Natural sounds, and bird song in particular, play a key role in building and maintaining our connection with nature - but a major new study reveals that the sounds of spring are changing, with dawn choruses across North America and Europe becoming quieter and less varied. An international team of researchers led by the University of East Anglia (UEA) developed a new technique, combining world-leading citizen science bird monitoring data with recordings of individual species in the wild, to reconstruct the soundscapes of more than 200,000 sites over the last 25 years.