Sunday, January 28, 2007

Death of vultures

Do read this Smithsonian story by Susan McGrath on the sudden and rapid decline in the vulture population in South Asia [link via Guru].

A part of it is a gripping detective story of how scientists identified the deadly killer that decimated almost 90 percent of vultures within a short span of a couple of decades. The killer turns out to be Diclofenac -- a drug used widely for treating livestock. Last year, India, Pakistan and Nepal imposed a ban on this drug.

Another part of the Smithsonian story is about the dedication of scientists and conservation activists, who are trying to breed these vultures in captivity. A third part of it is about the horrors that could be unleashed by the demise of vultures:

Diclofenac doesn't hurt the dogs. (No one knows yet why the drug kills birds but not mammals.) At the dump, 50 or 60 yellow-brown dogs tear at carcasses. Under every mesquite bush, sated dogs lie curled, asleep. "Yes, the dogs are many now that the long-necked vultures are gone," a skinner says. India doesn't cull dogs because of Hindu and Buddhist prohibitions on taking life. In the past, starvation and disease kept dogs in check. With vultures so vastly reduced in number, dogs have more than enough to eat; their population increased from 22 million in 1992 to 29 million in 2003, the last year for which figures are available. India's official human death toll from rabies is the world's highest—30,000 deaths annually, two-thirds of them caused by dog bites. In recent years, the government has made rabies vaccines more widely available in rural areas, but rabies deaths aren't decreasing at the rate they should be because the unvaccinated dog population is growing, according to rabies experts.

Public health officials say it's likely that India's rat population is growing too, sharing the bounty of abandoned carcasses with feral dogs, and raising the probability of outbreaks of bubonic plague and other rodent-transmitted human diseases. Livestock diseases may increase too. Vultures are resistant to anthrax, brucellosis and other livestock diseases, and helped control them by consuming contaminated flesh, thus removing reservoirs of infectious organisms. Some municipalities are now resorting to burying or burning carcasses, expending precious land, firewood and fossil fuels to replace what Rahmani calls "the beautiful system nature gave us."


  1. Raj said...

    A man-made chemical seems to have knocked off the humble house sparrow as well. Ornithologists ( investigating the mysterious disappearance of sparrows in many cities of the world, suspect that unstable toxins in unleaded gasoline could have been the culprit. It didn't kill the adult sparrows directly, but killed the insects that baby sparrows need till they are old enough to forage for their own food.

  2. Abi said...

    Raj: Thanks for the pointer. It's amazing how unintended consequences come back to haunt you.