs, reptiles, large invertebrates, mice, small mammals and, at times, carrion. The birds dart at their prey whenever they feel they have a chance at catching it.
Lesser adjutants, mainly due to their physical build, are not considered as iconic as sarus cranes (Antigone antigone) that live in similar habitats. “Their Nepali name bhudiphor garud (which translates to a stork that uses its beak to open the belly of its prey) also doesn’t help their popularity,” said Kamal Raj Gosai, co-author of a 2016 study of the species.
Perhaps this may be the reason that their population and status hadn’t been studied in detail, not just in Nepal, but also in the rest of South Asia and Southeast Asia where they are found. A handful of microlevel studies, conducted mainly in forested areas, suggested that the sighting of the bird was becoming increasingly rarer, and the IUCN, the international authority on biodiversity, categorized it as vulnerable in 1994.
According to IUCN, the bird has gone extinct in Singapore and most likely in China due to hunting, loss of nesting habitat, degradation of wetlands and intensification of agriculture.
However, a recent first-of-its-kind extensive study on the species in Nepal’s southern plains shows that the bird may be doing far better than expected. “We found that the breeding success of lesser adjutants was spectacular — a global record for larger storks,” said KS Gopi Sundar, co-author of the recent study and co-chair of the IUCN Stork, Ibis and Spoonbill Specialist Group.
Under the study, lead author Hem Bahadur Katuwal and his team conducted extensive surveys to locate and monitor lesser adjutant nests across the Terai. “We monitored 65 colonies with 206 active nests between July 2019 to January 2020 coinciding with the breeding season of the birds. We visited almost every colony twice a month to check on the chicks,” he said.
The team found that 280 chicks fledged from the 206 active nests — that’s around 1.35 per nest. “The number for larger storks [like the lesser adjutant] is around one. Remember that our method includes nests that failed and so it is a full record. Most studies only report success from successful nests, which inflates the metric,” said Sundar. “However, the figure of 280 is impressive and talks for itself.”
Previous estimates of the population of the bird suggested that fewer than 1,000 individuals remained in the wild in Nepal. However, as the survey counted 890 individuals without covering the entirety of the known range in the country, the authors believe that the population is likely to be much higher than 1,000.
The numbers were also unexpected for Katuwal. “We didn’t expect to find nests in such numbers, as previous studies had suggested that they had become rare,” he told Mongabay. “But their population is doing well, at least in Nepal,” He added, “Earlier studies had also incorrectly assumed that lesser adjutants require forests and wetlands to breed successfully. But that doesn’t seem to be the case.”
Not out of the woods yet
Despite the encouraging signs, conservationists warn that the species faces a host of threats that could lead to steady declines in their population. The biggest threat is the felling of trees used by the bird for nesting.
The study found that most of the colonies of the bird were on trees such as red-silk cotton trees (Bombax ceiba), called simal in Nepali, and at times kadam (Haldina cordifolia) and peepal (Ficus religiosa) were also widely used. “The trees, especially simal, are key to conserving the bird and its nests,” said Katuwal. “We also found that the taller the tree, the better it was for nesting,” he added. The authors noted that this was probably in order to reduce human-related disturbances and the possibility that trees could be uprooted by storm. The location of the tree, proximity to the forest or human settlement or wetlands didn’t matter to the birds as long as the trees were tall.
Gosai, who wasn’t involved in the study, said that the trees preferred by the bird have religious importance in some of the breeding areas. “Ficus religiosa, especially, is associated with Hinduism and people refrain from cutting the tree,” he said. “Similarly, until recently, it was illegal to fell the simal tree, even if it was on private land,” Gosai told Mongabay. “Our study had found that although trees are not abundant in the fertile plains used to grow rice, whatever trees remain provide crucial habitats for birds such as lesser adjutants.”
However, these days, people are resorting to cutting tall trees, which they believe disrupt agricultural activities, said Katuwal. “We found that traders visit the tree owners and pay them a certain amount for the tree. Then they call in their own machines to extract the wood and sell it in the market.” In addition to this, laying of roads and building of concrete houses on farmlands also pose a huge risk to the tall trees and the lesser adjutant population, said Sundar.
Gosai said his study suggested that marginalized communities that can’t afford meat hunted the birds for meat and eggs. As people don’t like the way the birds look, they shoot them away, and even kids attack the birds, he added. The excessive use of pesticides also had a telling effect on the birds’ prey, he said.
Katuwal said that while conservationists bask in the encouraging signs, it was now necessary for local governments to come up with a plan to raise awareness about the importance of the bird. “When people are aware about the importance of this bird, they will surely help save it,” he concluded.
Banner image: A lesser adjutant stork in a paddy field in Nepal. Image by Hem Bahadur Katuwal.
Related audio from Mongabay’s podcast: Hear this reporter discuss the birdlife of Nepal, a new bird-counting app that’s sparking greater interest in Nepal’s rich avian life, and some of the most recent conservation actions being taken in the country to protect birds, listen here:
Katuwal, H. B., Sundar, K. S., Zhang, M., Rimal, B., Baral, H. S., Sharma, H. P., . . . Quan, R. (2022). Factors affecting the breeding ecology of the globally threatened Lesser Adjutant (Leptoptilos javanicus) in agricultural landscapes of Nepal. Avian Conservation and Ecology, 17(2). doi:10.5751/ace-02235-170215
Sundar, K.S., Maharajan, B., Koju, R., Kitur, S., Gosai, K. R. (2016). Factors affecting provisioning times of two stork species in lowland Nepal. Waterbirds, 39(4). doi:10.1675/063.039.0406