|Captive breeding colonies of a critically endangered vulture are too small to protect the species from extinction.
Adding wild birds to the captive colonies, located in Pakistan and India, is crucial, but political and logistical barriers are hampering efforts, says lead author Jeff A. Johnson.
The study was published online August 15 in the journal Biological Conservation.
With a seven-foot wingspan, the oriental white-backed vulture (Gyps bengalensis) was an awesome presence in south Asia until the mid-1990s, when populations began to collapse. At first the cause was unclear, but researchers eventually zeroed in on an anti-inflammatory drug, diclofenac, that is used to alleviate arthritis-like symptoms in livestock but is toxic to vultures. Vultures that feed on carcasses of animals treated with the drug die of kidney failure within a day or two after eating the tainted meat. And although India, Nepal and Pakistan outlawed its manufacture in 2006, diclofenac is still available, and birds are still dying.