Plumage-Cycles and the Relation between Plumages and Moults

THE plumage-cycle of a species is the series of successive plumages that are peculiar to the species, or it may be said that the several plumages of the young bird together with those of the adult, make up a plumage-cycle.If plumages are viewed in the natural sequence in which they succeed one another, it will be found that plumage-cycles of species vary in many details difficult to put into words, for with broadening knowledge of the subject we find that many familiar terms are inadequate.They have lost definiteness of meaning through careless use, or they have outgrown their early significance or they have been paraphrased into a host of synonyms, in any or all of these ways occasioning much confusion of ideas.Ornithology seems to be lagging behind other branches of zo/51ogy in the slow movement towards exactness of statement and of language, and many of the vague ideas that prevail regarding the relation of plumage to moult need to be reduced to exact terms.Some steps have already been taken in this direction, and perhaps many more need to be taken before we shall reach a firm foundation on which to build an adequate system of plumages and moults, but it seems to me the time has arrived when the prominent facts admit of a more accurate grouping than has hitherto been attempted.Most of us are so committed to the old idea of seasonal plumages and seasonal periods of moult, that it is in the nature of a shock to realize that the seasonal idea fits neither birds of the tropics nor those of temperate regions.We are accustomed to think of the ' summer' and • winter' dress of birds as if they all changed their feathers twice in the year.While these adjectives of season may apply to birds that actually do moult twice in the year, we are at present without a suitable word to express the plumage of birds that, wearing the sanhe dress throughout the year, moult only once.Nor is it safe, if we wish to be accurate, to speak as we do of 'spring' and 'fall' moults, because the moulting periods vary so with species and with age that no ��� DwIGHT, Plumage-Cycles.