Friday, March 5, 2021

Marsh Wren

On 4 March 2021, Erika and I heard several Marsh Wrens at the Bill Frank Jr. Nisqually National Wildlife Refuge. Abundant birds in many North American marshes, Marsh Wrens are easy to hear but they can be hard to see. Marsh Wrens have amazing song repertoires. Males learn up to 200 song types and sing almost continually—day and night. Males compete with singing duels. Males often mate with two or more females, and the male song advertises his genetic fitness and his territorial wealth (Kroodsma and Verner 2020). Erika and I recorded this Marsh Wren’s song—click here.
The various races of Marsh Wrens differ in eastern and western North America. Western birds learn many more songs than do eastern ones. The western songs are harsher and more variable than those in the east. As a result, western males are more likely to be polygynous than eastern ones. Kroodsma and Verner (2020) suggest “Future studies may reveal...that these two wren groups would best be treated as two species—e.g., Eastern Marsh-Wren (C. palustris) and Western Marsh-Wren (C. paludicola).”

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