The Olive Ridley Turtles of Costa Rica
Scientists still debate how and why the Olive Ridleys synchronize mass egg laying events
The smallest of the marine turtles, the olive ridley grows to about two feet long, weighing up to 100 pounds at maturity and less than an ounce at birth. It is a tropical species that migrates to the open sea, rather than remaining in coastal waters. The species is named for the greenish coloring of its shell. A diet that includes crustaceans and mollusks makes the species visible in large groups as they feed along coastlines and islands. Observing the olive ridley is a memorable event on Costa Rica tours because of the species' unique habit of synchronized nesting. Thousands of turtles approach the beach at night in what is called the "arribada" (arrival). The signal to start laying eggs all at the same time is still a matter of debate among scientists.
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An abundant yet endangered species
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Though more abundant than any other marine turtle species, the status of the olive ridley is nonetheless endangered on the Pacific coast of Mexico and considered threatened elsewhere. Numbers have diminished dramatically over the past fifty years in many parts of the world. The species is at risk for three reasons: it gets caught in fishing nets; its nesting habit makes killing efficient and its eggs can be collected and sold.
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Ecotourism has proven a boon to Costa Rica’s olive ridleys. With support from the U.S. Fish and Wildlife Service, communities in the vicinity of nesting sites are upgrading tourist accommodations and being taught about protection of the species. The same villagers who would otherwise have been making a living by harvesting the eggs and slaughtering the turtles for meat, now earn a higher wage by protecting the species.
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Timing your travel to Costa Rica according to the olive ridley schedule is not easy since the species does not arrive at exactly the same date each year, though watching the nesting of olive ridleys somewhere in Costa Rica is a year round activity. Females nest twice a season. Generally speaking, turtle watchers should schedule their Costa Rica tours between July and December, the rainy season.
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High season for turtle-watching in northwestern Costa Rica is September and October. In Guanacaste Province, the arribada occurs in two main locations. Furthest north is Junquillal Bay National Wildlife Refuge in the Santa Elena Gulf near the northern tip of Costa Rica. Santa Rosa National Park contains two beaches favored by the species, the most famous of which is Playa Nancite. When the location became too popular for its own good, the government was forced to establish daily visitor limits.
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Though named for the leatherbacks that nest there, the same beaches of Las Boulas Marine National Park also attract olive ridleys in August and September.
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Another site further down the Nicoya Peninsula on the Pacific coast is the Ostional National Wildlife Refuge. One unique strategy to save the olive ridleys here is to allow the local communities to collect some eggs at the beginning of the arribada. The beaches become so crowded during the event’s first few days that many eggs get destroyed inadvertently by the turtles themselves. This conservation technique helps control poaching by sacrificing eggs that would be destroyed anyway. Hundreds, sometimes thousands and rarely hundreds of thousands of olive ridleys arrive here at least once a month, more often during some moon phases than others. Divers may view the species in the offshore waters of Cocos Island National Park.
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On Costa Rica’s central and southern Pacific coast are two sites that protect nesting sites of the olive ridleys, Marino Ballena National Park and Manuel Antonio National Park where arribadas usually occur between May and November. Five of Southern Explorations’ Costa Rica tours travel to Manuel Antonio National Park.
