From Wildlife Extra:
Male Eastern Bluebirds learn to shout above the traffic
A new study, led by scientists from the University of Exeter, has been looking at how Eastern Bluebirds in the US change their songs in response to increases in nearby background noise such as traffic.
They found that the birds altered their songs immediately after noise levels intensified, making ‘real-time’ adjustments in order to produce songs that are both louder and lower-pitched.
This enabled them to produce songs that were more likely to be heard by potential mates or rivals.
The results suggest that birds are able to perceive increases in noise and respond accordingly – not unlike the way humans do when they are in a noisy environment.
Dr Caitlin Kight, a behavioural ecologist based at the University of Exeter’s Penryn Campus in Cornwall, led the study entitled Eastern Bluebirds Alter their Song in Response to Anthropogenic Changes in the Acoustic Environment, and published in the scientific journal Integrative and Comparative Biology.
Dr Kight says that the research could help improve our understanding of environmental constraints on animal communication, as well as enhance our awareness of what sorts of human modifications can impact animals, and how we might be able to reduce any negative effects of these disturbances.
“Although many manmade noise regimes are often very different from those found in nature,” sahe says. “There can be surprising similarities in certain features, including volume, pitch, or timing.
“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 behaviours, the flexibility to respond to noise pollution. This certainly seems to be the case with bluebirds.”
Although it has previously been shown that birds in noisier areas tend to sing differently to those in quieter surrounds, it was not immediately clear whether birds were able to make vocal adjustments in real time.
However, real-time modifications have now been observed in five different avian species, although the current study is the first to describe this behaviour in a member of the thrush family.
Dr Kight recorded songs produced by 32 male Eastern 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.
Co-author Dr John Swaddle, from The College of William and Mary in Virginia, USA, cautions against interpreting these findings as evidence that noise pollution has no adverse impacts on wild animals.
Dr Swaddle says: “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.”