Gliding on watery wings, migrating peacefully around the world, sea turtles, among the most ancient reptiles, are disappearing from the world’s oceans. Despite the fact that turtles are resistant to chemical and physical changes in their environment their populations are dwindling. Many factors contribute to the sea turtle population decline: commercial fishing by-catch, poaching (eggs and adults), pollution, beach development, etc. All eight species are listed as threatened or endangered.

Sea Turtles have separate feeding and nesting grounds and can migrate across the oceans to mate. At the right time of year males and females travel to waters close to their parents' nesting beaches and, after some natural competition, they mate. Up and down the Central American Coast female sea turtles then break out of their wet home and heave their awkward bodies onto the beach to make a nest. They dig and dig until they cannot reach any further and then they go into a trance as they begin laying their eggs. A sea turtle can lay over a hundred eggs at a time and may come back to nest multiple times a season. After laying, she covers the eggs with sand to camouflage the nest. Then she crawls slowly down the beach until she finally makes it back into the surf and out to sea, never to see her offspring again. The nests incubate in the hot sand for about two months and then, in one mass exodus, swarms of little turtles go waddling in a race to the water. In those few meters of beach they are picked off by: birds, crabs, coatis, raccoons, and many more, including dogs. Once they get in the surf zone they are food for many fish and frigate birds have been known to catch hatchlings as far as four miles off shore. If they are lucky and survive to adulthood (anywhere from five to 30 years), they will return to the beaches as their ancestors did and repeat the life process.

Four sea turtle species nest on the shores of the Osa Peninsula:

1)  Olive Ridley or La Tortuga Lora, Lepidochelys olivacea, the smallest and most abundant of all sea turtles, is the most common on Osa’s beaches. Usually Ridleys have a carapace (shell) that is wider than it is long and, like the name conveys, they are an olive-green color. Many of the dead turtles that washed up all along the Pacific coast of Costa Rica last year were Olive Ridleys. They eat mainly crustaceans, which puts them at risk of being accidentally caught in shrimp nets that troll their feeding grounds. These turtles have a strange nesting behavior, the arribada, a mass nesting (up to 500,000 in a week), they crawl over each other and dig up nests because there are so many turtles, this occurs on only two beaches in Costa Rica: Playa Nancite and Playa Ostional. In the Osa, Olive Ridleys come up individually on the beaches to lay eggs all year round but are most common from May to December. The many community conservation projects scattered along the peninsula and gulf are focused on this turtle.

2)  The Leatherback or La Baula, Dermochelys coriacea, is the largest sea turtle alive today; the biggest ever recorded (a male that washed up dead) over three meters long. Leatherbacks, named for their leathery shell with seven light stripes, eat mainly jellyfish and often drown after mistakenly eating plastic grocery bags that have washed out to sea. They cover the most latitude of any sea turtle, from cold northern waters all the way down to the southern tips of South America and Africa. Unfortunately, because of their wide range, their migration routes run right through major commercial fishing runs and Leatherbacks are often caught up in long lines and nets.  Playa Grande near Tamarindo, Guanacaste is one of their major nesting beaches in the eastern Pacific. Leatherbacks nest from November to March and the Osa Peninsula does get a few scattered nests on the outer coast from Matapalo up to Drake’s Bay.

3)  The Hawksbill or La Carey, Eretmochelys imbricata, is the turtle that made tortoise shell jewelry possible. The scales on its carapace have a marbled brown and gold top layer that has been sought after by artisans and tourists since prehistoric time. Hundreds of years of hunting Hawksbills for their ornate shells have crippled their population and many countries, including Costa Rica, ban the sale of Hawksbill jewelry and items. The Hawksbill’s diet consists mainly of sea sponges and they have scattered nesting on the Osa.

Hawksbill Sea Turtle, Eretmochelys imbricata, copyright Doug Perrine/Seapics.com.

4)  The Black Turtle or Pacific Green or La Negra, Chelonia agassizi or Chelonia mydas agassizi, is the second most common sea turtle in the waters surrounding the Osa Peninsula. There has been a lot of inconclusive scientific debate on whether the black turtle is its own separate species or just a subspecies of the Green Turtle, Chelonia mydas. Mature Black turtles are mainly vegetarians and eat sea grasses. Their nesting season roughly coincides with the Olive Ridley's and they have scattered nesting on the Osa.

All of the sea turtles of the Osa are endangered. In the past few years there has been a marked decline in nesting of all four species. Hawksbill turtles have been fished and poached to a point of decimation. Leatherbacks have dwindled from bycatch of commercial fisheries and nest poaching to the extent that they will go extinct in the next twenty years if we do not aggressively protect their nesting, migration and feeding habitats. Nest and hatchling conservation projects are among the most successful and easiest ways to increase sea turtle populations. There are many community projects in Costa Rica that are assisting a worldwide effort to save the sea turtles. Just walking the beach at night and collecting turtle nests to transplant into a guarded hatchery greatly increases the survival rate of turtles by eliminating the threat of poaching. There are many community projects on the Osa that do just that: Playa Platanares, Playa Tamales, Playa Piro, Playa Carate, Playa Rio Oro and more. Every hatchling produced and released into the sea is one more chance for the survival of these graceful giants.

Depredated turtle nest on Playa Rio Oro, Osa Peninsula, photo by Rachel Silverman.