Bird of the Month: Bewick’s Wren
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
A bird of brushy habitats, Bewick’s Wren produces a melodious song described by Robert Ridgway as “one of the sweetest songs that ever was heard.”
Bewick’s Wren is, like the House Wren (Troglodytes aedon), active in both behavior and vocalizing. It seems to be constantly in motion, flitting in shrubby habitats and among small trees gleaning insects and larvae as it goes. It frequently wags its tail side-to-side, a behavior which may serve to startle insects making them easier to capture. This behavior most closely resembles that of a gnatcatcher.
Bewick’s Wrens in most plumages are brown from crown to tail and white on the chest and belly. However, in the Pacific Northwest Bewick’s Wrens are a richer brown above and grayer below (Alderfer). Southwestern subspecies are more brownish gray. The tail in all subspecies is barred with white tips on the feathers. All Bewick’s Wrens have a bright white supercilium (eyebrow) contrasting with the brown background. Once you realize the bird is a wren, the eyebrow alone may be enough evidence to identify the bird.
SUPREME SONGSTER
Bewick’s Wren
Scientific Name: Thryomanes bewickii
Length: 5.25”
Wingspan: 7”
Weight: 0.35 oz (10 g)
AOU Alpha Code: BEWR
This wren learns a wide variety of songs and calls some of which can resemble that of the Song Sparrow. A typical song combines an introductory wheeze (Bob Sundstrom), trills and short warbles, and finishes with a staccato three-note sequence. Often, Bewick’s Wren can be recognized by a series of buzzy calls it makes from deep in thickets. Photos, video, and vocalizations of Bewick’s Wren can be found at The Macaulay Library.
Bewick’s Wren has its own genus Thryomanes from the Greek Thruon, a reed or rush, and manes, a cup. The name refers to the cup-shaped nest the bird builds in brushy habitats. However, it is a bit of a misnomer as the bird is not usually one which frequents reeds or wetlands. It prefers dryer habitats. John James Audubon (1785-1851) bestowed the honorific name for Thomas Bewick (1754-1828) an English wood engraver who made plates for natural history publications.
BRUSHY HABITAT DESIRED
Bewick’s Wrens enjoy a variety of brushy and woodland habitat at low elevations and seek some sort of cavity in which to build their nest. They are adaptable to many different types of cavities which range from woodpecker holes, natural hollows in trees, and some artificial sites such as nest boxes, mailboxes, hanging baskets, deserted automobiles, a tin can, and in this author’s clothes dryer exhaust tube.
The nest is typically a soft cup of moss, leaves, feathers, and animal hair atop a bed of twigs. Usually, 5-7 white eggs with brown blotches are deposited. The female incubates the eggs for two weeks. After hatching both parents feed the young which leave the nest in another two weeks (Kaufman). Bugs, beetles, bees and wasps, caterpillars, crickets, and spiders comprise the diet.
STATUS AND DISTRIBUTION
Bewick’s Wren breeds from Southern British Columbia including part of Vancouver Island south through Washington and Oregon west of the Cascades and along the California coast to the Southwestern United States and from the central states to Mexico. Within this overall range there are 13 subspecies of Bewick’s Wren separated into two groups, eastern and western. The range east of the Mississippi River has fluctuated with time. Bent (1948) describes Bewick’s Wren as expanding its range northward. However, since then the bird’s range has contracted to west of the Mississippi River and 12 states have now listed Bewick’s Wren as endangered or threatened (Kennedy and White).
Habitat loss is listed as one factor in reduced breeding in the east, but another important dynamic is competition from House Wrens which are more aggressive and destroy the eggs and nests of Bewick’s Wrens. Some conservationists have recommended removing nest boxes where the species compete and installing them in areas where only Bewick’s Wrens reside, as one way to reverse the trend. Despite this decline in the east, Bewick’s Wrens are expanding their range in the west.
Photo credit: Mick Thompson
References available upon request from amccormick@eastsideaudubon.org
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