Aggression by vampire bats towards humans and domestic animals is frequent in mangroves in the Amazon region. Bats are sources of infection for several zoonotic microorganisms, including rabies virus. But why does this aggression occur? Is natural prey scarce, or is human presence altering bat feeding behavior? We will monitor bat behavior in human dwellings and mangroves, to learn more about how we can reduce bat aggression and prevent further disease transmission.