Jul 23, 2014 11:14 AM EDT By Russell Westerholm, UniversityHerald Reporter

A first among mammals, bats apparently use polarized light to set their inner compass, scientists have discovered in a new study.

According to BBC News, the study's senior author Dr. Richard Holland was part of a study in 2006 that discovered how bats rely on the Earth's magnetic field for flight. However, with his new study, he learned that bats used polarized light in the evening hours, the animal's wake-up time, to calibrate their inner compass.

Holland's team published the study in the journal Nature Communications.

"We initially didn't think that the bats would use polarised light," the researcher at Queen's University in Belfast told BBC News. "We thought that surely, the sun's disc itself would be a more likely cue."

To test their theory, the team placed a group of bats in a closed environment with polarized windows. The bats were found in a cave in Bulgaria, so the team of scientists tracked the bats as they were released to try and find their way from the boxes where they were kept back home.

"Every night through the spring, summer and autumn, bats leave their roosts in caves, trees and buildings to search for insect prey," study lead author Stefan Greif, also of Queen's University, said in a press release. "They might range hundreds of kilometers in a night, but return to their roosts before sunrise to avoid predators. But, until now, how they achieved such feats of navigation wasn't clear.

"Most people are familiar with bats using echolocation to get around. But that only works up to about 50 meters, so we knew they had to be using another of their senses for longer range navigation."

Dr. Marie Dacke, an animal vision researcher at Lund University in Sweden, said humans can perceive polarized light as well. However, bats were believed to be like certain birds, fish, amphibians and insects in that they could only detect polarized light.

"But in birds and fish and so on, we don't really have a clue about how they're able to perceive this kind of light," she told BBC News. "I did not expect them to find that in mammals, such as in a bat. So I thought this was really fascinating.

"The big challenge will actually be to find the mechanism by which bats are able to do this. There is still a bit to reveal before the full story is known."

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