Magnetic Sea Turtles

January 21, 2015

BOB HIRSHON (host):

Loggerhead sea turtle hatchlings crawl to sea - Blair Witherington - FWC Fish and Wildlife Research Institute - Flickr — If they survive to adulthood, these loggerhead sea turtle hatchlings will return to their natal beach to lay their eggs. (Blair Witherington/FWC Fish and Wildlife Research Institute/Flickr)

Turtles’ animal magnetism. I’m Bob Hirshon and this is Science Update.

Scientists have long suspected that baby loggerhead sea turtles remember the magnetic signature of their birth – or natal – beach, and use that information to return years later to lay their eggs. In the journal Current Biology, marine biologist Roger Brothers at the University of North Carolina, Chapel Hill reports strong evidence of this. He says the earth’s magnetic field changes over time.

ROGER BROTHERS (University of North Carolina, Chapel Hill):

So the magnetic signature that marked the natal beach as a hatchling is going to be somewhere else when the adult turtle returns.

HIRSHON:

He and his colleagues found that when the magnetic signatures spread out over the years, the nesting sites were further apart; when the magnetic signatures had moved closer together, the turtles dutifully nested nearer one another—strong evidence that the loggerheads navigate by earth’s magnetic guideposts. I’m Bob Hirshon, for AAAS, the science society.