The Yellow Warbler is a common migrant and summer resident in much of Western Washington. It begins to arrive in April and starts leaving in August. It passes through Edmonds every year and sometimes one or more remain for the summer. This warbler can often be found near water with willows, alders, and cottonwoods. Appropriate habitat can be found around the Edmonds marsh, the Willow Creek Hatchery, and Pine Ridge Park.
A long-distant migrant, the Yellow Warbler winters in Central America and northern South America. Its wintering habitats include mangrove forests, dry scrub, marshes and forests, usually in lowlands.
Insects make up most of the Yellow Warbler’s diet. Caterpillars comprise about two thirds of its diet. It also eats a very few berries. It forages anywhere from low levels up to tree tops. It gleans insects from twigs and foliage and will even hover briefly to pluck insects from the underside of leaves. This warbler does some flycatching by flying out from a limb to grab flying insects.
The male defends his nesting territory by singing and performing fluttering displays of flight. He courts a female by actively pursuing her for several days. The female builds a nest that is a compact open cup. Her construction materials include weed stalks, grass, and shredded bark. She uses plant down or animal hair to line it. She is not above stealing nest material from other nests. The nest can be anywhere from 2 – 60 feet above ground. It is usually in an upright fork of branches in small trees, shrubs, or briers. The female incubates her four to five eggs for 11-12 days while the male brings her food. Both parents feed the young until they leave the nest at 9-12 days of age.
The Yellow Warbler is a target of parasitism by the Brown-headed Cowbird, which will often lay one or more eggs in a Yellow Warbler nest. Sometimes the female Yellow Warbler raises cowbird young until they fledge and look for other cowbirds. Sometimes she successfully defends against parasitism by building a new nest on top of cowbird eggs or by deserting a nest with cowbird eggs.
The oldest-known Yellow Warbler was 11 years of age when she was recaptured and re-released during banding operations in New York. Although this warbler is one of the most numerous in North America, with an estimated population of 90 million, its population has been slowly declining by as much as 25 percent between 1966 and 2014. Nevertheless, its conservation status is that of least concern.
You can hear the song of the male Yellow Warbler here: www.xeno-canto.org/250924.
Carol Riddell manages the bird education displays, on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.