In September 2000, BNHS organized an international conference, funded by the MoEF and the RSPB. It turned out to be a turning point in the vulture saga, as we all agreed that we had to find out what was killing the vultures, and reverse the decline. The three-day Conference was attended by experts from over 10 countries, including officials from the MoEF, and scientists from the Indian Veterinary Research Institute (IVRI), WII, WWF-India, SACON, USFWS, BNHS, the RSPB, The Peregrine Fund, BLI, Cambridge University, AMU and many others.
All through 2001–03, we kept gathering more and more evidence that vulture populations were declining all over India, Nepal and Pakistan. The prevailing view at that time was that they were dying due to some infectious disease, most likely a virus, which was spreading from east to west, which is why Pakistani scientists reported the decline from 2000 onwards. The fear was that if the virus spread through the Middle East and from there to Africa, it would also devastate the African vulture populations, the way it was doing in Asia. In this context, in 2000, The Peregrine Fund initiated an Asian Vulture Crisis Project with the Ornithological Society of Pakistan (OSP), and in Nepal with the help of Bird Conservation Nepal (BCN).
Dr Munir Virani, a Kenyan of Indian origin, who worked with The Peregrine Fund, and Martin Gilbert from Cornell University, US, were the team leaders for the fieldwork, and J. Lindsay Oak from the Department of Veterinary Microbiology and Pathology, Washington State University, did the diagnostic investigations. While we were still awaiting permission from the GoI to send the samples to the Australian lab, scientists at The Peregrine Fund took some samples from Pakistan to the US and found no virus or any other pathogen that could have caused vulture mortalities. If virus was not killing them, then what was the culprit? The Peregrine Fund and OSP conducted a survey in over 37 villages in Pakistan. The aim was to find out what was getting into the livestock carcasses. Basically, they were looking for something that was relatively new in the market, something that causes visceral gout in birds, something that was effective and yet inexpensive – and diclofenac sodium perfectly fit that profile. It was a new painkiller recently introduced for veterinary use on livestock in Pakistan (like earlier in India). A quick Internet search by the scientists working on the case indicated that diclofenac is lethal to some species. In May 2003, at the World Conference on Birds of Prey held in Budapest, scientists of The Peregrine Fund presented a paper where they clearly demonstrated that the painkiller diclofenac sodium was causing visceral gout in vultures that consumed livestock carcasses contaminated with the drug.
Shortly after, Bob Riseborough, an American expert, sent me (and others) an email stating the information presented in the paper. As soon as I read it, I literally jumped from the chair and phoned Vibhu, telling him that we probably now knew the culprit behind the mass deaths of vultures. However, it was premature to announce this without more comprehensive data, as it would not satisfy the scientific community, including sceptics, particularly those who had been advocating the virus theory. There were also genuine questions on how diclofenac was reaching vultures to such an extent that it had killed over 90 per cent of the country’s vultures in about a decade. The scientists of The Peregrine Fund, Washington State University and OSP did some more experiments, re-analysed the data and published a paper in the prestigious Nature journal in January 2004. I would say that this paper was the second turning point in our struggle to save vultures. The beauty of this paper was that it was very simple, with basic statistics (which even I could understand) and clear results. The paper was written by 13 authors, who belonged to six different institutions, with J. Lindsay Oaks as the lead author, and showed 100 per cent correlation between the presence of diclofenac and kidney failure in vultures. After the paper came out, Vibhu and his team also analysed vulture carcasses, which we had meticulously kept in deep freezers. We too found a direct correlation between visceral gout and the presence of diclofenac in vulture bodies. The evidence was all over the place – in research papers, in labs, in widespread dead birds and in diclofenac ampoules in vet shops. Someone had to just knit them together.
This is exactly what Dr Rhys Green, a brilliant field biologist from the Cambridge University, did. In February 2004, while visiting BNHS after attending a workshop at Parwanoo in Himachal Pradesh regarding the Vulture Recovery Action Plan, Rhys asked some fundamental questions: What is the livestock population in India? How many livestock deaths take place every year? What is the lifespan of a vulture (Gyps species)? How much food do they eat and how often? How long does diclofenac remain in a live animal, and what happens when an animal that was injected with diclofenac sodium dies? We helped him piece together some of these answers. After knitting all this information together, using some intricate statistical analysis, Rhys came up with a paper in the Journal of Applied Ecology,35 which showed through simulation models that even if less than 1 per cent of the livestock carcasses available to vultures had diclofenac residues (which are lethal to vultures), they would die in the same way they indeed had been dying. Later, through carcass-sampling studies, we found that nearly 10 per cent of cattle carcasses in India had diclofenac residue. No wonder the vultures had disappeared so quickly, leaving our skies empty.
An excerpt from ‘Living with Birds’, the memoirs of Dr Asad Rahmani, published by the Indian Pitta Imprint of Juggernaut Books