height of up to . The nest-building lasts approximately six days, during which time the female works in 10–40 minute increments. The male frequently flies with the female as she collects nesting materials, and though he may carry some materials back to the nest, he leaves its construction to the female. The outer shell of the nest is built of bark, weeds, vines, and grass. The inside diameter of the finished nest is about . The rim is reinforced with bark bound by spiderwebs and caterpillar silk, and the cup is lined with plant down from milkweed, thistle, or cattail. The nest is so tightly woven that it can hold water, and it is possible for nestlings to drown following a rainstorm if the parents do not cover the nest. The clutch is four to six bluish-white eggs, which are oval in shape and about , roughly the size of a peanut. It is thought that they are laid during the night. The eggs are incubated by the female alone, though the male brings her food as she nests, and most mating pairs raise only one brood each year. The chicks hatch 12–14 days after incubation begins. Like all passerines, the chicks are altricial; they are hatched naked, with reddish bodies, pale grey down, and closed eyes. The mother bird feeds her young regurgitated seeds and insects as they grow. The hatchlings develop quickly, opening their eyes after three days, and completing the growth of olive-brown juvenile plumage after 11–15 days, at which time they begin to practice short flights close to the nest. For up to three weeks after fledging, they are still fed by the male, who locates them by listening for their fledging call. The chicks stop giving this call when they become entirely independent. The American goldfinch is occasionally victim to brood parasites, particularly brown-headed cowbirds. One study found that 9% of nests had brown-headed cowbird eggs in them. It likely evades parasitism partly because of its late breeding season. The American goldfinch also makes a very poor host for brood parasites, with studies showing low hatching rates of brown-headed cowbird eggs and no fledging success. This is despite the lack of known behavioral adaptations against brood parasites in this finch. It is thought that the inability of brown-headed cowbird chicks to survive is due to a failure to get enough nutrition; the seed-rich diet of