Vanishing vultures

Published : Feb 10, 2012 00:00 IST

The Himalayan vulture, a critically endangered bird, at Kedarnath in Uttarakhand in this September 2011 photograph. Also known as Himalayan griffon, it feeds on carcasses.-K.R. DEEPAK

The Himalayan vulture, a critically endangered bird, at Kedarnath in Uttarakhand in this September 2011 photograph. Also known as Himalayan griffon, it feeds on carcasses.-K.R. DEEPAK

Vultures continue to fall prey to diclofenac, banned as a veterinary drug, and remain on the IUCN's Red List.

UNTIL the mid-1990s, it was believed that there were about 40 million vultures in India. But towards the end of that decade, wildlife researchers noticed with alarm that vulture populations across the country were declining at a rate that many later described as steeper than the spiral down of the dodo. No other bird species had been known to lose population with such devastating speed as did the slender-billed Gyps tenuirostris, the Oriental white-rumped Gyps bengalensis and the long-billed Gyps indicus the three species of Gyps on the subcontinent that came close to extinction. Decimated, they now stand at around 60,000. Not for nothing was the phenomenon termed the Asian vulture population crash.

Post-mortems by the United States-based Peregrine Foundation, working in Pakistan, pinpointed the cause a non-steroidal anti-inflammatory drug (NSAID) called diclofenac, which was popular with veterinarians. Diclofenac, a fast-acting drug, was in wide use on cattle and other large animals. When vultures ate carcasses of animals that had been treated with diclofenac, the effects were catastrophic. A rapid accumulation of uric acid in the tissues and on the surfaces of internal organs caused visceral gout and, soon after, death from renal failure. Birds died within 72 hours of their diclofenac-spiked meal. It was not uncommon at one stage in the field to see birds develop the classic droop neck, a sure sign that death by diclofenac was near. (Unlike other vultures that eat other fleshy bits, these three Gyps species prefer the organs and muscles, which are the areas where drugs accumulate. This is why only these species have been affected by diclofenac.)

With solid proof against diclofenac, a campaign was launched to stop the veterinary use of the drug. In May 2006, the campaigners were rewarded with a notification from the Ministry of Health banning the drug for this use. Bans by Nepal and Pakistan strengthened the embargo. This gave the Gyps a new lease of life. In 2008 additional restrictions were placed on the manufacture, sale and distribution of veterinary formulations of diclofenac.

But the elation petered out when it was discovered that diclofenac continued to find its way into the vultures' food chain. Doubts about the success of the ban had been expressed almost immediately after it was announced. The substitute drug, meloxicam, was more expensive and some vets believed that it was not as effective as diclofenac. Besides, the ban did not apply to the human formulation of diclofenac.

Last year, Frontline (May 21, 2010) carried an article on the continuing threat to Indian vultures from diclofenac. At the time, Dr Vibhu Prakash, who is principal scientist at the Bombay Natural History Society (BNHS) and heads its vulture-breeding programme, said that though it had been made mandatory in 2008 for the human formulation to be specifically marked Not for Veterinary Use, vets continued to use it for a variety of reasons. One reason was that smaller pharmaceutical companies ignored this rule, a problem that persists to this day. At the time Vibhu Prakash accepted that practical problems would prevent an immediate end to the use of veterinary diclofenac, but even otherwise he was uneasy about the execution of the ban.

His misgivings were not misplaced. The vulture population, which should have stabilised after the ban on the drug, did not do so. In fact, in 2007 the annual rate of mortality continued to be about 40 per cent, indicating the continued presence of diclofenac in the field. A survey was undertaken from November 2007 to June 2010 to evaluate the effectiveness of the ban. The results, which were made public in September this year, showed that though the manufacture and availability of meloxicam is encouraging the continued availability of diclofenac is a major source of concern.

The study, Assessing the ongoing threat from veterinary non-steroidal anti-inflammatory drugs to Critically Endangered Gyps vultures in India, was published in the science journal Oryx. It was carried out by Richard J. Cuthbert, Ruchi Dave, Soumya Sunder Chakraborty, Sashi Kumar, Satya Prakash, Sachin P. Ranade and Vibhu Prakash. Over a period of 19 months, the team surveyed more than 250 veterinary and general pharmacies in 11 States in the country. The report states: Meloxicam was the most commonly encountered drug, sold in 70 per cent of pharmacies. Diclofenac and ketoprofen [both toxic to vultures] were recorded in 36 and 29 per cent of pharmacies, respectively, with States in western and central India having the highest prevalence of diclofenac (44-45 per cent).

There are other NSAIDs that are also in use but whose effects on the Gyps are as yet unknown. The research team also included these in the study, purchasing 12 different classes of NSAIDs. The study says, Other than meloxicam (of negligible toxicity to vultures at likely concentrations in their food), diclofenac and ketoprofen (both toxic to vultures), little is known of the safety or toxicity of the remaining nine NSAIDs on sale. Meloxicam was the most commonly encountered drug, sold in 70 per cent of pharmacies, but 50 per cent of the meloxicam brands sold had paracetamol (acetaminophen) as a second ingredient.

Some hope stems from another study, published in the science journal PLoS ONE. This found that the proportion of cattle carcasses in India contaminated with diclofenac had declined by over 40 per cent after the bans in 2006 and 2008. Thus, the mortality rate has reduced to about 18 per cent a year, down from about 40 per cent before the ban. Another survey to monitor vulture populations has just been completed in about 20 National Parks and Protected Areas. The data are still being analysed and will not be available for a month or so. Though Vibhu Prakash believes there will be a further, though slight, decrease in the mortality rate he puts it in frighteningly clear perspective when he says, The total population of these three species of Gyps is down by 99 per cent. It's only the rate of mortality of the remaining 1 per cent of the Gyps that has come down.

To counter the threat to Gyps vultures from human formulations of diclofenac being used for veterinary purposes, the study recommends reducing the size of vials of diclofenac meant for human use, to increase the costs of illegal veterinary use, and taking action against pharmaceutical manufacturers and pharmacies flouting the diclofenac ban. The recommendations were discussed at a recent inter-ministerial meeting initiated by the Ministry of Environment and Forests where it was sort of agreed by the Ministry of Health, the Ministry of Agriculture, which is in charge of animal husbandry, and the Drugs Controller General that there was a need to reduce the vial size of human formulation diclofenac. It is expected that the existing dosage sizes of 10 ml and 30 ml (which are considered large veterinary-sized vials) will be made available in quantities of 3 ml and 4 ml. A formal notification is hoped to be issued. This, says the study, is the path to provide a safer environment for vultures in South Asia.

From being as common as the crow, all three resident species of Indian Gyps vultures were listed as Critically Endangered on the International Union for the Conservation of Nature's (IUCN) Red List of Threatened Species, a status given to species that are marked for extinction unless drastic measures are taken to save them. It was hoped that the ban would mean that the birds would eventually be taken off this list. But five years after the Indian government officially ordered measures for their survival, the three Gyps species once India's commonest birds of prey continue to be on the IUCN's Critically Endangered list.

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