ECOWATCH
Spiral into extinction
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MEENA MENON examines why three species of vultures are dying in such large numbers in India.
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MA.A BADSHAH
A PICTURE of thousands of vultures huddled together near the Delhi airport — their great wings folded, necks arched in expectation. Taken 15 years ago, it's a picture worth more than a thousand words. Its fast decimating subjects are the cause of much debate and anxiety among scientists and wildlife researchers worldwide.
Vultures used to be a common enough sight in the Indian subcontinent till the mid -1990s when there was a sudden unexplained decline in their numbers. The white-backed vulture and two other species of vultures of the total nine found on the Indian subcontinent could well face extinction soon, says Dr. Robert W. Risebrough, of the Bodega Bay Institute, California. Like other conservationists, he stresses that unless action is taken within the next year to protect the birds, it could be difficult to locate the last of the three species at risk.
Already the impact of the decline in the vulture population is being felt. Researchers say there is an increase in the population of stray dogs and there are more wintering migratory vultures. The Parsis faced a crisis as the community's funerary rites involve leaving the dead for the vultures to eat in dakhmas (or receptacles for the dead), on top of the Towers of Silence in Mumbai. Now cremation is slowly becoming an option.
At a recent workshop, "A look at threatened species" to mark the release of the 100th issue of the journal of the Bombay Natural History Society (BNHS) in Mumbai, Dr. Vibhu Prakash of the BNHS, said at Keoladeo National Park (KNP) in Rajasthan, in 1985-86 there were 350 nests and 700 nesting birds in the park but by 2000-2001, there was no breeding. The mortality was highest between March and July. Dr. Prakash and his team have researched the decline of the vulture population of three species, white-backed, slender-billed, and long-billed since 1997. There was no evidence of paucity of food or habitat, and they showed symptoms of viral disease, he adds. BNHS, which has been monitoring the vulture population since the 1980s, sought support from Birdlife International and in 1999, vulture carcasses were sent for veterinary investigation first to the Hissar Veterinary School, which is part of the Wildlife Institute of India's project, Wildlife Health Cooperative.
The carcasses showed that the vultures died of visceral gout — they had deposits of uric acid on their intestines and throughout the body cavity. BNHS surveys in 17 National Parks and sanctuaries in India showed that the population of white-backed and long-billed vultures declined by 90 per cent or more. There was no evidence of chemical contamination or ecological changes. Even though tissue samples from dead vultures contained pesticides like organochlorines, it was not enough to cause such high mortality.
A three-year Vulture Declines project, beginning April 2001, set up an Indian Vulture Disease Investigation (IVDI) Centre at Pune in June 2001, apart from a Vulture Care Centre in Pinjore, in collaboration with the Environment Ministry and the Forest Department of Haryana and is the only one of its kind in India. Twenty-three sick vultures are being cared for there. The centre is a captive facility for disease investigation and is equipped with an avian pathology laboratory.
The Darwin Initiative for Survival of Species, United Kingdom, funds the Project involving the BNHS, the Royal Society for the Protection of Birds (RSPB), U.K., the Institute of Zoology, Zoological Society of London, National Birds of Prey Centre, U.K. and the Haryana forest department.
Meanwhile "convincing new evidence" from Dr. Lindsay Oaks of the Peregrine Fund, earlier this year, in Pakistan pointed to the commonly used non-steroidal anti-inflammatory drug Diclofenac — a new environmental poison — as responsible for the vulture deaths, according to Dr. Risebrough. This poison has been found lethal to the white-backed vulture, he adds. Till this new evidence, he believed the unexplained deaths of vultures could be due to disease. Birds eating the meat of cattle injected with this drug, died of visceral gout.
Diclofenac is intensively used in India. The drug was used in India since 1994 as a veterinary medicine, though not for elephants. It dominates the painkiller use and has the common side effects of similar painkillers like gastritis, peptic ulcers, and renal failure. Even if a single carcass contains lethal levels of Diclofenac, it is enough to do damage as vultures can live on that for a week.
While researchers and conservationists are unanimous on the need to protect the three species, there is no agreement on the cause of their decline.
Dr. Susanne Shultz of RSPB, project manager for the Vulture Declines Project working in India, Nepal, Central Asia and Middle East, said from 2000 to 2003, the overall decline was 99.6 per cent in white-backed vultures and 96 per cent in long-billed vultures. While in Pakistan, birds fed with carcasses of cattle injected with Diclofenac died within 36 hours, in India as yet, the evidence is not conclusive.
Diclofenac may have a role to play along with viral disease, so multiple causes cannot be ruled out, Shultz adds. An experiment with cattle is also under way in Kerala to determine if Diclofenac accumulates in the body tissue.
At Bayana, at the foothills of the Aravalli range in Rajasthan, 50 km from KNP, researchers monitoring a long-billed vulture colony since 2001, found 40 nests in 2002-03. But none of the 18 fledglings survived. There was low breeding success and high adult mortality and the sick vultures showed chronic lethargy, weakness and drooping heads. The symptoms were also consistent with viral disease, says Shultz.
Dr. Prakash, too, feels in India only five per cent of the deaths could be due to Diclofenac, adding that a viral disease was the most likely reason. The project has also been looking at infectious diseases and has identified a number of possibilities. The 23 sick birds at Pinjore were recovering. They were still sick but alive as they were in a less stressful environment, he adds.
While research is yet to conclusively prove why the vultures have all but vanished in India, the grim reality is that three species face extinction. The numbers now are less than half of what they were two years ago. Is putting these endangered vultures in zoos an answer to the problem? That would be like putting people in quarantine, remarks Dr. Risebrough. While research goes on, some immediate steps like captive breeding are needed. Moreover, vets need to look for substitutes for Diclofenac, if that is established as the cause.
However, the difficulty here is that these three species of vultures have not been bred in captivity before. Keeping such large birds in captivity is a job requiring much care. In this scenario the critical question is: can we save the three species? Or merely watch while a part of our natural history dies an unnatural death.
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