Bats Make Use Of Polarized Light To Navigate

Many people wear sunglasses to avoid polarized light, however this type of light for bats is actually pretty useful and they use it to find their way.

According to new research the greater mouse eared bat is the first mammal known to use polarized light to navigate. The bats make use of polarized rays that are scattered at sunset to adjust their internal compass so that they end up flying in the right direction.

“Every night through the spring, summer and autumn, bats leave their roosts in caves, trees and buildings to search for insect prey,” Stefan Greif, a biologist at Queen’s University Belfast in Northern Ireland and co-author of the study, said in a statement.

Bats are known to fly hundreds of kilometres in a single night and usually return home before the sun rises so that they avoid predators. However, according to Dr. Greif until now it was not clear how they achieved their feats of navigation.

It is a well known fact that bats make use of echolocation to communicate with others and sense prey, however this ability only reaches 50 meters, so it is obvious that these animals are making use of another sense in order to look much further ahead the researchers said.

The researchers showed two types of polarization patterns at sunset to a group of 70 adult females. They then released them at two different sites at 1 in the morning when there was no polarization visible. The bats were released roughly 25 kilometres from their roosts and the researchers attached a small radio transmitter to the bats in order to monitor their movements.

The group that was shown shifted polarized light ended up flying at right angles to the direction of the group that were shown non shifted polarized light. This suggests that the bats make use of polarization to navigate. Bats probably make use of a combination of the position of the sun or stars, echolocation, sight and the earth’s magnetic field to find their way.