Just months after the NSAID drug diclofenac had been licensed for veterinary use in Europe, two groundbreaking scientific studies have revealed that a greater diversity of birds of prey, including some eagles, are susceptible to its effects than previously thought.
In a paper, published today in the journal Bird Conservation International, scientists present results of tests carried out on two steppe eagles found dead at a cattle carcase dump in Rajasthan, India.
Both birds had diclofenac residue in their tissues and exhibited the same clinical signs of kidney failure as seen in Gyps vultures experimentally given diclofenac.
Steppe eagles are closely related to the golden eagles found in the UK, the vulnerable Spanish imperial eagle and other globally vulnerable or declining Eurasian eagles. Scientists fear all species in this genus, known as Aquila, are susceptible to diclofenac.
With 14 species of Aquila eagle distributed across Asia, Africa, Australia, Europe and North America, this means diclofenac poisoning should now be considered largely a global issue.
Toby Galligan, RSPB conservation scientist and one of the authors of the paper, said: “We have known for some time diclofenac is toxic to Gyps vultures, including the Eurasian griffon vulture, but we now know it is toxic to an Aquila eagle too.
“This suggests the drug is fatal to a greater number of birds of prey in Asia, Europe and around the world. We had suspected as much from observed declines in non-Gyps vultures in Asia, but this study confirms our worst fears.”
In another paper, published in April in Bird Conservation International, Dr Galligan led an examination of recent population trends in Egyptian and red-headed vultures in India. That study shows population declines of similar timing and scale as the declines observed in Gyps vultures, providing indirect evidence these species have been affected by diclofenac as well.
Veterinary diclofenac is said to have caused an unprecedented decline in South Asia’s Gyps vulture populations, with three species – the Oriental white-backed, the long-billed and the slender-billed vulture – declining by more than 97 per cent between 1992 and 2007. This equates to the loss of tens of millions of individuals.
After years of campaigning by conservationists, the governments of Bangladesh, India, Nepal, and Pakistan banned veterinary formulations of diclofenac between 2006 and 2010. Recently, experts have recorded a slowing of Gyps vulture declines as a result of the bans.
However, formulations of diclofenac intended for use in humans are still widely available and illegally used to treat livestock, the carcasses of which are the main food source for vultures in South Asia.
It was announced in March that veterinary diclofenac had been authorised for manufacture and use in Italy and Spain and had been distributed to other European countries. Since then, a coalition of organisations including the Vulture Conservation Foundation, the RSPB and BirdLife International have been campaigning for this decision to be reversed.
Dr Galligan said: “In light of recent developments in Europe, our findings take on an even more worrying meaning. All Europe’s charismatic Aquila eagles, like the Spanish imperial eagle and, closer to home, the golden eagle, are opportunistic scavengers and therefore could be at risk of diclofenac poisoning.
“As we have seen in South Asia, wherever free-ranging livestock are treated with diclofenac, population declines in vultures and eagles can occur. The European Commission needs to recognise this problem and impose a continent-wide ban on veterinary diclofenac before it can impact on our birds.”
Last week, the UK’s Veterinary Medicines Directorate (VMD), the agency that regulates veterinary medicines, announced measures against the drug.
In a statement the VMD said: “The UK’s Veterinary Medicines Directorate is taking the issue of diclofenac’s risks to vulture populations seriously. As a precautionary measure the VMD will not approve any requests from vets to import products containing diclofenac.
“Furthermore, the VMD has agreed not to issue any export certificates which name diclofenac-containing products in the list of products to be exported.”
Sacha Cleminson, head of international biodiversity policy at the RSPB, said: “The announcement from the VMD is a welcome signal to Europe that the UK is taking the issue seriously. This new evidence underlines the need for a ban across Europe, and ultimately beyond.”
The RSPB is a member of SAVE (Saving Asia’s Vultures from Extinction), which is a consortium of international organisations created to oversee and coordinate conservation, campaigning and fund-raising activities to help the plight of South Asia’s vultures. For more information, visit www.save-vultures.org