EVOLUTION OF THE COLORS OF BIRDS. 217 



were acquired first by the male, as sexual discriminative 

 marks, and afterwards perhaps transferred to the female 

 as general directive marks. 



It is an interesting matter to determine in what man- 

 ner, and to what extent the young, among these species 

 differ from the adult. Among a large number of them 

 the young are spotted or streaked. When the adults 

 have any distinctive mark or patch this is generally 

 wanting in the young, while the colors of the immature 

 bird are apt to be paler or duller than those of the adult. 

 As examples of species in which the young are spotted 

 or streaked may be mentioned the robin (Merula migra- 

 toria propinqua), Townseiid's solitaire (Myadestes toivn- 

 sendii), water wag-tails (Seiurus) spotted on the back 

 with rusty waxwings (Ampelis), lark-finch (Chondestes 

 sgrammacus), chipping sparrows (Spizella), Junco, etc. A 

 instances where the young are colored similar to the 

 adult but without the distinctive markings of the latter 

 the following may be mentioned: The chestnut crown- 

 patch of the Nashville warbler (Helminthophila rufi- 

 capilla), is somewhat variable in the extent of its devel- 

 opment, but is wanting in the young of both sexes and 

 present in full-plumaged adults. Lucy's warbler (Hel- 

 minthophila lucice), has, besides the crown-patch, a chest- 

 nut patch on the rump which is also wanting in the young. 

 The black-throated gray warbler (Dendroica nigrescens), 

 is marked with a black throat in the adult male which 

 may or may not be developed in the female, and 

 is always wanting in the young stage. The crown- 

 patch of the kingbirds (Tyrannus), is wanting in the 

 young. Perhaps one of the most complete changes from 

 the young to the adult plumage takes place in the red- 

 headed woodpecker (Melanerpes erythrocephalus). The 

 areas of the markings are the same for the young and 

 the adult, the markings of the wings and rump being 



