Common Name: Yellow-Rumped Warbler, Audobon’s Warbler
Scientific Name: Setophaga coronata
Subspecies: There are four subspecies, the one in Las Vegas is Audubon’s Warbler (Setophaga auduboni)
Order/Family: Passeriformes/Parulidae (New World Warblers)
Description: All subspecies groups of the yellow-rumped warbler are characterized by the yellow rump as its name implies, while intra-group and inter-group variations in appearance exist in spite of many similarities. The myrtle and Audubon’s groups, as two major subspecies, are distinguished by notable differences in features.
The Audubon’s subspecies group is not very dissimilar to the myrtle: in summers, males of both forms have streaked backs of black on slate blue, white wing patches, a streaked breast, and conspicuous yellow patches on the crown, flank, and rump (the latter giving rise to the species’s nickname “butter butt” among birdwatchers). Yet the color of the coronata and auduboni groups’ throat patches differs and distinguishes them, as the Audubon’s warbler sports a yellow throat patch while the myrtle warbler has a white throat and eye stripe, and a contrasting black cheek patch. Females of both forms are more dull, with brown streaking front and back, but still have noticeable yellow rumps.
Distribution: Audubon’s warbler breeds throughout western North America, coinciding with the Rocky Mountain range, from British Columbia to California and as far east as the Dakotas. Among warblers, the Audubon’s is by far the most widespread in North America in winter, being among the last to leave in the fall and among the first to return in spring. In Las Vegas, it disappears during summer.
Habitat: During the breeding season, the yellow-rumped warbler is generally known to be residing in either exclusively coniferous forested areas across the North American continent, or mixed coniferous-deciduous habitats. During the winter, when the yellow-rumped warbler is not in breeding season, it often inhabits resourceful open areas with shrubs or scattered the trees.
Although the Audubon version of the Yellow Rumped Warbler is the the usual form seen around Las Vegas, we do sometimes see the Myrtle form. There are two main populations of Yellow Warblers, “Audubon’s” breeds mainly in the mountains of the western U.S. and into British Columbia and “Myrtle” breeds from the eastern U.S. across Canada to Alaska. All plumages show a bright yellow rump and yellow on the sides. Most “Audubon’s” have a yellow throat, but dull immature females can be off-white. “Myrtle” Warblers have a white throat that wraps around below the cheek.