62 DwiGHT, Moults ajid Plumages of Gulls and Tcrtis. \ j "^^ 



deep gray color with buffy edgings. They are paler, however, 

 and the primaries are deep gray instead of black. The limited 

 moults of the body feathers during the winter, together with 

 fading, effect a slight paling. At the first postnuptial moult pale 

 brown, sometimes partly mottled remiges and rectrices are ac- 

 quired and a similar brown variegated body plumage. The pri- 

 maries are very nearly white. A specimen of Z. glaucns (Amer. 

 Mas. No. 64144, September i, Greenland) in fresh plumage, still 

 showing the sheaths of the first primary and several rectrices, 

 seems to prove that the brown mottled dress is a second winter 

 plumage, and not a first as generally supposed. Tliis is the plum- 

 age that later, at the second prenuptial moult, acquires a sprink- 

 ling of pearl gray feathers. Not till the second postnuptial moult 

 are the white primaries and partly pearl gray mantle assumed. 

 This seems to be the sequence of these plumages, as well as may 

 be judged from material that gives only slight clues as to age. 

 We may suppose the absolutely white "• Lams hutihinsii''' to be 

 an extremely adult glaucns similar to occasional nearly pure white 

 specimens of leucopterus. There is at all events nothing about 

 such birds, which are rare, to suggest immaturity. 



We come lastly to consider the gulls with gray-patterned pri- 

 maries, which include L. glaucescens, L. kinnliciu and L. nelsoni. 

 In Juvenal plumage glaucesceiis is only a trifle darker than glaucus, 

 though distinguishable by size, and like it appears to assume a 

 similar first winter and first nuptial dress by limited renewal of 

 body feathers. At the first postnuptial moult a similar brown 

 mottled dress seems to be assumed with pale primaries while part 

 of the gray mantle and a white head are added at the second 

 prenuptial moult. The first gray-patterned primaries and white 

 tail are apparently not acquired until the second postnuptial 

 moult, together with the first adult plumage. There is of course 

 possibility of error in examining series, large or small, and it may 

 be that the mottled specimens of both g/auais and g/aucescens are 

 exceptions, while the majority of the birds acquire a more adult 

 plumage at the first postnuptial moult, as does argcntains^ occiden- 

 talism etc. Do we know I may ask, how great is the proportion 

 of immature birds of the former two species as compared with the 

 latter? 



