Image copyright Getty Images Image caption Wild breeders say the family helps to feed female vultures
Vultures have evolved to become meat-eating relatives called chitres in tropical forests, a study finds.
The insects share a common ancestor as they share part of their DNA.
Discovery of chitres may help to explain why these vultures are roaming the planet.
They are found throughout tropical and sub-tropical regions and are vital predators of the competition.
In tropical regions, they have been shown to be essential to the very survival of the species they prey on.
To try to understand why, scientists sequenced the vulture’s genome – the total DNA of its species – from tissue samples collected by wild-caught birds of prey – including the fox vulture and the chitres.
Image copyright Getty Images Image caption Vultures are important predators of other species
But despite being related genetically, their stomach and gut bacteria have not been exposed to each other.
The research, published in the journal Nature Communications, suggests that chitres evolved specifically to eat meat – not sweet and fatty fruits.
However, they have other functions, including as a filter, which removes pathogenic bacteria from leaves.
They could have evolved in response to certain threats – such as predators.
The study was co-led by scientists from the Wildlife Conservation Society and Columbia University in New York and the Centre for Comparative Genomics in Florida.
Dr Adil Abed, a research fellow at Columbia, said: “We didn’t understand the complete genetic sequence and therefore couldn’t directly say that the chitres had evolved to eat meat, but what is clear is that the chitres do not have the nutrient-dense coliform bacteria, which is usually found in pastures, insects and animal parts such as poultry wings and feet.”
Natural selection was likely driving the evolution of their digestive system, he said.
“Wherever chitres have been documented over the last 60 million years, they contain a diverse and quite complex mix of bacteria.
“In terms of the actual stomach structure, we observed that all of them possessed structure commonly found in terrestrial mammals – namely, a slant tube that exits the throat through the stomach and an opened route out through the esophagus.
“The chitres’ ability to process meat was most likely developed during a temporary period of low food availability, when specific pathogens were more abundant, but when food returned, the capacity to chew meat became more important.”
How a ‘pigeon neck’ looks
Dozens of species of wild chitres are common in tropical and sub-tropical forests.
“A real example of this unique bird is the Baldica drosophila (Chitres word for swan neck),” said conservation biologist Corne Fraser at the Wildlife Conservation Society.
“Our researchers in Indonesia and the Republic of Congo stumbled upon it when they were counting “wildlife singlets” – a once common sight of avian refuges in the forest.”
In Europe, wild vultures have migrated to countries including Slovenia, Spain, Italy, Croatia, France, Germany, the Netherlands, Belgium, Switzerland, Ireland, and the Isle of Man.
They are known to be nesting in caravans and on mountaintops in New Zealand and Australia.
Birds’ diet helps to sustain the birds and they have evolved to feed on largely plant food.
“Wild chitres [have evolved] to become modern bee-eating vultures using plant food to enhance their ability to feed females without direct contact with their ecosystem. No such invasion has been seen, therefore, in relation to wild birds in North America or Europe,” Dr Fraser said.
“By marrying this with their previous adaptations to eat insects, a unique avian ecosystem has been recreated in central and eastern Africa,” he added.
While the newly identified chitres have specific gut bacteria, larger samples have shown that they can also be found in birds with equal genes.
Image copyright Getty Images Image caption Vultures are not shown to be dangerous to humans
Birds of prey can have their vulture DNA sequenced, making them the first vertebrates to be publicly accessed as genomic data.
“It is a public data product made available in an open access manner to researchers, and this allows the knowledge regarding the genetic diversity of the wild bird fauna to be shared with the public,” Dr Fraser said.
“Even if the scientific community does not necessarily need the data, you have one fewer factor that the species that you live with can be vulnerable to.”