Nature's clean-up crew: Quantifying ecosystem services offered by a migratory avian scavenger on a continental scale

Despite its importance for ecosystem and human health, the cleaning service provided by scavenging birds is frequently disregarded. We evaluated this ecosystem service provided by a migratory species at a continental scale, estimating the amount of annual organic material removal, and the cost of artificially replacing the service. Road surveys conducted between 2005 and 2011, indicated an abundance of Turkey Vultures (Cathartes aura) of nearly 9,000 birds along 27,658 km (22,127 km(2)), suggesting that the total global population could approximate 13 million birds. The calculated individual food intake (252 g/day) suggests that the surveyed population remove 1,000 tons of organic material per year - a monetized service of more than 500,000 USD, that could reach 700 million USD per year for the global population. Movement data from 22 tagged birds showed that the ecosystem service is maximized at the breeding and wintering areas, where Turkey Vultures spend most of the year (74-92% of time). The huge amount of organic material removed by Turkey Vultures at a continental scale, and the economic relevance of their service, highlight the importance of widespread and abundant populations of scavenging birds and their significant role in protecting the health of the environment and human wellbeing.