Vultures’ guts are full of microbes that sicken other creatures, a new study finds. Conditions in the birds’ intestines are so harsh that most other bacteria that pass through them get destroyed.
“For the avian microbiome, virtually nothing is known,” says study coauthor Gary R. Graves, an ornithologist at the National Museum of Natural History in Washington, D.C. “We’re getting the very first glimpses of what is inside and on the outside of birds.”
Graves and his team examined DNA from the recent meals of 50 black and turkey vultures on the birds’ faces and in their guts. Compared with DNA swabbed from the vultures’ heads, the DNA in their intestines was completely broken down by the extreme acidic conditions, Graves and colleagues report November 25 in Nature Communications.
The researchers also sifted through the microbiomes of the vultures’ guts and facial skin — areas exposed to dangerous bacteria when vultures feed. On average, the vultures’ faces contained about seven times as many species of bacteria as did their guts.
The most abundant bacteria were the fecal microbes Fusobacteria and Clostridia, the group that causes food poisoning and tetanus in humans.
Vultures tolerate these bacteria even though they are toxic to other animals. The bacteria may even benefit the birds by breaking down carrion in their bellies.
The vultures probably ingest these bacteria while they are subjecting their carcass feast to its final indignity; to gain easy access, vultures jam their heads into any orifice on a dead animal, including the anus.