Bats have a novel device for guiding them home on starless nights. In addition to their well-known sensory talents, it seems that big brown bats can tune into the Earth's magnetic field, using it as a compass to guide them to roost.
This ability comes in handy on long-distance flights, where their usual mode of navigation - bouncing sounds waves off objects using ultrasound - doesn't do much good.
Richard Holland from Princeton University, New Jersey, and his colleagues looked at 15 North American big brown bats (Eptesicus fuscus), which travel up to 100 kilometres to find hibernation sites for the winter.
To first test the animals' natural navigational abilities, they attached small radio transmitters to the bats and transported them 20 kilometres from their roost. One by one they let them go, and tracked them from a small aircraft. All of them headed directly back to their roost.
How did they do this? Scientists have previously suggested that bats might use the direction of the sunset to set their compass. Others have found traces of magnetic materials within bats, suggesting that they might use the planet's magnetic fields to find north.
To tease these effects apart in a single experiment, the scientists put the bats inside a helmet that generates a strong magnetic field offset from the planet's true north. They let the bats watch sunset while sitting in this artificial magnetic field for about an hour and a half. "We then took them to the same release site," says Holland. And they all took off in the wrong direction. "It was a neat trick".
This ability comes in handy on long-distance flights, where their usual mode of navigation - bouncing sounds waves off objects using ultrasound - doesn't do much good.
Richard Holland from Princeton University, New Jersey, and his colleagues looked at 15 North American big brown bats (Eptesicus fuscus), which travel up to 100 kilometres to find hibernation sites for the winter.
To first test the animals' natural navigational abilities, they attached small radio transmitters to the bats and transported them 20 kilometres from their roost. One by one they let them go, and tracked them from a small aircraft. All of them headed directly back to their roost.
How did they do this? Scientists have previously suggested that bats might use the direction of the sunset to set their compass. Others have found traces of magnetic materials within bats, suggesting that they might use the planet's magnetic fields to find north.
To tease these effects apart in a single experiment, the scientists put the bats inside a helmet that generates a strong magnetic field offset from the planet's true north. They let the bats watch sunset while sitting in this artificial magnetic field for about an hour and a half. "We then took them to the same release site," says Holland. And they all took off in the wrong direction. "It was a neat trick".
No comments:
Post a Comment