THE BIRD: ITS PARTS, VOICE, AND COLOR 259 
especially in the mating and nesting season as an expression 
of his happiness. Though some species begin to sing imme- 
diately upon their arrival and others continue their efforts 
till they leave us in autumn, the great concert season is in 
spring and early summer. 
CoLor 
Color and Environment. — Generally speaking, birds living 
on the prairies and elsewhere on the ground have dull or 
neutral plumage that harmonizes with their surroundings and 
protects them against discovery. In the foliage of trees and 
shrubs, we find the birds of brighter colors and, of course, 
also many of those in dull costumes. 
Color and Sex.—In many species the colors of the two 
sexes differ. In these cases it is almost invariably the male 
that wears the gayer feathers. . 
Color and Age. — When both parents are colored alike, the 
young resemble them; but if they are unlike, the young of 
both sexes may resemble one of them, more commonly the 
mother, or they may resemble neither parent. Immature 
birds differing from adults usually acquire the adult coloring 
the next spring, though sometimes it takes several years to 
complete the change. . 
Color and Season. — Some birds undergo changes of color 
with the season. Thus, the male Bobolinks and Lark Bun- 
tings after the nesting season become streaked, sparrow- 
colored birds like their mates, so that we may not recognize 
them. In the spring and through the mating and nesting 
season all birds wear their most conspicuous costumes. How- 
ever, among land birds, when both sexes are alike, there is 
little or no seasonal change in color. 
It is impossible to note all the details about the plumage of 
