Steppe eagle are susceptible to diclofenac poisoning
Toby Galligan
This week, Bird Conservation International, the journal of BirdLife International, published a
scientific paper written by SAVE (Saving Asia’s Vultures from Extinction) partners showing, for
the first time, evidence that diclofenac can kill a species outside the Gyps genus. That species
was the steppe eagle Aquila nipalensis.
The RSPB, BNHS (Bombay Natural History Society, India) and IVRI (Indian Veterinary
Research Institute, India) are expanding our knowledge of the species intolerant to diclofenac by
monitoring Indian livestock carcass dumps for the carcasses of birds of prey. This is how we
came across the two steppe eagles described in the present study. Both birds had signs of renal
failure – that is, visceral gout (a coating of white uric acid crystals on the organs) and uric acid
deposits and lesions in the kidney, liver and spleen – and one bird had diclofenac residue in its
tissues. All the wild Gyps vultures that we have recovered over the past decade with signs of
renal failure have had diclofenac in their tissues; and all those without signs of renal failure have
had no diclofenac in their tissues. Further, the captive Gyps vultures that we experimentally gave
diclofenac to confirm its lethality in earlier studies showed the same signs of renal failure.
Therefore, we have little doubt that diclofenac killed the two steppe eagles.
So what are the implications of this finding?
The steppe eagle is a winter migrant to South Asia, where it almost exclusively scavenges on
livestock carcasses. Therefore, veterinary diclofenac use in the past would have caused declines
in steppe eagle populations.
Veterinary diclofenac is banned in all South Asian countries where vultures range; however,
diclofenac manufactured for human use is being misused in livestock. Therefore, diclofenac
poisoning remains a threat for birds of prey in South Asia.
We know that diclofenac is toxic to five species of Gyps vulture. Therefore, diclofenac is likely
to be toxic to other species of Aquila eagle.
At least three other species of Aquila – i.e., tawny eagle (Aquila rapax), eastern imperial eagle
(Aquila heliaca) and Indian spotted eagle (Aquila hastata) – scavenge on livestock carcasses in
South Asia. Therefore, these species may have declined and continue to decline as a result of
diclofenac use in livestock.
Eight species of Gyps vultures inhabit Europe, Asia and Africa. Fourteen species of Aquila eagle
inhabit Europe, Asia, Africa, Australia and North America. Therefore, the potential number of
species at risk and the potential number of countries where the diclofenac-problem could arise is
greater than previously thought.
Bearing on this last point, we are particularly concerned about Europe, where diclofenac is being
used in Spain, Italy and other countries to treat livestock. Spain is home to the largest population
of Eurasian griffon Gyps fulvus and Spanish imperial eagle Aquila adalberti in Europe. These are
vulnerable populations, recovering from historic persecution and food shortages, but now at risk
of a renewed decline.