Just months after the news that the vulture-killing 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 the golden eagle, are also susceptible to its effects.
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These findings strengthen the case for banning veterinary diclofenac across Europe and for strengthening bans and enforcement of bans in South Asia to stop the illegal misuse of human diclofenac to treat livestock.
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 carcass 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 now fear that all species in this genus, known as Aquila, are susceptible to diclofenac.
With fourteen species of Aquila eagle distributed across Asia, Africa, Australia, Europe and North America, this means that diclofenac poisoning should now be considered largely a global problem.
Dr Toby Galligan, RSPB conservation scientist and one of the authors of the paper, said: “We have known for some time that 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 that 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 last month 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 that these species have been impacted by diclofenac as well.
Veterinary diclofenac 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% between 1992 and 2007. This equates to the loss of tens of millions of individuals.
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Golden eagle image via Shutterstock.