EVOLUTION OF THE COLORS OP BIRDS. 311 



by Beddard (see ante, p. 228) that when food changes the 

 color of the plumage certain parts are more readily 

 affected than others may account for the color running- 

 down the breast in Pyrrhuloxia and not including the 

 sides. 



Genus Habia. The Grosbeaks. 



(10) Adult male more conspicuously colored than 

 female; young male (first autumn) unlike adult of either 

 sex; young female like adult female. 



Prevailing colors, black, white, rose, yellow, brown. 



The two species constituting this genus are peculiarly 

 interpsting from the great difference in the adult males, 

 and the different stages of specialization from the com- 

 paratively unmodified young plumage. As these differ- 

 ent stages of transition were given previously they need 

 not now be repeated (see ante, p. 223). Sexual selection 

 has apparently been by far the most important factor in 

 the evolution of the colors of the adult male, but the 

 conspicuous white and black wing and tail markings are 

 doubtless recognition marks, partly directive and partly 

 discriminative. The striking example of correlative red 

 and yellow in this genus has been sufficiently dwelt upon 

 (see ante,-^. 155). 



Genus Passerina. The Varied Bunting, etc. 



(7) Adult male more conspicuously colored than 

 female; young like female, but generally somewhat 

 duller. 



Prevailing colors, black, white, red, purple, blue, 

 yellow, green, brown. 



This genus belongs properly to the tropics, and the 

 males have all the wealth and diversity of coloring of 

 birds from that region. The colors appear to be princi- 

 pally due to sexual selection favored by a tropical en- 

 vironment, the females being dull brown in remarkable 

 contrast to the males. 



