2a8 Dwight, Plumage-Cycles. Lj"ly 



PLUMAGE-CYCLES AND THE RELATION BETWEEN 

 PLUMAGES AND MOULTS. 



BY JONATHAN DWIGHT JR., 1\I.D. 



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 out- 

 grown 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 zoology in the slow movement towards exact- 

 ness 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 same 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 



