Sonic net too noisy for airport birds

A new way of using noise to deter birds could drive down their numbers around airports by more than 80 per cent.

A study published in the academic journal Ecological Applications describes a new way of driving birds away with noise. Rather than trying to scare the birds away with loud noises and sound of predators, the approach is to blanket the area near runways with sound that prevents the birds from hearing whether there are real predators nearby. For birds it’s the equivalent of being in an unbearably noisy bar or restaurant, where conversation is impossible.

The study notes that collisions between birds and aircraft cause billions of dollars of damage annually to aircraft. ‘Yet technology to reduce bird strike is not generally effective, especially over longer time periods,’ the authors say.

They deployed a spatially controlled noise described as a ‘sonic net’, designed to overlap with the frequency range of bird vocalisations at an airfield in Newport News, Virginia, US.

The researchers counted bird numbers near the airfield for four weeks before deployment of the sonic net, and for four weeks during deployment. ‘We found an 82 per cent reduction in bird presence in the sonic net area compared with change in the reference areas,’ they reported.

Crucially, the effect of the sonic net was consistent, unlike the traditional dispersal technique of loud noises, which birds quickly become used to. ‘This effect was as strong in the fourth week of exposure as in the first week,’ the study reported.

‘We propose that spatially controlled acoustic manipulations that mask auditory communication for birds may be an effective long-term and fairly benign way of excluding problem birds from areas of socioeconomic importance, such as airfields, agricultural sites, and commercial properties,’ they concluded.

Flight Safety Australia’s current May­–June 2016 issue leads with an examination of bird hazards. The feature looks at the distinctive dangers birds pose to offshore helicopter operations and points out the many variations of bird behavior which pilots and air operators serious about minimising bird strike risk should know.