194 BULLETIN OF THE 



Yearling and two-year-old birds are also often distinguishable from 

 older ones by the presence, after the spring moult, of a greater than the 

 ordinary amount of ferruginous, ashy, or yellowish edging to t lie feath- 

 ers, such as is often seen in the winter plumage of adult birds. In 

 some eases such a bordering to the clothing feathers, especially those 

 of the back, is often strictly distinctive of young birds, and is, more- 

 over, a feature of common occurrence. 



Generally speaking, several years elapse before the purity of the 

 colors and the definiteness of outline of the markings characteristic of 

 maturity is fully obtained, especially in highly colored species. In 

 birds of variegated colors the contrasts of color become for a time more 

 and more decided with each moult, and the markings better and better 

 defined, especially in respect to the white bars of the wings and the 

 spots on the tail common to a large number of species. The latter 

 markings usually gradually increase in extent for a considerable period. 

 A good illustration of this is seen in many of the gulls, particularly in 

 the genus Larus. In L. argentatus the following gradual change with 

 age occurs in the white markings on the tips of the primaries. At first, 

 as ornithologists are aware, the plumage of this species is uniformly 

 dusky, the adult colors not being acquired before the second year, and 

 apparently frequently not before the third, there being in the breeding 

 season usually a large proportion of individuals in the brown plumage.* 

 But there are wide ditferences in the intensity of the color in different 

 individuals in this stage of plumage, some being but slightly du>ky and 

 others extremely dark, — differences that probably result mainly from 

 differences in age, the darker birds being probably yearling birds and the 

 lighter ones two years old, though part of the difference is doubtless due 

 to individual differentiation. In this stage the wings and tail are of 

 nearly the same uniform dusky tint as the general plumage. In what 

 may be considered as the second stage, the general color is somewhat 

 lighter, the tail much lighter, and the primaries much darker, with a 

 distinct paler apical margin. At a third stage the tail becomes white, 

 the dorsal plumage begins to assume the blue tint characteristic of ma- 

 turity, the primaries change from dull blackish brown to black, and a 

 small white spot appears near the end of the inner vane of the first 



* Generally the largo parties that spend the summer on the coast of Massachusetts, 

 where none of these birds now breed, consist almost wholly of birds in the brown stage 

 of plumage. See American Naturalist, Vol. Ill, p. 640, 1870. 



