From Jonathan Wallace, Newcastle-upon-Tyne, UK
You report that a study by Satoshi Kojima and his colleagues may have solved the mystery of why birds sing at dawn, suggesting singing is suppressed by darkness, leading to a build-up of motivation that is released when the dawn breaks. This may explain the mechanism that mediates the diurnal pattern of singing, but it hardly explains why dawn singing has evolved (1 November, p 7). Other behaviours are also suppressed by darkness, so why, for example, do songbirds not respond to the daybreak with a burst of intensive feeding or some other behaviour?
