THE COLORS OF PLUMAGE 87 
Bunting. of October is transformed to the black and white bird ‘of 
June, and this without the acquisition of a feather. (Fig. 10.) The 
Bobolink, Red-winged and Rusty Blackbirds also illustrate color change 
by wear. 
With the Purple Finch and Indigo Bunting, as Dwight (’00) has 
shown, wear increases the brightness of the bird’s colors. 
October January March June 
Fig. 10. Feathers from back of Snow Bunting, showing seasonal changes in form 
and color due to wearing off of tips. (Natural size.) ° 
The Colors of Plumage.—Color is nature’s last touch in adapting a 
bird to the needs of its own special environment. In many instances it 
apparently has been given during the prevalence of existing conditions 
of haunt and habit; consequently, in studying color, there is a greater 
possibility of associating cause and effect than exists when we attempt 
to determine the origin of the older, more stable characters of form. 
One, therefore, may reasonably ask what is the significance of the mani- 
fold shades and tints, marks and patterns, not to mention various 
appendages found in the plumage of birds? But before a reply is justi- 
fied, the bird must be studied in nature, its food, its foes, its general 
habits and special actions learned; and at all times the student should 
avoid the human viewpoint, but imagine himself in the position of food 
or foe, an individual of the same species or one of a species with which 
the bird under consideration may come in contact. 
It is not to be expected that any color character should invariably 
achieve its end; if it does so more than half the time, it will in the aggre- 
gate prove beneficial to the species. (See A. H. Thayer, “Concealing 
Coloration,” p. 8.) 
In the study of color, there is a wide field for laboratory experiment 
on captive birds to determine the laws of molt, the effects of food, 
humidity, hybridizing, artificial selection, etc., into which it is not 
possible to enter here. (See Beebe, ’08.) 
Color and Age.—Most passerine birds acquire an essentially adult 
plumage not later than their first prenuptial (spring) molt. Prominent 
exceptions are the Orchard Oriole, Crossbills and Redstart, which breed 
