Every fall and winter in San Diego, a little bird starts to invade the San Diego area. They seem to come into the area all at once and quickly fill up every nook and cranny all over the county. They’re not an unpleasant bird, nor are they an invasive species. They are yellow-rumped warblers (Dendroica coronata) also affectionately called “Butter Butts”.
Many people don’t notice yellow-rumped warblers until someone points one out to them. Then, they begin to see them everywhere. Despite saturating the region, they still remain fairly inconspicuous. Most of the time, they can only be heard making a light “chirp” as they flitter around the tree and shrub branches. But, when they want to, they can sing a beautiful warbler song. They will also frequent feeders, though they are happy living off their natural foods in the trees and brush.
There are two kinds of yellow-rumped warblers in North America and, once, they were divided into two species. The kind that stays in San Diego in the winter is known as the Audubon’s warbler. They are best distinguished by their yellow chins. The other kind of yellow-rumped warbler, rare in San Diego, is the Myrtle’s warbler, which has a white chin. Males sport bright yellow on their sides and a darker gray over their backs with streaks on their sides. Females and juveniles tend to be duller and browner. All yellow-rumped warblers have a yellow rump that is most visible when they fly.
Yellow-rumped warblers are primarily insect eaters, though they will try seed now and then. They often “hawk” insects in the way that phoebes do by perching in one area and catching insects in the air as they fly by. Attracting this bird to your yard is not hard as they saturate the region. They tend to go for suet and peanut butter the most, but also like sunflower seeds and raisins.
Around April, all the yellow-rumps will, most likely, be gone. They seem to leave as quickly as they arrive. While there are year-round populations in California, none of them are in the San Diego area. Most of them will head inland and to the north to breed. Then, they will seemingly return, all at once, in the fall.