This tiny yellow bird may cause confusion for backyard birders in the western U.S., because Lesser Goldfinch territory overlaps with that of the far more common and widespread American Goldfinch.

Luckily there are a few easy ways to tell them apart. First, the beak is different. The American Goldfinch’s beak is bright orange, while the Lesser Goldfinch's have a more muted brownish-yellow hue. Then, look at their backs. Contrary to the American Goldfinch’s bright yellow back feathers, the Lesser Goldfinch sports olive green feathers (especially those that dwell in California) or black feathers (in Texas and New Mexico).

Though these are social birds that forage in large flocks, Lesser Goldfinches form monogamous pairs in the spring. The male sings his song high in the treetops, chasing the object of his desire. Eventually, the pair will sit near each other, stretching their necks, touching beaks and chattering softly. He’ll gather food and feed her. While she’s incubating the eggs, he’ll continue feeding her, and help feed the babies when they hatch.

Their nests are also tiny, at barely 3 inches wide and an inch deep. Females weave cups out of leaves, tree bark, cocoons and spider webbing, and line them with a dense layer of soft things like feathers, fur, hair and plant fibers. They nest in willow and cotton trees that grow along rivers and creeks, choosing spots where there’s plenty of leaf cover.

Near the end of summer, males will molt their brilliant yellow feathers, replacing them with their winter set of dull, muddy yellow plumage. Those that live in the northern half of the western U.S. will migrate south to Texas and southern California, and perhaps even Mexico and Central America.

If you live in the southwest U.S., expect those autumn and winter flocks of the Lesser Goldfinch to congregate at your feeder. Fill your feeder with Lyric Finch Small Songbird Mix and watch as they feast on the small seed varieties smaller birds love!

Lesser Goldfinch pair. Thinkstock