Blood Tests Show Where Loggerhead Turtles Go

Every year, thousands of endangered loggerhead sea turtles crawl ashore at Florida's Archie Carr National Wildlife Refuge to lay eggs before dragging their leathery bodies back into the sea. But where they go after their trek isn't well-known.

Scientists can use GPS devices to record turtles' travels, but these geolocator tags are expensive, and may be lost if turtles die. A group of researchers has come up with a less expensive, easier way to find out where loggerheads voyage: testing their blood. A new study, published Sept. 20 in the journal PLoS ONE, found that this technique is just as accurate as using GPS tags.

The technique examines carbon isotopes in the turtles' blood, which come from the food the animals eat. Carbon has different isotopes, or variants, present in all living things, and the exact mix of isotopes varies by region; for example, the mixture in the mid-Atlantic is different from that of the Caribbean. By examining the mixture of carbon isotopes in the turtles' blood, scientists could determine the region to which the turtles migrated.

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