By Matthew Grant in Calcutta
Only breeding vultures in captivity can prevent the bird of prey from extinction in South Asia, conservationists are warning.
It would take 10 years to reintroduce bred vultures to the wild, experts say
Time is running out, they say.
Unless they act now it will become impossible to find enough vultures to establish stocks for captive breeding.
The alert comes in a paper published in the Journal of Applied Ecology, written by groups including the British Royal Society for the Protection of Birds and the Bombay Natural History Society.
They are seeking funds for six captive breeding centres in India, Pakistan and Nepal.
A vulture care centre was opened in the Indian state of Haryana in February 2003. It can house up to 35 vultures and plans to start breeding vultures soon.
Drug ban delay
Scientists have proven the cause of the rapid decline in three species of vultures to be a drug given to cattle.
Parsis - vultures play an important role in their death rites
When vultures eat the cows' carcasses they consume traces of the pain killer, known as diclofenac. Even minute doses are deadly to the birds.
The Indian government is considering banning diclofenac, but the fear is it will soon be too late.
The animal husbandry department last month insisted research into affordable alternatives needed to be carried out before a ban could come into place.
"We're putting as much pressure as we can to get a quick reaction to prevent to the birds going extinct," said Chris Bowden, the RSPB's vulture programmes manager.
"But it's so urgent even if we could get the drug banned straight away they would very likely still go extinct, so hence we're instigating the breeding programme."
He estimated vulture numbers have fallen dramatically - from 30m to 40m a decade ago, to about one percent of that number today.
If the vulture breeding programme is a success, the birds would be reintroduced to the wild - but not for at least 10 years, he said.
The near extinction of vultures has a far wider impact than just among conservationists.
The birds used to play a vital social role by scavenging the carcasses of dead animals in the countryside and cities.
"In earlier times vultures used to come down to these dead bodies and they used to finish them off in 15 or 20 minutes and the bones were totally clean," explained Kushal Mookherjee, secretary of Prakriti Samsad, the West Bengal Nature Society.
"But now this function is not being done by these vultures."
Feral dogs have now taken the vultures' place - causing a rise in diseases including rabies.
India's Zoroastrian community - known as Parsis - also use vultures to dispose of their dead.
Parsis in Bombay have already looked into the possibility of breeding vultures themselves, although the high cost has so far prevented them.
For some Parsis the idea of captive breeding goes against the philosophy of their burial ceremony.
"A lot of people feel that the whole purpose of breeding vultures is against the entire ethic of the whole process being in tune with nature and being environmentally safe," said Aban Confectioner, one of Calcutta's Parsis.
"If you're actually going to capture and breed them then you're doing away with the practice that it is something natural."
But as the stark warning shows, without captive breeding the vulture may soon be no more in South Asia's skies.