To change, to cast off or shed the exoskeleton, hair, outer skin, horns, or feathers at certain intervals, prior to replacement of the castoff parts by a new growth. (This) is said of certain animals, as reptiles, birds, and insects. That is Webster's definition of "molt" or "molting."
That’s pretty simple but this process, when undertaken by birds, can be responsible for some interesting sightings and difficult questions. Identifying birds when they are experiencing the “fall molt” can be one of birding most challenging exercises.
In recent weeks, it has become evident the birds are losing their breeding plumage and molting into winter plumage.
Some just look scruffy but others look like a different species.
When questions began, I was thankful it is easy for many readers to take and send photos. However, there are times when even a good photo leaves you flipping through the field guides.
Brown-headed cowbirds are easy to identify or they should be.
Young cowbirds sometimes confuse people because they are nondescript and often following a “parent” they don’t resemble. They migrate south in the fall and I am beginning to think they molt into adult plumage after they leave our area.
When a reader in California sent several bird photographs and asked for identification, it turned out to be an interesting exercise.
The birds were black and white like piebald ponies and I was drawing a blank.
When a bird is difficult to identify, you disregard color and focus on other features. The answer still didn’t come easily. I studied the bird’s bill and looked at other birds it was traveling with. At least one photo hinted that it was a species that “walks” instead of “hops.”
That narrowed things down and I looked up cowbirds in the Peterson and Sibley guides.
Molting brown-headed cowbirds look nothing like the illustrations you see in most guides. Even those shown in the field guides are at best an example.
No bird molts exactly the same. Feathers fall out or break off and numerous patterns evolve.
Most of the time, it’s easy to recognize molting jays, towhees and song sparrows. Great blue herons, crows and flickers announce they are getting new plumage as they drop the occasional feather for us to find. Waterbirds such as guillemots, grebes and loons might look different but are usually traveling with others we immediately recognize.
Goldfinches do the same. Suddenly most of them look like females or juveniles but we know they are goldfinches and the males are trading breeding finery for winter dullness.
Fall warblers are one of the most challenging identification exercises a birder can encounter.
Many acquire winter plumage that makes them look like different birds. That’s bad enough but one reader took this fall identification to a whole new level.
Where their ranges overlap, the Townsend’s warbler and the hermit warbler will interbreed and produce hybrid offspring. In the fall, these birds migrate through Western Washington. They can be confusing.
Identifying a molting brown-headed cowbird was a brain drain but to be sent a photo of what looked like a fall-plumaged Townsend’s – hermit hybrid was icing on the cake. It proved once again that birdwatching never stops challenging you.
Write to Joan Carson, PO Box 217, Poulsbo, WA 98370. Include a self-addressed, stamped envelope for a reply. (or e-mail firstname.lastname@example.org)