The whistle came from a thick grove of old growth western hemlocks and Douglas firs. It might have been a tenth of a second long and then was followed immediately by a 2 second upward spirally flourish. It seemed like a flute or maybe an oboe was up in the trees. I stopped dead in my tracks along the dirt road and pointed my parabolic microphone in that direction.
Three seconds later a much softer whistle opened the tune followed almost immediately by a louder longer one and then a beautiful spirally flourish. The flourish was also a set of over-slurred phrases, each close together and slightly higher than the previous, getting softer as they went. My eyes closed to listen to this Swainson’s Thrush, a one-ounce bird who only recently arrived from his wintering grounds in South America. They breed in the temperate rainforests of Western Washington, and this one was defending its territory and maybe still trying to find a mate.
I’d read that each male has 3 to 7 song types. They vary in their detail and successive songs will be different. I cupped one hand behind an ear to listen closely. The opening whistles seemed to vary in pitch, sometimes one note and sometimes two. The flourishes were so complex and fast that I couldn’t tell how they varied. Maybe the sonograms of my sound recording would help me understand his melody.
The first tune in the sonogram opened with two notes and then the upward spiraling flourish. The second note was louder than the first (as shown by the brighter color on the sonogram) and then the first section of the flourish was loud before it became fainter and went really high in pitch. The opening over-slurred whistles seemed to peak around G6 on the note scale. The first second of the next part went from G6 to G7 to B7 in a series of up and down notes. Then the song became softer and went all the way up to B8 before trailing out for another second around F7. The highest pitches and faint parts I could not hear, but I’m sure the birds could.
The next tune was dramatically different from that first. It opened with a soft up-slurred note and then two over-slurred whistles that were slightly louder before moving into a quicker paced flourish that included a series of over-slurred, up-slurred, and down-slurred notes. The pitch of the entire tune never went as high as the first, only reaching about D8. The next several also appeared a little different from these first two and after six or seven tunes, the bird was clearly repeating itself.
Above is a Five-Minute Recording of the Swainson’s Thrush singing. The Sonogram of the recording will play as a movie and allow you to see the changing notes. The scale runs from 0 Herts to 10,000 herts.
The songs of Swainson’s Thrushes make my tension float away. These magical musical birds provide a gift of music to our souls.