American goldfinches (Spinus tristis), also called “yellow birds,” are small sparrow-sized birds with black wings. In summer, the males are brilliant golden yellow with a black forehead, and, despite the name, females are olive-yellow below and olive above.

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Most songbirds nest and raise youngsters in the spring when there is a great bounty of caterpillars to feed the offspring. But goldfinches are almost entirely seed eaters, and they feed their young regurgitated partially digested seeds. Because of this distinctive behavior, goldfinches do not nest in the spring like most other songbirds. Instead, they wait until their favorite plants (thistles and milkweeds) have gone to seed. These plants provide both fluffy fibers to build strong nests and seeds to feed offspring.

Indeed, goldfinches have pushed back their entire schedule: They nest later, they molt in the fall later, and they migrate later than most other songbirds. Their entire breeding season is synchronized with the seed crop. But despite this, they are a hardy species with about 44 million birds living in North America.

In 1906, ornithologist William Brewster wrote in The Birds of the Cambridge Region of Massachusetts, “Goldfinches used to breed nearly everywhere in and near Cambridge; in shade trees along our city streets; in orchards throughout the farming country; most abundantly of all in the maple woods and willow thickets which once covered so large a portion of the Fresh Pond Swamps.” He notes that lately, however, the English sparrow has pushed out goldfinches, but that “young birds, with their parents, continue to visit our garden in late August and early September, when the seeds of the sunflower are ripe.” Indeed, if you have sunflowers, you have probably spotted goldfinches eating the seeds. These birds have conical beaks perfectly suited for cracking open seeds.

In spring, male goldfinches partially molt into breeding plumage, becoming bright yellow with a black cap. Females sport an olive yellow bib. According to naturalist John Burroughs, “All the goldfinches of a neighborhood collect together and hold a sort of musical festival. . . . The males sing, and the females chirp and call.”

By early summer, goldfinches have paired up, although they wait until at least July to nest. The female spends about six days weaving a tight cup of roots and plant fibers, binding it to supporting branches and lining it with plant down. The finished nest is so durable it can remain in a tree for a couple of years and is woven so tightly that it holds water. (But females build nests beneath a canopy of leaves, so they do not get wet.)

The female lays about five jelly-bean sized eggs anytime from July to September. Nests are usually near good feeding areas containing thistle and sunflower seeds. Because of their love of thistle seeds, goldfinches are sometimes called thistle birds.

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The female incubates the eggs for up to two weeks. She spends most of her time on the nest, while the male brings her food, regurgitating seeds into her mouth. Ornithologist Alexander F. Skutch watched one male feeding his incubating mate: “He approached the nest with nothing visible in his bill but with his throat or crop well stocked with food, stood upon the rim, and regurgitated to her while she fluttered her partially spread wings like a hungry nestling.”

After the eggs hatch, the male does double duty—feeding both the female and the newly hatched chicks. As the chicks grow, both parents feed them regurgitated seeds. In two weeks, the hatchlings leave the nest, but they are not yet independent. The male continues to feed them for another three weeks.

By this time, it is late summer or early fall. Both the males and females molt completely, replacing all of their feathers. Both become mostly olive brown, but the male still has a bit of yellow around the face and shoulders.

In winter, the goldfinch population shuffles southward. Some birds, especially youngsters, migrate south, joining large flocks of migrants as they pass overhead. Other birds stay put and overwinter right here in Massachusetts, especially if food is plentiful. Still others, mostly from Canada, fly south to or through our region to overwinter. Goldfinches prefer to overwinter where the average January low is greater than 0°F. Overwintering birds survive on seeds from thistles and asters, sunflowers and grasses found in weedy fields, roadsides and gardens. They also eat from winter bird feeders (favorite bird feeder seeds are sunflower and nyjer).

Bradford Torrey (1885) painted this picture of the goldfinch: “Our American goldfinch is the loveliest of birds. With his elegant song, and his more beautiful soul, he ought to be one of the best beloved.”

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