The Ostional Wildlife Refuge in Costa Rica was created in 1984 to protect one of the most important nesting sites of the olive ridley sea turtles in the world. Only olive-ridleys and their close relatives, Kemp's Sea Turtles, the latter an Atlantic species synchronize their nesting in mass emergences or "arribadas", the Spanish word for arrivals.
You can witness something very special, a process that has been carried out for thousands of years by these turtles. Around the third quarter of the moon, hundreds, and sometimes hundreds of thousand sea turtles come to one specific mile of beach at Ostional to dig their eggs into the black, volcanic sand.
Some days or weeks before the mass nesting, the "flotilla", an increasing number of turtles, congregates close offshore. After some days, prompted by some secret signal, the "arribada" will begin. At first, a few hundred turtles will come out on the beach, followed by a steady stream of animals for the next three to seven days.
Telephone: USA (212) 931-4826 CR: 011-506-2682-0209
Arribada Pictures from Ostional
Turtles nest at Ostional year round, but peak time is during rainy season. From August through December arribadas occur regularly once, sometimes even twice a month and the number of nesting females are in the range of hundreds of thousands as opposed to tens of thousands for the dry season months.
The turtles generally ride in on the high tide at night but during an arribada they start arriving around 4 p.m. and keep coming until 7 a.m. the next morning. Used to a life in the ocean, the turtles painfully drag their heavy bodies over the beach until they get over the high tide line. There the turtles dig holes of about 40-60 centimetres deep and lay nearly 100-120 eggs. To complete the process of crawling the beach, digging the hole, laying the eggs and covering the hole, the turtle takes about 1 hour or more.
Over the course of a five-day arribada nesting turtles will leave up to 10 million eggs on the beach of Ostional. The hatchlings are born 50-55 days after they have been laid. They usually "climb up" from 4 to 7 a.m. and from 4 to 7 p.m. because this is the time when the sand is not so hot. The number of survivors is very small because the "newborns" are attacked by crabs, seagulls, vultures, dogs and other animals surrounding their environment. Some of them also drawn once in the water.
Ostional is the only beach in the world where egg poaching is legal. Scientists found out that most of the eggs deposed in the first nights of an arribada are destroyed by subsequent turtles who dig their nests. Therefore, since 1987, the government of Costa Rica allows on an annual, temporary suspension of the international ban on turtle-egg taking that the community of Ostional may harvest the doomed eggs on the first two dawns of an arribada. In return, the community must protect the turtles, clean debris from the beaches and patrol day and night for poachers.
The Ostional Wildlife Reserve extends 15 km along the shoreline, including the beaches of Ostional, Nosara and Guiones. It is a narrow, 200 meter wide strand of black sand beach, that extends inland along the estuaries of the rivers and mangrove swamps, protecting large colonies of birds.
During an arribada you must check in with the ranger booth at the southern end of Ostional where you pay the entry fee of $6 and another $7 for the guide without whom you may not go to the beach. No flashlights or flash photography is permitted.
Ostional is a short drive from Nosara. From the Nosara B and B, drive 2 kms north crossing the bridge over the Nosara River to Santa Marta where you will take a right turn. From here it is 7 kms to Ostional. There is no bridge over the Rio Montaņa which can be impossible to ford in rainy season. We can arrange a taxi tour to Ostional for you when there is an arribada.
Turtle Watching Costa Rica: "Arribadas" at Playa Ostional