Animal-borne video cameras reveal secret lives of sea turtles

There is no shortage of tomfoolery in the daily lives of sea turtles. Challenging a feisty crab. Chance encounters with stingrays. Playdates with their closest friends. And fighting siblings to keep them out of their personal spaces.

FIU researchers Mike Heithaus and Jordan Thomson are offering an inside peek into the daily lives of sea and loggerhead turtles in Shark Bay, Australia.

“Sea turtles are difficult to observe in their natural habitat because they spend so much of their time underwater. They’re among the longest breath-hold divers in the world and can stay underwater for up to 5-6 hours at a time,” said Thomson, a post-doctoral associate in the College of Arts & Sciences’ Marine Sciences Program. “Traditionally, researchers needed to analyze stomach contents from deceased or stranded turtles. Even getting diet samples from free-ranging turtles is something new. This animal-borne video technology is great because we can observe these turtles as they are in their natural habitats.”

Using GoPro video cameras attached to the turtles’ shells, the day-to-day activities of turtles were recorded in segments. After 24 hours, the camera’s harness would dissolve, the equipment would fall off and eventually float to the surface. Using a radio transmitter, the researchers were able to locate and retrieve the equipment.

Playfulness aside, Heithaus and Thomson are studying the foraging ecology, locomotion, diving behavior and social interactions of these endangered animals.

In six months of fieldwork between 2011 and 2013, Thomson and Heithaus deployed more than 120 video tags yielding nearly 400 hours of footage. They found strong patterns in sea turtle behavior associated with seasonal water temperatures, which have long been suspected but have proven difficult to observe. Specifically, they found turtles are more active during the warm season, spending most of their time swimming, surfacing, exploring vast seagrass meadows, feeding and interacting with other turtles. During the cold season, the turtles’ lives slow down as they spend most of their time resting on the seabeds and rarely surfacing.

“Understanding their diets, movement and behavior is essential to knowing what their function is in coastal ecosystems and for managing and conserving their populations,” Thomson said. “Their behavior and movement also has implications for regional management issues, including commercial fishing.”

Heithaus, who is executive director of the School of Environment, Arts and Society, has been using animal-borne video cameras in his research for years.

“The nice thing about using video cameras in the study was to be able to directly see what animals were doing and not having to make guesses based on other information like how long they spent underwater between each time they came up for air,” Heithaus said.

Animal-borne video allows for longer-term observation of behavior without the risk of observer presence influencing turtle activities. Sea turtles are ideal for hosting the video cameras because of their large body size, relatively flat shell for instrument attachment, and their accessibility in many regions, including nesting beaches and shallow foraging areas. Animal-borne video has also been used to study the underwater behavior of other animals, including penguins, seals, whales, dolphins, porpoises and sharks.

FIU researchers currently have a number of projects that use animal-borne video cameras on sea turtles in the Bahamas, Bermuda, Australia and sharks in the Pacific Ocean and Australia.

The research findings were published in an article titled “Animal-borne video reveals seasonal activity patterns of green sea turtles and the importance of accounting for capture stress in short-term biologging” in the Journal of Experimental Marine Biology and Ecology.

To see more clips of the turtle adventures, go to the Heithaus Lab Marine Biology and Science Adventures.