A scramble across a narrow strip of beach is perhaps the most perilous journey in the life of an endangered sea turtle.
Freshly hatched and no bigger than a mouse, turtle hatchlings emerge from sandy underground nests in the night and head for the surf. Before reaching the water they must evade hungry seabirds and poachers. They need to avoid getting disoriented by light pollution.
All told, just one in 1,000 to one in 10,000 make it to adulthood.
Now, scientists have developed a new sensor disguised as a turtle egg that could make this trip a little safer.
To help prop up ailing populations of sea turtles, turtle conservationists in hotspots around the world camp out at turtle nests around the time when the hatchlings are expected to emerge, to help usher them toward the waves. But predicting when this will happen is a bit of a guessing game.
“It’s absolutely magical to witness baby turtles poke their heads out of the sand and sprint towards the ocean, but it’s an event that can be very hard to predict,” said Erin Clabough, a neuroscientist at the University of Virginia who took part in the research.
Turtle nests can lie quietly for two months before emerging. The rush often comes in a sudden eruption of baby turtles known as a boil. Today, nest-watchers rely on estimates of how long turtles typically take to hatch. They also keep an eye out for a growing divot in the sand, indicating that the turtles below are digging their way out.
A team of self-described tech nerds decided to find a more accurate way to predict when the turtle race would happen. Beginning in 2013, a group that dubbed themselves “Nerds Without Borders” began testing tiny sensors inserted in turtle nests at the Cape Hatteras National Seashore in North Carolina.
The park’s beaches host nesting sites for five different species of endangered sea turtles, predominantly loggerheads. The National Park Service has blocked off stretches of beach for more than a month around the time when turtles might emerge. Pairs of volunteer nest “sitters” stand guard over the nests each night for a week or more, around the time when the turtles are expected to make a run for it.
The inventors wanted to see if their gadget could basically be a high-tech nest sitter. They built a little device that could detect small movements, much like the equipment in a cell phone that can sense when it’s being rotated. They encased it in plastic to resemble a turtle egg and wired it to a nearby communication tower.
Between 2013 and 2017, they placed the sensor egg, dubbed TurtleSense, in 74 loggerhead turtle nests along with several green and olive ridley nests, at Cape Hatteras. Then, they watched what happened.
The sensors revealed a clear movement pattern as the eggs matured. The nest grew restless as the turtles pushed their way out of their shells, typically starting 46 to 53 days after the eggs were laid. That effort was followed by a pause that generally lasted 1.5 days. Then came the final mad dash to the water, the scientists and inventors reported on Oct. 26 in PLOS One.
“As each turtle emerges from its shell, it climbs up to join its siblings at the top of the clutch of eggs, creating a wave of commotion among all the other baby turtles in the nest,” said Samuel Wantman, the retired software designer who started Nerds Without Borders. “When there is no more commotion there is a period of quiet, which may be the impetus for all the hatchlings to boil out of the nest together.”
The device, which costs around $300 per nest, offers a relatively affordable way to zero in on when the hatchlings are likely to head for the water, the scientists wrote. “As an automated system, TurtleSense can accurately predict hatching events and send alerts to wildlife managers and researchers.”
The sensors were more accurate than human observers in several ways. They can tell when the eggs in a nest haven’t survived (not all do), so people no longer need to police it. It also turns out that the sand depressions aren’t a terribly accurate way to know when the turtles are about to emerge. These indents were found in only 45% of the nests monitored for the research.
The inventors estimated the sensors could shrink the nest-sitting time to one to two days, during the lull in the nest that precedes the final migration. Volunteers nest sitters might still be needed, much like Dr. Suess’s fictional Horton the Elephant who perches atop an orphaned egg. But they wouldn’t need to sit for so long.
There’s one big glitch now: Today, no one is making the sensors. Due partly to government purchasing rules and turmoil at the National Park Service after Donald Trump was elected president, the park service never adopted the sensor-eggs for widespread use, said Wantman. Today, the original equipment is becoming outdated.
But if anyone wants to pick up the egg and run with it, so to speak, Wantman is ready to hand it off. “It would need some serious reengineering,” Wantman said. “But I’d be happy to work with someone to give them what we’ve got.”
Clabough, et. al. “The secret life of baby turtles: A novel system to predict hatchling emergence, detect infertile nests, and remotely monitor sea turtle nest events.” PLOS One. Oct. 26, 2022.
Image: ©Emirhan Karamuk/iStock