Monday, September 2, 2013

Marsh Wren

Reviewing my blog, I am surprised to find no entries for Marsh Wrens. The species an abundant breeder in many cattail marshes across northern North America. They winter further south and into most of Mexico. They are usually easily brought forth by an observer who makes spishing or squeaking sounds.

The Marsh Wren’s song is described by Petersonas “reedy and gurgling, running into a guttural rattle.” Thayer Birding Softwarekindly allowed me to link you to this sound file. Erika and I have always compared this song to popcorn popping in the marsh. After extensive study, ornithologists discovered that Marsh Wrens learn up to 200 song types. They sing almost nonstop, day and night.

Why so many songs? Marsh Wrens are polygynous. In any given population of wrens, about half the males mate with two or more females. The males also build dummy nests—sometimes up to six besides the one actually used by one of their mates. They may be advertising their fitness by displaying their variety of songs and showing off their real estate. 

Birders noticed that eastern and western Marsh Wrens differ. Western birds sing up to four times the number of songs than do eastern ones. The songs of the western birds are less liquid than eastern birds, the western ones being harsher, more complex and variable. Western males are more likely to be polygynous than eastern wrens. Kroodsma and Verner (1997) predict that these two populations will be split by ornithologists into two species, the Eastern Marsh-Wren and the Western Marsh-Wren. The first photo in this blog is an eastern Marsh Wren banded in Aberdeen, South Dakota. The last photo is a western bird, taken in Olympia, Washington.

No comments:

Post a Comment