Scientists uncover vulture’s secrets to eating death

Vultures snack on death, merrily munching away on rotting flesh that would make other animals ill. So how do they do it?

The answer, apparently, lies in their guts.

In a study published in the journal Nature Communications on Nov 25, scientists say that after analysing two North American vulture species – black vulture and turkey vulture – they found the birds possess a ferociously acidic digestive system and intestines loaded with two fiendish kinds of bacteria.

In the black and turkey vultures, this gastrointestinal one-two punch effectively knocks out much of the potential disease-causing microbes populating the carrion that the birds eat, says the researchers. “The vulture gastrointestinal passage is a hostile environment,” confirms co-researcher Lars Hestbjerg Hansen, a microbiologist at the Aarhus University in Denmark.

Common in many parts of North America, the turkey vulture, also called a buzzard, is covered with black feathers, has a featherless head with red skin, and boasts a wingspan of nearly 1.75m. Meanwhile, found in southeastern US, the slightly smaller black vulture, with a 1.45m wingspan, sports black feathers and a wrinkled featherless head with dark grey skin. 

They eat dead things: The black vulture (above, left) and turkey vulture, also called buzzard (above, right) – two American species that scientists recently discovered have the guts, literally, to stomach their literally rotten diet. Below, a turkey vulture in flight. Like most birds, vultures have excellent eyesight. But unlike most birds, they also have an amazing sense of smell. Both senses help them in their quest for food, enabling them to spot other vultures circling around food source and also sniff out the rotting meat of dead animals.

These two species are members of a group called the New World vultures that also includes the huge California condor and Andean condor.

Although vultures are more than happy to consume virtually any dead vertebrate – mammal, bird, snake, fish – even they don’t like their food too far gone. “They prefer recently deceased organisms rather than extremely putrid carcasses. For example, day-old road-killed deer are perfect,” says ornithologist Gary Graves of the Smithsonian Institution’s National Museum of Natural History in Washington, also a co-researcher.

The researchers examined the community of microbes, or microbiome, living in the guts of 50 vultures of the two species. The most common bacteria – Clostridia and Fusobacteria – turns out to be widely pathogenic to other animals. For example, Clostridia can cause a world of woes – botulism, gangrene and tetanus – in humans.

The researchers also found that the stomach acid of vultures is very strong and kills a good deal of the bacteria gobbled up by the birds with the rotting meat. “The majority of the food-ingested microbes will not survive these harsh conditions,” says co-researcher Michael Roggenbuck, who works as a microbiologist at the University of Copenhagen. – Reuters