Partial recovery of Critically Endangered Gyps vulture populations in Nepal

Abstract

SummaryPopulations of Critically Endangered White-rumped Gyps bengalensis and Slender-billed G. tenuirostris Vultures in Nepal declined rapidly during the 2000s, almost certainly because of the effects of the use in livestock of the non-steroidal anti-inflammatory drug diclofenac, which is nephrotoxic to Gyps vultures. In 2006, veterinary use of diclofenac was banned in Nepal and this was followed by the gradual implementation, over most of the geographical range of the two vulture species in Nepal, of a Vulture Safe Zone (VSZ) programme to advocate vulture conservation, raise awareness about diclofenac, provide vultures with NSAID-free food and encourage the veterinary use in livestock of a vulture-safe alternative NSAID (meloxicam). We report the results of long-term monitoring of vulture populations in Nepal before and after this programme was implemented, by means of road transects. Piecewise regression analysis of the count data indicated that a rapid decline of the White-rumped Vulture population from 2002 up to about 2013 gave way to a partial recovery between about 2013 and 2018. More limited data for the Slender-billed Vulture indicated that a rapid decline also gave way to partial recovery from about 2012 onwards. The rates at which populations were increasing in the 2010s exceeded the upper end of the range of increase rates expected in a closed population under optimal conditions. The possibility that immigration from India is contributing to the changes cannot be excluded. We present evidence from open and undercover pharmacy surveys that the VSZ programme had apparently become effective in reducing the availability of diclofenac in a large part of the range of these species in Nepal by about 2011. Hence, community-based advocacy and awareness-raising actions, and possibly also provisioning of safe food, may have made an important contribution to vulture conservation by augmenting the effects of changes in the regulation of toxic veterinary drugs.