By Steve Docker 6th June 2024

Steve Docker is a Resource Development Officer with Field Studies Council Publications. Here he reviews the evidence for a changing soundscape close to his Derbyshire home.

A changing soundscape

I read a Guardian article recently which struck a chord with me.

The article was about sound recordist Bernie Krause. He has been recording the soundscape at Sugarloaf Ridge near San Francisco for the last 30 years. At the highpoint of spring each year Bernie uses his acoustic recording equipment to capture the sounds at a specific location for a period of one hour. Last year, for the first time, he recorded total silence. In previous years he has recorded a range of sounds such as bird song and running water.

Although based in North America this seemed to align with my own perception that my local avian soundscape was also in decline, especially a gradual depletion in bird songs – but was this true? I decided to take a closer look at the evidence.

A search for evidence

The best source of evidence that we have for birds of the United Kingdom is the population trends from the Breeding Bird Survey, which began in 1995. It follows a rigorous scientific process and has a wide geographical coverage. Volunteers undertake the fieldwork. The latest report provides statistically robust population trends for 74 bird species for England. 41 species (55%) have suffered a long-term decrease, whilst the populations of 33 species (45%) have increased.

If we look a little closer, at those bird species that can be detected by their song, we find that Willow Tit, Greenfinch and Mistle Thrush have experienced the greatest declines, whilst Cetti’s Warbler, Chiffchaff and Blackcap have improved.

So, at the national level we have a mixed picture. Some species are increasing, but more species are decreasing.

The local story

Whilst the national bird trends provide the context, I thought that it would be interesting to look at some bird data for two sites close to home, to see what it might reveal about my local soundscape.

First up, Church Mayfield on the Staffordshire-Derbyshire border. Since 2008 my wife and I have contributed to the national bird population trends by volunteering to undertake a Breeding Bird Survey at this site. The randomly allocated 1km square mostly contains pasture farmland and rural village habitats. The survey requires two early morning visits per year (in May and June), walking standard routes, and noting all adult birds detected by sight and sound. These are known as bird registrations. So far, we have gathered over 6,000 registrations from 70 species. We detected 25 of these bird species by their song. The most frequently encountered species are Wren, Blackbird and Blue Tit. The most memorable encounter in 2024 was a pair of breeding Dipper, two adults returning to their nest beside a weir with food for their young.

Church Mayfield on the Staffordshire-Derbyshire border
The weir on the River Dove near Church Mayfield

In addition, ten years ago we conducted a bird survey along the disused Cromford Canal. It was part of my MSc Biological Recording and we used the MacKinnon Listing Technique. This involved walking a route at a steady pace whilst listening and watching for birds that were associated with the site and its habitat. On the ten-year anniversary, we repeated the survey and compared the results with the original baseline survey.

Cromford Canal, Derbyshire

Overall we detected 36 bird species. 22 species (61%) were present on both occasions, i.e. in 2014 and 2024. However, the composition of the bird assemblage was different on each occasion with 32 bird species noted in 2014 compared with 26 bird species ten years later in 2024. A net reduction of 6 species. 13 of these bird species were detected by their song. The most frequently encountered species in 2014 were Wren, Blue Tit and Blackbird. In 2024 it was Wren, Chiffchaff and Robin. However, the 2024 highlights included a Kingfisher in flight and then perched, a pair of Little Grebe collecting nest material and a male Blackcap, singing from nearby vegetation. We would like to have spent more time with these individuals, but we had a survey to complete!

A wren on the ground with tail cocked
Wren Troglodytes troglodytes. The most frequently encountered species, mostly by their very loud song.

So, I had two sources of local evidence that I could draw upon, both with good quality, comparable datasets. They both included a complete list of species detected, were controlled for survey effort, and provided a measure of change over time regarding the number of individual birds present (abundance).

Most bird species detected by their song followed the national long-term trends. Therefore, the local story appears to broadly align with the national picture.

Looking to the future

So, are we heading for a denuded, even silent soundscape? I don’t think so, but there is no room for complacency. Bird populations, and therefore bird sounds, of some species are decreasing, whilst for others they are increasing.

Our soundscape is not yet silent, as reported by Bernie Krause in North America. However, it does appear to be changing, dominated by fewer species. We must therefore continue to monitor the situation which makes the work of the volunteer bird surveyors extremely important – we cannot protect, restore and enhance what we do not measure.

Specifically, we need to watch out for the gradual, almost imperceptible, adverse changes. This is known as Shifting Baseline Syndrome or sometimes Generational Amnesia. It is the tendency for the concept of what is ‘normal’ or ‘natural’ to change over time, due to the experiences of subsequent generations. There is a very real danger that we may forget, over the generations, how biodiverse a natural environment should be.

So, why not join over 9,000 volunteer bird surveyors and take part in a Breeding Bird Survey – if you need help to improve your bird identification skills there are courses and resources available.

Want to learn more?

Check out my Learning bird song blog (Apr 2023).

Field Studies Council have a range of courses on Birds.

MSc Biological Recording and Analysis.

The xeno-canto website is an excellent resource.  This is a citizen science project dedicated to sharing wildlife sounds, including bird calls and songs.

To help us all appreciate and enjoy biodiversity and better understand the changing state of nature the Field Studies Council has produced a wide range of high quality identification resources. In particular the WildID fold-out guides and Aids to Identification in Difficult Groups of Animals & Plants (AIDGAP). The guides are available from the Field Studies Council online shop.