Padre Island National Seashore has given an endangered sea turtle a fighting chance. And it only took 30 years to do it.
By Amy Leinbach Marquis
On a summer day in 1947, an engineer named Andrés Herrera stumbled on the answer to one of the greatest wildlife mysteries of his time: where the world’s smallest sea turtle goes to nest. From his plane high above Mexico’s coastline, Herrera filmed thousands of Kemp’s ridley turtles swarming Rancho Nuevo to lay eggs on the 14-mile stretch of beach. He had no idea that a few minutes of grainy black-and-white footage would become so important to the species’ survival. So the film reels sat in a drawer until 1961, when biologists caught wind of the details. Later analysis confirmed that 40,000 females had nested on Rancho Nuevo that day.
That statistic would confound biologists for decades. Because when they returned a few years later, only about 10 percent of the population remained. In 1978, the worldwide nest count dropped to 924, making the Kemp’s ridley the most critically endangered of the seven sea turtle species. “This was not a natural population decline,” says Donna Shaver, head of Sea Turtle Science and Recovery for Padre Island National Seashore in Texas. “Humans caused it.”
Even in a healthy ecosystem, the odds are against most hatchlings: Just one in a thousand reach adulthood. Young turtles are an easy target for fire ants, raccoons, coyotes, and birds. Add to that Mexico’s demand for turtle eggs, plus deadly commercial shrimping fleets—whose trawling equipment claimed as many as 5,000 Kemp’s ridleys each year—and it’s no wonder the population floundered.
Recognizing this, Mexico passed laws against poaching and the U.S. government mandated turtle-exclusion devices on trawling nets to decrease turtle deaths. And an international, multi-agency group—which included the National Park Service—designated Padre Island National Seashore as an additional colony for nesting females. There was just one catch: ensuring Kemp’s ridleys would nest there.
So biologists devised a plan based on fascinating behavior that no one really understands: natal imprinting. Once female sea turtles are ready to nest, they return to the beach where they were born. How they find their way home is a mystery, but imprinting probably happens early—perhaps as soon as eggs hit the sand.
Using this information, biologists at Rancho Nuevo collected turtle eggs so fresh they hadn’t even touched Mexican soil, and then shipped them back to the park in boxes full of Padre Island sand. A couple of months later, emerging hatchlings were allowed to run a short distance into the surf before staff scooped them up with nets and shipped them to a third site in Galveston, Texas. Here, the turtles could live out their early years until they were large enough to escape most natural predators, when they were released into the Gulf of Mexico; this “head start” program ran from 1978 to 1989.
Then the park staff waited. And waited. Nearly two decades later, the first “head start” turtle returned to lay eggs on Padre Island—one of six nests in Texas that year, a number that doubled in 1998. In 2002, the count jumped to 38, and rose to 50 in 2005. Last year brought a whopping 128 nests. “We’ll likely have hundreds of nests soon,” Shaver says. “This is an endangered species success story in the making.”
As the population grows, Shaver’s team of 100 volunteers and a few paid staff will need to become increasingly efficient. So they’ve recruited an unlikely family member—Ridley, a two-year-old Cairn terrier. This Toto look-alike had a knack for sniffing out a target—starting with dog treats, then turtle eggs, and finally, turtle eggs buried in sand. Ridley’s skills are invaluable on the vast, windswept beach, where turtle tracks can be cryptic and faint. “Ridley found his first nest on a day when staff and volunteers had been digging for five hours with no success,” Shaver says. “We were thrilled.”
Casual beach visitors also play a critical role, finding as many as half of the Kemp’s ridley nests in Texas each year—an invaluable service on a national seashore that stretches 72 miles long. But the park and its visitors can’t abandon their conservation efforts just yet. Within the park, natural predators and high tides will always threaten hatchlings. Outside the protected seashore, light pollution still makes it hard for hatchlings to find the ocean at night, beach replenishment projects can turn nests into graves, and poaching may become more common as turtle populations increase.
If and when 10,000 females ever nest in a single year, the Kemp’s ridley will be downlisted from endangered to threatened. (The latest worldwide count is around 5,000.) No criteria exist for removing the turtles from the Endangered Species list entirely, but the recovery team is working on a plan to determine the proper benchmarks.
“The National Park Service should be very proud of the role we’ve played in helping to restore this species,” Shaver says. “The Kemp’s ridley has been a distinct species for 4 million years, and within a blink of an eye mankind almost wiped them out.”