Two olive ridley turtles laid first recorded sea-turtle nests on the US West Coast

The sight of one turtle nesting on a Southern California beach was noteworthy enough; however, the arrival of a second olive ridley three days later added another extraordinary detail.

The first turtle was observed at approximately 3 p.m. on September 16; she was discovered near Seal Beach while excavating a nest and laying eggs.

Three days later, approximately eight miles away, a second turtle was identified while nesting near the Huntington Beach Pier.

Both turtles were verified as separate individuals by comparing their body shape, barnacle presence, and shell pattern characteristics.

The finding represents the first documented record of nesting by any species of sea turtle on the United States’ West Coast.

They nested far from where scientists expected

Sea turtles generally nest farther south than the location of these two turtles; specifically, the closest previously documented olive ridley nesting site is in the western Cape region of Baja California, Mexico.

Their primary nesting season takes place approximately between July and December, and most females will typically lay two or three nests about two weeks apart in the same general area.

This timing is particularly intriguing because neither turtle simply passed through the area.

Both turtles began typical nesting behaviors hundreds of miles north of where olive ridleys usually nest.

Scientists still do not know exactly why the turtles nested there, but warmer-than-normal oceanic conditions may have played a role.

Something may have drawn them north

Due to ongoing marine heatwaves, the temperature of surface waters in this geographic area has increased.

El Niño conditions are already underway and are expected to strengthen and persist through the 2026-27 winter.

The Aquarium of the Pacific stated that the event could be explained as either a range expansion or a navigation error, or possibly both.

As olive ridleys are naturally nomadic and highly migratory, their ability to adapt to environmental changes likely contributed to this occurrence as well.

Potential navigation errors may have also led to these turtles choosing Southern California; however, scientists do not know exactly why, according to NOAA Fisheries.

That uncertainty remains important.

Two nests do not mean olive ridleys have established a new breeding population in California.

The nests now face another test

Between 100 and 200 eggs were collected from the two nests, but the egg-laying sites immediately faced another challenge.

Forecasted large waves from tropical storms developing off the coast of Mexico posed a threat of flooding or washing away the nests.

Federal and state scientists therefore removed the eggs from the sites and transported them to the Aquarium of the Pacific in Long Beach on September 25.

These eggs will be kept under human care as they undergo their normal incubation process, which lasts anywhere from 45 to 60 days for olive ridleys.

If they hatch successfully, the young turtles will be returned to their original nesting beaches.

At that point, they will embark on their first journey across the sand to reach the ocean.

The next turtles could change the picture

If the eggs hatch successfully, the story may not end there.

Sea turtles commonly return to the beaches where they hatched.

Olive ridleys may return to nest again approximately 15 years after hatching.

If these turtles successfully hatch and survive, they could eventually return to Southern California as adults.

That possibility gives scientists another reason to continue monitoring the beaches for future turtle activity.

Scientists are already watching for signs of additional turtle arrivals.

Each female olive ridley typically lays two or three nests during a season, with intervals of about two weeks between them and in the same general area.

That means another turtle could still arrive this season.

Another nesting event would provide additional clues about whether this unprecedented behavior was an isolated occurrence or something that may happen again.

If another turtle comes ashore, what first looked like two extraordinary appearances could begin to look like a pattern that scientists will need to follow closely.