The pros and cons of large ears

Date:  November 10, 2017

Source:  Lund University

Summary:

Researchers have compared how much energy bats use when flying, depending on whether they have large or small ears.

Large ears increase air resistance, meaning that long-eared bats are forced to expend more energy than species with small ears. On the plus side, large ears generate more lift and provide better hearing.

Good hearing is a prerequisite for bats' ability to echolocate, i.e. sense the echo of the sound waves they emit in order to locate and home in on their prey.

The research results therefore show that large ears have both pros and cons. Christoffer Johansson Westheim, senior lecturer at Lund University, believes that evolution has made a compromise.

"The crux is being able to fly as efficiently as possible while also having optimal echolocation ability. Bats can't be the best at both these things at the same time," he says.

The research findings also support the hypothesis that birds migrate to a greater extent than bats, and over longer distances, because bats' ears create resistance that makes flying more energy-intensive.

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