
The yellow-rumped warbler is Missouri’s most abundant migrant warbler and may also be seen in winter. Look for them in open woodlands, second-growth, scrub, and thicket habitat, and parks and gardens.
Adult yellow-rumped warblers have a yellow patch on the rump, the crown, and the sides near the bend of the wing. The yellow crown may be hard to see. The underparts are white, with bold black streaks on the breast and sides. Yellow-rumps in the eastern United States have distinctly white throats. In the spring and summer breeding plumage, the colors of males intensify with more pronounced gray on the back, white on the wings, and pronounced black on the breast. The plumage of females and of nonbreeding, wintertime males is more subtle and brownish. The general color pattern, however, remains the same year round.
The song is a sweet whistled series of (often) about 9 rapid notes and lasts only a few seconds: “Tew-tew-tew-tew-tew-tew-tew-tew-tew.” It most typically accelerates, then descends and grows softer at the last few notes, as if with the Doppler effect (it has been described like the tinkling sound of sleigh bells approaching and moving past). The calls include sharp “checks,” “chips,” and “sips.”
Subspecies: In North America north of Mexico, there are two different subspecies of the yellow-rumped warbler. In the past, they were considered separate species. Ornithologists still debate whether they should be “lumped” or “split.” One, called Audubon’s warbler (ssp. auduboni), occurs only west of Missouri. The mostly eastern subspecies, called the myrtle warbler (ssp. coronata), is the one that occurs in Missouri. The most obvious difference is that Audubon’s warbler has a yellow (not white) throat.
Similar species: The magnolia warbler is similar (it also has a yellow rump), but adult breeding magnolia warblers have yellow (not white) underparts and have gray (not yellow) crowns.
Length: 5½ inches (tip of bill to tip of tail).
Statewide during migration. In winter, locally common in southern Missouri, rare in the north.
Habitat and Conservation
Common transient in open woodlands, second-growth, scrub, and thicket habitat, and parks and gardens. In winter, when they are more likely to be seen in the southern half of the state, they are especially associated with cedar groves. This is our most abundant migrant warbler.
Relatively large and sturdy-looking for a warbler, and somewhat less shy as it forages, this species is often seen on the outer foliage of trees. With its more deliberate movements, it may seem less nervous than other warblers.
In winter, yellow-rumped warblers that remain in Missouri often join with other birds in forest foraging flocks. They, and titmice, woodpeckers, blue jays, chickadees, nuthatches, kinglets, and brown creepers, work gradually through a forest in groups. Each species in the group targets specific types of foods in specific types of places. If you are birding in winter, look and listen for these foraging flocks, and see how many species you can find.
Food
Like most other songbirds in breeding season, yellow-rumped warblers eat mostly insects in spring and summer. Insects provide ample proteins and other nutrition needed by the growing young and their stressed, hardworking parents. In addition to gleaning caterpillars and other insects and spiders from leaves and twigs, yellow-rumped warblers often fly out to snatch insects in midair.
During migration and winter, yellow-rumped warblers switch to a diet heavy in fruits, including the “berries” (actually fleshy cones) of eastern red cedar. This is why cedar habitats are a prime place to see them in Missouri in winter. They also eat the fruits of poison ivy, native grapes, greenbriers, Virginia creeper, and dogwoods. They also eat seeds of goldenrods and other members of the sunflower family, and they may visit birdfeeders in winter. In some regions in winter, the yellow-rumps join in large, same-species foraging flocks.
Status
Common spring and fall transient. As a winter resident, common in the south, rare in the north. As a summer visitor, accidental.
Life Cycle
Yellow-rumped warblers are in Missouri from mid-September to mid-May. Their numbers peak during migration: in March and April as they head north, and in October and November as they move south. They breed in northern parts of the United States and in Canada (western populations breed throughout much of the western United States). They overwinter in the southern United States, Mexico, Central America, and the Caribbean.
In their breeding territory in northern coniferous woods, female yellow-rumped warblers construct cup nests out of twigs, pine needles, and finer materials. These are usually built on pine, spruce, or other conifer branches. There may be 1 or 2 broods a year; a clutch comprises 1–6 eggs, which are incubated for 12 or 13 days. After hatching, the young remain in the nest for an additional 10–14 days before they start to fledge. Lifespan may exceed 10 years.
Human Connections
Nicknamed “butter butt” by birdwatchers, the yellow-rumped warbler is one of the more commonly seen and numerous of warblers. For many birders, this is one of the first warblers they see and learn to identify, and for that, they hold a special significance.
Sometimes it’s hard to find anything nice to say about poison ivy and the itchy rashes it causes. However, the fact that poison ivy berries are an important wintertime food for these beautiful birds is a good reminder that the natural world doesn’t revolve around our opinions.
Ecosystem Connections
By consuming leaf-eating caterpillars, leaf and bark beetles, scales, aphids, and other insects that feed on trees, these and other warblers help limit the damage the insects can do to trees. Because this warbler can consume a variety of fruits available in winter, it has a much more northern winter range than other warblers.
Our subspecies is called the myrtle warbler because of its fondness for native myrtle berries — the fruits of shrubs and small trees in genus Myrica. These are also called wax myrtles, bayberries, and candleberries. These do not occur in Missouri but are common in coastal states to our south and east. Yellow-rumped warblers are able to digest the waxy coating from the berries, which promotes germination of the seeds, once they pass out of the bird. Apparently this is the only warbler that can digest the wax, though northern bobwhite, Carolina wrens, and tree sparrows can also digest it.
The breeding ranges of the myrtle and Audubon’s subspecies overlap in British Columbia and Alberta. There, they may breed together, producing offspring with intermediate characteristics. The fact that the two interbreed is one reason biologists have decided to group them together as the same species. Apparently, the two subspecies diverged due to geographical isolation caused by Pleistocene glaciations, the world’s latest ice age.
























About 350 species of birds are likely to be seen in Missouri, though nearly 400 have been recorded within our borders. Most people know a bird when they see one — it has feathers, wings, and a bill. Birds are warm-blooded, and most species can fly. Many migrate hundreds or thousands of miles. Birds lay hard-shelled eggs (often in a nest), and the parents care for the young. Many communicate with songs and calls.