Veterinary medicine suspected to cause decline of vultures

MUMBAI: Scientists trying to understand the decline of vulture population in India may now be asking themselves: Could it be something they ate?
New studies in Pakistan show that many dead white-backed vultures had in their kidneys high levels of an antiflammatory pain killer used widely in veterinary medicine in the subcontinent.
Presumably, the drug entered vultures’ system through the carcasses of livestock they fed on.The results of the study were announced at the 6th Conference on Birds of Prey at Budapest on May 20.
The studies were conducted in Pakistan’s Punjab province by Dr Lindsay Oaks of Washington State University. Intensive international research on vultures in the subcontinent began after the discovery by biologist Vibhu Prakash of an alarming population decline.
Among others, the gyps or oriental white-backed vultures have declined by 90 per cent in India over the last decade. In recent years, the decline has spread to Pakistan and Nepal. Scientists previously have suspected an infectious virus to be the cause.
Dr Oaks reportedly obtained only negative results when searching for viruses and other disease pathogens. Tests for pesticides, metals and other poisons were also negative. Instead, he and his researchers found that birds with gout—a frequent finding in the dead birds—had high levels of Diclofenac, commonly used in medicine given to local cattle and buffalo.
Birds without gout had no traces of this chemical. In a statement, the Bombay Natural History Society (BNHS), which has joined with the Royal Society for the Protection of Birds and the Institute of Zoology on vulture research, labelled the findings “an exciting development in the search for a cause’’.
However, the BNHS said that it was not known whether the drug had played a part in the vulture decline in India.While work in India is more suggestive of an infectious disease, the possibility could not be discounted, they said.
But to make such a significant impact, the drug must “have been used across the subcontinent on the majority of livestock, probably at frequent intervals over the last decade, and it affects only certain species’’.
BNHS official Isaac Kehimkar pointed out that though the drug was also toxic to the dogs, there had been an increase in the population of feral dogs around carcass dumps.
There are also other differences: While birds poisoned by this drug died quickly, many of the vultures in India had slow, more lingering deaths.
Moreover,many of the sick birds held at the BNHS’s Vulture Care Centre in Haryana are chronically sick, and often have drooping necks, a symptom not associated with the drug-related deaths.