NORWICH, United Kingdom — The “dawn chorus” is getting quieter due to climate change, a new study finds. Researchers found that the pleasant sounds of nature which regularly fill our nearby trees are growing quieter and less diverse over the last 25 years due to the changing distribution of bird species as a result of global warming.
The findings show that the sounds of nature – and bird songs in particular – play a “key role” in building and maintaining our connection with nature. Unfortunately, as global temperatures continue to change, so are the sounds of spring.
An international research team, led by University of East Anglia (UEA) scientists, developed a new technique — combining citizen science bird monitoring data with recordings of individual species in the wild — to reconstruct the soundscapes of more than 200,000 locations over the last 25 years.
“The benefits of nature contact are widespread, from improved physical health and psychological well-being to increased likelihood of participating in pro-environmental behavior,” says study lead author Dr. Simon Butler from UEA’s School of Biological Sciences in a university release.
“Bird song plays an important role in defining the quality of nature experiences but widespread declines in bird populations, and shifts in species’ distributions in response to climate change, mean that the acoustic properties of natural soundscapes are likely to be changing. However, historical sound recordings don’t exist for most places so we needed to develop a new approach to examine this.”
The changing sound of nature could impact human health
The team combined annual bird count data from the North American Breeding Bird Survey and Pan-European Common Bird Monitoring Scheme sites with recordings for more than 1,000 species from Xeno Canto, an online database of bird calls and songs, to reconstruct historical soundscapes.
They then quantified the acoustic characteristics of the soundscapes using four indices designed to measure the distribution of acoustic energy across frequencies and time. Each index looked at the song complexity and variety across many species. They also quantified the diversity and intensity of each soundscape overall.
“We found a widespread decline in the acoustic diversity and intensity of natural soundscapes, driven by changes in the composition of bird communities,” Dr. Butler reports.
“These results suggest that the soundtrack of spring is getting quieter and less varied and that one of the fundamental pathways through which humans engage with nature is in chronic decline, with potentially widespread implications for human health and well-being.”
“Given that people predominantly hear, rather than see, birds, reductions in the quality of natural soundscapes are likely to be the mechanism through which the impact of ongoing population declines is most keenly felt by the general public,” Butler adds.
Which birds are disappearing from the morning chorus?
The researchers say the relationship between changes in the structure of bird communities and the resultant soundscape characteristics is not easy to predict.
“In general, we found that sites that have experienced greater declines in either total abundance and/or species richness also show greater declines in acoustic diversity and intensity,” says Dr. Catriona Morrison, a post-doctoral researcher in UEA’s School of Biological Sciences. “However, initial community structure and how the call and song characteristics of species complement each other, also play important roles in determining how soundscapes change.”
“For example, the loss of species such as skylark or nightingale, which sing rich and intricate songs, is likely to have a greater impact on the complexity of the soundscape than the loss of a raucous corvid or gull species,” Dr. Morrison continues. “Critically however, this will also depend on how many occurred on the site, and which other species are present.”
“Unfortunately, we are living through a global environmental crisis, and we now know that the diminishing connection between people and nature may be contributing to this,” the researcher concludes. “As we collectively become less aware of our natural surroundings, we also start to notice or care less about their deterioration. Studies like ours aim to heighten awareness of these losses in a tangible, relatable way and demonstrate their potential impact on human well-being.”
The findings appear in the journal Nature Communications.
South West News Service writer Stephen Beech contributed to this report.