At sunset, a distinctive pattern of polarised light sends a dark band across the sky, visible only to those who can see it.
Scientists have known for a while that birds, insects and amphibians can see these polarised light patterns – in fact, even some humans can see polarised light in the right conditions. But for the first time, mammals – bats – have been shown to not only see this light, but to use it as a ‘reset’ mechanism to help them calibrate their internal magnetic compass.
The senior author on the paper about this discovery, Dr Richard Holland from Queen’s University Belfast, was also one of the team that discovered how bats navigate using the Earth’s magnetic field. He, along with the rest of his team, placed the bats in specially-made boxes at sunset: one box reproduced the correct pattern, and the other rotated it by 90 degrees. All the bats were then released, and those who’d been in the 90-degree box had far more difficulty navigating home.
What still remains a mystery is how the bats can sense and use polarised light like this.
[Source: BBC News]