In a study published in Nature Communications , an international team of researchers led by the University of East Anglia (UEA) suggests that the sounds of spring are changing and that the songs of dawn in North America and Europe are becoming quieter and less varied .
To reconstruct the soundscapes of more than 200,000 places in the past 25 years, researchers have developed a new technique that combines bird tracking data from citizen science with recordings of individual species in the wild.
The decline of the birds
Studies like ours aim to increase awareness of these losses in a tangible and relatable way and to demonstrate their possible impact on human well-being.
To reconstruct the historic soundscapes, annual bird count data from North American Breeding Bird Survey and Pan-European Common Bird Monitoring Scheme sites was combined with recordings of more than 1,000 species from Xeno Canto, a database song and bird calls online .
The acoustic characteristics of these soundscapes were then quantified using four indices designed to measure the distribution of acoustic energy across frequencies and time.
These indices are based on the complexity of the song and the variety of contributing species, but quantify the diversity and intensity of each soundscape as a whole. According to the study’s lead author, Simon Butler , from UEA’s School of Biological Sciences:
Bird song plays an important role in defining the quality of experiences in the wild, but widespread declines in bird populations and changes in species distribution in response to climate change mean that acoustic properties of natural soundscapes are likely to be changing. However, there are no historical sound records for most places, so we needed to develop a new approach to examining this.