- The dramatic decline of South Asia’s vulture populations, particularly the Gyps genus, was traced to the veterinary drug diclofenac, which caused fatal kidney failure in vultures that fed on treated carcasses.
- In response to the crisis, Nepal implemented vulture safe zones, banning diclofenac, monitoring vulture populations, and establishing “vulture restaurants” providing uncontaminated carrion, and captive-breeding programs to support vulture recovery.
- Researcher Krishna Bhusal says conservation efforts have primarily focused on Gyps species, known as griffon vultures, because of their regional significance and the population collapse that caught global attention.
- Other vulture species, such as bearded vultures and Egyptian vultures, have received less attention despite also facing significant threats, highlighting a gap in research and conservation efforts.
KATHMANDU — The story of South Asia’s vultures has been a tragedy played out at warp speed, especially for griffon vultures, characterized by a slim head and long, slender neck, and belonging to the genus Gyps. Populations of these raptors are believed to have collapsed by as much as 99% between the 1990s and early 2000s.
Until 2004, the cause of this precipitous decline was a mystery. That year, U.S. veterinarian J. Lindsay Oaks and his team reported a high correlation between the kidney failure that they found was killing vultures, and residues of diclofenac, an anti-inflammatory drug given to livestock. The vultures, essentially, were being poisoned by feeding on carrion that had been fed the drug.
The finding sent shockwaves across the Indian subcontinent, and governments started testing the hypothesis among their own vulture populations. After finding strong evidence that this was indeed the case, countries across the region and beyond started taking active measures to save the birds of prey.
Autopsies showed that when an animal treated with diclofenac died, traces of the medicine remained in carcass for up to a week. Vultures that fed on the carcasses experienced a spike uric acid level in the blood and developed visceral gout, preventing the kidney from filtering out uric acid, and eventually leading to the death of the bird. A single contaminated cow carcass could kill around 350-800 vultures, researchers found.
Krishna Prasad Bhusal has been at the forefront of vulture conservation and research in Nepal since the diclofenac link was discovered. The country hosts nine vulture species, six resident and three migratory. Bhusal, who completed his master’s degree in zoology at Tribhuvan University in 2010, started his career as a field biologist at Bird Conservation Nepal, the local affiliate of the NGO BirdLife International, which advocated for the concept of “vulture safe zones” free from the risk of exposure to diclofenac-tainted carrion.
He was later promoted to conservation officer and worked there until 2021, when he decided to take up research independently.
Mongabay’s Abhaya Raj Joshi caught up recently with Bhusal in Kathmandu to reflect on his work on vulture safe zones and why it’s time to work on saving vultures other than the griffons, whose decline hasn’t been as well-documented. The following interview has been translated from Nepali and edited for clarity.
Mongabay: Let’s start the conversation with the idea of the vulture safe zone. What did it entail?
Krishna Bhusal: The vulture safe zone idea had multiple components. The first was to remove diclofenac from the market and discourage its use, carryout monitoring of the vultures’ populations across different parts of the country, and provide safe food to the birds by setting up “vulture restaurants” in various locations. We also wanted to introduce a captive-breeding program to shore up their populations.
Under this initiative, we organized campaigns and lobbied with the government at various levels to declare all of the 77 districts of the country as being “diclofenac-free,” one by one. This started with Dang district in western Nepal, and recently concluded in Kathmandu.
Responding to calls from conservationists, the government banned the drug for veterinary use in 2006. But as the shelf life of the drug is around two years, it took time for the drug to become completely unavailable. So campaigners organized different events to exchange diclofenac for alternative drugs such as meloxicam that had been tested to be innocuous to vultures. We also set fire to stockpiles of diclofenac so that they didn’t reenter the market.
We also stepped up monitoring, satellite collaring, population surveys along with community awareness and advocacy.
Two vulture restaurants were set up in Nawalpur and Kaskii districts, and a captive-breeding center was operational in Chitwan until 2022.
In recent years, Nepali researchers have satellite-tagged white-rumped vultures [Gyps bengalensis], slender-billed vultures [Gyps tenuirostris], red-headed vultures [Sarcogyps calvus], Himalayan griffons [Gyps himalayensis] and bearded vultures [Gypaetus barbatus], providing valuable insights into their movement, nesting, foraging and roosting behaviors, as well as the major causes of mortality.
Mongabay: During and even after the peak of the diclofenac crisis, it seems research and conservation was focused on griffon vultures, especially the white-rumped and slender-billed vultures. Why do you think this was?
Krishna Bhusal: That’s true to some extent. If you look at the research and literature available, my estimate is that around 80-90% of the work has been done on Gyps vultures. I think it’s because these vultures are found in countries in the region, such as Nepal, India, Bangladesh and Cambodia.
As a lot of conservation work in the region is driven by funding from various donor agencies, which tend to focus on issues and species that have a regional appeal. It’s also easier for them to show results. Gyps vulture populations collapsed for a long time and they caught the attention of all stakeholders, and their population is now being revived. This is the kind of impact people want to see.
Mongabay: What about the other vultures?
Krishna Bhusal: Although we haven’t been able to pay equal attention to vultures other than that griffons, they too face multiple threats. As the Gyps populations collapsed, mainly due to the diclofenac crisis, we knew relatively less about what was going on with other species found in Nepal. But even our limited knowledge suggested that the impact of diclofenac wasn’t as deadly for other species such as the bearded vulture or the Egyptian vulture [Neophron percnopterus]. However, that doesn’t mean they don’t deserve equal attention.
Bearded vultures, for example, don’t live in colonies with large populations. They’re solitary animals, where a pair occupies a nest. We don’t know to what extent their population has declined and whether it has recovered or not.
Mongabay: Is this why you chose to study Egyptian vultures for your Ph.D. project?
Krishna Bhusal: After I left BCN, I analyzed the gaps in vulture research in Nepal and found that a study focusing on Egyptian vultures would be the best way forward for me as an individual researcher.
Despite being a globally endangered species, targeted monitoring and conservation of Egyptian vultures in Nepal, and in South Asia in general, remains scarce.
While satellite tracking of European populations of Egyptian vultures (probably a different subspecies) has revealed their migratory routes to Africa and the Middle East, we don’t know whether the Asian populations also have such long migratory routes or not.
In Spain [the University of Oviedo], where I am working on my Ph.D., the researchers are quite ahead of us. There, the focus has been on Egyptian vultures all along. They have already studied their breeding and even genetics. We don’t know for sure whether the Egyptian vultures in South Asia may turn out to be a different species from those found in Europe. Although ascertaining that goes beyond the scope of my study, the satellite tagging that we do will obviously provide fresh insights into their movements.
Mongabay: Despite the ban on diclofenac, other threats to vultures remain in Nepal. What are some of the major ones?
Krishna Bhusal: Poisoning remains one of the most challenging issues, especially in areas with conflict between people and large carnivores. In the high mountains, snow leopards [Panthera uncia] prey on livestock, and in the plains it’s the tigers [Panthera tigris]. People poison dead livestock to kill these animals, and when they die, vultures feed on the bodies and they too are killed.
Similarly, electrocution by power transmission lines is also a big challenge.
In addition to this, there are other non-steroidal anti-inflammatory drugs (NSAIDS) available in the market [for livestock] that can impact the health of vultures, although not as lethal as diclofenac. Diclofenac spreads quickly in the body of the animal that’s administered the drug, but other NSAIDs don’t spread as quickly. Their effect has been found to be more localized.
Mongabay: As part of the vulture safe zone idea, vulture restaurants provide safe food to the birds. But we’ve seen that the density of vultures around such restaurants is quite high. Perhaps they also attract vultures from neighboring India. Is that a challenge?
Krishna Bhusal: Yes, that’s true. However, we are yet to study how this impacts the natural movement of the birds and whether higher densities in one area could be problematic. Also we need to assess whether these restaurants are altering the natural behaviors of these vultures.
Mongabay: A recent study reviewing data from India suggests that the diclofenac crisis could have led to the proliferation of deadly bacteria that may have killed around a million people. As a vulture researcher, do you think Nepal could have faced a similar situation?
Krishna Bhusal: Studies related to the diclofenac crisis first emerged from other countries in South Asia, such as India and Pakistan. Later, in Nepal also it was realized that the situation could have been similar as we have similar landscapes, cultures and bird species roaming our skies.
As Nepal is a small country compared to its neighbors, we often don’t have the means and resources to carry out large-scale studies. Our counterparts in India often tell us that we try to extrapolate a lot of the findings from their work. But the flip side of that is that because Nepal is comparatively small, intervention efforts bear quick results.
For example, India still grapples with diclofenac, but Nepal has been relatively more successful in implementing its ban. Maybe that’s why the recovery of the population of Gyps vultures has been observed to be better in Nepal. Similarly, our vulture restaurants have also been able to provide safe food to the birds in relatively small areas compared to the vast swaths of land in India.
Therefore, we could say that the diclofenac crisis could have had some negative impacts on human health in Nepal as well. But it needs further research.
Banner image: A white-rumped vulture (Gyps bengalensis) flying over a city. Image by Wade Tregaskis via Flickr (CC BY-NC 2.0).
Abhaya Raj Joshi is a staff writer for Nepal at Mongabay. Find him on Twitter @arj272.
Nests of hope: Nepal’s vulture colonies hold on amid new threats
Credits
