Hundreds of sea turtles cross beach for mass nesting in Costa Rica

OSTIONAL, Costa Rica - A beachgoer in Costa Rica happened upon an amazing sight: hundreds of sea turtles making their way onshore to lay their eggs.

Jairo Quiros Rosales was at Ostional Beach on Sunday when scores of olive ridley sea turtles began crawling up on the sand.

Rosales said the turtles synchronize their egg-laying, in what's called an "arridaba" or large-scale nesting.

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According to the US Fish and Wildlife Service, breeding colony populations of olive ridley sea turtles are considered endangered on the Pacific Coast of Mexico, while all others are listed as threatened.

The turtles get their name for the olive color of their shells, and are one of the smallest of the sea turtles.

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"The olive ridley is most noted for its massive nesting aggregations, known as arribadas or arribazones, with literally thousands of females nesting in large simultaneous emergences over small stretches of beach," the US Fish and Wildlife Service says. "Although the exact cues that trigger arribadas are unknown, they may be precipitated by strong offshore winds, tides, and lunar phases."

The turtles typically nest one to three times per season, producing up to 110 eggs on each occasion.