COURTSHIP COLORS - Male Goldfinch in transition to Spring plumage. Many birds molt once a year and simply replace their old feathers with a similar-looking set. Some species - such as the American Goldfinch - molt twice a year and change their appearance dramatically with the seasons. In early Spring male Goldfinches transform from their drab winter plumage to the showy yellow and black feathers they need for courtship. Hormones control the switch that allows the same feather follicle to grow very different feathers at different seasons.