Ecology: Declines in bird communities create quieter springs

The birdsong soundscapes of North America and Europe are becoming quieter and less varied due to declining trends in bird communities, according to a study published in Nature Communications. The findings suggest additional conservation efforts are needed to prevent further deterioration of natural soundscapes, which could have implications for human wellbeing.

Half of the world’s population now live in cities and natural soundscapes play a key role in maintaining a connection to nature, which is known to have positive impacts on human health and well-being. Birdsong is a major contributor to these soundscapes, but human activities have caused widespread declines in bird abundance and species richness. Such declines may have resulted in impoverished acoustic environments, but comparisons between past and present avian soundscapes are hindered by a lack of historical recordings.

Simon Butler and colleagues combined survey data and birdsong recordings from the past 25 years to reconstruct avian soundscapes in North America and Europe. The authors collated annual bird species records and data from citizen science monitoring programs, representing more than 200,000 sites in 22 European countries, Canada, and the USA. The authors matched each bird species to its vocalisations and produced a composite soundscape for each site every year. The authors found a declining trend in the acoustic complexity of the soundscapes, due to the reduction in bird species richness and abundance. Over time, in most areas, the soundscapes were found to become quieter and less varied.

The deterioration of natural soundscapes could reduce the human experience of natural sounds, which in turn could impact human wellbeing, the authors suggest, and conservation efforts should focus on preventing this deterioration.