Lost birds can use Earth's magnetic signature to get back on track

Feb. 12 (UPI) -- Dozens of studies have shown many species, especially those that travel long distances, rely on Earth's magnetic fields to orient themselves.

It turns out, magnetic field lines don't just act like guard rails or straight-line guides for a bird's migration path, they can also help birds that wander off course get back on track.

For reed warblers, the Earth's geomagnetic signatures offer directional cues that keep working far from home.

To better understand how birds regain their bearings after becoming blown off course mid-migration, researchers kept several reed warblers in captivity for a few weeks before releasing them into the wild and exposing them to the magnetic signatures of locations several thousand miles away -- far from their natural migratory corridor.

Despite being released into a place they knew well, a place that looked, smelled and felt like home -- because it pretty much was home -- all of the warblers set off to begin they migratory journey flying as if they were departing from the location simulated using the faux magnetic field signatures.

Scientists detailed their observations in a new paper, published Friday in the journal Current Biology.

"The overriding impulse was to respond to the magnetic information they were receiving," study co-author Richard Holland, researcher at Bangor University in Wales, said in a news release.

"What our current work shows is that birds are able to sense that they are beyond the bounds of the magnetic fields that are familiar to them from their year-round movements, and are able to extrapolate their position sufficiently from the signals," said Holland, a researcher at Bangor University in Wales.

This sophisticated ability allows birds to make their way back to their natural migratory route when strong storms and atmospheric winds blow birds well of their preferred course.

Researchers call this ability "true navigation."

"They are able to return to a known goal after displacement to a completely unknown location without relying on familiar surroundings, cues that emanate from the destination, or information collected during the outward journey," said lead author Dmitry Kishkinev, researcher at Keele University in Britain.

Scientists previously showed reed warblers can use magnetic clues to navigate their natural environs. The latest findings suggest the same navigational abilities work in foreign environs.

But researchers say additional studies are needed to determine whether they are using something comparable to map-reading or more akin to compass-reading.