VOl i^0? IH ] Dwight, The White-winged Gulls. 33 



ture' plumages are the result of the first postnuptial moult. The 

 subapical spotting of the primaries betrays first year birds when 

 it is present, but sometimes it is lacking. In second year birds it 

 is, I believe, always lacking. Another earmark of first year birds 

 is the dark bill. In second year birds it becomes more or less 

 yellow with dusky bluish clouding, and the red spot usually does 

 not develop till the second prenuptial moult has begun. The white 

 birds have dark bills, which would indicate immaturity here as 

 well as in plumage, and it will be noticed that, taken as a whole, 

 the birds having the most yellow in the bill also have the most 

 gray in their plumage, showing that both bill and feathers are 

 equally influenced by whatever factor makes for maturity. 



Second Nuptial Plumage. — The second prenuptial moult, at 

 its height in April, is confined to the body feathers and a few of the 

 lesser wing-coverts and scapulars. Gray, white, and brown feath- 

 ers are regularly found. Some birds, except for wings and tail, 

 are now like adults. The white birds acquire feathers of several 

 colors, less often showing gray ones than do the browner birds. 



Third Winter Plumage. — This plumage, acquired by the com- 

 plete second postnuptial moult, appears to be that of the adult in 

 the majority of cases. An occasional feather faintly sprinkled 

 with brown may be found among the body or the tail feathers, but 

 the adult primaries, pale pearl-gray like the mantle and fading to 

 white a couple of inches from their apices, are now acquired for 

 the first time. In still older adults the transition from gray to 

 white on the primaries becomes more pronounced (as it always 

 is on the secondaries and tertiaries) and the heads and bodies 

 become pure white with scarcely a trace of the dusky clouding of 

 younger birds. But here again the birds of the white type show 

 a curious reversion to the juvenal condition of plumage for, as 

 before stated, I have examined several that are exchanging white 

 primaries for pale drab ones and white body feathers for brown 

 mottled ones. On the other hand I have seen two others that are 

 passing directly from white to gray. All of these specimens have 

 the white wings and tails that are acquired at the first postnuptial 

 moult and must therefore be two years old, for I do not believe a 

 juvenal plumage could ever fade to the whiteness seen in these 

 birds. I am forced to conclude, therefore, that white birds are a 



