468 PROCEEDINGS OF THE ACADEMY OF [1899. 



beneath, as well as the elegant scapulars had entirely vanished, 

 and to all appearance a sexual metamorphosis had taken place. 

 But this change was of short duration, for about the latter end of 

 September one of the males began to reassume the masculine attire 

 .... and by the middle of October this bird was again in full 

 plumage. ' ' 



In 1838, Waterton* described a similar molt in the male Mal- 

 lard, and later on many other species were found to have the same 

 habit of molting, so that in Ridgway's Manual we find the follow- 

 ing species given, largely on the authority of Dresser, as having a 

 peculiar summer plumage resembling the female: — Mallard, Blue- 

 Wing and Cinnamon Teal, Gadwall, Widgeon, Pintail aiid Scaup. 

 Additional species are mentioned in the British Museum catalogue. 



Notwithstanding this, however, only a few of the above are men- 

 tioned in Elliot's Wild Fowl as having a peculiar summer plumage, 

 and other works have ignored the question entirely. 



A study of the magnificent collection of arctic birds made by 

 Mr. E. A. Mcllhenny, at Point Barrow, has shown conclusively 

 that the v^irious Eider ducks, the Pacific, Spectacled, King, and 

 Steller's Eiders all assume a peculiar summer plumage, and further 

 investigation adds the Red-breasted Merganser to the number. 



With all these facts before us it seems not unreasonable to pre- 

 dict that in all ducks where the plumages of the male and female 

 are markedly different we may axpect to find this double molt and 

 dull summer plumage in the male. So unexpected are some of the 

 laws governing molts, however, that there may be exceptions. 



As regards the reason for this double molt, Montagu was unable 

 to furnish any explanation. He says : ' ' The double molting in 

 so short a time, peculiar to some species of birds, is a most curious 

 and extraordinary circumstance that seems to bid defiance to all 

 human reasoning. That some birds change their plumage with 

 the season is evidently a gift of nature to accommodate their color to 

 their habits, as in the Ptarmigan, Avhich changes his mottled plum- 

 age in the autumn for that of white, in order that he may rest se- 

 <3ure upon the bosom of the snow during winter. But there is no 

 ;such evident reason for a double change in the short, space of two 

 or three months in the same season." 



1 Essays. 



