Ostional National Wildlife Refuge: Olive Ridley turtles nesting site
Area | 180 acres |
Location | Guanacaste Province |
Date of Creation | October, 1997 |
The Ostional National Wildlife Refuge is located in the counties of Santa Cruz and Nicoya in the province of Guanacaste. It is bounded on the north by Punta India 222550 N - 34750 E (Hoja Cerro Brujo 3046-II), the south by Punta Guiones Nosara 210400 N - 353150 E (Hoja Garza 3045-I) and extending three miles out to sea. The refuge comprises an area of 300 Ha on land and 800 Ha of ocean.
The best time to visit Ostional National Wildlife Refuge is just before and during an "arribada". These occur, generally, at the start of the last quarter moon. The best months to see the biggest "arribadas" are between July and December. After an undetermined waiting time, close to the last quarter of the moon cycle, 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.
So many turtles come onto the beach in a short time span that later turtles destroy most of the first nests. Therefore, in 1987, started a project to allow local people to collect and sell a percentage of the eggs from the first three days of each "arribada". This is the only place in the world where it is legal to harvest turtle eggs. This practice is oriented to prevent poaching and to help the local community.
"Arribadas" occur all through the year, at least once a month and, in some months, may occur twice. During the rainy season, in the months between June and December, it is possible to witness larger "arribadas". That means that the number of nesting turtles may be in the range of hundreds of thousands as opposed to tens of thousands for the dry season months.
The Ostional National Wildlife Refuge protects one of the world most important nesting beaches of the marine turtle Lepidochelys olivacea (Olive Ridley) or "Lora" as locals know it.
As marine turtles are normally shy and easily disturbed when nesting, the "arribada" is even more exciting and strange event. These animals, now in "arribada mode", will come out during the night and day and be almost oblivious to disturbance by man or animal, light or sound. Bumping into each other, crawling over each other, they are automatons on their way to fulfill a predetermined task; lay their eggs at all cost. This is why guards hired by the village of Ostional patrol the nesting beaches.
The largest "arribada" thus far recorded in Ostional, took place in November 1995 when a calculated 500,000 females came ashore.
The Olive Ridley Sea Turtles of Ostional National Wildlife Refuge in Costa Rica are world famous for their arribadas, huge egg laying seasons. The nesting beach at Ostional can appear covered with thousands of turtles during an arribada. Although some believe that arribadas may have a correlation with moon phases and tides, there are turtles laying eggs at Ostional Beach throughout most of the year.
