Zebra Stripes: Not Providing Camouflage, Says Study

If zebras' stripes are not used for camouflage, will the world look different to you?

It might to some of us.

Well, there's this: Researchers at the University of Calgary and University of California Davis say that their study of zebras from Tanzania shows that the animals' bold black patterns of stripes are not disguising them from lions or other predators after all.

Their study findings were recently published in the journal PLOS ONE.

"The most longstanding hypothesis for zebra striping is crypsis, or camouflaging, but until now the question has always been framed through human eyes," Amanda Melin at University of Calgary, and lead author of the study, said in a release. "We, instead, carried out a series of calculations through which we were able to estimate the distances at which lions and spotted hyenas, as well as zebras, can see zebra stripes under daylight, twilight, or during a moonless night."

Co-author Tim Caro at UC Davis had provided evidence in previous studies that suggest zebra stripes discourage biting flies. 

This new study showed that by the time that predators can glimpse zebra stripes, they have likely already picked up zebras' scent or sound.

In the course of the research, the scientists put digital images from Tanzania into color and spatial filters to learn how zebras would look to their top predators, lions and spotted hyenas. They also saw how the striped animals would look to other members of their own species.

Through other measurements, the researchers learned that beyond about 164 feet in daylight or 98 feet at dusk, during top hunting times, stripes are visible to humans but more difficult for predators to discern. On dark nights without a moon, most species would have trouble seeing the stripes at about 29 feet. So, most likely the stripes are not suitable camouflage for wooded areas, despite previous theories that dark stripes would look like tree trunks and light stripes would blend with light shafts through trees, according to a statement.

In areas without trees, where zebras live for most of their lives, the findings show that lions could discern a zebra outline just as well as they could pick out prey with a similar size and relatively solid-colored fur or hide.

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