Promptly after the termination of the breeding season both ducks and geese moult their winter plumage. The moulting period generally begins about the middle of the month of June and continues for five or six weeks. Geese usually undergo their moult more rapidly than do ducks and, moreover, the new coat of feathers acquired by them is of a more permanent nature; that is, good for the ensuing year. The wing feathers are the first to be shed and it is remarkable how quickly a new complement of flight feathers are developed. After the wings, the tail and body feathers follow and as a rule by the first of August the moult is completed.
With ducks, this process is not quite so simple. The first moult after the breeding season is a sort of temporary one for the male of most breeds of domestic ducks, although, where the plumage of both sexes is alike this temporary moult is not readily discernible. Still, it is, nevertheless, a fact that the drakes in all domestic breeds, save the Muscovy, take on plumage closely resembling that of the female during the summer months, regardless of the plumage similarities of the two sexes during the breeding season. However, this change is especially noticeable in breeds of the Rouen color pattern, where much of the iridescent plumage of the drake is replaced with the more somber penciled feathers of the female. The lustrous green head and neck become brown, the claret breast and finely penciled gray flanks are exchanged for more heavily penciled dull brown feathers while the curling sex feathers disappear entirely for the time being.
But the Rouen is not the only breed in which this period of undress is conspicuous. The Buff drake’s seal brown head fades into a light fawn and the Penciled Runner drake becomes scarcely distinguishible from his mate, as does also the Blue Swedish drake.
The moulting season is a very critical one for waterfowl. The old coat of feathers is shed so suddenly and the new ones grown so rapidly that the constitution of the specimen is severely taxed. The result is many birds, not in prime condition, just before shedding their plumage, fail to survive the added strain put upon the system. Oscar Grow