It’s pitch black outside, but you can hear a bird trilling its little heart out. Why would a bird start singing before the sun rises? Doesn’t it know you’re still trying to get a little shuteye before the day begins? Scientists at Canada’s University of Lethbridge think they might have found the answer.
David Logue, along with his research colleagues, tracked the songs of individual males of the Adelaide’s warbler species in Puerto Rico. They found that the order of performance had a significant impact on performance quality. In other words, the longer the birds practiced, the better their songs sounded. The researchers think that this warming up period before daybreak allows the birds to perfect their songs, and in doing so, increase their chance of attracting mates. According to the researchers, over time, as the birds compete against one another, individuals start singing earlier and earlier in the morning, as a sort of “melodious arms race.”
Why do birds sing so much in the morning hours anyway? Scientists hypothesize that the lack of light in the predawn hours means that it isn’t a great time to forage for food, so singing is a worthwhile alternative activity. Male birds sing not only to attract mates, but also to warn off members of their own species to stay out of their territory. Singing loudly in the morning alerts their avian neighbors that they survived the night and are strong and healthy and are not to be messed with. Singing the same song, or repertoire of songs, each morning on a consistent basis also helps other birds in the area recognize one individual over another, making it clear who owns what territory.
The development of birdsong itself is actually quite an interesting topic on its own. Most sounds made by birds can be categorized into two groups: calls and songs. A call is typically a brief and simple vocalization that indicates flight or danger. Calls are heard throughout the year. A song is often longer and more complex and only heard during the breeding season. Each individual bird has its own repertoire of songs, which typically consists of different versions of a single song, which is called a song type. Some birds only have a single song type, while others have five or more. And some birds have more than 1000 song types!
Birds learn songs very early in life. It occurs in a two-phase process. In the first phase, the bird memorizes a tutor song, and forms an auditory memory in their brain. In the second phase, the bird translates the memory into a motor activity by practicing the song, comparing it to their memory, and refining it to match. Scientists think that birds are born with the innate ability to distinguish their own species’ songs from songs of other species. Studies show that the heart rate and amount of begging increases in young birds when they hear their species’ songs, even if only hearing the songs for the first time.
So the next time you are awakened by early-morning bird karaoke, hopefully you will appreciate all the work that goes into perfecting their melodious tunes.