India Vulture Die-Off Spurs Carcass Crisis

Bijal P. Trivedi
National Geographic Today
December 28, 2001

For millennia the Parsis of India have relied on vultures to dispose of their dead. Their religion forbids burial and cremation and bodies are left exposed to be consumed by the sky. But the sudden decline in vulture populations throughout southern and eastern Asia, and India in particular, are forcing this community to reconsider their ancient tradition.

In the past decade more than 90 percent of two species of vulture, the white-backed and long-billed, once among India's most populous birds, have been wiped out. If the trend continues they could be extinct within the next five years.

The mysterious decrease in vulture populations began in the early 1990s, said Vihbu Prakash of the Bombay Natural History Society, who has been studying vultures for almost 20 years and was the first to notice their decline.

Since 1984 Prakash has monitored vulture sites at the Keoladeo National Park in Bharatpur—about 200 miles (300 kilometers) south of Delhi. In 1984 he noted 353 pairs of nesting vultures. By 1996 the number had fallen to 150. In 1997 only 25 nesting pairs remained and in 1999 all the birds were gone.

The cause is still unknown.

"The decline that has occurred is unprecedented and absolutely shocking," said wildlife pathologist Andrew Cunningham of the Zoological Society of London, in the United Kingdom, who is collaborating with Prakash to find out what is killing the vultures.

To date Cunningham has examined over 30 dead birds from India. He's found a buildup of uric acid crystals [the white part of bird droppings] in the kidneys, livers and hearts, a condition called visceral gout which Cunningham said could be caused by dehydration.

But so far it is what he doesn't see that he finds noteworthy. "What is remarkable is that we don't see much at all when we necropsy these birds."

"To say it is visceral gout is like saying someone died of a broken leg or a headache—it is non-specific," said Cunningham. "What we are trying to find out is what caused the dehydration that led to gout."

Vultures Don't Look Sick

The disease is particularly mysterious because other than gout the birds look fine. The organs look healthy, there is plenty of fat and the birds are well muscled. "These do not look like sick birds," said Cunningham.

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