Laura Erickson's For the Birds

Tragic Side-Effects

For the decade years or so, vultures of India, Pakistan, and Nepal have been decreasing at a dangerous rate. Populations of vultures on the Indian subcontinent were considered abundant as recently as the late 1980s. Dramatic declines in populations were first measured in Keoladeo National Park in 1996 with reductions in excess of 95% recorded across India by 2000. This is obviously tragic for the three species declining most dramatically, the Indian White-backed Vulture, the Slender-billed Vulture, and the Indian Vulture, which are now considered critically endangered. But it’s also terrible for the people of the area. Not only have the carcasses of dead cattle and other livestock been removed by these scavengers for centuries, protecting people from dangerous pathogens, but the scavengers also serve another purpose. Members of the Parsi group, a Zoroastrian sect, have an ancient tradition of disposing of their own dead by exposing them to scavengers, who carry the spirits of the dead to the sky. Without vultures, they will need to find another way of dealing with the bodies of dead people, in an area where soil is rocky and shallow so burial is difficult. And the practical issues aside, it’s a genuine tragedy to lose such a longstanding and deeply felt religious tradition as sky burial. The situation has ecological ramifications, too. As vultures decline, foxes have less competition for carcasses, and their numbers have skyrocketed, along with rabies.

The cause of this unprecedented and dramatic decline in vulture numbers left scientists completely stumped. Since 2000, researchers have conducted exhaustive testing of tissue samples from freshly dead vultures. These tests found no evidence of conventional viral or bacterial infectious disease, pesticides, poisons, heavy metals, or nutritional deficiency. The one thing they did find on dead vultures was renal failure. Then in April 2003 scientists finally pinpointed a cause for the decline, and it’s both scary and tragic. It turns out the vultures are dying after eating carcasses of animals that had been given a common anti-inflammatory medication related to ibuprofen, called diclofenac, which was first used in veterinary medicine in 1993. It became a popular veterinary pharmaceutical in South Asia because it’s cheap and effective at reducing lameness and fever in livestock, although many alternatives exist. Scientists discovered a 100% correlation between renal failure in dead or dying vultures collected in the field in Pakistan and the presence of diclofenac. Subsequently, experiments in Pakistan on unreleasable juvenile vultures demonstrated that very small doses of diclofenac (one tenth of the recommended dose for mammals) cause death from renal failure and that fatal amounts of diclofenac can be ingested by vultures eating dead livestock that were treated with recommended veterinary doses. The Peregrine Fund, a raptor conservation organization that spearheaded most of the research, says that barring prompt action, all three vulture species are likely to become extinct in the wild within five years. They state that a very short window of opportunity, perhaps months rather than years, now exists to take remedial action to prevent their extinctions, and so are calling for an immediate and outright ban on veterinary use of diclofenac in South Asia. Meanwhile, the Peregrine Fund has three decades of experience breeding raptors in captivity, and is recommending capturing as many vultures as possible to protect from further poisoning until the situation is reversed.

It’s amazing that a mere three years after a drug was introduced, serious declines in vultures were detected, and sad that it took 7 more years to figure out what the problem was, and yet another year before anything has been done about the situation. But who could possibly have guessed that something so seemingly innocuous as a simple non-steroid anti-inflammatory drug could decimate three species in such a short time? Looks like I’m going to have to reach into my pretty empty wallet to come up with something to donate to the Peregrine Fund, to help them with this emergency work.