I worked in Grand Teton National Park, Wyoming on songbird research one summer. It was beautiful there – I would walk through acres of waist-high sagebrush looking for nests while the snow-capped Tetons towered nearby. I even saw wolves, bears and moose. But, there was one slight inconvenience – the birds liked to get up and sing at dawn and I had to be there in order to find them.
The bird I was looking for was the Brewer’s sparrow. It’s a small, brown and relatively non-descript little bird with one of the most complex songs in the U.S. At dawn, it would sing its tiny heart out. It is well accepted that birds sing in order to find mates and declare territories. But why so dang early?
A 2003 study published in Ibis by Brown and Handford details an experiment to find out just that. They played swamp sparrow and white-throated sparrow songs in grassland and forest at both dawn and midday. Re-recording the songs at varying distances up to 100 m, they found that while the sound traveled just as far at both times of day, it was more consistently clear in the morning. They say that this consistency is vital for individuals to recognize each other.
It would have made my life easier to wake up at 7:00 a.m. instead of 4:00 a.m., but the birds obviously had more important considerations in mind. Awash in a sea of beautiful birdsong, they wanted to make sure that as many birds as possible would hear them clearly and know who, individually, they were hearing. This way the ladies ‘had their number’ so to speak, and the other males knew who they were dealing with.
A video of a Brewer’s sparrow singing the short version of its song: https://www.youtube.com/watch?v=uKWjp9Yfjkw&noredirect=1
To hear the long song: http://birdnote.org/show/brewers-sparrow-sageland-singer
Photo from: http://en.wikipedia.org/wiki/Savannah_sparrow
Reference: Brown, T. J. and Handford, P. (2003). Why birds sing at dawn: the role of consistent song transmission. Ibis 145: 120-129. doi: 10.1046/j.1474-919X.2003.00130.x.