This bird grows up to a maximum of 5 inches in length, with a size similar to a house sparrow. It weighs about 11 - 20 grams. The wingspan measures around 7.5 - 8.7 inches (19 - 22 cm). Goldfinches are pure vegetarians, feeding only on sunflower or other seeds. These are the only birds in their family to undergo a complete molting process twice a year; once in late winter, and then in late summer. The males can be easily recognized by their unique sunflower yellow color and a jet black spot on the forehead resembling a hood. Similarly, females do not have a spot, and have a slight tinge of brown in the yellow. The goldfinch loves weedy areas, fields, open floodplains, suburbs, and areas of human habitation like parks, backyards, etc. Its ideal habitat would consists of an area with plants like sunflower, aster, cosmos, zinnias, or other thistle plants for food; some shrubs and trees for nesting, and a nearby water source like a lake or a pond. The construction of the nest is carried out by both the male and the female, in union. The nest is neatly woven, using plant fibers, rootlets, and twigs; It is so strong and perfectly woven that it can even hold water without leaking. The binding cement often includes spider silk, and a sticky feathery material fetched from the thistles which these songbirds feed upon. The nests are usually seen in a shrub or a tree, especially in a spot where the branches unite. Nest building takes around 6 - 7 days. The finished nest is about 3 inches long, and 3 - 4 inches high. Females lay 2 - 7 eggs per brood. The nesting period is approximately 11 - 18 days, whereas the incubation period is 12 - 14 days. In comparison to the breeding seasons of other birds, the American goldfinch breeds a little late, beginning from the month of July to September. As these birds need to balance on the dandelions of thistles, they have the ability to eat hanging upside down as well as in the normal perching position. This unique ability of theirs allows them to access several food sources which other birds can't. The female isn't very territorial when it comes to her nest. Although a monogamous bird, she may very well leave her nest and join another mate to begin a new brood. Goldfinches usually binge on food and gain considerable weight during or prior to a storm. The American goldfinch is the state bird of New Jersey, Iowa, and Washington. These birds make flight calls similar to the rhythm of 'po-ta-to-chip'.