Wild vampire bats, thought to exclusively feed on bird blood, have been found feeding on humans for the first time, raising concerns of disease spread, scientists say.
Researchers analysed 70 faecal samples from a colony of hairy-legged vampire bats, D ecaudata, living in Catimbau National Park in north-east Brazil.
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They found that three samples out of the 15 they managed to get DNA from had traces of blood from humans.
"We were quite surprised. This species is not adapted to feed on the blood of mammals," said Enrico Bernard from the Federal University of Pernambuco in Brazil.
The bats typically target large birds at night-time, sucking a spoonful of blood from a single animal as a meal.
They are adapted to process fat, the main component of bird blood, as opposed to the thicker, high-protein blood of mammals, 'New Scientist' reported.
However, human encroachment may be driving the species to try new blood. The park is now home to several human families and the bat's usual prey, such as guans and tinamous, are disappearing due to deforestation and hunting.
Researchers also found that most of the samples they tested contained the blood of chickens, commonly kept on farms in the area.
"They are adapting to their environment and exploiting the new resources," said Bernard.
Previously, common vampire bats were found to start feeding on invasive wild pigs.
The species' new habits are a concern since it could spread disease, researchers said, adding vampire bats are a major transmitter of rabies, and there are often outbreaks in Brazil.
The research was published in the Journal Acta Chiropterologica.
