I had several options for today. Swallows, which spend so much time on the wing, will sit and sing at dawn. In 2007 I was able to sample the efforts of a Tree Swallow sitting on a nest box in an RV park. The link is at the bottom of the page. The same goes for some interesting sounds from individual Tricolored Blackbirds at a small colony in Sutherlin, Oregon. But the featured song for today is from the Eastern Bluebird, because they are so familiar and because they are such virtuosos.
"Roll the tape" and stop at 0:15. Notice the abrupt pitch changes and the zigzag notes. Then, at 0:20 notice the stacks of parallel, or nearly parallel, lines in many of the notes. These are the acoustical features that give bluebird songs their distinctive sound. Somehow it is pleasing to listen to, despite those very complex chords and occasional squeakiness. "Chord" is an accurate term for bluebird notes. A chord is several tones played at once. Birds do this with abandon, and they can change the tones continuously.
At 0:24 notice the three-note chatter call at the beginning of the song. Bluebirds often give this call when in an agitated state. If you have a bluebird nesting in your yard you know this call. Pieplow calls this combination agitated song.
Now, let's revisit the Siberian Rubythroat. Rubythroats and their close relatives in Eurasia are similar to American bluebirds in size, shape, and habitat, even though they are not at all closely related. This is one of many examples of convergent evolution in widely separated places. Do they also sing similarly? Take a look at the static sonograms on both the rubythroat and bluebird pages. (Today's bluebird cut is jut below, followed by another from the same bird.). The spacing and duration of the songs are similar, and both species sing with immediate variety, but they still sound different. The moving sonograms are your resource for teasing apart the differences. I've already given you some hints. Have fun.
