This warbler is named in honor of William MacGillivray, who edited and reworked the manuscript of Audubon's classic work. Another Scotsman, William Tolmie, is remembered in this bird's scientific name. Tolmie spent his adult life on the North American Pacific coast, where he undoubtedly encountered this warbler. Feeds on insects.
General: 5 to 5.75 inches in length.
Male Alternate: Olive-green upperparts. Yellow underparts. Gray head and neck. Black lores and breast patch. Broken, white eye ring. Pink legs. Small, pointed bill.
Male Basic, Female, Immature: Olive-green upperparts. Yellow underparts. Pale gray-brown head and neck. Yellow wash on throat. Broken, white eye ring. Pink legs. Small, pointed bill.
Thickets in broadleaf and riparian woodlands.
3-5 white eggs with brown spots. The eggs have an 11 day incubation period. Fledging occurs in ? days. The female incubates the eggs. The nest is a small open cup made from weeds and grasses, which is built in a low tree or shrub.