The spectre of extinction: Indian vulture population crashes

The cause of the 99 per cent drop in the Indian vulture population has been identified. But can this essential element of the ecosystem ever recover? Michael McCarthy reports

They're up there with poodles, rats, hyenas and snakes in the grass - singled out to represent some of the lousier sides of human nature. But what have vultures ever done to deserve such a bad name?

They're up there with poodles, rats, hyenas and snakes in the grass - singled out to represent some of the lousier sides of human nature. But what have vultures ever done to deserve such a bad name?

These big, long-winged birds - wonderful flyers, able to soar majestically for hour after hour - seem to be fixed as the universal metaphor for those who would take advantage of misfortune, especially those just waiting for the right moment.

Type "vultures" into an internet search engine and what do you get? Believe it or not, overwhelmingly, you get the sports pages. The Premiership vultures are circling relegation-threatened Melchester Rovers and beleaguered player-manager Roy Race, you read, and they may be about to swoop - or even pounce.

Boy, do they sound heartless. Boy, they sound ruthless. But in truth, vultures wheeling high in the air on the lookout for a meal are only following instinct and as a remarkable set of circumstances in India has recently made clear, they are among the most necessary of all birds to some human societies.

Granted, physical attraction is not their strong point. The long, bare, wrinkled neck of most species of vulture does not help. (It has evolved so they can thrust their heads deep into a carcass and come out without blood all over their feathers, although that may be a little more detail than you actually required.) And the fact that they are exclusively carrion eaters, consuming only dead prey, does not particularly endear them to us.

But think of it this way: it's a tough job, but someone's got to do it. And once vultures aren't around to do it, you have a problem.

Yesterday, Indian ornithologists announced they would be carrying out a census of vultures across the subcontinent. They will be assessing the damage done by the astonishing collapse of India's vulture populations over the past 10 years, in which it is estimated that tens of millions - that's right, tens of millions - of the birds have died.

The numbers of the three main species, the white-backed, the long-billed and the slender-billed vultures, are thought to have dropped by more than 99 per cent across India. The white-backed, in particular, was thought to be the commonest large bird of prey in the world, as common in India as sparrows; now it has been reduced to a tiny fraction of its former numbers, in what has been a social as well as an environmental calamity.

For such are the structures of Indian society that vultures play several essential roles. Perhaps the most important is as scavengers of cow carcasses. As cows are sacred to Hindus, they are not slaughtered, but allowed to die naturally; in cities, their carcasses are taken to carcass dumps; in the countryside, they are left where they fall.

Since time immemorial vultures have ensured that these carcasses, thousands upon thousands of them every year, are not a risk to public health: they can reduce a dead cow to a pile of clean-picked bones in an hour.

Another important role for the birds has been in the customs of the Parsees, or Zoroastrians, who are not allowed burial or cremation by their religion, and leave their dead on so-called "towers of silence" so they can be eaten by vultures in a "sky burial".

Both of these customs have been gravely compromised by the vultures' disappearance. There are serious concerns about public health from rotting cow carcasses, and one dangerous consequence already has been an explosion in the population of feral dogs, which are feasting on the unwanted carrion. There are fears of a sharp rise in rabies, because feral dogs are the main rabies carriers: more people die from rabies every year in India than anywhere else.

The great Indian vulture crash was a complete mystery at first; enormous though it was, there was no discernible cause - just as there is still no discernible cause for the disappearance of the house sparrow from the streets of London. It was thought that a mysterious virus was probably responsible.

Last year, however, the mystery was dramatically solved: the culprit was found to be not a virus at all, but a veterinary product, a painkilling drug given to cattle, diclofenac. Scientists found that the drug, which was harmless to humans and to cattle themselves, was highly toxic to vultures of the genus Gyps. (The white-backed vulture is Gyps bengalensis, the long-billed vulture Gyps indicus, and the slender-billed vulture, Gyps tenuirostris.)

A non-steroidal, anti-inflammatory drug, diclofenac has been widely used by humans for decades, but India and Pakistan only started using it for veterinary purposes in about 1990, when the effects on the birds began to be noticed. Post-mortems on dead vultures showed beyond doubt that the diclofenac they had ingested from the cattle flesh they had eaten caused fatal kidney damage. Tests on young captive birds revealed that the concentrations of diclofenac found in treated cattle were enough to kill them.

The widespread nature of its use accounted for the vast extent of the vulture mortality. Two months ago, the Indian government responded by announcing that diclofenac would be phased out for veterinary purposes over the next six months. But can the subcontinent's vulture populations ever recover?

"Their collapse has been truly catastrophic, probably the biggest collapse ever of a group of bird species," said Debbie Pain, head of international research at the Royal Society for the Protection of Birds. "But there is a good possibility that we'll be able to get vultures back throughout a lot of their former range, although I think the populations will be much smaller."

The RSPB is a member of a partnership of British conservation organisations, including the Zoological Society of London and the National Birds of Prey Centre, which is helping Indian conservationists cope with the vulture issue. Two years ago, before it was known that diclofenac was the problem, they set up a research centre to analyse the declines in Haryana, north of Delhi, with funding from the Darwin Initiative, the international wildlife grants programme of the Department for Environment, Food and Rural Affairs.

Now the centre is being devoted to captive breeding of the three affected species: it is hoped that eventually there will be 25 pairs of each, and birds will be restored to the wild to help the decimated populations grow back. But it will be a long process: the reproductive cycle of vultures, like that of numerous big, long-lived birds, is very slow. The vultures do not start breeding until they are four or five years old, and even then they only have a single chick.

There are two distinct groups of the birds, Old World and New World vultures. The 15 Old World species, which stretch right across Eurasia, include four which occur in western Europe: the Egyptian, griffon, black and bearded vultures, none of them is common.

Spain is the best place to see the first three: vultures are among the big attractions of the Iberian peninsula for Britain's birdwatchers, and in the remote and rugged country along the Spanish-Portuguese border the birds are seen at their best, soaring endlessly on thermals on their outstretched wings.

The bearded vulture, or lammergeier, is something else again: it is one of Europe's rarest birds, with a mere 250 pairs spread across Spain, southern France, Greece and Turkey. It is being reintroduced to the Alps as an icon of conservation and is to some extent to Switzerland what the osprey is to Scotland.

The Old World vultures are related, as they appear to be, to eagles, hawks and falcons. But the seven species of New World vultures - the "buzzards" traditionally seen in Westerns circling scenes of cowboy massacres - are a very different group, scientists have recently discovered.

Although they look virtually identical to their Old World counterparts - bare neck, preference for carrion, long wings and all the rest of it - analysis of their DNA has shown that they are not related at all. Instead, they are related to storks and cranes, and their similarity in appearance is merely a stunning example of co-evolution. Two completely different groups of birds have evolved in exactly the same way to fill exactly the same ecological niche.

Many ornithologists find vultures fascinating. Many birdwatchers find them exciting. And maybe the rest of us should remember, if we automatically think of them as metaphors for taking advantage of distress, that there's nothing in their actual behaviour to justify the stereotype. The vultures might be circling. They might even be circling Melchester Rovers and beleaguered player-manager Roy Race. But the birds themselves, well, they're just doing what comes naturally.