How to Become a Beach Detective: A Guide to Identifying Beach Tracks
How to Become a Beach Detective:
A Guide to Identifying Beach Tracks
Have you ever been walking along the beach and seen a strange pattern or track in the sand? If so, it could be any number of the beautiful but sometimes mysterious and elusive species found here on Bald Head Island. Some animals only emerge from their hiding spots at night and can be quite difficult to spot, but they often leave evidence of their identity and adventures in the sand. As a sea turtle intern, I have gained lots of experience identifying animals based on the tracks they leave in the sand. These seemingly random lumps of sand all tell a unique story and can help us put together an idea of what may have happened when we weren’t there to see it.
The Conservancy’s Sea Turtle Protection Team (STPT) main job is to be on the lookout for nesting sea turtles. The STPT patrols the beach every night searching for sea turtles or their tracks in the sand. Sea turtle tracks are usually in a straight line beginning at the high tide line, going up/down the beach perpendicular to the water/dunes. But, sometimes sea turtles do not crawl up the beach in a straight line; they might cross over their up track with their down track, creating a shape like a looped ribbon. Other times, they might crawl up or down the beach in a squiggly pattern. However, it’s usually a good rule of thumb that if the track in the sand is heading up the beach perpendicular to the water, there is a good chance it is a sea turtle track.
Working at night and relying on your vision can create some issues. The STPT drives with red headlights because red light is less disturbing to sea turtles than white light. But even with the red lights, it can still be difficult to make things out at night. Even experienced sea turtle biologists may be tricked by things in the sand that look very similar to sea turtle tracks, but really aren’t. There are tons of people that come to BHI and at night, most of the people have left the beach, but their presence is still there in the sand. People’s footprints walking straight out of the ocean and up the beach and back down can look a lot like a sea turtle’s tracks from far away. I have definitely been stumped many times by this. My fellow interns have heard me say, “Is that a track? No, it’s just people,” quite often.
Despite these false alarms, sea turtle tracks are actually quite distinct. You’ll know it when you see them. They are usually in a straight line going up/down the beach perpendicular to the water/dunes. From far away, they can look like 4-wheeler tracks. When you get up close to a sea turtle track, you can see the spots in the sand where their front and rear flippers have pushed the sand and propelled them forward. The way that the sand has been pushed can tell us some very important things.
Sometimes we may not actually see the turtle on the beach. She may have come up onto the beach and not nested (a false crawl) or nested while we were patrolling other sections of the beach or were busy with another turtle. This is when the real detective work begins. By looking at the direction the sand has been pushed, you can determine which way she came up and went down the beach. Essentially, the turtle was crawling in the opposite direction from where the sand had been pushed. Think back to Physics 1! Every action has an equal and opposite reaction. If the turtle is pushing the sand behind her, then she is propelling herself forward. This information is really helpful for the sea turtle team, especially if we missed a turtle and she ended up nesting. By following her up track, we can analyze her body pit and covering pit to determine the location of her eggs. Sometimes it’s like looking for a needle in a haystack, but being able to “read” her track can be very helpful in finding her eggs efficiently, so we can put our predator exclusion cages on her nest quickly and continue patrolling to intercept other nesting females.
We can also decipher which species of turtle was on the beach with only her track in the sand. Each one leaves distinct marks that can give us clues to her identity. On Bald Head Island, we mostly see one species of sea turtle, the Loggerhead. But it is possible to see other species on our beaches, such as the Green, Leatherback, and Kemp’s Ridley. So if we happen to stumble upon a sea turtle track but do not see a turtle, it is important to analyze the track to determine the species correctly. You can do this by looking at the orientation of the flipper marks left in the sand. Loggerhead sea turtles crawl with their flippers alternating. Meaning they will move their right front flipper and their rear left flipper at the same time, and then alternate (imagine a human army-crawl). This motion creates diagonal indentations in the sand (Figure 1). If you are still unsure if the track is alternating, try drawing a line to connect the indentations made by her flippers; if you end up with a diagonal line, it is most likely a Loggerhead. Kemp’s Ridleys also leave these lop-sided lumps in the sand, but they are much rarer in this area, and we have only documented one nest on BHI in 2020. The main way to distinguish a Loggerhead track from a Kemp’s Ridley track is based on width. Kemp’s Ridley tracks are typically only 2 feet wide, while Loggerheads are 3 feet wide or larger.
Figure 1. Loggerhead sea turtle track. Note the alternating flipper marks create a diagonal, as highlighted by the white line (left). Turtle track crawling down the screen (left). Turtle track crawling up the screen (right)
Although rare on Bald Head Island, we have also seen Green and Leatherback sea turtles. Both of these species crawl up the beach with both of their front flippers at the same time. This motion leaves a symmetrical track in the sand rather than the asymmetrical indentations of Loggerheads or Kemp’s Ridleys. You can distinguish between the two species by the width of the track. Leatherback tracks are significantly larger than Green turtle tracks. Leatherbacks are gentle giants and leave behind a track about 6 feet wide (Figure 2), while Green sea turtle tracks are smaller (but mighty!), only about 4 feet wide (Figure 3).
Figure 2. Leatherback sea turtle tracks, taken on Playa Grande, Costa Rica. Right: Me laying on a Leatherback track (for scale I am 5′ 5″).
Figure 3. Green sea turtle tracks on Bald Head Island. Note symmetrical flipper marks, highlighted by the white lines (right).
The STPT also monitors predation on sea turtle nests. Each morning on the last patrol, we check every nest for signs of predation. We install protective anti-predation cages atop each sea turtle nest to prevent animals from getting in and eating eggs. These protective cages do their job quite well! But some animals still try their luck, and evidence of them looking for a quick snack is something we like to monitor. Usually, we do not see any animals, but we do see what they leave behind: attempted or successful predation, curiosity, exploration, or perhaps even a new home. But how do we know who was checking out the nests? Let’s take a look at some of our common suspects.
Ghost Crabs
Ghost crab tracks are probably the most common tracks found near the nests. The thin, pointy legs of the crabs create distinct lines in the sand. Sometimes they may look similar to hatchling tracks, which can be problematic for us. However, if you look at the direction of the tracks, you can usually figure out the difference. The tracks left behind by the hatchlings will usually go straight from the nest to the water, while crab tracks may go in any direction. If you start to see tracks that go sideways and don’t go close to the water, it is likely a crab track (Figure 4). I think the easiest way to tell the difference between the two is by looking at the texture of the sand. Ghost crabs leave sharp, spikey, and angular tracks in the sand. While hatchling tracks appear more “soft” with curved edges from where their tiny flippers have propelled themselves towards the ocean (Figure 5)
Figure 4. Ghost crab tracks on Bald Head Island
Figure 5. Loggerhead hatchlings tracks. Note the soft and rounded edges of the tracks.
Birds
There are many species of birds on Bald Head Island, but we most often see Laughing Gulls and Wilson’s Plovers. You can tell the difference between these two species in their tracks by looking at the marks left by their toes. Laughing gulls have webbed feet because they spend some of their lives in and near the water. While Wilson’s Plovers are shorebirds and do not fly out to the water/swim, therefore, they do not have webbed feet and leave three separate toe prints in the sand. (Figure 6). This is by no means an exhaustive list of the bird tracks you can see on the island, but a good start.
Figure 6. Laughing gull tracks left. Wilson’s plover tracks (right).
Deer
We do sometimes see deer taking a stroll on the beach and exploring the dunes. Their tracks are quite easy to identify because their hooves leave two crescent-shaped lobes next to each other with the curved sides facing outwards. The hoof print may also look like an inverted heart and is approximately 2-3 inches long. At the tip of these two lobes are two small points that are created by the pointed tip of the hoof and can indicate which direction the deer was traveling. The direction that the two small circular indents are pointing is the direction the deer was walking. (Figure 7).
Figure 7. Deer Tracks. Note the two points at the tip of the hoof (left)
Coyote
There are a few coyotes on the island that we have seen at night walking along the beach looking for mischief. Their tracks are a little bit more difficult to identify because they look so similar to tracks left by dogs. However, the tracks left behind by coyote toe pads are typically smaller and tighter together than the toe pads of dogs, which splay more, especially on the two outward-facing toe pads. Additionally, coyotes have smaller middle toe pads compared to the overall size of the track. Another good way to tell the difference is by looking for claw marks left in the sand. Coyotes will usually leave two points at the tip of the middle two toe pads, while dogs will leave thicker, more circular claw prints at the tip of all four toe pads. (Figures 8 & 9).
Figure 8. Coyote tracks. Note the two prominent claw marks at the top of the two central toe pads (far right).
Figure 9. Dog tracks. Note the thick claw marks at the tip of all four toe pads.
Figure 10. Comprehensive diagram comparing mammalian tracks.
Alligator
It is also possible to see alligators on the beach here. They live in our ponds and marshes, but sometimes wander over to the beach. We have seen one alligator on the beach already and quite a few tracks. I was super excited to see it! The alligator was estimated to be 5-7 feet long, so it was quite exciting to view it from a safe distance. Alligators walk with an alternating gait, so their footprints will be diagonal to each other. Their feet leave distinct marks in the sand, and you can usually see the outlines of their toes. It looks similar to a sideways handprint. Their tail leaves a prominent drag mark down the center of the track like a squiggle mark. This indentation happens because, as the gator walks and moves its body, its tail slowly moves side to side. (Figure 11).
Figure11. Alligator tracks. Note the squiggly curved line from the alligator’s tail drag emphasized by drawn line (left and center). Close up of alligator footprint (right).
These are the majority of the types of tracks we see in the sand on the beach. And they are everywhere, with each footprint telling a story. I think it is quite fascinating what you can find and figure out just by looking at your surroundings. There are clues everywhere; you just need to know where to look and what to look for. I hope this guide to beach animal tracks has been helpful. Now go out there and see what you can find!
Olivia Bowers, Sea Turtle Protection Program Intern
