Noise net could save birds, aircraft

New York, May 8 (IANS) Introducing a noise net around airfields that emit sound levels equivalent to those of a conversation in a busy restaurant could prevent collisions between birds and aircraft, saving lives and billions in damages, new research has found.

Filling a controlled area with acoustic noise around an airfield, where the majority of collisions tend to take place, can reduce the number of birds in the area by 80 percent, the findings showed.

"We are using a different kind of deterrent - trying to stop birds from hearing one another by playing a noise that is at the same pitch as the alarm calls or predator noises they are listening out for," said lead researcher John Swaddle, professor of biology at College of William and Mary in Williamsburg, US.

"By playing a noise at the same pitch, we mask those sounds, making the area much riskier for the birds to occupy. The birds don't like it and leave the area around the airfields, where there is potential for tremendous damage and loss of life," Swaddle noted.

The researchers set up speakers and amplifiers in three areas of an airfield in Virginia state and observed bird abundance over eight weeks, the first four weeks without noise and the second four weeks with the noise turned on.

Results showed a large decrease in the number of birds in the 'sonic net' and areas just outside and found that it was particularly effective at deterring a number of species that were at high risk of bird strike such as starlings.

"We have conducted prior research in an aviary but this is the first study done out in the field to show the efficacy of the sonic net," Swaddle, who is also a visiting research associate at University of Exeter in Britain, said.

The study was published in the journal Ecological Applications.

Bird strikes cost the aviation industry worldwide billions of dollars annually, and were responsible for 255 deaths between 1988 and 2013, yet measures to reduce these have been largely ineffective, the study noted.

Techniques to deter birds from airports include shooting, poisoning, live-capture and relocation, and the use of scare technologies, but these have proved largely ineffective.