Big Tracks

Every morning during nesting season, there are dozens of new tracks in the sand. I got up early and went for a walk every morning to see who had come to visit the night before. It was fun to get a close look at the tracks left by turtles I saw on shore. After a few days without rain, the beach starts to look like someone's been doing construction work with heavy machinery.

Click on this or any other image to see a larger view. The tire tracks you see in many of the photos were made by the ATV used by the Turtle Patrol.



Scientists refer to the tracks as "crawls." The classic crawl has a horseshoe shape. The turtle exits the water, crawls up the slope of the beach, chooses a spot above the high tide line, then starts to dig her nest, which is a couple of feet deep. She deposits her eggs in the egg chamber, then carefully covers the nest with sand and packs it down. Once satisfied with her work, she turns around and crawls back down the beach to the water, sometimes resting on the way. Once she reaches the water, a few waves break over her, she pushes off, and disappears. Although most turtles crawl straight up and down the beach, some seem to wander a bit, perhaps to find sand to their liking. And there are numerous "false crawls", or tracks left by turtles who emerged from the water and went back in without having laid any eggs. This could be a sign that the turtle was spooked. One Turtle Patrol volunteer told me he thought some of the false crawls this year might be due to changes in the sand from recent dredging. Some turtles are very particular about the sand they choose, apparently.

Most of the tracks are left by loggerheads. Loggerheads walk on land by using an alternating diagonal gait, which some would call the default quadruped gait. The marks they leave in the sand are characterized by a wavy portion left by the belly, and alternating scooped marks left by the front flippers. Occasionally, a loggerhead also leaves what looks like a wavy tail mark in the middle of the track, but this is left by the cloaca.

How do you tell which direction the turtle was going? Flipper marks always point backwards.

Different views of loggerhead tracks are shown here:







Green turtle tracks are less common, but I still saw some every morning. Green turtles use a completely different method of locomotion. Instead of crawling, these turtles use a gait I don't even know the name of. Using all four flippers at once, they lift the flippers, bring them down, and drag themselves a few inches forward. The difference was very noticeable when I finally got the chance to see a green crawl down the beach. There is no lateral movement, and this leaves a wide, smooth track with symmetrical flipper marks. "They" say that you can tell a green's track because there is a tail drag mark. I think a lot of people see the cloaca mark in a loggerhead track and think it's a tail mark. From observation, it appears that the loggerhead cloaca mark tends to be wavy, whereas the green's tail leaves a thin, straight mark down the middle of the track. I also noticed that when the turtle drops its body in the sand and briefly rests after every step, the body backslides a bit and the tail leaves a little divot in the sand. This is visible in both pictures, below. Notice also that the turtle that left this track doubled over her incoming track when she reentered the water.





Next: Tiny Tracks