Wednesday, July 10, we went to watch the start of Green Turtle egg-laying season in the national park of Tortuguero. Green turtles, the same type Anna and I saw off the Nicoya, are called so because their fat is green, not because of their shell. It's kind of like calling them "green turtle" instead of "soup turtles." The females come to lay their eggs at the same place they were hatched only after they've matured to 25 or 30 years. Male sea turtles never come to land, mating in the shallower waters instead. So, the females go alone at night several times a season that starts officially in July to make their nests. In each one they lay 100+ eggs then cover them again. Apparently the temperature of the sand surrounding them determines the ratio of males ot females, females favored by higher temps. Tortuguero has traditionally yielded about 50-50 at 29°C. And it is one of the few beaches whose numbers of turtles has actually increased, however slightly, in the past several years.
Mom and I met for our free German-and-English turtle tour with Barbara the guide at 8 pm. We'd only agreed to go on this one because it didn't require the 5 mile-or-so sand-walk like the night before. Instead the groups went to a designated point in the national park proper to wait for park workers to spot a turtle and convey the information of its location and current activity back to the mass. Then 40 or so people would go through wooded path aside the beach to the said marker and wait till the moment was right. Lucky for us we were Group #1. We'd have first dibbs on watching. Also lucky, a turtle was spotted not three minutes after our arrival at the meeting point, and there was a half-oon shining plenty of viewing light on the sea. When we go to marker 44 we just waited in the dark for increments of play-by-play while Barbara mostly just chatted to her Germans.
We were waiting because actually the turtle's stay on the beach lasts about two hours. As a green turtle, she is able to sense the amount of salt in the sand so walks up ta suitable distance from the high-tide line and tries to find a place to put her nest. As was the case with the second turtle we saw, she may start cleaning the area (imagine this like a gurtle version of a snow angel), then decide it's not right and have to start all over again. Fort his entire time, especially when making her initial exit from the ocean onto the beach, she is extremely sensitive and given to fright. The watchers need to be very quiet and dark-clothed not to frighten her back to the sea.
Once she has cleared her circle, she starts to dig. Some turtles, though this does not include green ones, go into a sort of trance starting here, which lasts for the rest of hte time till her return to sea. Red lights, reasonably quiet voices, even touching her will not disturb her. For a good while she digs a rather deep hole, maybe 1.5 metes below the surface (maybe only a meter) abd about 2 feet in diameter. This is where her eggs will fall.
The park people gave the signal for us to come once she had started laying her eggs. This is when the green turtle starts her trance. We went over quietly to where she was, half under a bush and Barbara shown her red "torch" on the nest.
At first it was hard to tell what we were looking at. I could see small ping-pong looking shiney white things in the hole, but it wasn't till 2 eggs slid slimily but silently from one of the protrudances (her cloacum, it turns out, heh), that I could orient myself. Barbara was having to hold the left back flipper off to the side to be able to make the nest visible. The turtles use their very flat back flippers with the mini cobble stone print to cover their clutch. Up to five eggsmight come out at a time from the throbbing tail thing, oozing liquid witht hem, too, and landing on the other high surface-tension balls below.
The specimen herself was kind of hard to see, both in the dark and covered mostly by leaves, but it was clear she was large. Maybe 2/3 of a meter in width? Her back was covered in sand, and though it had the sort of geometric turtle pattern etched lightly into it, it had none of the high-rising bumps land turtles/tortoises do. Everything was very flat.
We got about 45 seconds to look at the eggs before it was another group's turn. We then rejoined the line under a sometimes drizzling sky and saw her dropping eggs 2 more times.
On the third, we stayed even longer as her back flippers began to move in a swimming-type motion, a fourth look she had finished with this and was stirring up sand in a slightly different place to try and "camoflauge" where her true nest was. She was kicking furiously and some sand got all the way up to our faces. It was still in my eyebrow when I got back to the hotel.
According to Juan, although many animals will eat baby turtles, they have a very hard time finding the eggs. The one exception to this is the crab, which can easily find them dig a hole streaight down, and carry off a delicassy. From this hole, other animals can start to smell the treats, and that's when the nest is in trouble. Most of the eggs are fertile, but only 1% of them will make it too adulthood, so it is a special tragedy when pet or stray dogs find their way to nests and disturb the entire things. Other, perhaps more natural, threats include snakes, hawks pelicans, fish and sharks. Plus hunting them is legal in Nicaragua, so that's even icing on the cake.
Anyway, to speed things up, we also got to see another girl, at mark 50-something, laying her eggs, too. It wasn't much different, but she was in the open, so I could see her full size. She was over a meter long and very flat, too. Her head and front flippers seemed slightly small for that giant shell.
We didn't get to see either one go back to the ocean before our time in the park ran out. Barbara said it's not that cool. Her three favorite things, she said, are seeing the mom cover the eggs, watching her come out of her trance, and watching the babies first rumble below, then break through the surface, like a volcano, when they hatch.
The first turtle we saw ended up having been untagged, so they did that while we were there, too. I wonder if she was a young one, or jsut had been missed before. Apparently they never come 2 years in a row, rather 3, 4, and 5 years in between egg-layings are average.