1899.] NATURAL SCIENCES OF PHILADELPHIA. 469 



An examination of Mr. Mcllhenny's series of Eiders sheds a 

 great deal of lio^ht upon this subject. 



In the first place this summer plumage is in no sense a niiptial 

 plumage ; while it may begin to appear before the young birds are 

 hatched it does not appear until the mating season is over and is 

 distinctly a post-nuptial dress. It is mainly restricted to the head, 

 neck, breast and scapulars, as already pointed out by Montagu ; 

 that is, to those parts -which are most conspicuously colored. 



The most important point in connection with this summer 

 plumage is that the annual molt of the flight feathers does not 

 begin until this dull plumage has been fully acquired, and as soon 

 as the new flight feathers have become functional the dull plumage 

 as well as the rest of the old plumage is lost and I he annual molt 

 of the body feathers progresses normally. 



It will thus be seen that this dull plumage lasts only during the 

 period when the bird is unable to fly, for, as is generally known, 

 ducks molt their flight feathers all at once and temporarily lose 

 the power of flight. 



At such a time a dull blended plumage would naturally be impor- 

 tant in rendering the bird inconspicuous and thereby protecting it, 

 and such I think is the explanation of this curious summer molt. 



Of the various names that have been suggested for it, " sum- 

 mer molting plumage ' ' seems the best, as it is different in charac- 

 ter from any plumage known among other birds, and, as has been 

 already shown, has nothing to do with the nuptial season, but is 

 entirely related to the annual molt. 



I may further state that the feathers of this plumage are very 

 poor and loosely constructed, like those of the " post-nidal " or 

 " first " plumage of young birds, which is also a mere temporary 

 summer dress. 



In connection with the summer molting plumage of the Eiders it 

 is interesting to note that Dresser, in his Birds of Ein-ojye, gives an 

 excellent description of this plumage in the King Eider, but 

 regards it as the " young male." In the same article he quotes 

 from Mr. G. Gillett," who saw several of these birds in Matthew's 

 Strait, August 6, " all apparently immature males," though two 

 specimens that were shot were found to be " entirely destitute of 



Ubis., 1880, p. 309. 



