Vultures in India and Pakistan are being poisoned by the painkiller and anti-inflammatory drug diclofenac, which is normally used to treat livestock, scientists have reported.
The populations of vultures in the region have been declining rapidly — by as much as 95 per cent in the past decade — but until recently, scientists have been unsure why.
Now, a team of US and Pakistani scientists has found that a build-up of diclofenac may be responsible. The researchers carried out autopsies on Oriental white-backed vultures that had died suddenly. They found that the birds suffered from kidney malfunction, and that their kidneys contained residues of diclofenac. They obtained the same result when captured birds were fed on cattle that had been treated with the medicine.
Vultures are an important part of natural ecosystems, as they are scavengers that dispose of carrion from wildlife as well as from domestic livestock.
"The identification of diclofenac as the cause of the Oriental white-backed vulture decline in Pakistan provides an opportunity for conservation intervention," the researchers argue in this week's Nature. But unfortunately there is virtually no substitute for the drug that acts in a different way.
In an article commenting on the research also published in this week's Nature, Robert Risebrough of the California-based Bodega Bay Institute says that an effective conservation programme must be implemented within a matter of months if the birds are to survive.
Reference: Nature 427, 630 (2004) / Nature 427, 596 (2004)