Migrating Sea Turtles Use Magnetics to Find Home

After they hatch, sea turtles travel for thousands of miles out in the open ocean, later to mysteriously return to the beaches where they were born. And now new research reveals that they use unique magnetic signatures to find their way home again.

"Sea turtles migrate across thousands of miles of ocean before returning to nest on the same stretch of coastline where they hatched, but how they do this has mystified scientists for more than fifty years," researcher J. Roger Brothers of the University of North Carolina at Chapel Hill said in a statement.

"Our results," he continued, "provide evidence that turtles imprint on the unique magnetic field of their natal beach as hatchlings and then use this information to return as adults."

While previous research has indicated that seat turtles use the Earth's magnetic field as a guide out in the open ocean, scientists still weren't sure if they used the same unique method to locate the comforting beaches they called home.

"We reasoned that if turtles use the magnetic field to find their natal beaches, then naturally occurring changes in the Earth's field might influence where turtles nest," Brothers explained.

So Brothers and his colleagues analyzed a 19-year database of loggerhead nesting along Florida's eastern coast, the largest sea turtle rookery in North America, looking for changes in behavior.

As described in the journal Current Biology, subtle shifts in Earth's magnetic field determined the spatial distribution of turtle nests. For example, when the Earth's field shifted so that magnetic signatures of nearby locales along the beach moved closer together, nesting turtles huddled along a shorter stretch of coastline. In contrast, areas where magnetic signatures deviated caused loggerheads to spread out their nests, making them few and far between.

Scientists suspect that tiny magnetic particles in turtles' brains allow them to sense magnetic signatures emitted by beaches and return to the sites chosen by their mothers; however, more research is needed to say for sure.

As for why they have their sights set on certain beaches, it's because successful nesting requires rare features such as soft sand, perfect temperatures, few predators and easy access; and there's no place like home.

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