At the beach of Ostional in the Nord-West of Costa Rica nearly once a month an incredible biological wonder happens. The week before new moon thousands sea turtles come to a specific place of the beach at Ostional to dig a big hole and lay their eggs into the sand.
Some days (or sometimes a week) before the Arribada, many turtles stay in the water, waiting until the “Arribada” begins. Afterwards thousands of sea turtles come out of the water on the beach to lay their eggs. The arribada usually takes 3 – 7 days.
Sea turtles at Ostional nest throughout the whole year but the best time to see this natural wonder is from July to December, during the rainy season. At this period the arribada happens regularly once and sometimes even twice a month. Furthermore the number of nesting turtles is much higher during this period than in the dry season month. The largest arribada which has ever been seen in Ostional, took place in November 1995, where approximately 500.000 sea turtles came ashore. Usually the turtles come at night to be protected from their predators but during an arribada the start coming ashore soon after the sunset and even often during daytime as well.
Sea turtles move on the beach until they get over the high tide line, so that their eggs are protected from the sea. Afterwards they use their flippers to dig a big hole to lay around 80-120 soft, flexible white eggs. When finished, they use again their flippers to pour sand over it to protect them from predators like vultures, crabs or as well jaguars. The whole process takes about 1-2 hours. During an arribada nesting turtles leave up to 10 million eggs on the beach of Ostional in Costa Rica.
Surprisingly, the beach of Ostional is the only one in the world, where harvesting turtle eggs is not illegal. The reason is that Scientists found out that most of the eggs laid in the first nights are destroyed by other sea turtles within the next days. Therefore local people of Ostional are allowed to harvest eggs within the first three days of an arribada. Sea turtle eggs are a delicate in some regions – the price for 200 eggs is about $10. In return the community of Ostional cleans the beach, help the turtles and protect the beach from poachers.
Usually the baby turtles hatch at night within 45-55 days but sometimes you can see baby turtles hatching during day time, depending on the temperature – usually they prefer coolness. As soon as the baby turtles struggled out of the sand, they smell the breeze and instantly run to the ocean. People, who want to help the little cute turtles, should not carry them all the way, because they need to run to develop their lungs and flippers, but they will appreciate a bit of support. But the little turtles still are not save in the ocean – a lot of other predators like sharks or crocodiles. The most dangerous predator of sea turtles is still the human species. Usually only 0-5% of laid eggs will survive and grow to an adult turtle. Those who managed it, remember their home beach and will return after many years to dig a nest and lay eggs, like their mother did.