FAU Study: Drones Map Loggerhead Sea Turtle Nesting Site Hotspots

Graduate student and lead author, Summer Manestar, holding the UX11 unmanned aerial vehicle that was used in the study.

Florida's beaches - particularly those in Palm Beach County - are among the world's most vital nesting grounds for loggerhead sea turtles (Caretta caretta), accounting for 90% of all loggerhead nests in the Southeastern United States. Where a sea turtle chooses to nest is a delicate balance between the energy spent searching for the right spot and the benefits that location provides for successful egg incubation.

Because nest placement directly influences hatchling survival, emergence success, and even sex ratios, understanding the factors that guide these decisions is critical. Changing coastal and environmental conditions, sea level rise, and other impacts threaten these fragile habitats, altering the limited environmental conditions that turtles depend on for nesting. By identifying areas with higher or lower nesting activity, researchers can better understand what makes certain habitats more suitable and work to protect them for future generations.

Researchers from Florida Atlantic University 's Charles E. Schmidt College of Science have taken an important step in uncovering these patterns. Using drones and surveys, they investigated the environmental and human-related factors that influence loggerhead sea turtle nest site selection. They also looked at how these factors vary between successful nesting attempts and false crawls - when a turtle emerges from the ocean but returns without laying eggs.

The research led by Summer L. Manestar, who completed her M.S. in marine science and oceanography in FAU's Department of Geosciences, was conducted on a high-density nesting beach in Boca Raton, one of the most active loggerhead nesting regions in the world.

Published in the journal Shore & Beach, the study combined drone-based photogrammetry - a technique that uses images captured by drones to create accurate, detailed maps and 3D models of the landscape - Real Time Kinematic GPS surveys, and sediment granulometry to measure beach slope, sand texture, and nest proximity to artificial structures such as dune crossover stairs. Statistical analyses, including generalized linear models and t-tests, were used to assess which environmental and anthropogenic variables most strongly influenced whether a nesting attempt was successful.

The results showed that the steepness of the beach and how close dune crossover stairs were to nesting areas were the most important factors influencing turtle nesting. Loggerheads were less likely to attempt nesting on beaches with steeper slopes or when the stairs were farther away. Beach width and sand type did not seem to make much difference. Overall, the distance to dune crossover stairs was consistently important, suggesting that even small changes in the placement of human structures can affect whether turtles successfully nest.

Analysis of nesting patterns showed that turtles tended to nest more in the northern and central parts of the beach, while the southern end had fewer nests but more failed attempts. Early in the season, there were many more false crawls than successful nests. Later in the season, the same northern and central areas remained popular for nesting, but false crawls were spread more evenly. Nest locations also shifted over time, with more early-season nests in the mid-beach area and more late-season nests near the backbeach, suggesting that changing conditions influence where turtles lay eggs.

"This research really demonstrates how new technology can deepen our understanding of natural processes," said Tiffany Roberts Briggs, Ph.D., co-author and chair of FAU's Department of Geosciences. "By combining drone-based mapping with on-the-ground data collection, our team has revealed how even small variations in beach shape or the presence of human structures can influence whether a sea turtle successfully nests. These findings are not just important for science - they directly inform how we manage and protect Florida's beaches for generations to come."

Compared to satellites or LiDAR, drones provide high-resolution, affordable data that help researchers see small features of the beach that affect where turtles choose to nest.

The research team emphasizes that understanding how both natural features and human-made structures influence sea turtle nesting can guide coastal development and conservation policy in meaningful ways. The framework established through this work could also be applied to other species of sea turtles, including green turtles (Chelonia mydas) and leatherbacks (Dermochelys coriacea), to gain a more comprehensive understanding of nesting ecology along Florida's dynamic coastline.

"Projects like this highlight how innovation and conservation go hand in hand," said Roberts Briggs. "When we can pinpoint what makes a beach successful for nesting, we can take concrete steps to ensure that Florida remains a haven for these incredible animals."

Study co-author is James Gammack-Clark, a senior instructor in the FAU Department of Geosciences.

Unmanned aerial vehicle (drone) aerial image of a beach in Boca Raton capturing the tracks of a nesting sea turtle.

An adult loggerhead sea turtle.

-FAU-