Bats pretend to be wasps to avoid being eaten by owls

The hum of a rat-eared bat can make the owl think it's a stinging insect, giving the bat enough time to run away. This is the first time that Bates mimicry has been documented in mammals, the team says. In this type of mimicry, a non-venomous species masquerades as a poisonous species in order to avoid being hunted by predators. Researcher Danilo Russo of the University of Naples Federico II in Portici, Italy, and colleagues report the findings May 9 in the journal Current Biology.

Large mouse-eared bats mimic wasps to fool owls.

Russo observed the behavior of rat-eared bats while conducting fieldwork. "When we removed the bats from the net or handled them, they buzzed like wasps," Russo said.

The team thinks that the humming sound is an unusual form of stress cry. They think there's another reason the bat makes a sound. Maybe it's warning its fellow humans or deterring predators. Russo's group put the problem aside and continued with other research problems. Years later, they decided to design a careful experiment to test the mouse-eared bat hypothesis.

In the study, Russo and his colleagues first looked at the acoustic similarity between the calls of bats and other stinging insects. Next, they played the captive owls with sounds to observe their reaction.

Different species of owls react very differently, depending on their previous experience. However, they both responded to the hum of bats and insects by shifting away from the source of the sound. In contrast, the calls of potential prey lure them closer. The team says the finding provides the first example of mimicry behavior between mammals and insects.

The team's analysis of the sounds revealed that the hum of bats and insects were even more similar when heard in the owl's way. They speculated that wasps definitely sting owls, but they don't have the data to prove it. There is other evidence that birds generally avoid venomous insects. For example, when a wasp moves into a nest or hole in a tree, the bird will not nest there.