Marsh Wren Split
This morning I took Donald Kroodsma‘s Singing Birds workshop at the ABA convention. During the course of the morning he let out one bombshell. “Unequivocally, there are two species of Marsh Wrens.”
Using the techniques he showed us in the class, Koodsma demonstrated clear differences in the songs of the Eastern and Western Marsh Wrens. Furthermore, the Western Marsh Wren apparently learns about three times as many (150 to 50) variations on the song as the Eastern does. This has been confirmed by brain analysis (the details of which I don’t understand; but apparently there are clear differences in the structure of the two species’ brains) and DNA testing performed by “Micron”? at the Smithsonian. There’s a river in Saskatchewan where both variants are found, and they do not appear to interbreed there.
This work has yet to be published or peer-reviewed, and the AOU has not yet ruled; but Kroodsma at least is confident. Once he publishes the work, I expect those of us who’ve counted Marsh Wren in California and New York will get to add one to our life lists. In the meantime, pay attention to where you record your Marsh Wrens.
