!920 ] Dwight, Plumages of Gulls. Zo5 



part of their adult body plumage, and they assume at the first 

 prenuptial moult a plumage that is adult save for wings and tail 

 and finally through the first postnuptial moult they become fully 

 adult. Larger Gulls are quite or very nearly adult in body 

 plumage after the second postnuptial moult but the largest are 

 usually not in full adult dress until after their third postnuptial 

 moult. 



4. Colors of bill and feet. — The bill is not only rather slow in de- 

 veloping color, but the color often varies between winter and sum- 

 mer. Doubtless there is much more to be learned from fresh 

 birds but museum specimens show indications of immaturity in 

 dark bands and dusky cloudings up to the third and possibly 

 fourth year in the larger species while in the smaller, the time 

 varies from perhaps less than a year to one or two years as the 

 size increases. 



The color of the feet and tarsi and eye-ring (the iris too) may be 

 studied successfully only in fresh birds for these parts change 

 color as skins dry so that no clue to their original color remains. 

 In young birds the colors are, as a rule, pale deepening with age 

 to the more brilliant tints or deeper shades of maturity. 



It has been my endeavor to show the characters as we find them 

 in average birds and it is difficult not to blur the picture with too 

 many details of exceptions. It is no easy matter to pick out typi- 

 cal average birds even with large series to choose from but the 

 accurate sketches by Mr. Hartshorn of wing tips and tails speak 

 for themselves. In explanation of them I will first give a brief 

 diagnosis of the plumages of a small species, Bonaparte's Gull 

 (Lams Philadelphia) which acquires adult plumage at its first 

 postnuptial moult and then of a large species, the Herring Gull 

 (Larus argentahis) which does not acquire adult plumage until its 

 third postnuptial moult, some few specimens retaining slight evi- 

 dences of immaturity even until the fourth. 



Larus Philadelphia. Bonaparte's Gull. 



1. Natal Down. Wholly a body plumage and like most Gulls at this 

 stage, the downy chick is whitish or buffy brown clouded with large and 

 small dusky spots. 



