Rabbits' Distinct White Tails may Provide Evolutionary Advantage

The fluffy, white "cotton" tail of a rabbit may have evolved to provide the animals with a tactical advantage while being chased by predators, according to a new study by German researchers.

Rabbits' bright white tails seem out of place compared to the creatures' darker brown fur, and some evolutionary biologists have wondered just why the rabbits' tails are so distinctive.

In a new study, Dirk Semmann, an evolutionary biologist from the University of Göttingen, contends that rabbits evolved their white tufts to distract and confuse predators.

As a rabbit is being pursued by predators, it makes quick, sharp turns. Semmann theorized that the rabbit's tail acts as a focal point and by making rapid movements, the rabbit's predator is forced to constantly refocus on the animal, which provides the rabbit with a better chance to escape.

Semmann came to reach his theory after seeing a rabbit while he was running along a park trail. As the rabbit moved about, it made swift turns, keeping Semmann guessing as to which direction it was heading.

"The whole animal is turning around, you don't see the tail anymore," Semmann told NBC news about that encounter.

To test his theory, Semmann devised a simple video game and asked 24 people to play. The object was to follow a virtual rabbit as it made sharp turns left or right. One virtual rabbit had a white dot for its tail tail and another had no tail.

As the game ran, the human participants has to press buttons corresponding to the direction of the virtual rabbit's movement; if the rabbit turned left, the player would have to then press the correct corresponding button. The players usually made the right choices when with the tailless rabbit, but not always with the white-tailed version.

"We found a significant difference ... when the 'tail' was present, the participants made more incorrect answers, more mistakes," Semmann told NBC.

In a second scenario, the test participants were offered a cash prize when they could correctly predict the rabbit's movement, much like a predator would have to do in order to have a successful hunt. In this scenario the the tail made all the difference, with the player's chasing the white-tailed rabbit making significant incorrect predictions, something Semman suggests is akin to being thrown off course.

Semmans presented his work at the Behavior 2013 conference in Newcastle, UK.