Wednesday, March 24, 2010

Bewick's Wren, an early spring singer

Bewick's WrenBewick's Wren, Jackson Bottom Wetlands, Hillsboro, Oregon on 4 March 2010 by Greg Gillson.

 

Throughout its range across North America, the Bewick's Wren (previous article) shows much plumage and song variation.

In addition, populations in Eastern North America are declining, while many populations in Western North America are expanding.

The 1979 book, The Birds of Canada by Earl Godfrey, shows Bewick's Wrens in extreme southern Ontario and extreme southwestern British Columbia. This species disappeared from Ontario in the 1970's and, in fact, retracted its range about 700 miles in the East. By the year 2000, according to the map in The National Geographic's Complete Birds of North America (2006) edited by Jonathan Alderfer, the wren perhaps now breeds no closer than southwestern Kentucky.

In contrast, the Bewick's Wrens in the Pacific Northwest are expanding their range inland along the Columbia River. Historically, they were common along the Columbia River only west of the Cascades, with a small isolated population near Yakima, Washington. In the last 30-40 years, though, they have expanded upriver until they are regular to the Walla Walla River and other areas surrounding the corner where Washington, Idaho, and Oregon meet.

The photo above shows a typical example of the population called the Seattle Wren (Thryomanes bewicki calophonus). This is the form found from SW BC, western Washington and Oregon (from Cascades to coast) south to Roseburg and Coos Bay, Oregon. [It is also likely the form expanding up the Columbia River to the east, but this has not been proved definitively.] It is browner and darker than most other forms in the West, slightly more reddish on the flanks and larger, with longer bill, tarsus, and middle toe.

The subspecies name, calophonus, means a beautiful singer. This bird does, indeed, have a variety of songs. Most take the form of Song Sparrow, with a few introductory chip notes and a trill. But there is much variation. These birds are one of the first singers of spring, singing away in March or, indeed, even the odd sunny day in mid-winter. They sing throughout the day, and throughout the remainder of the year to late fall.

For more information on this wren, including the calophonus subspecies of the Pacific Northwest, see the Bewick's Wren account in Bent's Life Histories of North American Birds.

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