Abstract
On 8 April 2024, a total solar eclipse disrupted light-dark cycles for North American birds during the lead-up to spring reproduction. Compiling more than 10,000 community observations and artificial intelligence analyses of nearly 100,000 vocalizations, we found that bird behavior was substantially affected by these few minutes of unexpected afternoon darkness. More than half of wild bird species changed their biological rhythms, with many producing a dawn chorus in the aftermath of the eclipse. This natural experiment underscores the power of light in structuring animal behavior: Even when "night" lasts for just 4 minutes, robust behavioral changes ensue.