Bats imitate hornets to avoid being eaten by owls
When a greater mouse-eared bat (Myotis myotis) is caught by an owl, it mimics the buzzing of hornets to fool the predator.
The buzzing call of the mouse-eared bat may lead an owl to think it is a stinging insect, buying the bat enough time to escape. The researchers say this is the first documented case of Batesian mimicry in a mammal. In this type of mimicry, a harmless species imitates a harmful one to avoid being hunted by predators. Danilo Russo of the University of Naples Federico II in Portici, Italy, and colleagues reported the finding on May 9 in the journal Current Biology.
The greater mouse-eared bat mimics the sound of hornets to fool predatory owls. (Photo: Marco Scalisi)
Russo observed the behavior of mouse-eared bats while conducting field research. "When we removed the bats from nets or handled them, they kept buzzing like hornets," Russo said.
The team thought that the buzzing sound was an unusual kind of distress call. They suspected the bats had another reason for making the sound, perhaps to warn others of their kind or to deter predators. Russo's group set the question aside and moved on to other research. Years later, they decided to design a careful experiment to test their hypothesis about the mouse-eared bat's buzzing.
In the study, Russo and colleagues first examined the acoustic similarities between the bats' calls and those of stinging insects. Next, they played the sounds to captive owls to observe how they reacted.
Different owl species responded in a variety of ways, depending on their previous experience. However, they all reacted to the buzzing of both bats and insects by moving away from the source of the sound. In contrast, the calls of potential prey drew them closer. The team says the finding provides the first example of mimicry between a mammal and an insect.
The team's analysis of the sounds revealed that the buzzing of the bats and the insects became even more similar when heard the way owls hear them. The researchers suspect that hornets do sting owls, but they have no data to prove it. Other evidence shows that birds tend to avoid venomous insects. For example, when hornets move into a nest box or tree hole, birds will not nest there.
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