Winter has settled in, and so has the yellow-rumped warbler. This fairly large warbler, averaging 5½ inches long, is the only warbler species likely to be seen in New Mexico in winter. Most warbler species are exclusively insect eaters and after the summer nesting season must migrate south to Mexico, where insects, their main food source, are more abundant during winter.
Unlike other warblers, the yellow-rumped warbler has the ability to digest waxes found on certain berries, which allows them to eat fruits in winter. Having this additional food source enables them to winter farther north than other warblers.
There are two types of yellow-rumped warblers in North America. The myrtle, found in the East, has a white throat, and the Audubon, found in the mountainous regions of the West has a yellow throat. During the summer nesting season, the Audubon yellow-rumped warbler is a striking black-gray with white wing bars, a brilliant yellow throat and yellow sides. In winter, their coloration dulls except for their yellow rump.
The yellow-rumped warbler lives up to its name. In every season, the yellow rump patch is very conspicuous, making it one of the easiest warblers to identify, especially in flight. Just look for the flash of yellow at the base of the tail. A common nickname for this warbler is butter-butt.
The yellow-rumped warblers’ winter diet is as varied as the way they forage for foods. They search for insects by clinging to tree bark, perch on tree branches to fly out and catch insects in midair and even hover to pick insects out of spider webbing. They eat berries from bushes and trees, such as juniper and Virginia creeper, and eat a variety of native grass seeds. They are not a common sight at backyard seed feeders but can be lured in by feeding foods other than seeds. Providing suet, in particular bark butter (spreadable suet), and or seed/nut cylinders is a sure bet to attract these colorful birds all winter.
In Albuquerque this month, there is no better place to get an up-close view of this warbler than at the Rio Grande Nature Center State Park Bird and Bat Festival.
Watch for small flocks flitting in the treetops, and listen for their loud, single-chirp call. Once you know what to look for and listen for, they are hard to miss. The yellow-rumped warbler is a common and widespread warbler, over 130 million strong.
Mary Schmauss, owner of Wild Birds Unlimited in Albuquerque, is a lifelong birder and author of “For the Birds: A Month by Month Guide to Attracting Birds to Your Backyard.”