VOL. IX.] MOULTS IN BRITISH DUCKS. 35 



convinced me that in the sequence of plumages in the 

 ducks, " colour change " plays no part, and that the 

 different plumages are simply and naturally acquired 

 by a moult only. This is as one would have expected, 

 especially after a perusal of Mr. R. M. Strong's valuable 

 paper on the Develop^nent of Colour in the Definitive 

 Feather, A\'hicli demonstrates that all the histological 

 conditions render the possibility of the repigmentation 

 of the feather highly improbable. 



Perhaps the most interesting fact I have to record is 

 that female surface -feeding ducks in spring have a 

 complete body-moult, the tail and inner secondaries also 

 being involved. The down, too, is shed and replaced 

 by the usual down, and in addition by a luxuriant down 

 much longer and coarser than the ordinary down. Mr. 

 Millais has apparently overlooked both these moults, and 

 there seems to be no mention of them in literature. 

 The fact that the female Long-tailed Duck moults its 

 whitish winter do^n and acquires just before the breeding- 

 season an almost black down was first discovered by 

 Dr. E. Hartert, who told me about it. Subsequently 

 I chscovered that the females of the surface -feeding ducks 

 and those of the genus Nyroca also acquired a special 

 down just before the breeding-season. Female Tadorna 

 tadorna also have a down moult in spring, but my 

 investigations of the moults of this species are not yet 

 complete. Tiiis down is evidently used for embedding 

 the eggs in during incubation, and has been designated 

 ■■ nest down " by Dr. Hartert, a term I propose to use 

 in describing it. 



The only remark Mr. Millais makes about the spring 

 moult of the female is as follows : of the adult female 

 Mallard {op. cit., p. 27) he says that " late in the spring 

 (May, in fact) . . . there is sometimes a slight influx of 

 new feathers on the breast, especially where the bird has 

 heavily plucked herself of both down and feathers for 

 the ' building up ' of her nest. The whole plumage 

 then (by means of a colour change) becomes much darker. 



