After more than one study found that drones are better than humans at monitoring wildlife populations, their use in endangered animal studies has quickly increased.

Researchers at Duke University and the University of North Carolina have begun using drones to count endangered sea turtles along the Costa Rican coast. Sea turtles populations have been difficult to estimate because the animals spend much of their lives at sea, coming ashore only to lay eggs during the nesting season.

Counting the animals has typically been done by boat or by counting the turtles on nesting beaches, which only gave scientists a snapshot of a small area.

The drones are equipped with high-resolution cameras with near-infrared vision. During their flights, the fixed-wing crafts would hover 300 feet above water off the Ostional National Wildlife Refuge. The position allowed researchers to view a wide area at once and spot turtles below the surface that wouldn't have been visible while looking over the side of a boat.

During the season, researcher spotted hundreds of thousands of olive ridley sea turtles coming ashore and they estimate that there were about 2,100 sea turtles per square kilometer at the peak of the season. The numbers were much higher than the scientists expected showing how the drones are giving researcher better vantage points to produce more accurate numbers.

“Our findings confirm drones can be used as a powerful tool to study sea turtle abundance at sea, and reveal incredible densities of turtles in Ostional’s near-shore habitat,” said Vanessa Bézy, a Ph.D. candidate at UNC and co-lead of the study. “The development of this methodology provides vital new insights for future conservation and research.”

This study was the first to use drones for counting sea turtles, but with this evidence will likely not be the last.