The American goldfinch begins its breeding season later in the year than any other finch and later than any other native North American bird, besides occasionally the sedge wren. This may be related to the abundance of seeds in the late summer months, as seeds represent the majority of their diet.
The courtship rituals of the American goldfinch include aerial maneuvers and singing by males, who begin courtship in late July. The flight displays begin as the male pursues the female, who flies in zigzagging evasive patterns. The male is able to signal his quality and fitness, both in the short term (current body condition) and long term (genes), through ornamentation (bill color and plumage). If a female accepts the male as a mate, the pair will fly in wide circles, as the male warbles throughout the flight.