The Social Costs of Keystone Species Collapse : Evidence From The Decline of Vultures in India

The loss of a keystone species can theoretically lead to large social costs because their complex ecosystem interactions may be important for environmental quality. We quantify these effects for the case of vultures in India where they play an important public health role by removing livestock carrion from the environment. The expiration of a patent for a common chemical painkiller led to its increased use in cattle, unexpectedly rendering carcasses fatal to vultures, leading to a catastrophic and near-total population collapse. Using habitat range maps for the affected species, we compare high to low vulture suitability districts before and after the patent for the painkiller expired. We find that, on average, all-cause death rates increased by more than 4% in vulture-suitable districts after the vultures nearly went extinct. We find suggestive evidence that feral dog populations and rabies increased, and that water quality deteriorated in the affected regions. These mechanisms are consistent with the loss of the scavenging function of the vultures. Quantifying the costs of biodiversity losses has critical implications for optimal investments into species conservation and rehabilitation.