An anonymous reader quotes the Scientific American report: Vultures are birds that are hard for people to like. They are obligate scavengers, meaning they get all their food from already dead prey – and this association has long regarded them as harbingers of death. But in reality, vultures are nature’s flying sanitation team. And a new study adds to this positive picture by detailing the role of these birds in a surprising process: the reduction of greenhouse gas emissions. With their impressive eyesight and the range they can cover in their long soaring flights, the 22 species of vultures found around the world are often the first scavengers to spot and feed on a carcass. This scavenging provides a vital service for both ecosystems and people: it maintains nutrient cycling and controls pathogens that might otherwise spread from dead animals to living ones.
Decaying animal bodies release greenhouse gases, including carbon dioxide and methane. But most of those releases could be prevented if vultures got to the remains first, a new Ecosystem Services study shows. He estimated that an individual vulture eats between 0.2 and one kilogram (kg) of carcass per day, depending on the species of vulture. Left uneaten, each kg of naturally decomposing carcass emits about 0.86 kg of CO2 equivalent. This estimate assumes that carcasses not eaten by vultures are left to decompose. But many carcasses are composted or buried by humans, resulting in more emissions than natural decay, so eating vultures could prevent even more emissions by replacing these methods. The avoided emissions may seem small, but multiply these estimates by the estimated 134 to 140 million vultures worldwide, and the number becomes even more impressive: tens of millions of metric tons of emissions avoided per year.
But this ecosystem service is unevenly distributed around the world. It occurs mainly in the Americas, says lead study author Pablo Plaza, a biologist at the National University of Comahue in Argentina. Plaza and his colleagues found that three species found only in the Americas — black, turkey, and yellow-headed vultures — were responsible for 96 percent of all vulture-related emission reductions worldwide. Collectively, America’s vultures release about 12 million metric tons of CO2 equivalent into the atmosphere each year. The U.S. Environmental Protection Agency estimates that’s like taking 2.6 million cars off the road every year. The situation outside America is in stark contrast. “The decline of vulture populations in many regions of the world, such as Africa and Asia, has resulted in the loss of ecosystem services that vultures provide,” says Plaza.