Fatal
Affliction
A dramatic population crash leads scientists to believe that the cause may be a deadly virus. But doubts remain.
By Vijay Jung Thapa
Call it Operation Sick Scavenger. Over the next few months, forest officials, wildlife activists and volunteers will scour the Indian countryside looking for dying or dead vultures. They will comb the dense bushes, climb up scraggy trees and camp around smelly carrion looking for these unhealthy creatures of feather. Once these birds are trapped, they will be transported to the Poultry Diagnostic and Research Centre in Pune where scientists will carry out a variety of tests to try and confirm the presence of an infectious disease or virus that's affecting vultures en masse.
 |
| THREATENED SPECIES: Pesticides or a virus are to blame |
If the investigators find conclusive evidence to show that all these sickly or dead vultures were afflicted with the same disease, it will do two things. It will unilaterally confirm that the huge decline in the Indian vulture population is due to an infectious disease. And it will caution that this disease or virus could well be passed on to other species like poultry or humans.
Vultures rarely figure in anybody's list of the most popular birds but over the past few years ornithologists have been concerned about their dramatically dwindling numbers. No one was sure about the extent of the decline until recent surveys done by researchers attached with the Bombay Natural History Society (BNHS) showed vulture populations in some areas had fallen by more than 95 per cent. The Indian subcontinent is known to have eight vulture species, out of which two are on the fast track to extinction. They are the white-backed vulture and the long-billed vulture. Says ornithologist Vibhu Prakash of BNHS, author of one such study conducted in the Keoladeo National Park in Bharatpur: "In specific places, where earlier I could see thousands of vultures feeding on carrion, today there are less than 50."
Initial investigations of this population crash seemed to point towards the large-scale use of pesticides. Toxicology studies suggest it may be true-tests show that cattle ingest DDT after which the pesticide moves into the vulture's system. Besides, vulture tissue samples show four times more pesticides than, say, pigeons. Reports also indicate vultures aren't an exception and the same affliction is bothering sarus cranes, ring doves and eagles. But all experts aren't buying this theory. Vultures are nature's incinerators and for this they possess an extraordinarily strong digestive system that can absorb the strongest pesticides. In fact, this is what makes them so important in a country like India. They dispose of a potential source of disease-the carrion-and recycle the nutrients contained in the carcasses. Experts suspect a viral epidemic because only an infectious disease could, they feel, cause such a sudden decline in numbers.