This week, Savannah River Ecology Lab scientist Bobby Kennamer began testing the “acoustic hailing device” as a tool to keep unwanted birds away from airports and landfills.
“One thing they tell you is, don’t ever stand in front of it,” said Kennamer, who aimed a variety of shrill, noisy bursts at redwing blackbirds roosting at Phinizy Swamp Nature Park.
The device, formally called the HS-18 HyperSpike, is part of a study being conducted by the lab for the U.S. Department of Agriculture’s National Wildlife Research Center to improve tactics of repelling birds that can threaten aviation or damage military sites.
Harassment of unwanted birds, according to scientific journals, is becoming more popular because it can control blackbird numbers in sensitive areas with nonlethal means.
According to the Federal Aviation Administration, bird collisions with aircraft have increased dramatically, from 1,804 in 1990 to more than 10,000 in 2011.
Phinizy Swamp Nature Park, with hundreds of acres of constructed wetlands, has been a perennial draw for migratory redwing blackbirds – and a frequent test site for methods to harass them.
Scientists observed as many as 15 million blackbirds moving through the area annually in the first few years after the wetlands were completed.
Since then, thinning of vegetation and the use of airboats to flatten aquatic weeds used as roosting habitat have reduced those numbers.
But there are still plenty of redwings, Kennamer said.
“We counted about 10,000 here last night,” he said.
So far, just one noisy round has been completed in a series of tests that will be repeated Tuesday evenings for a few more weeks.
During the tests, sections of the nature park will be closed off and signs will be placed to warn visitors to stay away from the noisiest areas.
In terms of volume, the portable device can produce 156 decibels at a distance of one meter.
By comparison, Kennamer said, a world-record noise level for an outdoor sports stadium was set Sunday, when Kansas City Chiefs fans cranked out 137.5 decibels during the closing minutes of a 24-7 NFL win over the Oakland Raiders.
What about the birds? Some of the sound bursts didn’t seem to faze them.
Cranking up the volume, however, appeared to get their attention.
“That’s running some of them off,” Kennamer said. “You can see them moving.”