MUSEUM OF COMPARATIVE ZOOLOGY. 193 



Generally, aside from the paler tints of late-collected birds, as com- 

 pared with those taken early in the season, there is a total absence of 

 the grayish, yellowish, brownish, or rufous suffusions (the particular 

 tint varying of course in different species) that tinges the feathers early 

 in the season. The general aspect of the plumage at the two pe- 

 riods in question is thus essentially different. The common chickadee 

 (Parus atricapillus) will illustrate this point, in which the brownish 

 tint so conspicuous on the lateral portions of the ventral plumage in au- 

 tumn and winter is gradually lost as spring approaches, and in summer 

 is almost entirely wanting, especially in nesting females, which at this 

 season have the plumage generally much more worn than the males. 

 The savanna sparrow will also illustrate the differences resulting simply 

 from the fading of the color during the breeding season. In spring 

 both sexes have a greenish-yellow, superciliary stripe, varying more or 

 less in intensity in different specimens, but rarely or never of the pale 

 soiled-whitish so frequently met with late in the breeding season. In 

 the large series of specimens before me collected at that season in Mas- 

 sachusetts, few if any have this stripe so bright as average spring spe- 

 cimens have it, in many it having faded to soiled white. Scores of sim- 

 ilar cases might be cited, but the above are sufficient for illustration. 



Variations in Color depending upon Age. — So well known are many 

 of the variations depending upon age, that it seems necessary to advert 

 to only a few of the lesser known phases. In many species there is no 

 marked difference between old and young birds, after the moulting of 

 the first or nestling plumage, which usually occurs in the oscine groups 

 in a few weeks after they leave the nest. But even in these, in many 

 cases, sufficient marks of immaturity remain for a time to enable any 

 one acquainted with such features to recognize birds of one or two years 

 of age from those that are older. Yearling birds of this group are often 

 recognizable by their having more or less well-defined bars across the 

 wings, formed of light-colored, hastate, or drop-shaped spots on the ends 

 of the greater wing-coverts and inner secondaries, which in many 

 genera are peculiar to yearling birds, though in other respects, so far as 

 the plumage is concerned, they are not distinguishable from adults, — 

 a difference which in some instances has been considered specific. 

 Similar marks are also seen in older birds, in species that do not obtain 

 their adult colors till later in life. 



