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We’ve reconstructed the sounds of birdsong from over 200,000 places. They’re getting quieter

We’ve reconstructed the sounds of birdsong from over 200,000 places. They’re getting quieter

A nightingale sings on a branch

Imagine going to hear your favourite orchestral piece played in a world-class venue – and only the woodwind and brass sections turning up. Whether we’re aware of it or not, this sparse soundscape is similar to what we’re often experiencing when we head out to our favourite parks or nature reserves. The sounds that are produced by nature are changing. This means that the benefits we get from being in nature will also change.

There is growing recognitionSpending time in nature is good for our health and well-being. At the same time, we’re living through a global environmental crisis, with ongoing and widespread declines in biodiversity. This means that the quality of our interactions with nature – and the positive effects we receive – are also likely to be declining.

All our senses can contribute to the experience of nature, but sound is especially important: sounds of natureYou have the power of boosting mood, decreasing pain, and reducing stress. Our researchExplores the long-term effects of biodiversity loss and shifts in species’ habitatsClimate change is prompting changes in the soundscapes of nature.

Our research

Recordings of past soundscapes aren’t available from most sites. We needed to develop a way to reconstruct historical soundscapes so we could track how they’ve changed over time.

A nightingale sings on a branch
The UK’s most endangered species is the common nightingale.
Bernard Dupont/Wikimedia Commons

We used bird monitoring data collected annually through to accomplish this. EuropeanAnd AmericanBird surveys have been conducted in more than 200,000 locations across North America and Europe. These surveys are conducted by a network of volunteer ornithologists in late spring and early summer and generate lists of which species and how many were counted at each site each year.

This data was combined with sound recordings of individual species were used to create soundscapes. Xeno-cantoA database online of bird songs and calls.

We first cut all downloaded sound files down to 25 seconds. We then used a five-minute sound file as a starting point and added the same number sound files for each species as individuals. This means that five individuals of a species were counted in the survey. We then added five sound files each of 25 seconds.

We were able to create a soundscape that represented the sounds of each species by layering the sound files. You can listen to one our soundscapesBelow, a reconstruction of data taken in 1998 at a Bromsgrove site in Worcestershire.

Reconstruction of bird calls at a UK location.
Author provided2.29 MB (download)

To measure the characteristics of each soundscape, we used acoustic marker to create them. These markers allow us to quantify how the acoustic energy in each soundscape is distributed over frequencies and time. This allows us to measure how acoustic diversity has changed and how intense it has become.

Our results show a steady decline in the acoustic diversity of soundscapes across Europe, North America, and Asia over the past 25 year period. This suggests that spring’s soundtrack is becoming more quiet and less varied.

We found that sites with lower numbers of species or total individuals also had greater declines on acoustic diversity.

Below is a spectrogram that shows how sound energy spreads across a particular soundscape. The amplitude – meaning the energy or loudness – of bird noises is shown through colour, with dark blues corresponding to lower amplitudes (quieter sounds) and brighter colours like pink corresponding to higher amplitudes (louder sounds). The frequency (displayed on the y-axis) can be thought of in terms of the pitch or ton of a song.

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Spectrogram
A spectrogram that shows multiple bird species singing.
Author provided

How birds organize their communities and how they complement each other’s call and song characteristics play important roles in determining the soundscape characteristics that are changing.

For example, the loss species such as the skylark (Alauda arvensis) or nightingale (Luscinia megarhynchosThe presence of rich and complex songs by () is more likely to influence the soundscape’s complexity than the loss or raucous. corvid or gull species. The exact effect of their disappearance will depend on the number of individuals that were present at the time and if there are any other species singing similar songs.

Our findings suggest that humans are losing touch with nature through chronic decline. Nature’s orchestra is fast losing both players and instruments.

We hope to raise awareness and encourage support by translating the hard facts about biodiversity loss into tangible images, recordings, and videos. conservationProtecting and restoring high quality natural soundscapes to ensure that people can enjoy and benefit from nature again.

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