Where's the Gold in Goldfinch
Color can be confusing. All winter long, you've adjusted your eyes to drab-looking birds at your feeders. Then spring comes, and you see a whole new array of color, plus some odd-colored birds you just don't recognize. What's going on? Color confusion throughout the year can be explained by three things: sex differences (sexual dimorphism), molting into winter plumage, and juvenile birds.
Photo courtesy of Roy Brown
It's All About Attraction
All beginning bird-watchers quickly become aware of the obvious color differences, or sexual dimorphism, between brightly colored males and drabber females. You learn to recognize ducks, woodpeckers, hummingbirds and many songbirds like Northern Cardinals and Eastern Towhees in spite of their sexual dimorphism. The best explanations for this color discrimination is that males use their bright colors to attract females and that those same females need to be camouflaged on their nest. So, color differences between male and female birds, even in winter, shouldn't cause confusion.
Photo courtesy of Tom Wilson
Molting Starts in Late Summer
What you may not know is that even brightly colored males can become dull in winter. Many species of birds molt all their feathers in late summer or early fall, which allows a new fresh plumage to replace the older summer feathers that have become worn from nesting and foraging in abrasive vegetation during the breeding season. This fresher, stronger plumage helps them survive the colder temperatures of winter or, for those that migrate, allows for a safer journey to Central and South America. While many male birds replace their feathers with the same colors, many do not. Instead, they molt into duller plumages. After all, males don't need to attract females during the non-breeding seasons, so why wear party clothes when there's no party? This explains the loss of the scarlet in male Scarlet Tanagers, the indigo in male Indigo Buntings and the gold in male American Goldfinches during the fall and winter.
The Strange Colors of Juveniles
What about young birds? There are plumage differences between juvenile birds (juvenal plumage) and adult birds (definitive plumage). Juvenile birds, recently hatched during the summer, may not attain their adult plumage until fall or even the next year. Their plumage might be dull, mottled or lacking the bold field marks of an adult. Some species even retain some juvenal feathers for two, three or four years such as Bald Eagles and many gulls. Immature male Ruby-throated Hummingbirds lack their iridescent gorget in the fall which can make you shuffle frantically through your field guide, trying to identify it.
Photo courtesy of Roy Brown
Identifying Birds through the Seasons
So how do you avoid color conundrum? Learn your birds well enough during the spring and summer in order to avoid the confusion in the fall and winter. Pay attention to the shapes of their bills, wings and tails. Also, take note of their body postures and behaviors, so that you're able to recognize your birds as if you were colorblind. Then, when spring arrives and the eminent nesting season unfolds, the gold will be back in the goldfinch and, once again, the partying begins.
Find out more about identifying birds