Birdsong is a fascinating study subject and living in this ‘day and age’ when one can step outside, record a bird in song with their smartphone, step back inside, upload the recording to their computer and analyze the recording via spectrograms (such as those outputted on xenocanto) = simply amazing. There’s nothing quite like the enjoyment of “seeing songs” while listening to them and following along on a spectrograph; this is especially true of using one’s recordings for this exercise.
My attention has recently turned toward Chestnut-sided Warblers ever since reading Kroodsma (2005). Below is a summary of some interesting facts about Chestnut-sided Warbler songs. Male Chestnut-sided Warblers sing Accented and Unaccented songs. The accented song is the one we all come to know as beginner birders: please-please-pleased-to-MEETCHA or wheedle-wheedle-wheedle-wheedle-sweet-sweet-MEETCHA. A bachelor sings this song until he meets his summertime fling; so, as expected, this song is sung over and over and over early in the summer season until pair up occurs. Each male Chestnut-sided has a repertoire of 4-5 accented songs (Kroodsma 2005), of which are learned in the first year of their lives, presumably during migration. The variation in accented songs originates from variance in the notes leading up to the widely-recognized MEETCHA part of the song. In Kroodsma’s book, he refers to some of the lead-up song phrases as “wheedle,” “see,” “swee” and “che.”
Now comes the magical part: the unaccented song. Unaccented songs are not learned until each male survives his long, hard journey north to the breeding grounds during the second calendar year of his life. Where he settles, whether it’s a hydro cut in southern Ontario or an area of post-logging regenerative forest in Interlake, Manitoba, is where he will first overhear and subsequently memorize his neighbour’s unaccented songs as they are sung day after day in the dawns early light. Each male develops a repertoire of up to 12 unaccented songs, which is quite impressive in and of itself but here’s the fascinating part: each cluster of Chestnut-sided Warblers forms its very own micro-dialect of unaccented songs! The possible combinations of unaccented songs are therefore essentially innumerable. As for their purpose, unaccented songs are thought to serve an entirely aggressive function and are used primarily at the edges of territory boundaries and during male-to-male counter singing battles. If the accented MEETCHA songs are love songs, then the warbled unaccented songs are battle songs (Kroodsma 2005).
Photo: Chestnut-sided Warbler songs. Accented song to the left and an unaccented song to the right. Note, near the end of the accented song, the paired, up-swept meet-meet notes followed by the emphatic down-slurred CHA note. Recorded using my iPhone 4S while walking Dolman Ridge Rd. in Mer Bleue Conservation Area, Ottawa, Ontario. 19 June 2016.
Accented Song: http://www.xeno-canto.org/323130
Unaccented Song: http://www.xeno-canto.org/323133
Kroodsma, D. E. 2005. The Singing Life of Birds. The Art and Science of Listening to Birdsong. Boston, Massachusetts, Houghton-Mifflin Co.