White-rumped Vulture

Oaks, J.L., Gilbert, M., Virani, M.Z. et al. (2004). Diclofenac residues as the cause of vulture population decline in Pakistan. Nature, 427(6975), 630–633.

Diclofenac, widely used to treat livestock, causes fatal kidney failure in vultures that feed on the carcasses of animals treated shortly before death. Vultures' communal feeding habits — dozens of individuals on a single carcass — spread the effect across the subcontinent in barely a decade.

Frank, E. et Sudarshan, A. (2024). The Social Costs of Keystone Species Collapse: Evidence from the Decline of Vultures in India. American Economic Review, 114(10), 3007–3040.

By comparing changes in human mortality in regions once highly favorable to vultures against regions where they were already scarce, the authors isolate the causal effect of their disappearance: about half a million additional deaths in total over the period, for a social cost estimated at $69.4 billion a year — without vultures, carcasses rot in the open or attract feral dogs, which fuels the spread of diseases including rabies. An earlier, methodologically less rigorous estimate had put this cost at about $34 billion cumulative between 1993 and 2006 (Markandya et al., 2008) — the gap between the two shows how much the estimate has been refined with better methods, not that the phenomenon worsened.