Orchestra of bird song growing fainter because of climate change

The bird flew 4,000 miles in just seven days, astonishing scientists from Thetford. Photo: Edmund Fe

The call of the cuckoo is becoming less common as the species declines - Credit: Edmund Fellowes/BTO

Fewer cuckoos call in spring, while the turtle dove's purr and the nightingale's virtuoso trill are becoming less familiar to our ears.

Bird song is growing fainter as species decline because of climate change, scientists say.

Experts led by a team at the University of East Anglia (UEA) in Norwich have combined bird counts from thousands of sites around the globe with recordings of birds' songs, to reconstruct how so-called natural soundscapes have changed over the last 25 years.

Their research has underlined a “widespread decline in the acoustic diversity and intensity of natural soundscapes”, heralding the swan song of once-common species.

Lead author Dr Simon Butler, associate professor from the UEA’s school of biological sciences, specialises in acoustic ecology, using sound as a yardstick to measure biodiversity.

"You get overwhelmed with numbers quite often in biodiversity," he said. "What that means for day-to-day life is quite difficult to to get across tangibly."

Dr Butler said researchers had layered sound clips of birds into five minute files to show how soundscapes have changed.

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Where five skylarks were seen at a location, the calls of five birds would be added. 

A brief extract from the Suffolk countryside shows the loss of the curlew's distinctive bubbling call.

We experience birds far more frequently by hearing their song than seeing them. Nature has been a lifeline for many through lockdown.

Dr Butler fears as soundscapes grow less diverse, the loss could have a far-reaching impact on our relationship with birds and our feelings towards them.

"This approach is thinking about them as an orchestra and modelling the quality of that orchestra as a whole, not individual players," he said. 

 a curlew flying over titchwell marsh

The curlew's call has become a less common sound as the species has declined - Credit: citizenside.com

"It's about measuring the sound of the environment s a means of measuring biodiversity health.

"You get this vicious circle, how the quality of our relationship with nature declines. 

"As that shift occurs, there's a risk we care less and less about our environment because we've got less to lose."