Vol. XVIII 

 igoi 



I DwiGHT, Moults and Plumages of Gulls and Terns. C h 



feathers, just as in S. hirundo. A blue-gray mantle and paler head 

 are assumed, the retained wing markings and banded tail of the 

 Juvenal dress characterizing young birds until their first postnup- 

 tial moult. 



4. First Nuptial Plumage, acquired by a partial first prenuptial 

 moult during March and April on the Atlantic coast. Much of 

 the body plumage is renewed, the mantle and lower parts resem- 

 bling the winter dress, while the deep plumbeous hood is partly, 

 and probably in many birds fully acquired. I have examined 

 early May specimens from New York which still show new growth 

 of feathers at the usual points. Some specimens appear to reas- 

 sume the winter dress, or merely a dusky somewhat mottled head, 

 analogous to the change in " Sterna portlandicay 



5. Second Winter Plumage acquired by a complete first post- 

 nuptial moult, beginning about the middle of July in New York 

 and fully a month earlier in California. Maine specimens show 

 the beginning of the moult early in August. It is doubtful 

 whether birds that appear on our coasts very early have been breed- 

 ing birds, and the same question may be raised in regard to other 

 species. At this moult birds assume adult characters, a wholly 

 gray mantle, a white tail, and primaries showing large white areas 

 extending to the outer webs, obvious even with the wings closed. 



6. Second Nuptial Plumage assumed by a partial second pre- 

 nuptial moult at which the full dark hood replaces the grayish 

 white one outlined on the winter dress. It is unnecessary to trace 

 later plumages, which resolve themselves into successive adult 

 winter and adult nuptial dresses. 



Species that moult precisely like Z, Philadelphia are Z. atricilla, 

 L.franklinii, L. ridiluindus, Rodostethia rosea, Xema sabinii and 

 Rissa tridactyla. All of these I have examined and find that the 

 dark-banded juvenal tail and wings are retained until the first 

 postnuptial moult when young and old become practically indis- 

 tinguishable. The bill in several species reddens or becomes 

 yellow in summer, changing to black or plumbeous in winter. 

 The adult postnuptial moult is seldom completed before October 

 in any of these species, and the postjuvenal often occurs still 

 later. Rissa tridactyla is peculiar in assuming a juvenal mantle 

 that is gray without distinct edgings, and the first winter mantle is 



