Epic Discovery: Drones Unmask World’s Largest Giant River Turtle Haven

What a wild ride—drones buzzed the Guaporé River for days, exposing 41,000 huge turtles nesting like never before. Ready for the details?

Drones have enabled scientists to identify and accurately count over 41,000 giant South American river turtles at a massive nesting site along the Guaporé River on the Brazil-Bolivia border, marking the largest such aggregation ever recorded. This breakthrough, detailed in a study by the University of Florida and the Wildlife Conservation Society, demonstrates how drone technology combined with statistical modeling addresses longstanding challenges in wildlife population surveys.

Innovative Drone-Based Survey Method

Researchers deployed drones over 12 days to monitor the turtles’ nesting behavior on the sandy banks of the Guaporé River, a major tributary in the Amazon basin, reports Discover Wildlife. The team flew drones four times daily, capturing 1,500 images per flight. These images stitched into high-resolution orthomosaics, allowing detailed analysis without disturbing the animals.

To enhance accuracy, scientists marked 1,187 turtles with white paint and tracked their movements. This approach accounted for errors like double-counting or missed individuals, common in traditional methods. Ground surveys estimated around 16,000 turtles, while unadjusted drone image reviews suggested nearly 79,000. The refined model yielded a more reliable figure of 41,000.

“These numbers vary greatly, and that’s a problem for conservationists,” says lead author Ismael Brack. “If scientists are unable to establish an accurate count of individuals of a species, how will they know if the population is in decline or whether efforts to protect it are successful?”

This method builds on drone advantages—speed and non-invasiveness—while integrating probability models to correct for animal dynamics.

Brack notes, “We describe a novel way to more efficiently monitor animal populations. And although the method is used to count turtles, it could also be applied to other species.”

Technical Details of the Giant River Turtles

The giant South American river turtle, or Podocnemis expansa, grows up to 90 cm (about 35 inches) long and weighs as much as 80 kg (about 176 pounds). Females exhibit social nesting, gathering annually in July or August to lay eggs. Despite legal protections, threats from poaching and habitat loss persist.

Drones provided clear visuals of turtles varying in color from dark grey to brown or olive green, aiding in identification during surveys. The study’s focus on movement tracking refined estimates, highlighting drones’ role in capturing real-time data over expansive areas.

Implications for Conservation and Drone Applications

Accurate counts are essential for assessing population trends and guiding conservation. The turtles serve as seed dispersers and prey, maintaining Amazon riverine ecosystems. This raises questions about prioritizing nesting site protections based on reliable data.

The approach extends beyond turtles; it suits surveys of seals, elk, or mountain goats where movement affects counts. Researchers plan expansions to Colombia, Peru, and Venezuela, combining surveys to detect trends.

“By combining information from multiple surveys, we can detect population trends, and the Wildlife Conservation Society will know where to invest in conservation actions,” says Brack.

For drone operators in wildlife monitoring, this underscores the value of orthomosaic stitching and statistical integration. It offers a less invasive alternative to ground work, potentially reducing costs and risks in remote areas like the Amazon. Building on that, regulatory bodies may increasingly endorse drone use in endangered species management, fostering broader adoption among professionals.

This development illustrates drones’ evolving role in ecology, balancing technological precision with conservation needs.

Photos courtesy of Omar Torrico, Wildlife Conservation Society