Of course you can recognize a Northern Cardinal when you see one. They are among the most common of backyard birds. But you may be overlooking their tremendous seasonal and age diversity. Unlike many birds, they do not molt into bright breeding plumage – they come into it by wearing away of gray-brown edges of feathers attained by their fall molt – leaving them with frayed, but brighter colors just in time for attracting a mate. Males are always brighter than females – likely a function of the female’s roles in incubating eggs and brooding new-hatched chicks. A male’s more extensive bright colors serve to attract a female and to defend the territory from intruding males. Adult males and females both have a bright red bill. Fledglings leave the nest with a black bill. The black pigment adds strength to the bill as the fledgling is learning to feed on its own. Perhaps more importantly it sends a strong “up-front” message to adult cardinals – “Hey! I’m just a kid. Leave me alone.” Adult males and females both have black around the base of the bill. The black strengthens those feathers, reducing wear as the adult forages for seeds, fruit, and insects in dense brush.
Unlike many birds that molt into breeding finery in spring, adult Northern Cardinals molt only in fall – gaining a plumage that has gray- to brown-edged red feathers that gradually wear through the winter – leaving them with a worn but much brighter plumage in the breeding season. Fledgling young are still fed by their parents after they leave the nest – and they regularly stay on a perch waiting for food to arrive -- thus have little need for the wear prevention provided by the black on an adult face.