In the early hours of the morning, one can sometimes get the impression that the birds are jubilating wildly outside our windows. But in reality, there is a strict order among the choirboys. Each bird species has a fixed time at which it demonstrates its skills. Already one and a half hours before sunrise, for example, the redstart makes its appearance. Half an hour later you can listen to the robin. The starling is heard much later and waits until the sun is almost completely up. In the time leading up to sunrise, there are of course overlaps between the different bird species. However, birds of the same species do not usually interfere with each other and match the singing pauses of their conspecifics. The daily repetition of bird songs in the morning is often referred to as the bird clock. If you don’t want to miss the performance of your favourite feathered friend, it’s best to set an alarm clock.
Ornithologists have discovered that urban birds start singing significantly earlier than their counterparts in the countryside. The researchers attribute this to the different brightness conditions due to artificial lighting in urban areas. The birds also adapt the timbre and volume of their chirping to their environment. For example, city birds usually sing much louder in order to assert themselves against street noise, and birds that live in the forest, for example, adapt the sound frequencies they produce to the acoustic conditions. But why do birds sing at all?