^°\914^T DwiGHT, Plumages of the Scoters. 297 



along definite paths. This shows clearly in the Scoters where the 

 black feathers of the head begin to show chiefly anteriorly and the 

 moult moves slowly backward, leaving a gap on the neck before 

 it joins the spot on the breast and back where a similar backward 

 movement has been in progress (Plate XXVIII, Fig. 2; XXIX, 

 Fig. 2; and XXX, Fig. 2). Feather growth next extends along 

 the sides and flanks and the last area to be affected by a moult is 

 the middle part of the abdomen (Plate XXVIII, Fig. 3; XXIX, 

 Fig. 3; and XXX, Fig. 3), although in the downy chick this area 

 is clothed before the wing-quills sprout. 



There is no haphazard growth. Moult may be delayed, espe- 

 cially in females, or it may be checked in some young birds before 

 it has extended as far as it does in others, but birds of the same age 

 have approximately the same plumages. The difficulty has always 

 been to classify plumages and moults by name, and this is particu- 

 larly difficult in the Scoters because there is no month in the whole 

 year when some individuals may not be found moulting. Espe- 

 cially is this true of young birds arriving from the northern breeding 

 grounds, in full juvenal plumage, some showing the growth of a 

 few winter plumage feathers in October and others being no farther 

 advanced in March. Furthermore some males have become largely 

 black by January while others are at a similar stage in April, so 

 that young birds may be found in active moult throughout the 

 entire winter. Specimens examined when freshly-killed show many 

 pin feathers that easily escape notice in skins and I am convinced 

 that there are two moults concerned in the changes of the first 

 winter, a partial postjuvenal and a partial prenuptial. Both 

 produce black feathers in the male and brown ones in the female, 

 but where one leaves off and the other begins it is impossible to say. 

 As we find new black feathers among old black ones we may as- 

 sume such birds have undergone two moults, but as a rule we find 

 new black among browm feathers only which indicates the post- 

 juvenal moult and the growth of first winter feathers. When such 

 growth occurs in spring birds however it seems rather absurd to 

 call them first winter feathers rather than first nuptial, but we must 

 either do this, consider the first winter plumage suppressed in 

 some individuals, or consider the postjuvenal moult as aborted and 

 its place taken by the prenuptial. It is merely a question of what 



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