Coast News

Drones Sneak Peek at Seldom Seen Sea Turtle Behavior

Elizabeth Bevan wrecked a lot of pantyhose when she was a little girl. “I’m from South Florida, and I’ve always been absolutely fascinated by anything and everything that swims in the ocean,” she said. “I would pretend to be the Little Mermaid by putting both feet in one leg of a pair of pantyhose and swimming around.”

As she grew up, Bevan never lost her fascination with the sea. She earned a degree in marine biology at Florida International University. Then the 2010 Deepwater Horizon oil spill brought her to Alabama — and the doctoral program in the UAB College of Arts and Sciences Department of Biology, where she studies sea turtles with her mentor, professor Thane Wibbels, Ph.D.

Commercial fishing, pollution and other environmental stressors have devastated sea turtle populations all over the planet. Bevan and Wibbels study a particularly endangered species, the Kemp’s ridley sea turtle. The Kemp’s ridley is the smallest of the world’s seven sea turtle species, and is mainly found in the Gulf of Mexico. It may also be the most mysterious.

For decades, famed naturalist Archie Carr searched in vain for its nesting grounds. Even after they were located, on a small stretch of beach in Tamaulipas, Mexico, researchers knew little about where the Kemp’s ridley mated, and when. They still don’t, says Bevan. And the question is far from academic. Finding the answer could well be the key to the species’ ultimate survival.

But Bevan and Wibbels are pioneering a high-tech tool that could help solve the mystery: drones. In a new paper in the journal Herpetological Review, the UAB team describes an exciting new technique that Bevan thinks will revolutionize not only marine biology, but many other fields of animal study as well. “Drones have changed everything,” she said. “UAV technology has incredible potential to significantly advance the way we do science.”

Why turtle mating matters
The governments of the United States and Mexico have cooperated since the 1970s to protect the endangered Kemp’s ridley in the Gulf of Mexico. Their binational effort includes support for the UAB researchers, who drive down to the main nesting beach in Rancho Nuevo, Mexico, several times a year. Bevan is particularly interested in the Kemp’s ridley’s courtship and mating behaviors. “These behaviors are incredibly important,” she explained. “Governments need to know where courtship and mating occurs, and when, so they can restrict human activity and help the population recover.”

The trouble is, “these occur out in open waters that are really difficult to access,” Bevan said.

Scientists know roughly when to expect the mass nesting event, known as an arribada, that represents the end of that cycle. But where, and when, does the rest of it occur? First you have to find them, out in the open ocean. Then you have to find a way to stick around for the hours-long process. Researchers have tried boats, snorkeling gear and land-based elevated platforms. None are very good solutions, which explains this large blank spot in the scientific literature.

“Only five published studies have focused on courtship and mating behavior” in any sea turtle species, Bevan said. The most recent, carried out at a commercial sea turtle “farm” in the Cayman Islands, came out in 1990.

Flight school
But Wibbels and Bevan realized that scientists now have a new option. Wibbels had bought a small, camera-equipped drone — also known as an unmanned aerial vehicle, or UAV — for Christmas.

“We brought it to our field site to see if it was any good for studying sea turtles,” Bevan said.

Turned out it was. The machine could sweep the sea for a few kilometers up and down the nesting beach far quicker than a boat on the often-choppy seas in the area. And its camera could easily pick out the shapes of swimming turtles.

Soon, the researchers had upgraded to a more powerful DJI Inspire 1 UAV, which was able to transmit live video back to the beach. “We found that the best way to locate turtles is to have one person watching the camera while the other concentrates on flying,” Bevan said. (Bevan is usually the pilot.) “It records high-resolution video, and can transmit pictures back from over three miles away.”

Bevans and Wibbels recorded nearly 50 hours of video, and spent five months studying it. They recorded crystal-clear footage of Kemp’s ridley and Green sea turtles engaged in many different mating behaviors. In fact, as the UAB researchers explain in Herpetological Review, they recorded eight of the 11 courtship and mating behaviors identified in the landmark 1990 study by Comuzzie and Owens. That included seven instances of copulation, “something that very few scientists have been able to witness,” Bevan said. “In that case, we reduced altitude to get a closer look. It did not have any effect on the behavior.”

mix bevan2 2

Elizabeth Bevan pilots the UAB team's DJI Inspire in Rancho Nuevo. Photo credit: UAB

Drone catches spurned turtle trying to ruin rival’s honeymoon

Marine biologists call it “escorting.” A spurned male, catching a rival with an available female, will swim alongside a mating pair. “He’s mad,” said Bevan. “He’ll cut in front of them, trying to dislodge the other male.” Bevan’s video footage of these and other encounters, captured from a drone overhead, form the basis of a new paper, “Using Unmanned Aerial Vehicle (UAV) Technology for Locating, Identifying, and Monitoring Courtship and Mating Behavior in the Green Turtle (Chelonia mydas).”

Flying along up to two kilometers (1.24 miles) from the beach, and a height of 30 meters (90 feet), Bevan and other researchers recorded eight courtship and mating behaviors. These include couples nuzzling, males chasing fleeing females and the “chemosensory investigation” known as a cloacal check, in which a male inspects the female’s tail region.

Next steps
Interesting turtle behavior occurs on the beach as well, Bevan said. The UAB team has already flown over nesting mothers, to get an unprecedented look at the process. “No one else has observed nesting from this perspective,” said Bevan, showing a video. “This technology is revolutionizing the way we see sea turtles.”

During this year’s nesting season, the researchers are hoping to film an arribada, when thousands of Kemp’s ridley turtles swarm the beach within a few hours to lay their eggs.

Drones are definitely noisy, Bevan said. Even though they didn’t notice any behavioral effects, even when they descended to a spot only 20 feet above the turtles, Bevan says the researchers are investigating this angle.

“We are designing experiments to determine what effect noise has on the behavior and physiology of the animals,” she said. “Turtles don’t hear in the same way we do, but they do pick up vibrations in the water, so we’re interested to look into that.”

Although the potential is clear, it is also evident that researchers have a steep learning curve when it comes to using UAVs in the field, Bevan said. She has been experimenting with ways to take the team’s flights even further offshore. The Inspire’s battery and camera range currently limit flights to within five kilometers of the beach. Taking off from a boat would let the UAB team reach deeper into the Gulf. But the Inspire is equipped with a high-tech rangefinding sensor on its undercarriage, which refuses to let the drone take off on an unstable surface for safety reasons.

“A boat is always going to be unstable, so we’re still trying to figure that one out,” she said.

Bevan will be paving new territory this nesting season at Rancho Nuevo, "because she will be evaluating a recently released infrared/thermal camera on the DJI Inspire for monitoring sea turtle nesting and predators preying on sea turtle nests during the night, as well as during the day," Wibbels said. "This is the camera that DJI has developed for the Inspire that will be the mainstream camera and drone that will revolutionize the capabilities for all fire departments and police departments in the U.S. in terms of looking for people during fires, or at night, or those lost in the woods, etc. Elizabeth will be spearheading the technology for sea turtle biology and conservation."

Enticing new drone models are always hitting the market, Bevan adds. “We just need the grant funding to get them.”


By Matt Windsor, University of Alabama at Birmingham

ECO Magazine is a marine science publication committed to bringing scientists and professionals the latest ground-breaking research, industry news, and job opportunities from around the world.


8502 SW Kansas Ave
Stuart, FL 34997


Newsletter Signup

Please type your full name.

Please type your full name.

Invalid email address.

All emails include an unsubscribe link. You may opt-out at any time. Clicking subscribe confirms your acceptance of our privacy policy.