Meet Our Bird of the Month, the Yellow-rumped Warbler!
These cute warblers are common in the Rio Grande Valley in winter, before migrating north and west for breeding.
Fun Facts
Commonly known as "butterbutts" due to their yellow rump!
Often form large flocks.
There are two subspecies, Myrtle and Audubon's—both recorded in the Valley. The most noticeable difference is the yellow throat of the Audubon's male vs. the white throat of the Myrtle. They can also interbreed and form "intergrade" or "intermediate" forms.
Females look similar to males, but may be duller with some brown.
Unlike other warblers, Yellow-rumped Warblers can digest the waxes of bayberries and wax myrtles. These fruits can persist into winter in some northern areas, so some butterbutts will winter there.
They're versatile eaters, foraging for insects everywhere from trees to beach seaweed, and even catching insects on the wing. In fall, they quickly switch to berries, including those from poison ivy. They've even been recorded drinking "honeydew" (aka, aphid excretions) in Mexico.
