A rare conservation good news story is the subject of a paper co-authored by Prof Rhys Green, published in the journal Ibis. The study described examines the recovery of previously critically endangered vulture species in Nepal.
Beginning in 1994, populations of three species of vultures endemic to South Asia began a catastrophic population decline. Rates of decline varied between 20% per year and 50% per year, depending on species and happened simultaneously in several countries (India, Pakistan, Nepal, Bangladesh).
It took until 2004 to find the cause- veterinary use on cattle for pain relief of the non-steroidal anti-inflammatory drug (NSAID) diclofenac. Diclofenac causes kidney failure and death within 2 days when vultures feed on the carcass of a recently-treated cow. One of the vulture species was suffering an annual death rate of 40% per year from diclofenac poisoning when the decline was at its most rapid.
Governments banned veterinary use of the drug in 2006. Monitoring showed that its use declined after the ban, but there was no enforcement, so it didn’t decrease to zero everywhere and remained high in some places. Also, some other toxic NSAIDs that were not banned partly replaced diclofenac. Consequently, vulture declines stopped in most places, but the much-reduced populations did not recover significantly.
The exception is Nepal, where rare teamwork between government agencies and a conservation NGO (Bird Conservation Nepal, Nepal partner of BirdLife International) raised awareness among vets, livestock keepers, pharmacists and the public so that diclofenac ceased to be available in Nepal in 2012.
The area was then declared to be the only “Vulture Safe Zone” in South Asia by the international vulture conservation organisation SAVE. In that year, population monitoring data showed a sudden switch from rapid long-term decline to rapid and sustained increase.
The new paper investigates the changes in demography underlying the increase by measuring annual survival rates of adult and immature vultures and their breeding success. The remarkable high rate of increase since 2012 (13% per year) has occurred principally because of unusually good survival rates of both immature (96% survive from one year to the next) and adult (95% survival) vultures, sustained over a period of more than ten years. This has happened because vultures are no longer poisoned by diclofenac in Nepal and the huge reduction in their numbers meant that there was less competition than formerly for food and nest sites.
The study gives reasons to hope that recovery of currently stable but low vulture populations elsewhere in the region can be achieved if effective ways can be found to prevent the use of toxic NSAIDs.
Read the paper:
Mallord, J. W., Joshi, A. B., Chaudhary, I. P., Thakur, D. C., Thapa, I., Bhusal, K. P., Rana, D. B., Dhakal, B. K., Galligan, T. H., & Green, R. E. (2026). Continued population recovery and high annual survival rates of White-rumped Vultures in Nepal. Ibis. https://doi.org/10.1111/ibi.70094
Pictures:
Top: White-rumped vultures feeding. Photo by Jonathan Eames
Middle: Co-workers from BirdLife International partner Bird Conservation Nepal counting vultures during a road transect survey. These standardised annual surveys were first used to measure the vulture decline caused by the toxic veterinary drug diclofenac and then to measure the vultures’ recovery after a ban and public-awareness campaign removed the drug from use. Photo by John Mallord
Bottom: A White-rumped Vulture fitted with a solar-powered GPS tracking tag. Monitoring of these tagged birds showed that a high proportion of them survived from year to year after diclofenac was removed and that none of them died from diclofenac poisoning. Photo by John Mallord