Dan's Feathursday Feature: Yellow Warbler

In the Chicago area in late April, after spending the whole winter and early spring looking at mostly gray and brown birds, the colors of the "warbler invasion" are just plain stunning. At the height of the spring migration in early May, the trees are full of warblers, and the energy is exhilarating. In a small tree in Jackson Park, for example, one morning I counted over twenty tiny warblers—four species—flitting about, non-stop, occasionally making quick dives at the strange "eye" of my camera lens. The previous day, those same trees had been virtually empty. That's how sudden and dramatic the migration magic can be!

Unfortunately, just as suddenly as it begins, it ends. Come June, most of the flashy warblers have continued north to their nesting grounds in Wisconsin and Canada, and that Jackson Park twenty-warbler tree is downgraded to one or two birds. There is still plenty of energy in the tree, and plenty of activity, but it’s not the flashy energy of spring. It’s the stolid, deep-rooted energy of summer. Fully leafed out—and the leaves now a deep forest green—the tree quietly goes about its business of converting sunshine and dirt to another growth ring in its slowly expanding trunk and to food for the insects that the birds eat.

Lucky for us, there’s a good chance that one of the few birds visiting that tree in summer is the Yellow Warbler. By the end of May, when most other warbler species are sitting on their nests further north, the Yellow Warbler has camped out right here in our region. But if you hope to see one, you’ll have to work a bit harder than usual.

That’s because in spring and early summer, before the trees leaf out, the tiny Yellow Warbler is easy to pick out. When the new leaves first appear—yellowish green spring leaves—it’s amazing how well the Yellow Warbler blends in. But there is still more open space than not, and the movements of this energetic bird make it relatively easy to spot. But once the tree fills in completely it can be difficult enough to find a large crow in that tree, let alone a tiny five-inch, yellow bird.

Summer becomes the time to rely more on the ears than the eyes. Along with the Warbling Vireo and the Indigo Bunting, the Yellow Warbler is one of the singingest of our nesting songbirds, so if you want to see a Yellow Warbler during the summer, learn to identify its song. I like to think that the Yellow Warbler created its song by pulling licks from both the Warbling Vireo and the Indigo Bunting. It obviously likes the crisp couplets of the Indigo Bunting, often starting its song with one. Then it immediately moves into a series of cascading arpeggios similar to the rambling Warbling Vireo, only to suddenly cut it short, as if it forgot the rest of the lick. Or maybe it’s just thinking, “That vireo is overdoing it. Half the length, twice the beauty.”

I guess I’m not being fair to the Yellow Warbler. Maybe it was the other two birds who stole licks from it. Anyway, even if you learn the Yellow Warbler’s song, and it does sing for you, good luck getting a look at it in a tree with dense foliage. My recommendation: don’t sweat it. You don’t need to see the musician. Sit back and enjoy the concert. And by the way, as gig venues go, willow trees seem to be favorites of the Yellow Warbler—at least that's where I can pretty much always count on hearing one.

The coolest tidbit I know about the Yellow Warbler has to do with its nemesis, the Brown-headed Cowbird. When the Yellow Warbler discovers the parasitic Cowbird's eggs in its nest, it doesn't bat a nictitating membrane. It just proceeds to build another nest on top of the original nest. Yellow Warbler nests have been found up to 6 tiers high, thanks to the stubbornness of the Cowbird and the never-say-die spirit of the tiny Yellow Warbler.

Dang, birds are cool.

Dan's Feathursday Feature is a regular contribution to the COS blog featuring the thoughts, insights and photography of Chicago birder, Dan Lory on birds of the Chicago region.