Birds Eat Bats

From the "ecological pressure paired with opportunism can lead to surprising innovations in animal behavior" department:

Five-inch songbirds known as great tits (Parus major) have been found to feed on 2-inch-long hibernating pipistrelle bats (Pipistrellus pipistrellus) at a Hungarian cave.

Over two winters, researchers directly observed 18 predation events. The birds "specifically and systematically searched for and killed bats for food," the researchers write in Biology Letters.

When scientists provided other food, the birds stopped hunting bats. The scientists used recordings and loudpseakers to mimic the sounds of bats waking up. "The tits could clearly hear the calls and were attracted to the loudspeaker," the scientists write.

When the birds do get a bat, the death goes like this:

"The birds don't kill the bats before they start eating them," researcher Björn Siemers said in New Scientist, "but the bats eventually die when the birds peck open their brain case."