Bird Lore: Yellow-rumped Warbler

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A widespread and sometimes common songbird, the Yellow-rumped Warbler calls Edmonds home. During winter, this warbler prefers deciduous woods and thickets, gardens and beaches. During breeding season it nests in coniferous and mixed forests. It usually stays on the forest edge, avoiding dense, unbroken forest interiors. Except during breeding season, this is a highly social warbler that is usually in the company of several others of its species.

The Yellow-rumped Warbler has a mixed diet of insects and berries. In season it eats aphids, gnats, caterpillars, wasps, spiders, and many other insects. It is the fly-catching warbler because it often perches, flies out to grab an insect in mid-air, and then returns to its perch. While most warblers migrate to the tropics in winter, the Yellow-rumped will remain as far north as Western Washington and New England because it can digest the wax in berry coatings. In winter it feeds on bayberry, juniper, wax myrtle, poison ivy, and other available berries. It can be seen hovering as it feeds on berries.

The nest of the Yellow-rumped Warbler can be anywhere from 4 – 50 feet above ground. It is usually out on a horizontal branch, away from the tree trunk. The female builds an open cup of bark fibers, twigs, roots, and weeds. She lines it with hair and feathers in such a way as to partly cover her 4 – 5 eggs. The female incubates her eggs for a period of 12 – 13 days. Both parents feed the nestlings, which leave the nest after about 10 – 12 days. This warbler usually has two broods per year.

 

There are two subspecies, which were once thought to be separate species. The Audubon’s subspecies has a bright yellow throat, best seen on the adult male when this species is in breeding plumage, as it is now. It is most commonly a western bird. The Myrtle subspecies, most commonly seen the the East, has a bright white throat in breeding plumage. Adult females are similar with more subdued hues. The adult male Audubon’s has a noticeable white wing patch, which you can see in LeRoy’s first photo. The Myrtle has two white wing bars instead of one larger patch. The Myrtle subspecies can be seen in the Pacific Northwest. It is seen in small numbers here in Edmonds. It favors stream-side trees in the West Coast states so the marsh is a good place to sort through Yellow-rumped Warblers to find the one Myrtle. LeRoy’s second photo is shows the drab plumage of a fall bird.

You can listen to the songs of both the Audubon’s and Myrtle subspecies at this site: http://www.allaboutbirds.org/guide/Yellow-rumped_Warbler/sounds. Notice the slightly different songs of the two subspecies.

— By Carol Riddell

Carol Riddell manages the bird education displays on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.

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