Over the past decade, the populations of Gyps vulture species across the Indian subcontinent have crashed, in many areas by more than 95%. The dramatic decline and potential extinction of vultures have serious implications for a human-dominated ecosystem in which scavengers (rather than predators) play such an important role, with heightened risk of disease from decaying unconsumed carcasses and from proliferating four- footed scavengers -- dogs, cats, and rats. At first mysterious, the likely cause of the vulture decline in Pakistan was recently pinpointed as the widely-used veterinary anti-inflammatory drug diclofenac administered to cattle: Vultures fed on carcasses of diclofenac-treated cattle develop fatal kidney failure.
Green et al. now show that diclofenac is the probable cause of Gyps decline across the entire subcontinent. A simulation model of vulture demography provides a quantitative range of estimates of the proportion of cattle that would need to be treated with diclofenac in order to produce the observed levels of vulture decline. Fewer than 1% of cattle would be sufficient to produce the catastrophic declines observed. To stave off the possible imminent extinction of Gyps species, an urgent search for alternatives to diclofenac is required. Captive breeding programs may also be necessary to maintain stocks of vultures for eventual reintroduction -- AMS
J. Appl. Ecol. 41, 793 (2004).
