Drones uncover the hidden world of turtles worldwide

Revolutionary Drone Survey Uncovers Largest Turtle Nesting Ground on Earth

Key Findings

• More than 41,000 Giant South American River Turtles recorded along the Guaporé River
• First ever revelation of the world’s biggest known turtle nesting site
• Method combines high‑resolution aerial imagery with statistical movement correction

Traditional Counting Fall‑Shorts

Ground‑based observations are slow, invasive and frequently miss turtles that move between counting periods. The new drone‑driven approach speeds up data collection and improves accuracy by accounting for animal movement through statistical modeling.

Research Collaboration

Project kicked off with Wildlife Conservation Society (WCS) scientists working in Brazil, Colombia and Bolivia. WCS monitors the Giant South American River Turtle, a species threatened by poaching for meat and eggs. Turtles congregate each July or August in Guaporé sandbanks between Brazil and Bolivia to nest.

Methodology Highlights

Lead researcher Ismael Brack, a post‑doctoral fellow at the UF Institute of Food and Agricultural Sciences, met WCS scientists during a conference. The team uses drone footage to construct orthomosaics—high‑resolution composite maps formed by stitching together hundreds of overlapping aerial photos. These orthomosaics allow quick, precise, non‑invasive counting of turtles from above rather than from the ground.

Reinventing Turtle Counts with Drone Technology

Fresh footage from a Guaporé River island revealed two iconic South American river turtles in unexpected clutches: newborn Arrau turtles—the continent’s largest river reptile—and yellow‑spotted river turtles. Tiny, glass‑cleared plastic containers inside cardboard boxes contained the ships of these paddling infants, as confirmed by AFP/File MANAN VATSYAYANA.

High‑Altitude Video, Low‑Altitude Tracking

White paint marked 1,187 turtles on the sandbank, then a drone hugged the island in a tight back‑and‑forth sweep. The aircraft hovered four times a day, each pass yielding 1,500 sharp images. Advanced software stitched the shots into composite frames, and researchers then inspected the mosaics.

• Marking status—was the shell painted?
• Behavior snapshot—was the turtle nesting or walking?

Armed with these details, scientists from UF and the Wildlife Conservation Society (WCS) engineered probability models that accounted for turtles entering or leaving the island, their observed movements, and the chance of spotting a distinctive shell paint.

Eliminating Double‑Counts and Missed Individuals

Traditional orthomosaic counts, researchers noted, could miscount a single turtle up to seven times. Their new method slashed sampling errors and prevented repeated tallies.

Key Error Sources

• Only 35% of island turtles appeared during a drone flight.
• On average, 20% of moving turtles surface multiple times in orthomosaics.
• Ground counts reported ~16,000 turtles, but orthomosaic reviews recorded ~79,000. Using the corrected models, the estimate dropped to ~41,000.

Brack’s Vision for Future Conservation

“We present a novel way to more efficiently monitor animal populations,” explained Dr. Brack. “Our method’s applicability extends beyond turtles to any aggregated species monitored by drones.”

Other Species, Other Markers

Previous drone‑based projects have clipped seals’ fur, collared elk, or hurled paint‑ball pellets onto mountain goats. The same principle—accounting for movement, mark visibility, and repeat detection—could streamline counts for any species.

Research Publication

The study appears in the Journal of Applied Ecology as “Estimating abundance of aggregated populations with drones while accounting for multiple sources of errors: A case study on the mass nesting of Giant South American River Turtles.”