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THE SEQUENCE OF PLUMAGES OF THE 



COMMON EIDER. 



BY 



J. G. MILLAIS. 



Many accounts have appeared in the works of naturahsts 

 on the subject of the plumage of the male and female 

 Eider {Somateria m. mollissima) and the age at which 

 the sexes arrive at maturity. In nearly all of these 

 there is much guesswork owing to the small series of 

 specimens examined, although in several of the accounts 

 it is stated correctly that the male bird becomes adult 

 in its third year. 



So long ago as 1756 we find the description of the 

 typical (Swedish) Eider by M. Thrane Briinnich, who, 

 roughly, yet accurately, states that it is not until 

 the third year that the male " in all things resembles 

 the adult male " and " they do not pair until the third 

 year unless through an irregularity or an occasional 

 wantonness." With his description of the plumages 

 of the immature female I cannot agree, for he states 

 that " During the first year the female bird alone attains 

 almost the same plumage as the mother bird, the only 

 difference being that they are somewhat Hghter," etc. 

 Later, in his Supplement HI., he states that the two 

 white bands on the wings do not become distinct until 

 after several years' moulting. This is somewhat contra- 

 dictory. Various authors such as Nilsson, Lilljeborg, and 

 M. von Wright, all give descriptions of various stages 

 of the plumage, but in no way seem to come to definite 

 conclusions. Faber {Prodromus der isldndisch. Ornith., 

 p. 70, 1822) says that the male bird is not capable of 

 procreation until its fifth summer and that it retains its 

 youthful plumage four years. Kjaerbolhng {Skandina- 

 viens Fugle, p. 691) thinks that in the first and 

 second year the male bird lacks the beautiful markings 

 on the head, and the white is entirely absent on the neck 

 or begins on the throat. Brehm, too {Handhuch der 

 NaturgescMchte alter Vog. Deutsch.), is equally inaccurate 



