Why do Birds Sing at Dawn? The Ecology of the Dawn Chorus - Stuart Brooker. The avian dawn chorus is a period of high song output performed daily around sunrise during the breeding season. Singing at dawn is of such significance to birds that they remain motivated to do so amid the noise of numerous others. Yet we still do not fully understand why the dawn chorus occurs. This talk will review the physiological, behavioural and environmental factor affecting the dawn chorus and the current theories that attempt to explain its existence.