A cautionary tale: Diclofenac and its profound impact on vultures

In the late 1990s, populations of three species of Gyps vultures, once considered the most abundant large raptors on earth, underwent a precipitous decline on the Asian subcontinent. After less than a decade, they had virtually been extinguished. Here, we detail the numerous lines of investigation that were urgently but scrupulously undertaken to establish the nonsteroidal antiinflammatory drug diclofenac, via ingestion of residues in livestock carcasses, as the cause of the mortality. We outline the safety testing process to find the sole vulture-safe alternative NSAID to date, consider others flagged or confirmed as unsafe, and discuss governmental actions taken and regulations enacted to protect Asian Gyps vultures. We also ponder lessons learned throughout, identify other potentially vulnerable scavenging species and highlight where the strong warnings issued following the “Asian Vulture Crisis” are still not being heeded.