Why do we have a dawn chorus?

Dawn chorus - the song of the birds at dawn has given pleasure to millions of people and has been celebrated in poetry and prose for many years. The most usual explanation given in the Middle Ages was that the birds sang each day in praise of God and the beauty with which he had clothed the world. More recently, there was the feeling that the birds sang joyously to welcome the rising of the sun, which meant food, warmth and activity. However, scientists now think that the dawn chorus is made of the warning signals of each bird as he reestablishes his territory. The establishment of a territory for courtship, nesting and food getting is the first step in the breeding cycle and the area is defended against competing birds of the same species by a warning song, although seldom by actual fighting. A robin, incidentally, has a particularly strong sense of territory.