Yellow Warbler (Setophaga petechia)
Singing a sweet, sweet song, the yellowest of wood warblers has found a way to outsmart the Brown-headed Cowbird.
Length: 5 inches
Wingspan: 8 inches
Weight: 0.33 ounce (9.5 grams)
AOU Code: YEWA
By Andy McCormick
The Yellow Warbler is aptly named, for it is the most yellow of all North American wood warblers and the only one with yellow spots in the tail. The male has a bright, unmarked, yellow face and yellow throat and underparts. He has red streaks on its chest, and the depth of the red is quite variable. In both male and female, the tail and undertail coverts are entirely yellow when seen from below. The dark black eye is prominent and beady.
The Yellow Warbler is one of a group of warbler species that was formerly in the genus Dendroica and is now organized into the genus given the name Setophaga. The genus name is from the Greek for moth eater, setos, a moth, and phagein, eat. The species name, petechial, is from petechiae, meaning small red or purple spots on the skin containing blood: The reference is to the red streaks on the male’s breast (Holloway).
Photo: Yellow Warbler, by Larry Engles
The habitat of the Yellow Warbler is wet and willowy. This warbler is an active forager as it gleans along branches and sometimes sallies out to catch insects on the wing. It is almost always seen in low brushy areas, though at times it will sit on a higher perch to sing its loud and buoyant Sweet Sweet Sweet Oh-so-Sweet song with an emphatic final Sweet. Listen to a Yellow Warbler recorded in Oregon.
In migration Yellow Warblers use all four North American flyways, and those that breed farther north migrate very long distances to Central and South America. There they winter in brushy habitats, city parks and gardens, and riparian woodlands. They are early fall migrants, leaving the north in July to spend seven months on their wintering grounds.
Take That, Cowbirds
Yellow Warblers arrive in Washington beginning in mid-April, and migration peaks in May. They locate nesting sites in streamside thickets. The open cup nest is built by the female, usually within 20 feet of the ground in an upright fork of branches in a shrub or small tree. Four to five greenish-white eggs are deposited and incubated solely by the female for 11 to 12 days. Young leave the nest in 9 to 12 days (Kaufman).
Yellow Warblers are frequently parasitized by Brown-headed Cowbirds, but they have developed a defensive measure that involves building a new floor on the nest to cover the cowbird eggs and then laying new eggs of their own (Lowther, et al).
Although Yellow Warblers are widespread and common in North America, the population has declined in some areas. A subspecies that once bred in Texas has been extirpated from the state, and the population in the Southwest also has declined.
Brown-headed Cowbirds have been implicated in failed nests in western states, and overgrazing and replanting of riparian habitat have reduced suitable nesting habitat. In other parts of the country the Yellow Warbler’s preference for second-growth areas and woodland edges has helped the population as the birds have moved into areas of previous timber harvest.
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