The American Goldfinch Mating Habits
American Goldfinches are monogamous although some females may change mates after producing their first brood. The female then leaves the nest to begin another brood with a new male while the first mate stays to look after the fledglings.
Courtship for the American Goldfinch begins in the spring when one or more male birds chase one female. The female will fly off in a zigzag direction while the male sometimes flies into a slow straight flight. During this courtship period, a pair of American Goldfinch will fly in a circular motion with the male singing while flying. It is during the later part of summer that mating and nest building take place.
To signal that an area is his territory, a male American Goldfinch will warble and go from perch to perch. He will also circle around the territory and do two kinds of flight. One flight is low and flat while the other is his regular roller coaster flight during which his wings are close to his body as he dives down and then spreads them again as he flies upward in several loops.
Another behavior displayed during the mating season is the grouping of two or three pairs. This action may help the birds in informing each other pertaining to food and defense of their territories against potential predators. Many nests exist in areas where food and water abound.
American Goldfinches normally breed from July to September. They are, so far, the only member of the finch family that changes its plumage during the breeding season by molting or shedding of all its feathers. Scientists suggest that the long molting of this bird may be its way of achieving the protein energy demands of breeding which may have not been fulfilled by its seed diet.
During the incubating stage, the female sits on her eggs while the male looks for food and feeds her with seeds. When the eggs hatch, it takes three days when the young’s eyes start to open. During their first week, the nestlings are still quiet and begin to be active and noisy only by their second week. The parents bring undigested seeds which they regurgitate into the bills of their offspring.
While still very young, the adult American Goldfinch especially the female takes responsibility in removing the fecal sacs of their young and bringing them to a far place. Later on, the young birds will defecate over the rim of their nest. Upon reaching their 11 to 15 days, the young American Goldfinch leaves their nest and starts to develop the olive yellow plumage as well as the chick-kee or chick-wee call.