A dramatic decline in South Asian vulture populations, particularly in the Zipper's vulture genus, was blamed on the veterinary drug diclofenac, which caused fatal kidney failure in vultures that fed on processed carcasses. In response to the crisis, Nepal has established vulture-safe zones, banned diclofenac, monitored vulture populations, set up “vulture restaurants” that serve uncontaminated carcasses, and implemented captive breeding programs to help vultures recover. According to researcher Krishna Bhusal, conservation efforts have focused primarily on Zipper's vulture, also known as the white-spotted griffon vulture, because of its regional importance and the worldwide attention it has received for its dramatic decline in population. Other vulture species, such as the bearded vulture and Egyptian vulture, also face major threats but have received less attention, highlighting gaps in research and conservation efforts.
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KATHMANDU — The story of South Asia's vultures is one of tragedy unfolding at warp speed, particularly for the griffon vulture, a species of bird of prey with a narrow head and elongated neck that belongs to the Gyps genus. Populations of this bird of prey are thought to have declined by 99% between the 1990s and early 2000s.
The cause of this sudden decline was a mystery until 2004. That year, US veterinarian J. Lindsay Oakes and his team reported a high correlation between kidney failure, a cause of vulture deaths, and residues of diclofenac, an anti-inflammatory drug given to livestock. The vultures were essentially being poisoned by eating carrion that had been given the drug.
This discovery sent shock waves across the Indian subcontinent and governments began testing this hypothesis on their own vulture populations.After finding strong evidence that this was the case, countries in the region and beyond began taking aggressive steps to save the raptors.
Autopsies showed that when animals treated with diclofenac died, traces of the drug remained in the carcasses for up to a week. Vultures that ate the carcasses experienced a spike in uric acid levels in their blood and developed visceral gout. Their kidneys were no longer able to filter the uric acid, which ultimately led to their death. Researchers found that one contaminated cow carcass could kill around 350-800 vultures.
Krishna Prasad Bhusal has been at the forefront of vulture conservation and research in Nepal since the diclofenac link was discovered. Nepal is home to nine species of vultures, six resident and three migratory. After earning his Masters in Zoology from Tribhuvan University in 2010, Bhusal began his career as a field biologist with Bird Conservation Nepal, the local arm of the NGO BirdLife International, which advocates the concept of “vulture safe zones” where there is no risk of exposure to diclofenac-contaminated carrion.
He was then promoted to conservation officer, where he worked until 2021 when he decided to begin his own independent research.
Krishna Bhusal and his book “Vultures – Nature's Scavengers.” Image courtesy of Krishna Bhusal.
Mongabay's Abhayya Raj Joshi recently met with Bhusal in Kathmandu to talk about his work with vulture safe zones and why it's time to focus on protecting vultures other than the griffon vulture, whose decline has been less documented. The following interview has been translated from Nepali and edited for clarity.
Mongabay: Let’s start with the idea of a vulture safe zone. What did that mean?
Krishna Bhusal: The idea of a Vulture Safe Zone had several components: firstly, to remove Diclofenac from the market and discourage its use, monitor the vulture population in different parts of the country, set up “vulture restaurants” in different locations to provide safe food for the vultures, and we also wanted to introduce a captive breeding programme to increase the vulture population.
Under this initiative, we have been organising campaigns and lobbying governments at various levels to declare 77 districts across Nepal as “Diclofenac Free” one by one, starting from Dang district in western Nepal and recently completed in Kathmandu.
Responding to calls from conservationists, the government banned the drug for veterinary use in 2006. But because the drug has a shelf life of about two years, it took time for it to become completely unavailable. So activists organized various events to replace diclofenac with alternatives such as meloxicam, which has been tested to be harmless to vultures. They also set fire to stocks of diclofenac to prevent it from returning to the market.
We have also increased surveillance, satellite collaring, population surveys, and community awareness and advocacy.
Two vulture restaurants were opened in Nawalpur and Kaski districts, while a captive breeding centre was to operate in Chitwan district until 2022.
In recent years, researchers in Nepal have satellite-tagged the Bald Vulture (Gyps bengalensis), Bald Vulture (Tenuirostris), Scarlet Vulture (Calbus), Himalayan Griffon Vulture (Gyps himalayanus) and Bearded Vulture (Gyps barbatus), providing valuable insights into their migration, nesting, feeding, roosting behaviour and major causes of mortality.
Krishna Bhusal monitors a vulture nest on the Gelabir cliffs in Arghakhanchi, Nepal. Image by Krishna Bhusal.
Mongabay: During and after the diclofenac crisis, there seemed to be a lot of research and conservation focus on griffon vultures, particularly the bald and narrow-beaked vultures. Why do you think this was?
Krishna Bhusal: That is true to an extent. If you look at the available studies and literature, my guess is that about 80-90% of the studies have been done on zipper vultures, and that is because they are found in countries in this region such as Nepal, India, Bangladesh and Cambodia.
A lot of the conservation work in the region is funded by various donor agencies, who tend to focus on issues and species that are of local concern, so it's easier to show results. Vulture populations were in decline for a long time, but they caught the attention of all stakeholders and are now rebounding, which is the impact people want to see.
Mongabay: What about other vultures?
Krishna Bhusal: We have not been able to give equal attention to other vultures, which also face various threats. There has been comparatively little knowledge about what is happening to other species in Nepal, mainly due to the diclofenac crisis, which caused a sharp decline in their populations. However, even our limited knowledge suggests that the impact of diclofenac is not as deadly for other species, such as the bearded vulture and the Egyptian vulture (Neophron percnopterus). However, this does not mean that the griffon vulture does not deserve equal attention.
For example, bearded vultures do not live in large flocks – they are solitary animals, with nests occupied by mated pairs – and it is not known to what extent their populations have declined or whether they have recovered.
Krishna Bhusar holds an Egyptian vulture for a satellite tag at the Central Asia Vulture Project in Uzbekistan. Image courtesy of Krishna Bhusar.
Mongabay: Is this why you decided to study Egyptian vultures for your doctoral project?
Krishna Bhusal: After leaving BCN, I analysed the gaps in vulture research in Nepal and found that focusing on Egyptian vultures was the best path forward for me as an individual researcher.
Despite the Egyptian vulture being a globally threatened species, there is little targeted monitoring or conservation effort in Nepal or South Asia in general.
Satellite tracking of European populations of the Egyptian vulture (possibly a separate subspecies) has revealed migration routes to Africa and the Middle East, but it is unclear whether Asian populations follow similar long-distance routes.
The researchers in Spain (University of Oviedo), where I am doing my PhD, are way ahead of us. The focus there has always been on Egyptian vultures. They have already studied their reproduction and even their genetics. We don't know for sure if the Egyptian vultures in South Asia are a different species from the European ones. It is beyond the scope of my research to confirm that, but the satellite tagging we do will definitely provide new insights into their movements.
Mongabay: Despite the diclofenac ban, other threats to vultures remain in Nepal. What are the main ones?
Krishna Bhusal: Poisoning remains one of the most challenging problems, especially in areas where there is conflict between humans and large carnivores. In the high mountains, snow leopards (Panthera uncia) prey on livestock, and in the plains, tigers (Panthera tigris) prey on them. People try to kill these animals by poisoning the dead livestock, and when the animals die, vultures eat the carcasses, which kills the vultures too.
Similarly, electric shock from power lines is a major issue.
In addition to this, there are other non-steroidal anti-inflammatory drugs (NSAIDs) on the market (for livestock use) that, although not as deadly as diclofenac, can still affect the health of vultures. Diclofenac spreads quickly in the body of the animal it is administered to, whereas other NSAIDs do not spread as quickly and their effects are known to be more localized.
Mongabay: As part of the Vulture Safe Zone initiative, vulture restaurants provide safe food for vultures. However, we have found that there are significant vulture populations around such restaurants, possibly even from neighbouring India. Is this a problem?
Krishna Bhusal: Yes, that is correct, but we still need to study how this affects the natural movement of the birds and whether congregating them in one place will be a problem. We also need to assess whether these restaurants are altering the natural behaviour of the vultures.
Himalayan griffon (Gyps himalayensis) in Gilgit-Baltistan, Pakistan. Image by Imran Shah/Birds of Gilgit-Baltistan, via Flickr (CC BY-SA 2.0).
Mongabay: A recent study examining data from India suggests that the diclofenac crisis may have led to the proliferation of a deadly bacteria that could have caused around 1 million deaths. As a Vulture researcher, do you think Nepal could have faced a similar situation?
Krishna Bhusal: Studies on the diclofenac crisis first emerged in other South Asian countries such as India and Pakistan. Later, it was realised that the situation could have been similar in Nepal too, given the similarity of topography, culture and the bird species circulating in the skies.
As Nepal is a small country compared to its neighbours, it often does not have the means or resources to carry out large-scale studies. Our Indian counterparts often say that we try to extrapolate a lot of findings from their studies. But the flip side is that as Nepal is a relatively small country, intervention efforts have immediate results.
For example, India is still struggling with Diclofenac, while Nepal has been relatively successful in enforcing its ban, which is probably why vulture population recovery has been observed to be better in Nepal. Similarly, our vulture restaurants have been able to provide safe food for vultures in a relatively small area compared to the vast land area of India.
Therefore, it is possible that the diclofenac crisis may have had some adverse effects on people’s health in Nepal. However, further research is needed.
Banner image: Bald vulture (Gyps bengalensis) flying over a city. Image by Wade Tregaskis and available via Flickr (CC BY-NC 2.0).
Abhaya Raj Joshi is Mongabay's Nepal correspondent. Find him on Twitter. Translator.
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