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 

 FIG. 10 



January 



March 



June 



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 . Gofer 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 origki 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 ail 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 



