Squawking at the top of their voices! Birds are being forced to belt out their songs in order to be heard over the noise from passing aircraft, study finds
- Almost a million audio clips were analysed as part of a research project
- Found birds increase noise level by two per cent when aircraft nearby
- Birds were still louder than normal three hours after the aircraft had passed over
Birds are being forced to sing at the very top of their little lungs in order to be heard over the overwhelming ruckus from aeroplanes, a study has found.
Aircraft noise can drown out the gentle twittering of birds, and the birds have started increasing their own volume to compensate.
Analysis of 894,060 audio clips from around the US found birds increased their volume by two per cent when aircraft sound was detected.
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Data collection points (pictured) were set up around the US to capture audio of birdsong. Almost a million audio clips were taken in total and it found that birds increased their sounds by two per cent when aircraft sound was detected
WHY DO BIRDS SING?
Birds use their voices to communicate with other birds.
Sharp tunes are an efficient way to communicate over long distance, especially when you are small and live in dense habitats like rain forests.
Most bird species use specific calls to identify themselves and to communicate a nearby threat.
Birdsong is a specialised type of call used by many species to help them mate.
Almost exclusively a male activity, birdsong helps the singer to indicate he is fit, healthy and ready to breed.
Data was collected from 130 sites in 48 different parks and scientists analysing the information were surprised by the findings.
Doctor Kurt Fristrup, a National Park Service scientist, said the team expected it would be harder to detect bird calls when other sounds were nearby.
On average, across all parks monitored, the odds of hearing a bird sound increases by two per cent when aircraft sound is detected within that 10-second sample.
Likelihood of detecting bird noise dwindled over time, but birdsong was still more likely (0.3 per cent) to be detected two hours after a plane passed overhead.
The research is being presented during the 178th Meeting of the Acoustical Society of America this week in San Diego,
More research is needed, Dr Fistrup believes, to determine how significant the history of exposure the birds have had is and whether those that live in common plane routes now naturally sing louder their undisturbed peers.
However, the ubiquity of planes in the US skies and popularity of flying means future research faces a logistical struggle.
Dr Fistrup said: ‘The extensive presence of aircraft noise exposure in time and space implies that birds are chronically producing more sound in many locations.
‘We’ll reanalyse existing data to determine the types of sounds that are more common – song, call notes, etc – and which species of birds are affected.’
Future studies will also explore the physiological impacts on birds singing louder in the presence of aircraft noise.
Dr Fristrup said: ‘If findings emerge of significant physiological or ecological consequences for wildlife, then aircraft noise may be grouped with other environmental concerns for which dilution is not the solution.’
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