Beach Patrol

The Goldring-Gund Biological Station here at the Parque Nacional Marino Las Baulas is charged with protecting the sea turtles who lay their eggs here. To do so, we patrol the beaches at night, when the turtles are most likely to nest. The patrol times are set by the high tide - we begin 3 hours before the high tide and end 3 hours after. The beach is marked by posts every 100 meters and is divided into three sections: South (marker 36 to marker 21), North (21 to 6), and Ventana (6 to 0, and continuing up Ventana 0 to 11).

The panorama of the beach from just outside the hatchery - South at the far left, North to the left, and Ventana to the right

I patrolled North last night, going from marker 21 to marker 6. Each marker denotes 100 meters, so each “sweep” is approximately 1.5 kilometers (about a mile). We walk down for 20 minutes, rest 20 minutes, then walk back for another 20 minutes… back and forth for the night. If there are no turtle sightings, we’d walk approximately 6 miles… in sand. And since we’re required to wear closed-toed shoes, the sand that gets stuck in our socks makes for some really lovely blisters…

For the North patrol, we drive with the South team to an entrance near marker 29. Our first sweep took us a bit longer to get to marker 6, where the station is and where the hatchery is located. North is nice because you take your breaks with other groups - to the north we stay at the hatchery and can go back to the station for the restroom or more water; to the south we meet up with the South patrol (Nathan, Dean, and Adrian) up on the berm. 

Our group consisted of biologist Lauren, Suzanne (a retired professor from Minnesota), and I. We started our patrol around 8PM, and for four and a half hours, all was quiet. Every so often we'd run into a buscador - one of the guides who look for turtles for paying tourists. Many are former poachers, but now help finding turtles and with conservation (more turtles = more tourists = more $!).

South and Ventana also didn't see anything, which was upsetting for us since the night before, two groups had olive ridleys. We had all just about resigned ourselves to a quiet night when suddenly, on our final lap up, a red light flashed from up the beach. It was past midnight, so it was either the park police (MINAE) telling us they were leaving, or it was a turtle. 

And 5 minutes later, we spotted the distinctive large black tracks coming from the water up onto the sand. A small group of buscadors and tourists were standing over a leatherback, who was in the process of digging her egg chamber. She was huge - about six feet long and three feet wide. Having dug her self into a body pit, she was scooping out the sand alternating between her two back flippers. When she couldn't reach down any further, she was ready to lay her eggs.

Our job was to take measurements of the turtle and count her eggs. Suzanne, who was doing the counting, crawled on her belly behind her (as not to collapse the egg chamber) and looked down into the pit. With one hand, she moved the turtle's flipper aside to get a good view of the eggs. The eggs are the size of billiard balls, and she lays 1 to 4 at a time. Every so often she would also lay a SAG, a smaller infertile egg, which we do not count.

In the meantime, Lauren and I took data. While sea turtles are in the act of laying, they go into somewhat of a trance - which means we could get right up close and even touch her. Lauren scanned the turtle's left and right shoulder to get the tag numbers, then we measured the width and length of her carapace (shell). All the information was recorded, then we just waited for her to finish her job.

While we were collecting our data, both the Ventana and South teams came to watch. Nathan showed us different parts of her anatomy, and we were all allowed to touch her flipper (it felt like old lady skin - soft but wrinkly). When the turtle was finished laying and had covered her eggs, she camouflaged the area. Moving slowly around, she used her enormous front flippers to throw sand behind her. Then she'd use her back flipper like windshield wipers to smooth it out.

When she was finally finished, she slowly made her way back to the water. The city of Tamarindo is on the south end of the beach, and it is clear how much the lights affect the turtles. Every so often, she'd get confused and turn the wrong way, towards the lights. Eventually, she figured it out and finally disappeared into the water. The entire process took about 2 hours - it was 2:30AM when we finally got back to the station.

The next morning, the Morning Walk shift could see her convoluted tracks:

Best of luck to those 68 eggs!!