Male and female birds must find each other, but how? Trees, plants, hills and human structures are sight barriers. Even birds in a heavily foliated tree may not see each other. The simple solution, of course, is sound. A bird’s song sends a message: “I’m over here. I’m healthy — just notice how pretty my song is and how strong my voice.” Drawn within sight of each other, the birds can then do a visual assessment. It’s mostly males who sing, to attract females. But, females of some species, like the Northern Cardinal, also sing.
Birds tend to be up early, singing even at 4:00 a.m., when the day is at it’s quietest, to re-establish their territory. They can sing anytime of day, but dawn brings louder, livelier and more frequent songs. The sounds of traffic, lawn mowers and other power tools tend to drown out their singing later in the day.
Scientists have a couple of theories as to why birds sing in the early morning. They call it the dawn chorus and speculate that birds sing then because light levels are too low to forage. Or that early strong singing signals to other birds about the vitality and strength of the singers — they were healthy enough to survive the night.
Most song birds sleep at night, but there are a few who sing when the sun goes down. American Robins sing into the night. Northern Whip-poor-wills, Northern Mockingbirds and Nightingales sing at night.
In the north, birds stop singing in the winter and begin again in late winter, even while it’s still freezing out there!
*Top photo: © Brittamay / Flickr