Laura Erickson's For the Birds

Yellow-rumped Warblers

(Recording of a Yellow-rumped Warbler)

Spring is so full of welcome new arrivals that it’s hard to even imagine having a favorite, but one of the sounds I eagerly anticipate every year is the chip of the Yellow-rumped Warbler.

(Recording of a Yellow-rumped Warbler)

Yellow-rumps are the first warblers to return north in spring. Birds that winter in the southern United States return before those that winter down in Central or South America–more tropical warblers like the Blackburnian and the Black-throated Green Warbler don’t bother to cross Mexico until they’re sure it’s really spring across the border. Their migration is triggered by daylength, which, unlike unseasonable warm weather, is constant from one year to the next. Some Yellow-rumps winter as far south as Panama, where they’re flourishing in second growth areas and slashes-warblers that need the rain forest habitat aren’t faring nearly as well. Many yellow-rumps go only as far as the central states, and occasionally one even winters in Wisconsin or Minnesota. Yellow-rumps follow warmth, returning to an area as soon a few aquatic insects emerge. If a cold spell comes, Yellow-rumps don’t head south again; they can survive for several days eating berries and seeds if it gets too cold for insects. Sometimes they even show up at feeders.

When I started birding back in East Lansing, Michigan, a lot of my friends called the Yellow-rumped Warbler the “Butter Butt.” It’s an appropriate nickname. There are several other warbler species that have yellow rump patches, but the patch is most conspicuous on the Yellow-rump. Adult males are handsome birds with bright yellow epaulets and a yellow crown stripe, a rich black face mask and pretty black, gray, and white markings. Females and fall immature males are much browner and duller, but you can usually pick out at least a trace of the yellow epaulets, and the rump is conspicuous in all plumages. The most diagnostic feature is its chip note. Once you get familiar with it, you can call out a positive identification of a Yellow-rumped Warbler as it flies a hundred yards above you. This kind of quick ID amazes and astounds non-birding friends, and if you casually toss out the species’ scientific name—Dendroica coronata—word will quickly spread about your superior knowledge of the avian world.

Yellow-rumps nest in the Northwoods, in coniferous or mixed forests. During the nesting season, they’re easier to hear than see—they stick pretty close to the tree tops most of the time. The problem with their song is that it’s a nondescript trill, like a junco or a Chipping Sparrow might sound after root canal surgery. They nest as far north as the timberline in Alaska and Canada, so the ones that stay with us are actually the soft and spoiled southerners of the species.

Yellow-rumps are by far the most abundant migrating warbler that we see in our area. This past fall, over 20,000 warblers were counted flying over the Lakewood Pumping Station, up the shore aways from Hawk Ridge, and most of the identifiable ones were yellow-rumps. During foggy spells, they migrate low and hang out on beaches and lawns. Birders always look forward to fog for abundant birds. If you’ve never had a chance to get a good look at a yellow-rumped warbler, try watching for one next time fog socks you in.

(Recording of a Yellow-rumped Warbler)

This is Laura Erickson, and this program has been “For the Birds.”