Artificial Light at Night Found to Extend Birdsong Duration Worldwide

A new study published in Science reveals that artificial night lighting significantly prolongs daily birdsong, marking the first global-scale validation of this phenomenon.

Researchers from Oklahoma State University and Southern Illinois University analyzed 4.4 million birdsong records spanning 583 species, collected through the global citizen science initiative "BirdWeather". They found that in areas with the highest light pollution, birds sang on average 50 minutes longer each day—beginning 18 minutes earlier at dawn and ending 32 minutes later at dusk—compared to those in darker habitats.

Species with larger eyes, such as the killdeer, were particularly sensitive to artificial light. The effect was amplified during breeding seasons, as artificial illumination disrupted natural cues for daily rhythms, extending activity beyond traditional daylight hours.

While the long-term consequences remain uncertain, risks include disrupted sleep cycles, though extended foraging opportunities may also arise. The findings underscore how human night lighting is quietly reshaping natural soundscapes and ecological rhythms, highlighting the urgent need to address its growing impact on biodiversity.