"Mysterious Plague" Spurs India Vulture Die-Off

Pallava Bagla in Pinjore, Haryana, India
for National Geographic News
February 25, 2003
Winged scavengers were once commonly seen everywhere over India. But now vultures have become so rare that birdwatchers go into raptures when they sight these carrion-disposal machines of nature.

In spite of many efforts by researchers nobody has been able to pinpoint the cause of the mysterious crash in the numbers of India's vultures.

The collapse in populations that started in East Asia and was first seen in India by 1999 is believed to be spreading westwards into Pakistan, and bird experts fear that the mysterious plague may continue advancing into Europe since some species are known to migrate there.

Theories for the decline of these large scavenging birds range wildly, from the emergence of a new disease to increased accumulation of pesticides in the vultures' tissues to the drastic reduction in availability of food.

"Such a large-scale die off of this hardy group of scavenger birds is unprecedented in the world," said Deborah Pain of the UK-based Royal Society for the Protection of Birds (RSPB), who is involved with the recovery project in India.

The British Government has made a grant of 148,000 pounds (U.S. $235,000) to support an initiative to restore India's vultures. The money is being paid through the Darwin Initiative and the project is being implemented with the technical support of the Bombay Natural History Society (BNHS), Mumbai.

The first Vulture Care Center in Asia was inaugurated at Pinjore near Chandigarh in northern India on February 7, 2003, by Elliot Morley the visiting British Minister for Nature Conservation and Biodiversity. Morley said, "the project aims to definitely identify the reasons behind the declines and develop possible corrective measures. This, in turn should lead to a recovery plan."

The facility, which also houses a small laboratory, currently holds five vultures and hopes to increase the numbers to 40 in a few months. Researchers hope to radio-collar five birds in an effort to identify migration patterns, using satellites to track flights across Eurasia. One Griffon vulture has already been tagged.

"The vulture die off has created an unprecedented emergency situation needing the most urgent attention," said Asad R. Rahmani, director of BNHS. At places in India the stench of decaying uneaten carcasses has been almost overpowering.

For a while it seemed that very few in the central government paid any heed to the situation; the Indian Ministry of Environment and Forests refused permission to worried researchers to capture dying birds in an effort to identify the causes of death.

But researchers have now enlisted some of the best known bird-disease experts in the world. Recently tissue samples from three or four birds was allowed to be exported for analysis to a research laboratory in Australia in the hope of identifying any disease-causing agent.

Vultures, the best known scavengers of nature, help cleanse the natural ecosystem of decaying carcasses and, more importantly, help in keeping the rural and urban environment free of dreaded diseases like anthrax.

In areas of India where vultures remain, many still show signs of a mysterious illness that is characterized by prolonged periods of neck drooping. Adults, juveniles, and nestlings are all affected by the disease, and invariably die as a result.

Preliminary investigations have shown that the most likely cause of the decline is a yet-to-be-identified infectious disease, possibly a new virus. This is unusual, as vultures are highly efficient scavengers and are normally resistant to many diseases.

India's once highly abundant white-backed vulture (Gyps bengalensis) and the long billed vulture (Gyps indicus) are now listed as "critically endangered" by Bird Life International.

The Bombay Natural History Society was the first institution to sound the alarm about the vultures in India, noting a 97 percent decline in the abundance of the birds at the world famous Keoladeo National Park, Rajasthan, in 1999.

There are many other ramifications and health hazards associated with this vulture die off, said Vibhu Prakash, a principal scientist of the BNHS, who is also the lead investigator for the vulture-recovery project. "The decline of vultures has led to the sudden increase in population of stray dogs in northern India, posing a huge rabies risk for the rural population."

The "superabundance of uneaten cattle carcasses in India poses a direct health threat," agreed Andrew Cunningham, head of wildlife epidemiology at the Zoological Society of London, Institute of Zoology, UK.

In the a multi-author paper published in the latest issue of Biological Conservation Prakash said, "if the cause of declines is not identified soon and remedial action taken, then it is possible that affected species will become extinct."

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