53 California Sea Turtle Nest Facts - Olive Ridleys

By Share a Fact Editorial Team · Published September 26, 2026

The Orange County Nests

On 16 September 2026 an olive ridley sea turtle was seen digging a nest and laying eggs on a beach near Seal Beach in Orange County.
It was the first recorded natural nesting by any sea turtle species on the US West Coast.
The first nest was on the Surfside stretch of shore, next to Seal Beach.
On 19 September a nesting olive ridley was spotted near the Huntington Beach Pier, a few miles to the south.
At first observers thought the same turtle had nested twice.
Experts compared body shape, shell pattern and barnacles and confirmed that two different females had nested.
Huntington Beach Fire Department crews helped photograph the second turtle.
According to NOAA, olive ridleys had never before been documented nesting in the United States.

Both nest sites were fenced off and marked with interpretive signs so beachgoers would keep away.
Local, state and federal partners are monitoring the nests for the whole incubation period.
Olive ridley eggs usually take about 45 to 60 days to hatch.
If the eggs survive, any hatchlings from the September nests would emerge between late October and mid-November.
Coyotes, people, high tides and storm swells all threaten eggs buried on a busy urban beach.
Beachgoers have been asked to keep a respectful distance and not disturb the fenced areas.
If you see a nesting sea turtle, stay about 15 metres (50 feet) away and tell a lifeguard or NOAA.

The olive ridley's scientific name is Lepidochelys olivacea.
It is named after the olive-green colour of its heart-shaped shell.
It is the second-smallest sea turtle species in the world.
Adults grow to about 2 to 2.5 feet long and weigh up to about 100 pounds.
Olive ridleys are estimated to live between 30 and 50 years.
Nobody knows for certain where the name "ridley" comes from.
Olive ridleys eat both plants and animals, including algae, crabs, shrimp, tunicates and molluscs.
They can dive to around 500 feet to feed on animals living on the seabed.
It is the most abundant sea turtle species in the world.

Olive ridleys live in tropical waters of the Pacific, Indian and Atlantic oceans.
In the eastern Pacific their range stretches from Southern California to northern Chile, but they had not been known to nest that far north.
Major Pacific nesting populations are in Mexico, Nicaragua, Costa Rica and Panama.
Females nest once a year, one to three times per season, laying roughly 100 eggs in each clutch.
Nesting usually happens at night, though daytime nesting occurs, especially during mass arrivals.
Females reach breeding age at about 14 years old.

Olive ridleys are known for arribadas, mass nesting events in which thousands of females come ashore together.
Only turtles of the ridley genus, Lepidochelys, nest this way.
Scientists still do not know exactly what triggers an arribada.
Well-known arribada beaches include Playa Escobilla in Oaxaca, Mexico, and Ostional and Nancite in Costa Rica.
In India, arribadas happen at Gahirmatha, Rushikulya and the Devi river mouth in Odisha.
In 1991, more than 600,000 turtles nested along the coast of Odisha in a single week.

In 2026 a powerful El Niño pushed coastal water temperatures along California well above normal.
Scientists see warm water from El Niño as the leading explanation for the nests, but they have not ruled others out.
Other possibilities include recent hurricane activity and simple navigation errors by the turtles.
A 2025 study found olive ridley habitat in the eastern tropical Pacific shrank and shifted south during El Niño years.
A 2026 study projected that olive ridley habitat could move toward the poles under some climate scenarios.
Researchers are still working out whether the nests are a one-off or a sign that the species' range is expanding.

The temperature of the sand decides whether a hatchling becomes male or female.
For olive ridleys, eggs at 29–30°C produce a mix of sexes and 31–32°C produces only females.
Eggs incubated at 28°C or below produce mostly males.
Incubation above about 87.8°F (31°C) produces almost entirely female hatchlings.
Hatchlings measure only 37 to 50 millimetres across the shell when they emerge.
Research at some warm nesting beaches has found hatchlings are becoming overwhelmingly female.

Under the US Endangered Species Act, olive ridleys that breed on Mexico's Pacific coast are listed as endangered.
All other olive ridley populations are listed as threatened.
The IUCN classes the species as Vulnerable, and CITES Appendix I bans commercial international trade in it.
NOAA estimates the global population has shrunk by 30 to 36 percent over the past century.
Major threats include fishing bycatch, egg and turtle harvesting, habitat loss, boat strikes and swallowed debris.