Here’s how white noise could save millions of birds

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In the United States, bird populations decreased by around 3 billion since 1970. In fact, in New York City alone, approximately 200,000 birds die each year while flying in buildings. As our high rise cities expand upward and outward, the problem is only likely to grow exponentially, with more and more birds dying by crashing into large glass buildings, communication towers and power lines. However, with a great design, that doesn’t have to be the case.

May study says we could prevent migrating birds from colliding with tall metal structures, tall buildings and possibly even wind turbines by installing “acoustic beacons” that emit white noise in short bursts , a press release indicates.

The system, called Acoustic Lighthouse, was invented by a group of researchers led by Timothy Boycott of the College of William & Mary. While there are other strategies involving patterned glass and laser lights, the researchers thought the sound would be a better warning, as most birds sometimes have a blind spot right in front of them due to the position of the bird. their eyes.

Two types of sound signals have been shown to decrease bird activity around communication towers by up to 16 percent in field studies performed during fall migration in North America.

During the field tests, the researchers used loudspeakers to broadcast white noise around two communications towers on the Delmarva Peninsula on the US east coast in 30-minute bursts. For six days, two distinct types of white noise were tested to see the reactions of the birds. One of them was tuned to fit the hearing range of many birds, while the other was tuned to stand out against background noise at higher frequencies.

The flight behaviors of more than 1,500 birds passing within 328 feet (100 m) were recorded, so the researchers were able to determine the number of potential birds rescued. The two sounds tested prevented birds from flying too close to the towers; however, the low frequency sound (4-6 kHz) was more successful in ensuring that more birds moved away from the towers earlier than under normal conditions.

“[Birds] stayed further away from the towers and oriented their flight paths more in relation to the towers, ”Boycott explained. While this may vary among bird species, it could indicate that birds can hear lower frequencies more clearly.

“Future studies would be really important to see how these differences in flight behavior actually translate into ground mortality,” Boycott added.

However, it should be noted that sound alone may not be enough to deter birds, which is why visual cues can be helpful as well. In fact, another study has shown that painting wind turbines black can reduce bird mortality and the risk of collisions by 70%.

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