Olive ridleys and arribadas

Editor’s note: This is part of a series highlighting the seven species of sea turtles during #SeaTurtleWeek. A different species will be highlighted each day. For more information on other Sea Turtle Week activities offered by the Sea Turtle Preservation Society, please go to our website or visit us on Facebook and Instagram.

For those of us here in Florida, an olive ridley sea turtle may be unfamiliar, but this species is actually the most numerous worldwide. Olive ridleys occur globally and are found mainly in tropical regions of the Pacific, Indian, and Southern Atlantic Oceans.

Olive ridleys are well known for their mass nesting events, or arribadas. In an arribada, large groups of female sea turtles emerge at the same time to lay eggs. For olive ridleys, these arribadas generally take place at night over a period of one to three days and recur every 30 days. Anywhere from 100 to 10,000 or more turtles may be part of an arribada.

Arribadas of olive ridleys take place in Mexico, Nicaragua, Costa Rica, Panama, Australia, parts of Africa, and a few beaches along the coast of India. The largest arribadas take place in Costa Rica, Mexico, and India. This species also may nest individually on other beaches, and overall olive ridleys nest in about 40 countries.

The other species of sea turtle in the Lepidochelys genus, the Kemp’s ridley, also exhibits the arribada nesting behavior, though typically during daylight hours.

Ostianal National Wildlife Refuge in Costa Rica is renowned for the large olive ridley arribadas that take place there.  Dr. Vanessa Bézy has been researching these turtles and has founded an organization dedicated to the protection and conservation of sea turtles and other wildlife at the Ostional National Wildlife Refuge in Costa Rica.  To learn more about olive ridleys and Dr. Bezy’s efforts to save them, go to: https://www.nosarasustainability.org/