Three endemic vulture species
Gyps bengalensis
,
Gyps indicus
and
Gyps tenuirostris
are critically endangered following dramatic declines in South Asia resulting from exposure to diclofenac, a veterinary drug present in the livestock carcasses that they scavenge. Diclofenac is widely used globally and could present a risk to
Gyps
species from other regions. In this study, we test the toxicity of diclofenac to a Eurasian (
Gyps fulvus
) and an African (
Gyps africanus
) species, neither of which is threatened. A dose of 0.8 mg kg
−1
of diclofenac was highly toxic to both species, indicating that they are at least as sensitive to diclofenac as
G. bengalensis
, for which we estimate an LD
50
of 0.1–0.2 mg kg
−1
. We suggest that diclofenac is likely to be toxic to all eight
Gyps
species, and that
G. africanus
, which is phylogenetically close to
G. bengalensis
, would be a suitable surrogate for the safety testing of alternative drugs to diclofenac.