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For the first time, scientists have observed Diphylla ecaudata, a species of vampire bat in Brazil, feeding on human blood.

Researcher Enrico Bernard spoke with As it Happens about this bat — sometimes called the "hairy-legged vampire bat."

Bernard is a biologist at the Federal University of Pernambuco and the author of this new study. Here's part of his conversation with guest host Helen Mann.

HELEN MANN: Professor Bernard, how has this particular vampire bat's diet changed?

"The local large bird species were gone — hunted to extinction. So, this species is now feeding on chicken and also on human blood." - Biologist Enrico Bernard

ENRICO BERNARD: Well, if you look in the literature, all the previous reports pointed out that this species was specialized on feeding on the blood of birds. For the first time, we reported human blood [present in] the diet of Diphylla. So, basically, we proposed this species is changing its diet because they don't have natural prey anymore in the area. The local large bird species were gone — hunted to extinction. So, this species is now feeding on chicken and also on human blood.

HM: Before we get to the human blood... Why would it be unusual that they feed off chickens, given chickens are birds?

Enrico Bernardo installs monitoring equipment in a cave in Catimbau National Park, Brazil. (Eder Barbier) EB: Yeah, but you have to remember that a chicken is not a wild animal. It is a domesticated animal that is raised by humans. The historical natural prey of this species is large birds like the white-browed guan and the yellow-legged tinamou. Yeah, but you have to remember that a chicken is not a wild animal. It is a domesticated animal that is raised by humans. The historical natural prey of this species is large birds like the white-browed guan and the yellow-legged tinamou.

HM: So, basically, this proves to you that they're running out of their regular diet?

EB: That's correct. In our paper, we discuss exactly that point. We are hypothesizing that this species [doesn't] have the natural prey anymore and is keeping the diet for other common species in the area, which are chicken and eventually human blood.

We're showing that at least a second species of vampire bat is now feeding on human blood. - Enrico Bernard

HM: I suspect that Hollywood has convinced many people that vampire bats do drink blood from humans. Is this unusual?

EB: Worldwide we have three species of vampires bats. We have 1,500 species of bats. Just three feed on blood. Among these three species, one — which is the common vampire bat — is quite common in Latin America. There are previous reports of this species feeding on cattle, pigs and eventually on humans. The other two species of vampire bats are more rare and [are] supposed to be specialists on birds. So, we're showing that at least a second species of vampire bat is now feeding on human blood.

HM: How were you able to make this discovery?

EB: Well, we are monitoring a cave in this national park for almost three years. The first time I went to this cave, I [saw this] small colony of Diphylla. Diphylla is a quite rare species of bat. I've been working with bats for almost 20 years and that was the first time I saw live specimens of Diphylla in front of me... The colony was doing well. The bats were doing well. They have babies. They are reproducing. I said, 'What kind of animals are these bats feeding on, considering that, outside the cave we are in an area strongly affected by human presence?' So, we decided to use DNA to discover the prey the Diphylla were feeding on. So, we collected the feces of these animals, we sent the samples to the lab, we did an extraction of the DNA... and we discovered chicken and human. That's very interesting because it shows the diet of the species is more adaptive than we presumed.

Professor Enrico Bernard studied vampire bats in Brazil's Catimbau National Park. (Enrico Bernard)

HM: Do you know if any people who live in the region have been complaining about being attacked by bats?

EB: By coincidence, this morning, I just spoke with [health workers] in the area. There are no reports of people complaining of being bitten by bats there. So, that opens another question. We don't know how far this species is able to fly. But, it's probably feeding on humans that are far from the roost. We now have several other open questions that we need to investigate. Who are these people that have been bitten by bats? How far are these people from the roost? How frequently are they being bitten?

HM: Is it dangerous for these humans to be bitten by bats?

EB: Like any other mammal, bats are able to transmit some diseases to humans. Like dogs, cats, raccoons, bats may also transmit some virus. It's concerning. We have to be careful. This person has to look for a hospital and request for vaccination as soon as possible. The fact a person was bitten by a bat doesn't mean she or he will contract rabies. But, this person has to receive a vaccination as soon as possible.

This transcript has been edited for length and clarity. For more on this story, listen to our full interview with Enrico Bernard.