Decline of Vultures in Asia

Abstract

The random samples item “Vulture Culture” (3 Feb., p. [587][1]) presents the appearance of large numbers of Eurasian griffon vultures in Rajasthan, India, as good news, but this is far from the case. In India, populations of three species of vultures endemic to South Asia (oriental white-backed, long-billed, and slender-billed) have declined to less than 3% of what they were about a decade ago and the decline continues ([1][2]). The Eurasian griffons are mostly immature birds from Central Asia, Tibet, and Mongolia that return there to breed, probably attracted in larger numbers by plentiful supplies of livestock carcasses left uneaten now that the resident species have almost disappeared. There is now substantial published evidence that the cause of the Asian vulture decline is veterinary use of the drug diclofenac, which vultures take in when they feed on the carcass of a cow or water buffalo treated with the drug ([1][2]–[3][3]). Eurasian griffons are as susceptible to kidney failure caused by diclofenac as their Asian relatives ([4][4]), so it is likely that the source populations of this species that winter in India will also be affected. Such an effect will not be detected soon, however, because there is virtually no systematic monitoring of numbers of vultures breeding in these inaccessible areas. Numbers of immature Eurasian griffons wintering in India may continue to grow, but this will probably just indicate a growing drain on their source populations. A ban on the veterinary use of diclofenac, announced by the Indian prime minister in March 2005 ([5][5]), will therefore probably benefit Eurasian griffons as well as the resident species, but only if it can be implemented successfully. The Random Samples item also contained inaccuracies about recently published findings on the safety to vultures of meloxicam, an alternative to diclofenac that could help to save the vultures by speeding the removal of diclofenac from their food supply ([6][6]). The vultures used in the experiments were captive, but not captive-bred, and 72 birds (not 35) were treated, of which 66 were given meloxicam itself, rather than meat from treated cattle. 1. 1.[↵][7]1. R. E. Green 2. et al. , J. Appl. Ecol. (2004)41, 793. 2. 2.1. J. L. Oaks 2. et al. , Nature (2004)427, 630. 3. 3.[↵][8]1. S. Shultz 2. et al. , Proc. R. Soc. London Ser. B (Suppl.) (2004)271, S458. DOI 10.1098/rsbl.2004.0223. 4. 4.[↵][9]1. G. E. Swan 2. et al. , Biol. Lett. (2006)doi:10.1098/rsbl.2005.0425 9. 5. 5.[↵][10]1. P. Bagla , Science (2005)307, 1851. 6. 6.[↵][11]1. G.E. Swan 2. et al. , PloS Biol. (2006)4 (no. 3), e66. [1]: /lookup/doi/10.1126/science.311.5761.587a [2]: #ref-1 [3]: #ref-3 [4]: #ref-4 [5]: #ref-5 [6]: #ref-6 [7]: #xref-ref-1-1 View reference 1. in text [8]: #xref-ref-3-1 View reference 3. in text [9]: #xref-ref-4-1 View reference 4. in text [10]: #xref-ref-5-1 View reference 5. in text [11]: #xref-ref-6-1 View reference 6. in text