BIRD OF THE MONTH: YELLOW-RUMPED WARBLER

The Yellow-rumped Warbler is a fairly large warbler with a sturdy bill and a long narrow tail. In the summer, both male and female show flashes of white in the wings and yellow on the face, sides and rump. The female is duller and may show some brown. In winter, the birds are paler but still show the bright yellow rump and some yellow on the sides.
This warbler is very active, foraging in tree canopies and snatching insects from the air. It will also come to suet feeders and is attracted to moving water as most birds are.
In the Pacific Northwest, this beautiful warbler occurs all the way down to sea level wherever conifers are present.
The Yellow-rumped Warbler eats mainly insects in the summer. In the winter it eats a great number of berries, particularly bayberry and wax myrtle which its digestive system is uniquely suited to among warblers. This habit is one reason why the Yellow-rumped Warbler winters so much farther north than other warbler species. It will also eat seeds and may come to feeders for sunflower seeds, raisins, peanut butter and suet.
The female builds the nest sometimes using material the male carries to her. The nest is a cup of twigs, pine needles, grasses and rootlets. She may also use animal hair, moss and lichens. The nest is lined with fine hair and feathers, sometimes woven into the nest in such a way that they curl up and over the eggs. The nest will be 3 - 4 inches across and about 2 inches tall when it is finished.
The female will lay 1 - 6 white eggs that are speckled with brown, reddish-brown, gray or purplish gray. She will incubate the eggs for 12 - 13 days and the chicks will fledge in 10 - 14 days. The chicks when hatched are helpless and naked with sparse brown down.
The Yellow-rumped Warbler flits through the canopies of coniferous trees as it forages. The male tends to forage higher in the trees than the female. It will cling to the bark surface looking for hidden insects more than many warblers do, but it will also sit on an exposed branch and catch passing insects like a flycatcher does. In the winter, it may join a flock and switch to eating berries from fruiting shrubs.
The Yellow-rumped Warbler will confront an intruder bird by holding its body horizontally, fanning its tail and raising it to form a right angle with its body. When it finds itself foraging with other warbler species, it will usually let Palm, Magnolia and Black-throated Green warblers do as they wish, but it will assert itself over Pine and Blackburnian warblers.
When a male courts a female, he will fluff his feathers, raise his wings and the feathers of his crown and hop from perch to perch chipping. He may also do a display flight by gliding back and forth or flying slowly with exaggerated wingbeats.
The oldest recorded Yellow-rumped Warbler was at least 7 years old.