Study Challenges Long-Held Ideas About Sea Turtle Nesting Habits

Aug 2, 2013

USGS study finds some Loggerhead Sea Turtles traveling up to 250 miles between nesting beaches in a matter of days.
Credit U.S. Fish and Wildlife

New findings on the movement of nesting Loggerhead sea turtles in the Northern Gulf of Mexico challenge some long-held ideas about the threatened turtles’ movement patterns and suggests greater protection efforts are needed for the recovery of the species.

The U.S. Geological Survey study identifies individual turtles that come ashore to nest at sites in Gulf Shores Alabama and the St. Joseph’s Peninsula in the Florida panhandle.  It’s widely held that sea turtles remain relatively close to a particular beach throughout the nesting season, but the USGS study finds that some Loggerheads travel distances of up to 250 miles between nesting events.

“It was surprising to us that within a span of even a week or two, we had animals literally depositing nests at two different sites within that distance,” said USGS Research Ecologist Kristen Hart.  “It’s a much greater area than off just one single beach.  And it’s obviously not just Alabama and not just off Florida.  I mean, some of these animals went all the way to Louisiana and all the way down to Southwest Florida and back.” 

The findings give clues to what’s been a 14 year mystery for study co-author and USGS biologist Margaret Lamont, who’s responsible for the portion of the study based out of St. Joseph’s Peninsula.  “We were finding that we would tag a turtle.  Then we would not see it again.  So we weren’t sure where the turtle was going,” said Lamont.  “Are they dying?  Are they moving someplace else and if they are where are they moving?”

Habitat protection efforts have traditionally focused on areas that are known to be nesting hotspots, but these findings suggest Loggerheads would benefit from expanded beach protections. 

“It is, I think, critically important to understand that it’s not just the high density nesting beach that’s necessary, but it is also these maybe lower density or further away beaches that are potentially being used,” said Hart.

The study also suggests that estimates of this Loggerhead subpopulation could be overinflated.  “If we didn’t’ see the animal, we just saw her tracks, and I saw it in Alabama and then Meg saw it in Florida maybe seven to 10 days later, she would be assuming she saw the track of one turtle that maybe stayed close to her beach,” said Hart.  “And I would have assumed in Alabama that I had seen the track of a turtle that was a different turtle.  So we would have had two turtles that we thought were there when it fact, it was one laying both of those nests.”

The study, “Movements and Habitat-Use of Loggerhead Sea Turtles in the Northern Gulf of Mexico during the Reproductive Period,” was published in July in the journal PLOS One.  The USGS Loggerhead tagging study is ongoing.  “Each year we’ll have some new discoveries of what these turtles do,” said Hart.  “This year we definitely have some turtles that are making us scratch our heads.”