Zebra Stripes Are Probably Not For Camouflage, According To Recent Study

Zebra stripes are probably not for camouflage, according to a recent study conducted by the University of California Davis in conjunction with the University of Calgary. Although the camouflage hypothesis is long-standing and was widely accepted, the reasoning may be flawed, as scientists have always viewed the magnificent animals “through human eyes.”

Out to Africa explains the camouflage hypothesis, which is commonly attributed to biologist and naturist Alfred Russel Wallace.

“The black and white stripes are a form of camouflage called disruptive coloration that breaks up the outline of the body. Although the pattern is visible during daytime, at dawn or in the evening when their predators are most active, zebras look indistinct and may confuse predators by distorting true distance.”

In addition to camouflaging, or crypsis, there are four other hypotheses about zebra stripes. National Geographic reports scientists have suggested the bold patterns may serve to confuse predators, reduce body temperature, repel insects, or aid in social interaction.

Although numerous studies have been conducted to determine why zebras have stripes, it is still unclear whether they serve one specific purpose or a combination of several.

Biologists from the University of California, Los Angeles, concluded that “temperature is the factor most strongly linked to striping: More specifically, the warmer it is, the more stripes on the zebra.”

The researchers, who published their results in the journal Royal Society Open Science in January 2015, studied 16 different African zebra populations.

National Geographic reports the biologists compared “29 different environmental factors” to determine whether they were related to the zebras’ stripe density and patterns.

The researchers have two theories that may explain why the stripes were denser on zebras living in warmer climates.

Brenda Larison, who led the study, noted zebras in warmer climates have “lower skin temperature than other non-striped animals in the same area.” This may be due to the “cooling eddy” theory, which suggests currents of warm air move faster over the zebra’s black stripes and slow down over the white stripes. As the speed of their air flows conflict, they could form eddies, which may cool the zebras’ skin.

The other theory suggests the striping patterns serve to confuse biting flies, which are more prominent in warmer climates.

An early study, conducted by researchers at Sweden’s Lunds University, also supports the theory that the stripes are a natural insect repellant.

As reported by National Geographic, the researchers used patterned and plain glue strips to determine which ones attracted and which ones repelled biting flies.

The biologists concluded the strips with a black and white zebra stripe pattern attracted fewer flies. Evolutionary ecologist Susanne Åkesson, who led the study, said the zebra stripe pattern essentially confuses the flies and repels them away from the animals’ skin.

Although the stripes may serve as a form of camouflage to protect zebras from biting flies, a recent study dispels theories that the patterns also protect them from larger predators.

Voice of America reports the University of California Davis and University of Calgary researchers found zebra stripes do not provide protection from predators, as they will likely smell the animals before they would see them. Therefore, a visible camouflage would essentially be useless.

The researchers also concluded the stripes, as seen through predators eyes, simply do not “disrupt the outline” of the zebra’s body as previously believed.

Wildlife biology professor Tim Caro, who co-authored the University of California Davis and University of Calgary study, said the research clearly disproves zebra stripes serve as a form of camouflage.

“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… Instead, we reject this long-standing hypothesis… “

The study also discredits theories that zebras use the stripes for identification purposes.

Although the researchers did not reach a conclusion as to what purpose zebra stripes do serve, they suggest the theory about deterring biting flies is the most probable.

[Image via Jamen Percy/Shutterstock]

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