Having suffered an extremely rapid decline in numbers due to a previously unknown cause, the slender-billed vulture is in danger of imminent extinction without immediate conservation action. By 2000, dead and dying Gyps vultures were being found so frequently in Nepal and India it was thought that they were suffering from an epidemic. The unnaturally high death toll was thought to be caused by a fatal virus, but testing has revealed that the vultures were suffering from kidney failure following the consumption of cattle that had previously been treated with the anti-inflammatory drug, diclofenac (2). In fact, the decline is a result of a lethal level of the drug in a small proportion of the ungulate carcasses available to vultures, but as vultures travel long distances to reach carrion, a considerable proportion of the population has been affected (7).
In the east of India, the almost complete loss of the slender-billed vulture occurred prior to the current drug disaster and is thought to relate to the reduction in large wild mammals, and the human consumption of livestock that dies naturally (2).
The full extent of the decline of slender-billed vultures, and other vulture species, is already felt by humans, as rotting carcasses remain untouched, posing a health hazard, as well as encouraging feral dog populations which carry rabies (8).