All over the world, aircraft noise is an issue for those living close to airports. Anyone who has stood by a runway during a take-off or landing knows how loud it can be. This noise also affects wildlife living by airports and new research shows that birds living close to airports are more likely to suffer from hearing loss and become more aggressive than birds that live in quieter areas.
Airports and birds don't go together and millions of dollars are spent every year to try and keep birds away from planes. While most concerns lie around the safety of planes being damaged by bird strike, flying into a plane is almost always fatal for the bird. This week research published in the Journal of Animal Ecology found that aircraft noise was also a life-threatening challenge for birds living close to an airport.
Anthropogenic noise has been shown to shape wildlife populations by reducing the total number of species present at specific locations and altering the composition of species in different areas.
At up to 100 decibels, aircraft noise is typically much louder than that created by cars. Human exposure to noise levels of 105 decibels for more than one hour is considered traumatic, leading to permanent hearing loss, however, we don't create the same hearing safety sheets for animals. To look into the effect of loud noises on the hearing of birds, a new study looked at Phylloscopus collybita - a bird better known as the common chiffchaff - and frequent exposure to aircraft noise.
Chiffchaffs are territorial birds and usually use their voices rather than physicality to defend their territory by singing from strategic positions throughout the breeding season.
In the study, the researchers played a pre-recorded male chiffchaff song through a speaker to mimic a nearby bird rival and then studied the response from the birds living in the area. The birds were split into two groups, those that lived close to a large airport (between 180 to 2100m from the runway) and those that lived far from an airport, which was defined as 20km away. Tests were carried out at Manchester Airport in the UK and Schiphol airport in Amsterdam.
The researchers found that the bird populations which lived close to the airport were much more aggressive, attacking the speaker five times more than the birds who lived 20km away. Physically attacking a rival instead of settling a conflict through song drains energy from the birds, making them more vulnerable to predation and reducing their reproductive efforts. They also found that the birds which lived by the airport sang a different style of song when compared to birds that lived further away. Their modified songs used a lower maximum and peak frequency and delivered syllables at a slower rate. Previous studies on laboratory-bred birds with hearing impairments have shown similar changes to their song, indicating that the birds living by the airport were likely to be suffering from aeroplane-induced hearing loss.
The International Air Transport Association expects the number of air passengers to double over the next 20 years to 7.2 billion making aircraft noise much more prevalent in the future.
We are only just beginning to understand the impact of urbanisation and noise levels on the diverse wildlife unique to New Zealand. Findings like these show that increased air travel has potential implications for both conservation and environmental regeneration projects in Aotearoa. While the pressure is on to create innovative aircraft solutions to help reduce their fuel pollution perhaps more of a push towards noise reduction should be added to the wish list too.