Birds of a Feather
with Mike Lushington
Most people know, in a general sort of way, that birds undergo plumage changes each year. Feathers need to be replaced as they wear out, and to meet the demands of different seasons. Many birds also undergo plumage changes in response to their own breeding cycles.
Ducks have one of the more interesting plumage change schedules, especially for this time of year. In the late spring, courtship completed, females settle down to brooding and hatching eggs, while males, according to their species, drift off away from the nesting area. Males of most sea duck species actually take off completely for the summer. Usually they head off to sea, leaving the females - and the available food supplies - behind. Puddle duck males usually don't go far, but they don't stick around the nest site either. At this time, nearly all adult ducks undergo a pretty thorough moult - so much so that many of them lose their ability to fly for a short period. When they re-feather, the males resemble the females much more closely than they may have a couple of months previously. They no longer need their bright display plumage and their resulting dress is quite subdued, even drab.
However, this state of affairs doesn't last very long. They will have a second moult in late fall, this one a partial moult, but the resulting plumage is full courtship and breeding regalia.This moult is a much more leisurely affair; the birds don't lose all of their flight feathers at once, or their body plumage either. As a result, should you have the chance to observe a few Mallards (certainly one of our most colourful winter species) several times over the course of the winter, you will notice that they seem to be becoming brighter as the winter progresses. That is exactly what is happening - each new feather has the richness of breeding plumage instead of the more subdued basic plumage of autumn.
Ducks actually begin their courtship routines at this time of year, and it will persist throughout the winter. That is why they are often the most beautiful birds to spot in wintertime. Recently, I wrote about Barrow's goldeneye, describing this handsome bird in terms of the black-and-white penguin tuxedo look - that is his breeding plumage and can be gorgeous, especially if you are fortunate enough to be able to get a look at one contrasted against ice and snow on a bright early February day.
Ravens have begun their courtship rituals, and so have the larger owl species, especially Great horned owl. However, Ravens replace dull black with a brighter black - a rather subtle change at best, and we really don't get much of a chance to observe plumage changes in the owls. Gulls are currently wearing winter dress, but they will begin to assume breeding plumage in early winter. (You can really notice this with Herring gulls - right now, their heads and necks are very heavily streaked with brown feathers - by mid February, those brown feathers will have disappeared, and the bird will once again sport its pristine white, grey, and black look.)
Most birds alternate between two plumage designs: some of the older birding guides used to refer to them as their summer and winter plumages. Today, most guides refer to them as Alternate, or Breeding plumage, and Basic plumage - the one that they wear for much of the year.Some of the larger birds - gulls and eagles, for example, undergo plumage variations for the first several years of their lives - part of the reason why gulls, in particular, have been known to drive some would-be birders into early retirement. (More on this later.)