The Spanish government should rescind approval of a veterinary drug that threatens Europe´s largest population of wild vultures, researchers argue in a letter published online yesterday in Conservation Biology.
The drug, diclofenac, is commonly used to treat pain in livestock. It has already caused the decline of nearly 99 per cent of India´s vultures, which ingested the drug while feeding on carcasses.
It has also triggered an ecological chain reaction there, resulting in, among other impacts, record numbers of rabies cases.
“It is undeniable that European vulture populations could be seriously affected by the ingestion of diclofenac, and its use has become a matter of great concern for ecologists, politicians, and conservationists,” write the five scientists, who represent agriculture, ecology, and biology departments at universities in both Spain and Switzerland.
Although European grazing and sanitation practices are substantially different from those used in India, potentially reducing the drug´s threat to scavenging birds, the researchers remain concerned about its potential impact in Spain, which is home to an estimated 95 per cent of Europe’s wild vultures.
The drug was approved by the Spanish Agency for Medicines and Health Products (AEMPS) in March 2013. It is a nonsteroidal anti-inflammatory drug currently approved in many countries for both human and veterinary use.
It reduces pain and inflammation caused by a variety of conditions, such as arthritis, kidney stones, and endometriosis.
It is the active ingredient in more than 100 trade named medications, some of which are available over the counter. In veterinary application, diclofenac is most often used to treat joint pain and swelling.
In 2003, researchers fingered diclofenac as the cause of the sudden and widespread disappearance of three of India´s most common vultures: the white-backed, the slender-billed, and the Indian vulture. Diclofenac “cause[s] deposition of uric acid crystals in the visceral organs, and kidneys in particular, and it is kidney failure that actually kills the birds,” says Chris Bowden of the Royal Society for the Protection of Birds and the Saving Asia’s Vultures from Extinction (SAVE) program in Bedfordshire, U.K.
It took less than 20 years for the drug to wipe out most of India’s vultures, and all three species are now listed as either endangered or critically endangered. The missing vultures have left an ecological hole that is being filled by a burgeoning feral dog population, which have helped spread rabies.
Since its dangers were revealed, the drug has been banned for veterinary use in India, Nepal, Pakistan, and Bangladesh, and vulture numbers have shown small signs of rebounding. Efforts to ban its use in Africa are under way, and SAVE is pushing the European Union to ban the drug across the continent.
In Spain, the authors of today’s letter are urging the Spanish government to rescind diclofenac’s approval for veterinary use under “the precautionary principle, which was recognized as a fundamental element of environmental policy at the Rio Conference of 1992.”
Four species of European vulture are at risk, they note: the griffon, bearded, cinereous, and Egyptian. The cinereous and Egyptian vultures are considered near threatened and endangered, respectively.
Although bearded vultures are not considered endangered worldwide, they have been almost completely extirpated from their historic central European range “the 125 breeding pairs in Spain are the result of 30 years of concerted repopulation efforts.
Recent changes in Spain’s farm sanitation laws may put the vultures at greater risk of diclofenac poisoning, says one of the letter’s authors, conservation biologist Antoni Margalida, of the University of Bern in Switzerland and the University of Lleida in Spain.
José Tavares of the Vulture Conservation Foundation in Switzerland says that advocates have already sent formal requests to address the issue to the Spanish government, the European Commission, and eight other E.U. governments.
Additionally, the Convention on Migratory Species (Bonn Convention) has also requested that the Spanish government ban the drug.
So far, there has been no government response, but ecologists and conservation groups are hoping today’s letter adds to the pressure.