Order in the dawn chorus: songbirds take turns to sing one after another

Efficiently partitioning the available acoustic space presents a fundamental challenge for vocal animals that communicate at the same general location and time. Selection may favor strategies such as turn-taking that reduce interference by temporal or spectral partitioning, or strategies that exploit signal synergy by synchronous vocalization^1–4. As yet, however, there is no large-scale analysis of what bird species and types of traits associate with turn-taking or synchronous vocalization, and whether such behaviors vary in time and in space. We collected five years of audio recordings at 34 locations across Finland, Sweden, and Norway, and used a machine learning model to annotate the audio data to one-second resolution. The data contains 229,412 one-minute recordings on co-vocalization behavior of 131 species pairs that represent 33 different species. We show that most songbirds play by the same orchestral rules, avoiding simultaneous song and rather singing 4-6 seconds after the previous species. Songbirds that follow such turn-taking are predominantly small-bodied, migratory passerines with complex vocalization patterns. Their tendency for turn-taking was strongest during periods of high acoustic activity. Our results provide community-level evidence for ubiquitous, sequential turn-taking among songbirds. This appears to be the most effective strategy for attracting mates and defending territories during the short, intense breeding period characteristic of northern latitudes.