a1 Royal Society for the Protection of Birds, The Lodge, Sandy, Bedfordshire, SG19 2DL, U.K.
a2 Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, U.K.
a3 Bombay Natural History Society, Hornbill House, Mumbai, 400023, India
a4 The Peregrine Fund, 5668 West Flying Hawk Lane, Boise, Idaho 83709, U.S.A.
a5 Haryana Forest Department, Van Bhawan, sector 6, Panchkula, 134109, Haryana, India
a6 Wildlife Institute of India, Post Bag #18, Chandrabani, Dehradun, 248001, Uttaranchal, India
a7 Ornithological Society of Pakistan, 109/D P.O. Box 73, Dera Ghazi Khan, Pakistan
a8 Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
a9 Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington 99164-7040, U.S.A.
a10 International Centre for Birds of Prey, Little Orchard Farm, Eardisland, Herefordshire HR6 9AS, U.K.
a11 Bird Conservation Nepal, P.O. Box 12465, Lazimpat, Kathmandu, Nepal
a12 Indian Veterinary Research Institute, Izatnagar 243122, Uttar Pradesh, India
a13 School of Biological Sciences, Dept of Plant & Soil Science, University of Aberdeen, AB24 3UU, U.K.
a14 Rhino & Lion Wildlife Conservation NPO, “Vulture Programme”, Kromdraai, South Africa
Gyps vulture populations across the Indian subcontinent collapsed in the 1990s and continue to decline. Repeated population surveys showed that the rate of decline was so rapid that elevated mortality of adult birds must be a key demographic mechanism. Post mortem examination showed that the majority of dead vultures had visceral gout, due to kidney damage. The realisation that diclofenac, a non-steroidal anti-inflammatory drug potentially nephrotoxic to birds, had become a widely used veterinary medicine led to the identification of diclofenac poisoning as the cause of the decline. Surveys of diclofenac contamination of domestic ungulate carcasses, combined with vulture population modelling, show that the level of contamination is sufficient for it to be the sole cause of the decline. Testing on vultures of meloxicam, an alternative NSAID for livestock treatment, showed that it did not harm them at concentrations likely to be encountered by wild birds and would be a safe replacement for diclofenac. The manufacture of diclofenac for veterinary use has been banned, but its sale has not. Consequently, it may be some years before diclofenac is removed from the vultures' food supply. In the meantime, captive populations of three vulture species have been established to provide sources of birds for future reintroduction programmes.