UAS proves value in U.S. Fish & Wildlife pelican survey

Using an unmanned aerial system (UAS) to count pelicans nesting at the Anaho Island National Wildlife Refuge in Nevada demonstrated the value of UAS to achieve a far more accurate bird count while reducing risks and lowering costs.

Last May, Mark Bauer, a UAS pilot and geospatial analyst with the U.S. Geological Survey, made three flights over Anaho Island with a fixed-wing AeroVironment RQ-11A Raven as part of an annual pelican survey conducted by the U.S. Fish and Wildlife Service.

At the same time, Donna Withers, a wildlife refuge specialist with the Stillwater National Wildlife Refuge Complex, led a team on to the island that counted the pelicans in the usual manner from high on a hill to avoid disturbing the nesting bird colonies. Recently, she was able to compare the results of the manual count to the data gathered by the UAS.

“Based on the difference between the data that Mark ran from his imagery and the ground crew count, we were almost 4,000 birds off; we had about 12,000,” Withers said. “In a good year, we used to say we had 8,000 to 10,000 pelicans. Now we know it’s more like 12,000.”

Withers said there are two reasons for the wide discrepancy. The angle from which the ground crew can view the pelican colonies doesn’t allow all the birds to be seen. In addition, shrubbery on the island also masks the view.

Anaho Island is about 60 miles northeast of Reno, Nevada, and is located on Pyramid Lake. Withers said it’s the second largest pelican nesting ground west of the Rocky Mountains and a place where the birds choose to nest because it lacks mammalian predators, such as coyotes.  

“They need an island habitat without any egg predators on it,” she said. “The adults weight up to 12 pounds. It’s not them that are threatened; it’s the eggs and the young birds.”

Bauer said the wildlife division of USGS often works cooperatively with the U.S. Fish and Wildlife Service. It has operators who are approved to fly UAS under a U.S. Department of Interior program.

“Right now, fish and wildlife doesn’t have a UAS program ramped up,” he said. “We collaborate a lot on a number of these different requests and projects.”

In addition to lower costs and improved safety, using UAS to overfly the nesting pelicans didn’t disturb the birds. Withers said that if the counters move even five feet closer to the birds, they notice it and become agitated.

The battery-powered Raptor UAS flown at 300 feet made a humming noise that didn’t affect the birds.

“They really didn’t do anything,” Bauer said. “They pretty much behaved the same way they normally do.”

Withers agreed, adding, “The UAV is about the same size as a pelican. At times, it looked like the pelicans were following it around. It wasn’t spooking them at all. They didn’t know what it was, but they didn’t really care. There were other smaller birds there, too, and they even ignored it.”

Both Withers and Bauer were impressed with the images captured by the UAS and the ability of the ArcGIS software Bauer used to count the birds.  

“The UAS imagery is just fantastic,” Bauer said. “You can pick the pelicans out plain as day. I used software that basically pulled them all out for me.”

The results have convinced Withers that UAS technology is the future of wildlife surveys.

“If we can use this UAS technology, it gives us a lot more consistency,” she explained. “You take the human factor out of it because you have the photographic image and the computer is set to run it. There’s still error involved, but it’s not the same as if you’ve got different people counting the birds.”

The information gathered will be stored in a database that will give Withers and the National Wildlife Service the ability not only to accurately count pelicans every year, but also to see how their nesting patterns change.

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