Periodically birds replace all or most of their old feathers during the process known as molting. Typically, birds keep their feathers for a year, with molting taking place in late summer, after nesting. Sometimes extra molts also occur in early spring, converting somber winter camouflage plumage to brightly colored ones appropriate for courtship rituals.

These plumage changes can be confusing to us birders trying to identify what we see. We grow used to seeing a bird look one way, then later it looks completely different!  The drawing here shows how the same Willet may look, depending on whether it's winter or summer.  Willets are common wading birds along the US coasts and inland during the summer in the West.

Male American Goldfinches, during nesting season, are splendidly bright yellow and black. In the fall they molt into a drab plumage similar to the female's. When spring comes, the male molts back to its yellow-and-black plumage. Sometimes its plumage emerges irregularly so that bright patches appear next to dull ones in splotchy patterns. Since American Goldfinches are frequent visitors to backyard feeders, sometimes people seeing these in-between plumages believe they've spotted a rare bird!

Not all bird color-changes are caused by molting. For example, the European Starling's late-summer molt produces a black plumage with very conspicuous white speckles, as shown in the photo at the right. When spring comes, the speckles disappear and the plumage becomes an iridescent black. This happens not because of a molt, but because the feathers' white tips wear off, leaving just the black lower part. In the photograph you can clearly see that the white speckles comprise a good portion of each feather's tip, so this gives you an idea of just how much feather material is worn away before the starling becomes its summertime coal-black, unspeckled color.

Young birds often have a plumage different from the adults'. The adolescent birds of many species look like their mothers. Female birds are often less colorful than males, though in many other species males and females look the same.

In fact, the plumage situation is even a lot more complex than that. In some species there are first, second and third winter plumages. There are postjuvenile molts, prebreeding molts and postbreeding molts. If you want to get all the plumages, molts and terms straight, check out the Ontario Field Ornithologists' webpage on Plume & Molt Terminology.