Ecosystem services and disservices associated with vultures: A systematic review and evidence assessment

Nature’s contribution to people (i.e. ecosystem services) is becoming integral to conservation science and policy, yet our knowledge is restricted to only a few services and taxa. Vultures (family: Accipitridae and Cathartidae), most of which are threatened with extinction, have been touted for delivering regulation and maintenance services via their capacity to rapidly consume organic matter. As such, their appellation as “nature’s clean-up crew” has become very popular. However, a comprehensive evaluation of the supporting evidence for such appellation was absent from the published literature. We performed a systematic review and evidence assessment to quantify the global contribution of vultures towards over 20 ecosystem services and disservices. Our analysis determined a critical imbalance in the scope and focus of published research. In contrast to the birds’ popularised image as cleaners of the environment, we found only weak evidence to support any regulation and maintenance services for vultures. Moreover, studies on regulation and maintenance disservices were prominent. The only ecosystem services supported by strong evidence were cultural, although even these were evidenced by a limited number of studies. Finally, we unveil major knowledge gaps in the ecosystem service and disservice literature on a taxonomic and spatial scale related to vultures. Our analysis highlights the urgent need to quantify the net contribution of vultures to people.