330 CALIFORNIA ACADEMY OF SCIENCES. 



family, and are to be explained by pigment assortment 

 and sexual selection. 



Genus Setophaga. The Redstarts. 



(7) Adult male more conspicuously colored than 

 female; young similar to female, but duller, or (2) adult 

 male like female, young with a peculiar first plumage. 



Prevailing colors, black, white, yellow, red, chestnut, 

 brown. 



The colors in this genus are the result of sexual selec- 

 tion. By pigment assortment the olive green has 

 become entirely replaced by its component black and 

 yellow. The yellow has become intensified into the cor- 

 relative orange or red, and by sexual selection has been 

 located under the wings, where it will be most conspic- 

 uous when the bird is in motion. The female has in- 

 herited the yellow color in place of the intensified red, 

 and the black is replaced by olive gray. As in the orioles 

 where chestnut occurs apparently intimately connected 

 with yellow and intensified red, so here also a species is 

 found (S. miniata) with a crown-patch of chestnut, ap- 

 parently intensified from yellow. In this species the 

 red of the under parts is on the breast, extending down 

 on the belly, instead of on the sides, and is much more 

 intense than in S. riiticilla. The different species have 

 doubtless been originated by sexual selection and isola- 

 tion in a tropical climate. The fact that in some of the 

 most brilliant species the female is colored like the male 

 is an evidence of a high degree of specialization. 



Genus Cardellina. Red-faced Warbler. 



Genus Ergaticus. Red Warbler. 



(2) Adult male like female; young with a peculiar 

 first plumage. 



Prevailing colors, black, white, gray, brown, red, 

 vermilion. 



