Vampire bats do not respect the myths and stories and they don’t feast on human blood. Or so we thought. Scientists conducted a study that found the first species of vampire bat to consume human blood.
The protagonist of the study is the hairy-legged vampire bat (Diphylla ecaudata), found in the forests in northeastern Brazil. It is one of the three species of vampire bats that feed only on blood. Scientists thought that birds were the only prey of this type of vampire bat, but after further analysis they discovered a new favorite on their list of food – humans.
An explanation to the shift in the diet of vampire bats may be the difficulty to find birds. Therefore, they switched to a prey that is easier to find. This hints that even the most specialized bats can change their diet if necessary.
Vampire bats are to be found only in America. Their way of feeding reminds of the old vampire myths. They puncture the skin of their prey and produce small incisions through which they consume the flowing blood that, by mixing with saliva, is prevented from coagulating too quickly. Also, vampire bats appear not to store fat in their bodies and can go on without eating for more than a couple of days.
In order to find out what other choices they have to feed upon, the scientists collected 70 fecal samples form a cave in Catimbau National Park, Brazil. The analysis showed that the bats were feeding on chickens and – here it comes – humans. Bird blood is richer in water and fat than mammal blood and has higher concentrations of protein. This suggests that the bats were probably not able to survive only on human blood and fed also on birds that are not usually their prey, but are easier to get.
It is still the humans’ fault for the scarceness of birds in the forests around the vampire bat colonies. About half of the 510 species of birds native to Caatinga – the region surrounding Catimbau National Park – are very sensitive to human action.
The switch in the diet of vampire bats was regarded by the scientists as “an interesting ecological exercise”, but it also raises concerns about public health, since the risk of rabies transmission will be increased.
Image Source: Wikimedia Commons