This could be the biggest sea turtle swarm ever filmed- via Herp Digest

Hundreds of thousands of olive ridley sea turtles flock to Ostional, Costa Rica, each year—but development and tourism may threaten their future.

By Douglas Main, National Geographic.com 11/26/19

Go to https://bit.ly/2r5L76M

to see video

Every month at Costa Rica’s Ostional National Wildlife Refuge, tens to hundreds of thousands of female sea turtles arrive, often within a few days of each other, to lay their eggs on the beach.

Biologist Vanessa Bézy has been studying this remarkable phenomenon, known as a mass arrival, or arribada in Spanish, for years. As part of her research, she filmed the reptiles, mostly olive ridley sea turtles, aggregating in the ocean before reaching shore. One lucky day, she recorded, via a drone, an immense gathering of the creatures—the greatest density of sea turtle species ever recorded.

“I immediately knew there was something special going on,” Bézy says of filming the turtle swarm in November 2016. “To this day I’m still blown away by the video. They look like bumper cars out there.”

Ostional is one of the only places in the world where such large arribadas occur; it’s thought only Mexico’s Escobilla beach in Oaxaca receives more turtle visitors.

Bézy says she’s releasing the footage now because the turtles are increasingly threatened by growing numbers of tourists, who can crowd the beaches at critical times, and, potentially, development. The video helps show just how unique this place is—and that it needs to be protected, says Bézy, a National Geographic Explorer.

“This is the only time I’ve seen a video capturing this phenomenon in the water,” says Roldán Valverde, scientific director of the Florida-based Sea Turtle Conservancy and a biologist at Southeastern Louisiana University. “Most of the photography documenting this occurs on the beach.”

The drone footage shows the animals gathering in a density of something like one turtle per square meter, which is unheard of elsewhere. Over the course of the wet season, an average of 250 turtles per square kilometer has been measured—which is likewise off the charts. Furthermore, the video also shows turtles regularly rising into view, suggesting that there are actually more beneath the surface than above.

Bézy hopes her research will help reveal why and how so many turtles gather here, primarily between August and October. It may have to do with sea currents, beach orientation, sand type, and the like. Such arribadas may also provide “strength in numbers” for females and their eggs, possibly maximizing their chances for survival, Bézy adds.

Olive ridley sea turtles are one of the six sea turtle species considered under threat by the International Union for Conservation of Nature, and such mass aggregations are a vital part of their life cycle, she adds.

“It’s an enigmatic natural phenomenon,” she says. “We don’t know how the turtles coordinate this and why.”

Settlements surrounding and within Ostional are growing quickly, and regulations are needed to ensure they expand in a responsible manner, Bézy says.

One of the communities abutting Ostional, the municipality of Nicoya, is working on a set of guidelines for development in a “buffer zone” surrounding part of the wildlife refuge. About 80 percent of comments received from residents are supportive of these proposed rules, says Francisco Jimenez, with the Nosara Civic Association, which works closely with Nicoya officials to develop the regulations.

But some developers are not thrilled. Jeffrey Grosshandler, CEO of The Gilded Iguana Hotel and co-owner of a real estate franchise in the region, says the regulatory process could create “legal insecurity” for developers. He claims that the proposed guidelines have not been vetted by the federal government, and applies a “one-size fits all” approach to areas that would, ideally, be zoned according to granular differences in demographics or geography.

Jimenez contends the process is appropriate, and that the proposed rules have been repeatedly shared and tweaked based on public input. The commission will soon introduce the latest draft regulations in the coming weeks, and the public will then have 10 business days to comment, either in person, at an upcoming meeting, or via email. He hopes this process can be completed sometime in early 2020.

Bézy says the regulations limit building height, light usage, and other factors that could impact the environment and the turtles. She regards the regulations as being relatively lenient for developers, but she says they’re better than nothing since the area is growing so quickly.

Development is already not allowed on the first 200 meters of the beach from the water, as is true elsewhere in protected areas of the country.

During the first two days of arribadas, people can legally harvest some eggs that are likely to be trampled by turtles that arrive later. Locals sell the eggs, and some of this income helps support community projects like infrastructure, security guards, and beach cleanups. (Related: Over 100,000 sea turtles nest at the same time. How?)

Valverde’s research suggests the legal harvest is sustainable, he says, in part because there are some established rules that limit when and where eggs can be taken. While the olive ridley population at Ostional appears stable, it also appears to have declined somewhat over recent decades, he says. (Learn more about how sea turtles are surviving—despite us.)

However, illegal harvesting of the eggs also takes place, says Bézy, who formed an NGO called TortuGuiones Sea Turtle Conservation Project, which uses citizen science input to measure the level of harvest and nest disruption. Bézy also created another group, called the Wildlife Conservation Association, which works “to protect what’s here,” she says, for example by partnering with tour groups to responsibly view the turtles without disturbing them.

She hopes the public will care more about the turtles after seeing the film—and will support protecting the areas.

“Everybody I’ve shown this video has an emotional response,” she adds.

Return of the olive ridley: Sea turtles make spectacular comeback in Mexico - via Herp Digest

by  Patrick H. McDonnell OCT 26, 2018  Playa Morro Ayuta, Mexico

They appear as ghostly shadows riding beneath the surf, their beaks and shells illuminated in the moonlight as they drift in the swells.

As dawn approaches, columns of the primordial figures emerge clumsily from the sea, and by mid-morning, the lumbering, 80-pound-plus amphibious invaders will have overtaken the beach, their flippers kicking up tufts of sand and the pounding of their shells against the wet sand complementing the crashing waves.

One of nature’s most cinematic scenes — the synchronized mass-nesting, or arribada (arrival), of female olive ridley sea turtles along Mexico’s Pacific coast.

Hundreds of thousands of golfinas, as they are known here, may hit the beach during arribadas, occurring roughly once a month between July and February.

Still officially listed as endangered, the olive ridley has nonetheless made a spectacular recovery. Conservationists credit both legal protections and a generational shift in attitude among Mexicans who once sustained the industrial-scale looting of eggs, which were eaten and regarded as a male aphrodisiac.

“We can see that this species of turtle is on the road to recuperation,” said Angel Guillermo Gonzalez Padilla, coordinator of the Mexican environmental agency’s protection efforts here, as he observed thousands of nesting olive ridleys on a stretch of this white-sand beach.

While the species still faces threats such as floating fishing tackle, climate change, beach erosion, plastic and other sources of pollution, biologists say the upswing in nests here is a clear sign that the reptile’s numbers may be stabilizing, if not increasing.

An olive ridley sea turtle arrives to spawn at Ixtapilla in Michoacan state. (Enrique Castro / AFP/Getty Images)

Some little-understood primal imprint—possibly related to the Earth’s magnetic field, wave patterns, currents and singular smells—drives egg-bearing females to return from prolonged marine wanderings to the beaches where they were born years earlier. They deposit individual clutches of about 100 eggs. Mass nestings also take place on beaches in Costa Rica and India.

A record 4.6 million olive ridleys nested last year on Mexico’s Pacific coast, mostly here at Playa Morro Ayuta in Oaxaca state and up the coast at Playa Escobilla.

It’s a stunning turnaround from the 1980s, an era of vast egg poaching and commercial turtle slaughter in Mexico when the annual arrival of the turtles averaged about 120,000.

In 1990, a presidential decree outlawed the capture of sea turtles and banned collecting their eggs in Mexico, where beaches provide nesting sites for six of the world’s seven sea turtle species. Mexican troops and environmental teams now patrol nesting beaches to deter hueveros, the illicit egg gatherers.

While other sea turtles such as the endangered Kemp’s ridley have also staged comebacks in Mexico, the scope of the olive ridley nesting assemblages is unmatched. Scientists view the phenomenon as an evolutionary adaptation — known as “predator swamping” — in which there is simply more prey than predators.

Last year, authorities say, 77 million olive ridley hatchlings made their way toward the sea on Mexican beaches, though only 1 in 1,000 are said to actually reach adulthood.

While human poaching remains a problem, it is now regarded here as less of a peril to the turtles than other dangers, such as the “ghost nets,” the abandoned fishing tackle floating in the sea that can entangle the turtles.

In late August, more than 300 olive ridleys, apparently females poised to nest, were snared in nets floating off the coast of Oaxaca. All drowned. Images of the trapped, helpless turtles drew global alarm.

Though now considered the most abundant sea turtle, the olive ridley — 2 to 2½ feet long and weighing 80 to 110 pounds -- is still listed as “in threat of extinction” in Mexico.

“Yes we have succeeded in increasing the number of nesting turtles, but that is not to say that this species is out of danger,” said Valeria Towns, who oversees threatened species for Mexico’s National Protected Areas Commission.

Added Christine Figgener, a marine biologist at Texas A&M University: “We need a lot more answers to questions about how many olive ridleys are out there and what threats they are facing.”

Olive ridley sea turtles dig nests to lay their eggs at Ixtapilla in Michoacan state. (Enrique Castro / AFP/Getty Images)

The olive ridley inhabits tropical and warm waters of the Pacific, Atlantic and Indian oceans, feeding on crustaceans, jellyfish and mollusks. Its name derives from the pale green hue of its roughly heart-shaped top shell, though the etymology of “ridley” remains unclear.

Less than a generation ago, the olive ridley in Mexico seemed to be hurtling on a headlong path toward doom.

Divers caught multitudes at sea each year during the 1980s and earlier to be harvested for meat, skin and shells, and coastal slaughterhouses served as a grisly final stop for the peripatetic turtles.

Grainy footage from the era recently aired on Mexico’s Televisa network showed a grotesque scene with a row of captive olive ridleys arrayed on a table where a worker would fire a pistol into the animals’ heads. Another clip displayed a pile of butchered turtles, some with their limbs still flapping spasmodically.

“The blood ran into the ocean,” recalled Miguel Garcia Lopez, 70, who worked in a turtle slaughterhouse at San Agustinillo, a beachside hamlet up the coast from here. “It was quite horrible, yes. But the factory provided work.”

Now, San Agustinillo and neighboring Mazunte are thriving beach resorts lacking any trace of the old turtle killing grounds.

During the turtle-harvesting days, armies of locals on foot and horseback regularly descended on nesting beaches.

“It was like a party,” recalled Arsenio Rey, 65, a lifelong resident of the nearby coastal village of Tapanala. “People on the beach would sell coffee, tamales, the whole town went to gather eggs.”

Poachers on horseback still prowl the nesting zones, digging into the sand and filling sacks with hundreds of eggs. But their numbers are greatly reduced.

Throughout the coastal area, a concerted public awareness effort has sought to refute the deep-rooted notion that consuming turtle eggs enhances male virility. Hatchling releases —in which children get to place newborns on beaches-- have become popular and appear to have reinforced the idea that sea turtles are a resource to be preserved, not consumed.

Mexican marines stand guard, protecting the olive ridley sea turtles from egg thieves as they spawn at Morro Ayuta Beach in Oaxaca state. (Ronaldo Schemidt / AFP/Getty Images)

“We have seen a big change in attitude, especially with the young,” noted Luis Angel Rojas, who coordinates marine turtle protection efforts here for Wildcoast, a California-based conservation nonprofit. “Children are now telling their fathers and grandfathers: ‘Please, don’t eat turtle eggs.’”

On a recent morning, the arribada commences before dawn under the glow of a full moon. Soon the beach is teeming with turtles, their tracks crisscrossing the sand like tank tread markings.

Ping-pong-ball-sized eggs litter the area. In their exertions, the mothers regularly dig up incubating eggs left by previous waves of olive ridleys.

Dogs stalk the beach seeking turtle-egg snacks. Vultures and predatory birds hover.

The turtles advance beyond the high-tide line, find an appropriate spot and begin excavation with both sets of flippers, seemingly oblivious to the presence of others, sometimes in shell-to-shell proximity on the beach. They pound down with their shells to create oval-shaped body pits. Hind flippers spade out cavities for the eggs.

The creatures go into a kind of trance as they release their eggs then use their hind flippers to cover them with sand, hiding them from predators and ensuring the eggs remain moist and maintain proper incubation temperature.

The nesting turtles generally spend an hour or so on land.

There is no mother’s care for the hatchlings, which will emerge as dark-toned diminutives in about 50 days, facing astronomical odds against survival.

Done with their maternal duties, the wearied olive ridleys often pause at the shoreline, content to let the tide carry them back to sea, where they are graceful swimmers, not plodding terrestrial beasts driven by instinct to fulfill their evolutionary burden.