Posted on August 23, 2013 by Abi Cushman

Unfortunately for Cosette, her natural brown coloring does nothing to camouflage her in our apartment.

Wild rabbits are well concealed in the brush by their brown (agouti) coloring. But one thing gives them away – that flash of white from their tails as they’re bounding away.

So why did rabbits evolve to have a white tail, and not a brown one? (Or a green one?)

Evolutionary biologist Dirk Semmann of the University of Göttingen in Germany thinks he knows the answer.

White Tail as a Distraction

Semmann believes the obvious, white coloring of the rabbit’s tail actually distracts and confuses predators as the rabbit darts back and forth. A predator focuses on the white tail during the chase, and then when the rabbit turns, the white disappears.

It takes a second for the predator to regain focus on the rabbit after every sharp turn… and these seconds can add up to enough time for the rabbit to escape.

According to Semmann, “The idea first appeared when I was running,” says Semmann. “I met this rabbit; it was always running and turning at some point. That got me thinking about the problem.”

Putting the Theory to the Test

To test his theory, Semmann used a video game on a group of people which involved either a flashing, bright circle (the white tail) or a non-flashing circle that blended in with the background.

The presence of the flashing circle reduced the participants’ ability to “catch” it.

Learn more on Nature.com.