Tropical bats of Central and South America regularly eat fermenting fruits and nectar. But they can fly and use their built-in "sonar" just as well while inebriated as while sober—even with blood-alcohol contents that would exceed legal limits for people.

(See more pictures of Central American bats.)

"We went into the study fully expecting that some of the species wouldn’t be able to hold their drink," said study co-author Brock Fenton, a biologist at the University of Western Ontario in Canada.

But "the bats, unfortunately, hadn’t read the proposal," he said.

(Also see "Vampire Bats Biting People.")

In April 2009 Fenton and colleagues caught 106 bats representing six different species in northern Belize. The team gave the bats either sugar water