DELHI // Vultures are on the verge of extinction in India because a banned drug is still being used illegally to treat suffering cattle.

The endangered birds eat the remains of the drugged animals and suffer kidney failure and visceral gout, which is usually fatal.

The drug was banned five years ago, but pharmacies continue to sell it under the counter, a study has revealed.

More than 97 per cent of vultures have disappeared from India's skies in the past 15 years - the fastest decline ever recorded in a bird population anywhere in the world.

Only about 10,000 still exist in the wild, down from tens of millions in the 1980s.

The white-rumped vulture - once the most populous large bird of prey - is under particular threat, having declined by 99.9 per cent.

The cause of their demise is a drug called diclofenac, an anti-inflammatory used by farmers and veterinarians to ease pain in cattle. It is particularly popular in India since for religious reasons, older, dying cattle are often not killed in India. The drug was banned by the governments of India, Pakistan and Nepal in 2006 - but a survey for the journal Oryx found that more than a third of the 250 Indian pharmacies investigated were still selling diclofenac in some form.

Richard Cuthbert, the lead author and principal conservation scientist at the UK's Royal Society for the Protection of Birds (RSPB), said: "The ban is still quite easy to avoid because human formulations are for sale in large vials, which are clearly not intended for human use.

"Preventing misuse of human diclofenac remains the main challenge in halting the decline of threatened vultures."

Vultures' culinary tastes have given them a sinister reputation but they perform a crucial role.

"When an animal dies, it becomes a breeding ground for all sorts of pathogens," said Vibhu Prakash, of the Bombay Natural History Society (BNHS), a co-author of the study.

"The vultures used to feed off the animals before bacterial and fungus could develop, preventing the spread of rabies, anthrax and many other diseases.

"The feral dog population is multiplying because they have so much more food and that is a major problem for India, which has the highest rate of human rabies in the world."

Even if the government ban is fully implemented, it will take many years for the vulture population to recover. Vultures breed slowly and take five years to reach adulthood.

"We are still seeing several cases each month of dead birds coming to us with traces of the drug in their system," said Mr Prakash. "I don't think there's been any improvement since the ban came in."

A non-toxic substitute to diclofenac is meloxicam, although it has less of an immediate effect.

But there have been positive reports, with one study finding a reduction of 40 per cent in the number of cattle contaminated with diclofenac. A conservation scheme - run by the RSPB and the Saving Asia's Vultures from Extinction group - has been breeding vultures in captivity and now has 271 in three breeding centres in India.

Last year, for the first time ever, three white-rumped vultures were successfully bred and fledged.

"We're more confident than ever that there will be sufficient numbers for reintroduction to the wild as soon as it's safe for them," said Chris Bowden, the RSPB's head of vulture programme.

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