Juvenile salmon traveling in the Columbia River near McNary Dam in Oregon are vulnerable to hungry birds that lurk overhead. Thanks to the Walla Walla District of the Army Corps of Engineers, which deployed lasers in the area, the endangered fish are now protected from above as well as in the water.
McNary Dam, maintained by the Corps, stretches 1.4 miles and spans the Columbia River between Umatilla County, Ore., and Benton County, Wash.
Lasers installed by the Army Corps of Engineers deter birds from feasting on juvenile salmon at McNary Dam in Oregon. Courtesy of Caleb Willard.
The Corps used two AVIX Autonomic class 3B 499-mW lasers for the job of protecting the river’s fish. One laser is positioned on the navigational lock wing wall on the downstream side of the dam, and it provides coverage of the fish outfall pipe and the surrounding area, including the dam itself. The other is positioned directly on the outfall pipe and covers the water right below it. The lasers generate a green dot that birds see as a solid object and interpret as a threat. The lasers, which are harmless to humans and wildlife, are programmed to move in random patterns within a predetermined area. They have a range of ~950 ft to 1 mile, depending on the weather. Technology and nature are often thought of as adversaries, but in this case, they make excellent partners.
According to Bird Control Group — the company that distributes the AVIX technology and has offices in Oregon and the Netherlands — the lasers have been shown to be an effective deterrent against a wide variety of birds, including gulls, geese, pelicans, herons, and crows, making the lasers a type of modern-day scarecrow. The technology has been shown to reduce bird nuisances by up to 70% in areas where it has been used. According to Caleb Willard, a mechanical engineer with the Corps, the lasers run from dawn to dusk in April through October, the passage season of the juvenile fish.
He said that the Corps used only one laser last year, but two are currently being used for logistical reasons.
“The first laser didn’t quite have the range to keep birds from roosting on our juvenile outfall pipe on a sunny day, so we installed a second to specifically cover the pipe,” Willard said. “This was our district’s first experiment with an off-the-shelf automated laser bird deterrent.”
Beginning in August, the lasers will be used in conjunction with a long-range acoustic device (LRAD). The devices are essentially speakers that broadcast a tone similar to a car alarm over a wide area. They are commonly used at airports across the country. Like the lasers, they have also proved to be an effective bird deterrent.
“We are testing a much smaller version than what is being used at airports,” Willard said. “Currently we are using the smaller LRAD to test and make sure it will not negatively affect the surrounding community. The goal is to only project sound where the birds are feeding.”
Tech-induced dieting for birds? For the sake of the endangered salmon, the Corps certainly hopes so.