A Song for August 09

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If the playback aborts before the end, trying playing the sound from inside the checklist.

Carolina Wrens are territorial all year, so the dog days of summer, which silence most singing, have no impact on them. As I walked down the street I heard several male wrens singing. I recorded the first one, then went on. I recorded the second one. That recording is above. He was singing the same song-type as the first bird. So was a third bird in the distance. Gene Morton and associates have done some fascinating research on this "song-matching" behavior of Carolina Wrens. They found that males use the acoustic characteristics of shared songs to assess the level of territorial threat from neighbors. They compare the quality of the incoming sound to the template of a perfect song in their memory. The more attenuated by distance and degraded by leaf scatter, the lower the threat. But they need that template. They can't make this assessment with an unfamiliar song. This probably tells you why neighboring wrens share may song-types. A known rival is easier to assess than an unknown rival.

Female Carolina Wrens don't sing, but they do have many interesting vocalizations, and they do duet with their singing males. They overlap their male's song with their own rattle trill, perhaps augmenting his effect, perhaps warning neighboring females to stay away. In the cut below, the male was singing from the roof of my house. Another wren, presumably his mate, sat on a wire a few yards above me. I had the microphone trained on her, waiting for the rattle. It never came. Did she make any faint sounds while sitting there? I don't know. You can listen and decide for yourself.


In writing the commentary for these posts I have made extensive use of the invaluable bioacoustic resources listed below. For phylogenetic information, I often start with a web search of "Phylogeny of x," where x is an avian genus, family, or order. That is a hit-or-miss proposition. A recently-released resource that makes phylogenetic queries more systematic is the Birds of the World website from the Cornell Lab of Ornithology. If you follow the link and type the name of an avian family into the search box, you will be able to visit a home page for that family that presents the number of genera and species, and an illustration for each genus. If you subscribe, you will get more information. Also available to subscribers is the Birds of the World species accounts. Rolled out in 2020, this is currently an amalgam of the Birds of North America series, that was initiated by the American Ornithologists' Union around 1990, a recently-initiated online equivalent for Neotropical Birds, and the Handbook of Birds of the World series that was produced by Lynx Edicions, also beginning in the 90s. BNA has been hosted by the Lab of O for some time, and they recently added HBW to their portfolio. Especially useful for my purposes is the Systematics History subsection of the BNA accounts. EBird still has its separate species pages for all the birds of the world. These feature photos, recordings, range maps, and numerical eBird statistics, but little text. Overall, the abundance and availability of resources is astounding. Never has so much been available to so many for so little.

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Email: web at archmcallum.com

Nathan D. Pieplow. 2017. Peterson Field Guide to Bird Sounds of Eastern North America. Houghton Mifflin Harcourt.
Nathan D. Pieplow. 2019. Peterson Field Guide to Bird Sounds of Western North America. Houghton Mifflin Harcourt.
Donald Kroodsma. 2005. The Singing Life of Birds. Houghton Mifflin.