Clayton, North Carolina

What is that Ugly Bird!

North American Cardinal

Molting is a process that many different creatures undergo. Insects and crustaceans molt their exoskeletons; snakes and other reptiles shed their skin; and, of course, birds molt their beautiful plumage. However, with most birds, molting is often a fairly inconspicuous event. They lose their feathers a few at a time. They shed their flight feathers in pairs, symmetrically, one from each side, so as not to affect flight. The entire process could take from days to months (depending on the species and the time of year), and the casual observer would not notice a thing.

Of course, there are a few exceptions. Many ducks, geese and other waterfowl lose most or all of their flight feathers at once, leaving them flightless for a short while, until new feathers grow in. Due to a waterfowl’s size and shape, the loss of even a couple of flight feathers would drastically inhibit its ability to remain airborne. It makes more sense for them to get the process done in one fell swoop. They molt all the feathers at once, rendering themselves flightless for a brief period. If they shed a pair of feathers at a time, they would be “practically” flightless, and for much longer duration.

Why Do Birds Molt?

Molting is basically a tire change. Birds are able to rid themselves of worn, damaged feathers and replace them with beautiful new plumage. Since feathers are responsible for more than just a bird’s ability to fly, molting is even more critical than one might initially think.

Feathers also provide weather protection, making a bird virtually waterproof. The feathers on a bird’s body overlap and the individual tines on each feather actually interlock. The net effect is an aerodynamic rain-sheet - wind and water slide right off with little resistance.
Some species even change into a colorful breeding plumage in order to attract a mate. The male American Goldfinch, a bird commonly seen at
bird feeders throughout much of the U.S., molts before the breeding season, changing into its distinctive bright yellow suit with a black cap. In the late summer to early fall, after the young have fledged, he molts into his basic plumage - a somber olive green, very similar to his mate’s coloring.

When Do Birds Molt?
Most birds molt but once per year. Several, though, like the Glossy Ibis, the Common Redpoll, and the aforementioned American Goldfinch, have two molts every year. Some birds experience more wear and tear on their feathers - whether it is from long migrations or foraging through trees and brush - and require that extra molt to keep their feathers in shape.

As far as the actual timing of the molt, there is much variation from one species to another, and even within individual species. The exact dynamics and mechanics of the process are still not fully known; what is known is that molting does tax a bird’s energy. Therefore, it always takes place during a relatively uneventful time of the year - for example, after a migration or after raising a nest full of baby birds.

What is the Significance of Molting to a Birder?

The answer to this question can easily be inferred from the previous paragraphs. Birds that molt into a breeding plumage are often stunningly beautiful. In the late winter, a birder may anxiously anticipate the coming change of clothes for his favorite bird. Molting also serves in the opposite capacity. A Purple Martin landlord may notice a few stray flight feathers on the ground under the birdhouse in the days before his gregarious tenant leaves on its winter migration.

In any case, molting is another fascinating aspect of the nature of our charming, enigmatic avian friends. Enjoy them, cherish them, and respect them.