Sanibel and Captiva’s record sea turtle nesting season continues, with 1,171 nests laid across the islands as of July 26.

While nearly all the nests laid on Sanibel and Captiva each year are from loggerhead sea turtles (Caretta caretta), the islands also see around 10-30 green sea turtle (Chelonia mydas) nests per season, with higher green nest counts every other year. This year, 23 green sea turtle nests have been laid so far. 

The tape and stakes marking off nests may not differ between loggerheads and green turtles, but each species possesses unique characteristics. SCCF Sea Turtle Biologist Jack Brzoza explains some of these differences below. 

Tracks

The differences between loggerhead tracks and green tracks can be quite distinct. Loggerheads crawl with an alternating gait, meaning they move up and down the beach using their right and left front and rear flippers separately, which leaves asymmetrical marks in the sand. You can think of it like an ‘army crawl.’

Alternatively, greens turtles crawl using their left and right flippers simultaneously. This produces a track with symmetrical flipper marks. Green turtles’ tails also typically cause a drag mark through the center of the crawl, whereas loggerhead tails usually don’t. 

Lastly, green turtles tend to be larger than loggerheads, so their tracks are generally wider. A green crawl might be 3 to 4.5 feet wide, whereas a loggerhead crawl is usually around 2.5 to 4 feet wide.

The Nest

The nest area where a clutch has been deposited can also give us clues to which sea turtle species laid it. Compared to loggerheads, a green turtle nest is much larger. They disturb a larger area of sand during the nesting process and spend a long time covering and camouflaging, throwing tremendous amounts of sand and digging a secondary body pit after laying. 

By comparison, loggerhead nests are smaller, and while they still go through the same process of covering the nest by throwing sand with their flippers, the area of disturbed sand is often smaller. 

Head Size

Loggerheads are aptly named with their large, bulky heads equipped with powerful jaws. These traits functions well for consuming hard-shelled prey items such as mollusks, conchs, and whelks. 

Green turtles have much smaller heads, especially in proportion to their body size. However, they are still well-equipped, with a serrated lower jaw that helps them cut through common prey items like sea grasses and algae. Indeed, green turtles are named because their fat tissue has a green tint due to their mostly herbivorous diet.

Nest Timing

In Florida, loggerhead nesting season starts in April and usually winds down by the end of August. Green turtle nesting season typically runs from June through September.

Green turtle nesting in Florida seems to follow a biennial pattern, where females migrate from their foraging grounds to mate and lay eggs every other year.

Please remember to turn off beachfront lights after 9.m., fill in holes, level sandcastles, pick up trash and furniture, and respect posted nesting areas. 

SCCF Sea Turtle Hotline: 978-728-3663

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