10 Fun Facts About the Yellow-rumped Warbler

Who are you calling a butterbutt?
A small gray warbler with patches of bright yellow and a white belly perches on a branch in front of a blurred green background.
Yellow-rumped Warbler (Audubon's form). Photo: Mick Thompson

If you’re looking for a gateway warbler, it doesn’t get much better than the Yellow-rumped. During fall and spring migration, this small songbird can be spotted in large numbers from coast to coast, and it maintains a presence on the North American continent year-round. Eye-catching and active, Yellow-rumped Warblers are relatively easy to observe and identify compared with many other species of warbler, making them a favorite of novice and experienced birders alike. Whether you’re already familiar with this species or just dipping your toes into the world of warblers, there’s plenty to know—and love—about this tough little bird. 

1.) More than 50 species of warblers can be found in North America, but the Yellow-rumped Warbler is by far the most common. In fact, the Yellow-rumped is one of the most abundant birds in all of North America. 

2.) Yellow-rumped Warblers can be found in various types of habitat across the continent, from Mexico up through Canada, but they are most at home in conifer forests, where they prefer to breed during spring and summer. In winter, they can be found in low-elevation habitats, deciduous woodlands, and mixed forests as they search for food.    

3.) Unlike most other migrant warblers, the Yellow-rumped doesn’t go far to overwinter, traveling to the southern United States, Mexico, and the Caribbean. Out west, populations of summer residents along the coast live year-round, and in the east, hearty coastal populations stick out winters as far north as New York and Connecticut.

4. Also unlike other warblers, Yellow-rumped Warblers are able to survive harsh eastern winters due to their ability to eat berries when insects and other foods might not be available. High levels of bile salts allow them to digest the wax found in the coating of berries from a variety of plants, including bayberry, juniper, wax myrtle, and poison ivy.

A drab brown, yellow, and white warbler perches on a branch eating berries upside down.
A female Yellow-rumped Warbler. Photo: Karen Brown/Audubon Photography Awards

5.) Along with Pine and Black-and-White Warblers, Yellow-rumped Warblers are one of the first signs that spring migration is ramping up. Beginning as early as March and through April, these species move northward as part of the first major wave of migrating songbirds. In the fall, they are among the last to migrate south. 

6.) If you see one Yellow-rumped Warbler, chances are good you'll see others. During spring and fall migration, these birds often forage in groups, along with other neotropical migrants such as Magnolia and Black-throated Green Warbler. During the winter months along the East Coast, flocks roam widely in search of berries for sustenance. 

7.) Yellow-rumped Warblers are talented foragers, primarily feeding on insects like grasshoppers, spiders, gnats, and caterpillars during spring and summer. They glean prey from leaves as they skulk along branches or hover in mid-air, and they frequently flycatch, sallying out from exposed limbs like a pewee. The birds can also be found on the ground in search of food. 

8.) Many birds have nicknames, including timberdoodle (American Woodcock) and peep (sandpipers), but the Yellow-rumped has one of the more memorable monikers in the bird world: butterbutt. This, of course, refers to the bright yellow rump patch for which the bird is named.

A gray, black, and white warbler with a patch of bright yellow on its rump perches on a branch and looks back over its shoulder.
Yellow-rumped Warbler (Myrtle form) showing off its namesake yellow rump. Photo: Mick Thompson

9.) In 1973, the American Ornithological Society's naming committee lumped Audubon’s Warbler and Myrtle Warbler, which look similar and are known to hybridize, under the name Yellow-rumped Warbler—a name previously used by the likes of Alexander Wilson and John James Audubon in the early 1800s. Generally speaking, the Myrtle form can be found in the eastern U.S. and the Audubon in the west. 

10.) Despite being considered the same species (for now), the Myrtle and Audubon forms have some distinct differences that are most notable on males in breeding plumage. Both sport yellow rumps, armpits, and caps that contrast with their slate-colored body feathers, but the Audubon form also has a bright yellow throat and more white on its wings. The male Myrtle, meanwhile, has a white throat and distinct black mask. Females, with their brown body plumage, are harder to tell apart, but the white eyeline and heavy streaking on the Myrtle version helps to differentiate. As with most warblers, the non-breeding plumage  of both versions is much more subdued, making them tougher to quickly ID during fall migration.