Why the birds make noise?
One reason may be that dawn is the best time for sound to travel, because there is little wind and less other noise and disturbance. Songs broadcast at dawn can be 20 times as effective as that broadcast at midday. And this is a time when birds can’t do much else. Light intensity is low, making it difficult for them to hunt and forage. Low temperatures keep their insect prey on the ground. By singing at dawn, when their energy reserves are low after the night, male birds may be telling females that they are nevertheless still fit for breeding. A male singing lustily is demonstrating that he has spare energy in abundance. Dawn may be a good time to sing, but there is likely to be a lot of vocal competition.
