New research shows vultures have the effect of mitigating greenhouse gas emissions by consuming dead flesh that otherwise will emit more emissions while decomposing. Decaying animal bodies release carbon dioxide and methane, but if vultures get to the remains first, the carbon footprint of such bodies would decrease, as some of the carbon will be locked in the animals’ bodies instead of going directly to the atmosphere.
Vultures, by being animals, will continue to breathe out CO2, but some of the carbon they consume will stay locked in their muscles and bones while they are still alive. Conversely, more carbon will end up in the atmosphere faster if the bodies are left to decompose by bacteria and insects.
The study, titled “Mitigating GHG emissions: A global ecosystem service provided by obligate scavenging birds” and published in August 2022 in Ecosystem Services, shows that an individual vulture eats between 0.2 and one kg of carcass per day, depending on the vulture species, and each uneaten kg of naturally decomposing carcass emits about 0.86 kg of CO2 equivalent. If carcasses are composted or buried by humans, this result in more emissions than natural decay, so vulture consumption is even more efficient at reducing emissions. It is estimated that the 134 to 140 million vultures around the world avoid tens of millions of metric tons of emissions every year.
Pablo Plaza, a biologist at the National University of Comahue in Argentina, and one of the authors of the study, said that three American species, the Black, Turkey and Yellow-headed vultures, are responsible for 96% of all vulture-related emissions mitigation worldwide, collectively preventing about 12 million metric tons of CO2-equivalent to go out in the atmosphere annually. However, vulture populations in Africa and Asia have been declining, which is contributing to climate change by removing the effect these birds have on mitigating emissions.