Technology makes community-based sea turtle monitoring more efficient
Scientists in Trinidad and Tobago are using thermal drones to guide on-the-ground survey efforts for endangered leatherback sea turtles.
Over the course of 52 flights, the drones helped researchers record and identify 394 leatherback sea turtles as well as relocate rangers to high-activity areas.
“Because leatherback turtles nest at night, thermal cameras make sightings very easy,” said Adrian Wilson, a research officer at Nature Seekers, a local sea turtle conservation organization.
Guiding on-the-ground efforts
Leatherback (Dermochelys coriacea,) hawksbill (Eretmochelys imbricata) and green (Chelonia mydas) turtles all nest on Matura Beach in northeastern Trinidad, though the leatherbacks occur in much higher densities. Poaching has largely stopped on the beach, but endangered leatherbacks still face problems such as habitat loss, climate change and sargassum blooms that make it challenging for nesting and hatchling turtles to navigate on land. Nature Seekers rangers, who used to patrol the beach looking for poachers, now use these surveys to monitor the population and protect them.
When a ranger encounters a turtle during their patrol, they collect measurements and notes. They also conduct flipper and PIT tagging. This takes time—the 5.5-mile beach would ideally have around 20 people on patrol each night. “It’s difficult, if not impossible to have enough patrols to cover the entire beach,” Wilson said. With only six or seven rangers out each night, Wilson wanted to ensure there was a way to maximize the number of turtles they could measure. That would mean making sure the rangers were in the parts of the beach where the turtles were. “Having the drone in place, we can zoom all the way down the beach in 20 minutes and find where we should place our patrols.”
For a study published in the Wildlife Society Bulletin, Wilson and his colleagues evaluated the use of drones to help monitor leatherback nesting.
The team flew the drone four times a night, every two hours starting at 8 p.m., making two complete passes. Although it varies, each turtle generally stays on the beach to nest for around 90 to 120 minutes, so the drone was able to capture footage of nearly every turtle that came to nest each evening.
The researchers found that they could distinguish leatherbacks from hawksbill and green sea turtles based on their overall shape and size, as well as the kinds of tracks they left behind in the sand. As the female turtles crawl up the beach, they displace the cooler top layer of sand, making the differences visible on thermal cameras.
Creating a community of conservation
Matura Beach is one of the three major protected nesting sites for leatherback sea turtles on Trinidad and Tobago, which together support around 80% of the turtle’s population in the Caribbean.
However, Matura Beach hasn’t always been a haven for sea turtles. Before local Suzan Lakhan-Baptiste founded Nature Seekers to protect turtles, poachers threatened the population by removing high numbers of both adults and nests. Although Wilson said the last recorded poaching incident, which involved egg harvesting, happened 14 years ago, the beach is still highly protected.
To protect nesting turtles, the beach is now closed to the public during nesting season except if individuals have a special permit. Community members are granted special permits, though, which are mostly used for fishing. “It’s not a high use-recreation site, but there was still a lot of pushback when the beach was first closed,” Wilson said. For coastal communities, access to beaches for daily life is crucial, he added.
Through the closures and support from Nature Seekers, leatherback sea turtles at Matura have bounced back.
Nature Seekers also employs community members to help with nighttime surveys, some of whom have been a part of the organization since its inception over 35 years ago. Wilson is excited to see how the drone will continue to support the rangers’ data collection on the ground. “There were turtles that would have been missed if we didn’t have the drones,” Wilson said. They also hope to use drones to distinguish the green and hawksbill turtles from one another, which they can’t yet tell apart on the videos due to limited records.
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