Despite the common misconception that zebra stripes are used for camouflage in order to avoid predators, a new study by researchers at the University of California, Davis suggests that this is not the case.
"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, lead author of the study, said in a press 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."
The team utilized digital photos of a field in Tanzania and passed them through spatial and color filters in order to simulate how zebras would appear to lions and spotted hyenas, their primary predators, as well as other zebras. Furthermore, they measured the width and light contrast of the stripes in order to get an idea of the maximum distance that they could be spotted using information about hyena, lion and zebra visual capabilities.
The results showed that stripes are unable to be a camouflage mechanism due to the fact that the point that predators can see zebra stripes is at a range close enough that they likely already heard or smelled the zebras. Furthermore, in open, treeless habitats, the areas that zebras spend most of their days, lions could spot the outlines of zebras just as easily as smaller-sized prey.
"The results from this new study provide no support at all for the idea that the zebra's stripes provide some type of anti-predator camouflaging effect," said Tim Caro, co-author of the study. "Instead, we reject this long-standing hypothesis that was debated by Charles Darwin and Alfred Russell Wallace."
The findings were published in the Jan. 22 issue of PLOS One.