32 Dwight, The White-winged Gulls. [f^ 



Some, however, at the prenuptial moult in March or April acquire 

 to some extent white feathers about the head and body and a few 

 pearl-gray ones on the back, but brown feathers are predominant, 

 rather less distinctly mottled than those which preceded them. 



Second Winter Plumage. — There is no dearth of moulting speci- 

 mens taken during August and early September to show what 

 changes take place at the postnuptial moult, but which birds illus- 

 trate the first and which the second (a year later) it is not so easy 

 to determine. If the age of the different specimens could be known 

 the matter would be simple, but it is probable that, as is the case 

 with other species, the great majority of 'immature' plumages 

 result from the first postnuptial moult. In glaucns the variety of 

 plumages appears to be considerable. In a very few birds brown 

 mottled feathers still predominate, although birds with fairly 

 developed gray mantles, white tails sprinkled with brown, and 

 having pale ecru-drab or white primaries are perhaps the most 

 usual type of plumage. The white heads and bodies are much 

 obscured with smoky gray. An extreme is represented by birds 

 absolutely pure white, the ' hutchinsii' type. I was in error some 

 years ago when I conjectured such birds to be old ones, for they 

 are undoubtedly in a second year plumage, and moulting birds 

 examined show the transition into it and also out of it at a later 

 moult. Curiously enough, in some specimens new brown mottled 

 feathers are succeeding to the white ones, both at the prenuptial 

 and at the postnuptial moults, at the latter period pinkish drab 

 primaries replacing snow white ones! Between the two extremes, 

 the brown mottled and the white birds, every sort of variation may 

 be found, and in some of the specimens examined, new brown, 

 new white and new gray feathers (and even a triple mixture in 

 single feathers) may be found growing side by side. It is evident 

 therefore that not only does the vigor of individual birds vary, but 

 the pigmentation of the feather germs of the individual varies to a 

 considerable degree, possibly influenced by cold or food-supply. 

 If white were the regular second year plumage there would be more 

 of such specimens and not so many of tricolor plumage that cer- 

 tainly are suggestive of albinism on a large scale. Such white 

 birds eventually assume normal gray plumage as specimens in 

 moult clearly show. I am of opinion that nearly all of the 'imma- 



