Male bluebirds will shout to cut through the noise and make themselves heard

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Noise pollution is a nuisance that forces us to shout at top of our voices to make ourselves heard. Birds too are forced to do so as a new study has found that blue birds can alter their songs in response to increase in background noises, in many cases, because of human activities such as traffic.

A new innovative study – possibly the first of its kind – by a team of researchers led by an expert from the University of Exeter looked at how bluebirds altered their songs in response to increase in background noises. Researchers found that the birds – in real time – altered their songs and at times even produced songs that were both louder and lower-pitched to cut through the noise.

The findings suggest that even birds can perceive noise pollution and adjust their songs accordingly – a finding that will enable researchers to enhance their understanding about how animals and birds respond to man-made noise pollution and how we can reduce the negative impacts.

Dr Caitlin Kight, a behavioural ecologist based at the University of Exeter’s Penryn Campus in Cornwall, led the study. The team found that there are surprising similarities in certain features of noise including volume, pitch, or timing. Researchers cited traffic noise and said these are not hugely different from noises produced by waterfalls or heavy winds.

This means that animals and birds that have lived and evolved in such habitats would already be aware of how to respond to such noise levels and how to tune their songs to make themselves heard.

For their research, Dr Kight recorded songs produced by 32 male bluebirds, and analysed two from each male – those produced during the quietest and loudest period of ambient noise – to investigate whether males changes their songs between these two conditions.

She found that, as background noise increased, male bluebirds produced songs that were louder and lower-pitched. This suggests that the birds are able to both perceive and respond to increases in noise. This enabled them to produce songs that were more likely to be heard by potential mates or rivals.

Co-author Dr John Swaddle, from The College of William and Mary, in the United States, cautions against interpreting these findings as evidence that noise pollution has no adverse impacts on wild animals.

Dr Swaddle said: “Unfortunately, the world is getting so noisy that even the most flexible of species will eventually reach a threshold beyond which they will have difficulty communicating—which will impact their ability to breed successfully. When we build roads and airports near human neighbourhoods, we employ noise abatement protocols in an effort to mitigate against the negative impacts of noise pollution. It is time to apply similar caution to conservation, management, and landscaping plans that impact wildlife and their habitats.”