Pigeons 'trust their gut' to get home

For decades, scientists have been studying how animals find their way around Earth.

Now, new research on homing pigeons suggests that the birds could be trusting their guts - literally.

Scientists have known for years that homing pigeons rely in part on Earth's magnetic field to navigate - but the big question was how they did it.

A study published in Science journal suggests that special cells in the liver of pigeons can sense Earth's magnetic field, effectively giving the birds an internal compass.

Scientists in Germany found millions of iron-filled white blood cells near the birds' liver, suggesting these cells could tell the brain which direction to go, based on the Earth's magnetic field - in the way iron responds to a magnet.

Usually pigeons use sunlight as their first guide and rely on the magnetic field in poor weather conditions, so the scientists had to make sure it was a cloudy day to test their theory.

About 24 hours before a cloudy day, the researchers gave some homing pigeons a treatment that affects the iron in their cells, and left some pigeons as normal.

They drove them all 19km away and then released them - with GPS trackers attached.

Those without the treatment reached home in about 70 minutes.

The rest flew in random directions and didn't make it back home until the Sun came out the next day.

When it was tested on sunny days, the pigeons who were given the treatment were able to fly directly home, using the Sun.

"Animal navigation is one of the most fascinating phenomena in nature," says Professor Martin Wikelski, who co-wrote the study.