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Some Ducks Change Plumage

Dear Bird Folks,

I’m sure most people enjoy the spring, but fall is my favorite time of year. I look forward to apples, pumpkins and the return of ducks to my local ponds. Today, while reviewing the different ducks in my field guide, I noticed that some ducks were labeled as “eclipse.” The eclipse ducks look like a strange hybrid. What are eclipse ducks and why do they look so unusual?

– Diane, Princeton, MA


I totally agree, Diane,

Fall is the best. In my mind spring is way overrated, and it knows it. For every nice day in spring there are fifty days of raw, windy drizzle. When the sun finally does come out, we get bugs, lots and lots of bugs. Instead of apples and pumpkins, spring gives us skunk cabbage and poison ivy. Of course, spring does have good birding, but it’s not relaxing birding. Much of spring bird watching centers around straining our necks to see those blurry, caffeine-filled wood warblers, as they zip around the tiptops of trees. I think it’s far more civilized to spend a late autumn afternoon watching and identifying ducks as they float on a quiet pond. And, the best part of duck watching is that most of them are identifiable. Even I can do it. Well, I usually can do it. Those dull eclipse ducks can be a challenge. They look more like floating sparrows than the handsome birds we see in the field guides. After about five minutes of trying to figure them out I begin to wish it was spring and I was looking at those blurry warblers.

In birds, the term “eclipse” has nothing to with the sun being blocked out by the moon, or whatever it is that causes people to run outside and stare at the sky as if they’ve never seen it get dark before. The bird eclipse refers to a change of plumage, most notably in ducks. Molting is important for birds because it replaces worn and damaged feathers. Feathers not only give birds their ability to fly, but they also protect them from the elements. Feathers insulate birds from both heat and cold and causes rainwater to roll off them like…well, like water off a duck’s back. Feathers also give each species of birds its unique look. Without feathers, birds would be flightless, cold, sunburned, unidentifiable and very unattractive to just about everyone, except perhaps Frank Perdue.

Since songbirds are small and light, they can afford to slowly molt away a percentage of their feathers while still being able to fly. Ducks, on the other hand, are heavy birds. The loss of even a few flight feathers will impact their ability to fly. It’s in their best interest to grow new feathers as soon as possible. So after the breeding season adult ducks waddle off to a quiet, protected pond and rapidly molt away their colorful plumage. During this rapid molt the birds are flightless and must swim or dive to avoid danger. For the next several weeks the male ducks are no longer the handsome drakes we all know and love; instead they become generic brown, looking more like females. This generic brown plumage (aka the “eclipse” plumage) helps hide the birds during this vulnerable flightless period. Although, I’m not sure if the drakes are hiding because they can’t fly or because they don’t want to be seen looking like females.

Right now you may be thinking, “So? Lots of birds molt into a dull plumage after the breeding season, only we call it their winter plumage. Why use this fancy eclipse name?” Well, just as a solar eclipse is a short-lived event, so is the eclipse plumage of a duck. Songbirds typically select their mates in the spring, but ducks begin forming pairs in late fall and winter. Because of this, drakes can’t afford to wait until spring to change into their flashy courting clothes. They have to be all pimped out and ready to strut their stuff much earlier. So, only a few weeks after losing their breeding plumage and turning dull, the males start the process of looking sharp once again. Their “winter plumage” is often on the way out by late summer. Just like an eclipse, the dull plumage comes and is gone rather quickly.

The drakes would probably be safer if they retained their cryptic color throughout the winter, but without their bright colors they have little chance of attracting a mate. They may be alive but they would be lonely. Studies have shown that males with the best and brightest colors have the strongest chance of attracting a female. You women are so shallow.

As I mentioned earlier, Diane, ducks in eclipse plumage are tricky to identify. Your “hybrid” analogy is pretty accurate. Some drakes look like the females, some look like juveniles and others look like a weird cross between the two. Fortunately, for those of us who enjoy watching them, this whole mess is over fairly quickly and most drakes are as handsome as ever by the time we see them in late fall. It’s too bad the same thing isn’t true for us humans. I’ve been wearing the same eclipse plumage for the past twenty years and there’s no improvement in sight.