According to the survey, common chiffchaffs living close to the noise of aircrafts taking off and landing were five times more likely to attack a speaker emitting bird song than their counterparts who lived away from airport noise.
Published in The Journal of Animal Ecology, the research by Manchester Metropolitan University in partnership with Manchester airport, also found birds living close to airports are exposed to extreme noise levels from jet engines that interfere with their communication with mates and rivals, since males defend their territories by singing from strategic positions throughout the breeding season.
Noise from aircrafts landing or taking off can reach 100 decibels at a distance of 100 metres, levels which can cause permanent hearing damage to humans as well as birds.
Researchers from Manchester Metropolitan University, Leiden University, and the University of Manchester recorded the songs of birds close to Manchester airport and Amsterdam’s Schiphol airport at a distance of between 180m and 2,100m from the runways, and from birds living 20km away.
Using a remote-controlled playback speaker, pre-recorded male songs were played, mimicking a nearby rival. Populations close to the airport were more aggressive, attacking the speaker 5 times more than control birds.
The study also shows that the airport birds changed their style of song, using lower maximum and peak frequencies and delivering syllables at a slower rate. This indicates possible Noise Induced Hearing Loss (NIHL), a potential reason behind the birds’ aggression. Laboratory studies of hearing-impaired birds have shown a similar change, but this is the first time it has been observed in wild birds.
The findings have implications for conservation and environmental regeneration projects close to airports, as well as helping airport planners to adapt for wildlife conservation.
Researcher Dr Selvino de Kort, Senior Lecturer in Animal Behaviour at Manchester Metropolitan, said: “This is important because air travel passenger numbers are expected to grow globally, increasing the need for new or expanded airports as we see with the current discussion surrounding a third runway for Heathrow airport.
“It’s important that we understand the impact of aircraft noise and ensure that birds – and other wildlife – are adequately protected.”