192 BULLETIN OF THE 



the North are also common to those from the South, and vice 

 versa. 



In species in which the (Vmale usually differs from the male in being 

 paler colored, the' pattern of coloration being the same in both sexes, 

 females occur more or less frequently which arc as brightly colored as 

 the brightest males, and males that are paler than the generality of the 

 females. 



Variation in Color depending on Season. — A word in this connection 

 seems necessary concerning some of the more obscure variations de- 

 pending upon season and age, since it is sometimes difficult to avoid 

 confounding these differences with those resulting from individual vari- 

 ation. In many species there is a marked change in the color of the 

 plumage without a change of the plumage itself. No experienced col- 

 lector can have failed to notice the much brighter and livelier tints 

 the plumage of mo?t song birds presents immediately after the autum- 

 nal moult, in species in which there is no marked seasonal change 

 of color, in comparison with the faded appearance they exhibit to- 

 wards the close of the breeding season. This brighter autumnal tint 

 is particularly marked in the Vireos, the different species of Em- 

 pidonax, Sayomis, Contopus, and in some of the Sylvicolidee, and 

 is clearly traceable in hundreds of other species. But almost as 

 great a difference is seen when specimens of any species taken in 

 spring, on its first arrival at its breeding station, are compared with 

 those collected several weeks later, or just before the autumnal renewal 

 of the plumage. In this case the variation results in part from an ac- 

 tual lading of the color, and in part from the wearing of the edges of 

 the feathers. Seasonal differences of this character are often only read- 

 ily appreciable to the experienced eye, and the failure to recognize 

 the cause of these differences has led in many instances to their being 

 regarded as of specific value. Especially noteworthy instances of such 

 mistakes will be noticed later. Collectors, and even naturalists, gen- 

 erally place little value on failed or dull-colored specimens, so that or- 

 dinarily in collections of our native birds only fine-looking specimens 

 are preserved. But travellers and explorer- of new localities are often 

 compelled to content themselves with any representative they may be 

 able to get, so that the " closet " or exclusively "museum naturalist" 

 has not usually the material necessary to furnish him with a clew to the 

 cause of these variations. 



