bat flying in forest bat flying in forest Bats and windows don't mix. (Photo: Bernd Wolter / Shutterstock)

Why bats can't help flying into windows

New research sheds light on the biological glitch that's threatening the survival of the species.

You know that phrase "blind as a bat"? Well, leave it to science to tell us we've been insulting bats all these years every time we say it. Bats aren't, and have never been, blind. All 1,240 bat species actually see very well, even at night. They also have the benefit of echolocation to help them navigate darkness, and some species even have the ability to detect ultraviolet light, which are wavelengths of color that humans can't even see.

But amid all this eye-opening information, there is one setback that could be threatening the future of these animals. It's a biological glitch in their ability to distinguish smooth, vertical surfaces – like windows – from open pathways. Sometimes they even think the surfaces are water and try to drink it.

bats hanging from a caveThere's some pretty groundbreaking work being done at the Bat Lab at Tel Aviv University. (Photo: Ethan Daniels/Shutterstock)

Darkly comical as that may sound, it's actually quite serious; the error is causing the bats to consistently crash into these surfaces, causing sometimes fatal injury. The surfaces act as sensory traps for the bats and are harming their ability to interpret their environment, especially when they're moving quickly.

That's the findings of a new study led by Stefan Greif, a zoology researcher at Tel Aviv University, and colleagues from the Max Planck Institute for Ornithology in Seewiesen, Germany.

The researchers studied three bat species in a small flight room where they could control the speed of the bats' flight to avoid injury. They also observed the bats in the wild, sneaking in flat metal plates in both locations and monitoring the bats' responses.

Conclusion? Sharp vision and echolocation can only go so far when you add unnatural obstacles like windows and mirrors to the mix. The structures just don't compute with a bat's navigation behavior.

A group of bats hang on a tree in Cairns, Australia.A group of bats hang on a tree in Cairns, Australia. (Photo: The Editors/Shutterstock)

This is especially a problem in urban areas with tall buildings and large glass facades, Greif said.

"If there are no echoes coming back to the bat except strong, perpendicular echoes from underneath, it is a clear sign of water for the bat," he said. "The exact same echoes coming from the side, however, signal an obstacle for the bat in the flyway that so far was perceived as open." Greif is currently getting a post-doc in Israel where he's studying with Dr. Yossi Yovel, founder of The Bat Lab and a professor of neuroscience at Tel Aviv University.

While not exactly good news, the new study does explain why so many bats are being injured or killed by man-made structures. And it gives us one more reason to help save them: after all, bats are really good at eating invasive insects, significantly reducing the need for pesticides for farmers. Also, one bat species is a key pollinator of agave, the plant used to make tequila. Cheers to bats! Someone please invent a bat air bag!


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Why bats can't help flying into windows
Bats aren't blind, contrary to popular belief. But they do have a biological glitch that lets them fly into windows, according to a new study.