Scientists agree that human activity is causing the loss of animal and plant species at alarmingly high rates—designated as the sixth mass extinction in the history of our planet (Ceballos et al. 2015, Jaureguiberry et al. 2022). It has therefore never been more important to understand how the loss of other species might affect human welfare.
We study the functional extinction of vultures in India and find that the disappearance of these birds led to a significant increase in human mortality. In the span of just a few short years during the mid-1990s, vulture populations in India fell by over 95% from a starting point of about fifty million birds (Watson et al. 2004). This is the fastest decline in the population of any bird species in recorded history, and the largest decline since the extinction of the passenger pigeon in the United States. We found that the destruction of vultures raised all-cause human death rates by more than 4% in districts which were once highly suitable for vultures and later lost them. The mechanisms through which these costs occurred are a compelling example of how non-human species provide highly valuable ecosystem services to society.
The role of vultures as environmental sanitisers and their unexpected population collapse
All scavengers—but vultures in particular—are considered to be “keystone species,” defined by the National Geographic as species “that hold the [eco]system together.” When a keystone species collapses, the effects on the ecosystem and the societies that depend on them can be large…