Ostional Wildlife Reserve
In rainy season, July to November, a week before the new moon, hundreds and up to thousands of olive-ridley, sea turtles come to one specific mile of beach at Ostional to dig their eggs into the black sand. This phenomenon is called an ‘arribada’
At first, a few hundred turtles will come out on the beach, followed by a steady stream of turtles for the next three to seven days. Most come from dusk to dawn but there are always some in mid day.
From August through December arribadas occur regularly once, sometimes even twice a month, and the numbers of nesting females are in the range of hundreds of thousands as opposed to tens of thousands for the dry season months. Each female lays between 80 - 100 soft-shelled, white eggs, the size of a ping-pong ball. The baby turtles hatch within 45-54 days.
Ostional is the only beach in the world where harvesting turtle eggs is legal and only locals are allowed to partake. Scientists found out that other turtles coming later to dig their nests destroy most of the eggs deposed in the first nights of an arribada. There is not a lot of room on this beach given the number of nesting females. For this the locals have organized as guides for anyone wanting to venture out and see this first hand. Fees are charged and they guide groups to viewing sites. No one is allowed on the beach during nesting unescorted. They also clean the beach and protect the females.
The baby turtles hatch within 45-54 days. The community of Ostional accompany the hatchlings as they race toward the sea, protecting them from dogs and vultures. At night they face an additional threat from very large toads and cats.
Once in the water they won’t return for another 10-15 years when they reach full maturity.
Nesting is a very sensitive time and if you get in the way the females will simply turn around and head back into the water. So being respectful and using the local rangers is the best way to enjoy your visit and to preserve this ritual.