A 2016 issue of the journal Acta Chiropterologica provided evidence that vampire bats species D. ecaudata  have recently shifted their diet from strictly birds to include humans and livestock.

What could cause this (terrifying) adjustment? The evidence points to humans. Birds in Brazil, the vampire bat’s habitat, are known to be extremely sensitive to human interference, and heavy deforestation in Brazil may be causing the birds they feast upon to be harder and harder to find.

Thankfully, these bats can not survive on strictly human blood, as it lacks the water and fat content of the bat’s natural prey. However, this could pose a very large risk to humans, as bats are carriers of rabies.

If you live in Brazil, maybe reconsider leaving your window open at night…

(https://www.yahoo.com/news/well-sucks-vampire-bats-found-152300535.html)