Indispensable Indecency

TDS, May 4, 2015

YES, ANY POINT IS A TURTLE - MEET THE “ARRIBADA”

The arrival of olive ridley turtles (Lepidochelys olivacea), seen from the air in Playa Ostional, pacific coast of Costa Rica.

The olive ridley has one of the most extraordinary nesting habits in the natural world. Large groups of turtles gather off shore of nesting beaches. Then, all at once, vast numbers of turtles come ashore and nest in what is known as an "arribada". During these arribadas, hundreds to thousands of females come ashore to lay their eggs. At many nesting beaches, the nesting density is so high that previously laid egg clutches are dug up by other females excavating the nest to lay their own eggs.

There are many theories on what triggers an arribada, including offshore winds, lunar cycles, and the release of pheromones by females. Despite these theories, scientists have yet to determine the actual cues for ridley arribadas. Not all females nest during an arribada, instead some are solitary nesters. Some olive ridleys employ a mixed nesting strategy. For example, a single female might nest during an arribada, as well as nest alone during the same nesting season. Arribada nesting is a behavior found only in the genus Lepidochelys: Kemp’s ridley sea turtles and olive ridley sea turtles. Although other turtles have been documented nesting in groups, no other turtles (marine or otherwise) have been observed nesting in such mass numbers and synchrony.

Photo by Marta Andelson - Stein