Bluebirds ‘shout’ to be heard above noise pollution

Western bluebird
A mountain bluebird in Dillon, Colorado. @bberwyn photo.

Biologists say noise impacts should be part of wildlife conservation planning

Staff Report

FRISCO — Outside a few remote wilderness areas, human-caused noise pollution is so common that birds have started to “shout” in order to communicate with each other.

Biologists with the University of Exeter took a close look at how bluebirds alter their songs in response to increases in nearby background noise caused, in many cases, by human activities such as traffic.

The study found that the birds react in real time, producing songs that are louder and lower-pitched. The findings suggest that birds are able to perceive increases in noise and respond accordingly — just like humans do in raucous settings.

The study was aimed at helping improve environmental constraints to animal communication, and to explore how human activities affect wildlife, said Dr. Caitlin Kight, a behavioural ecologist based at the University of Exeter’s Penryn Campus in Cornwall.

“Although many manmade noise regimes are often very different from those found in nature, there can be surprising similarities in certain features, including volume, pitch, or timing,” Kight said. “Sounds caused by traffic, for example, may not be hugely different from those produced by waterfalls or heavy winds. Animals that evolved in habitats with those natural features may therefore already have, within their existing repertoires of behaviors, the flexibility to respond to noise pollution. This certainly seems to be the case with bluebirds,” Kight said.

But that doesn’t mean noise pollution doesn’t have an impact on wildlife, said co-author Dr. John Swaddle, from The College of William and Mary.

“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,” Swaddle said.

: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,” Swaddle said. “It is time to apply similar caution to conservation, management, and landscaping plans that impact wildlife and their habitats.”

Previous studies had shown that birds in noisier areas tend to sing differently than those in quieter surroundings, but the new study tried to determine whether birds can react in real time,

 

Dr, Kight recorded songs produced by 32 male bluebirds, and analyzed 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.

 

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