COLOR AND SEX. 45 



exact value remains to be determined by closer obser- 

 vation. 



Color and Sex* It is not possible here to discuss at 

 length the vexed question of sexual coloration. But, as a 

 means of directing observation, I present a synopsis of 

 the principal types of secondary sexual characters, with 

 some of the theories which have been advanced to ac- 

 count for them. 



SYNOPSIS OF THE SECONDARY SEXUAL CHARACTERS 

 OF BIRDS. 



I. STRUCTURAL. 



Size 



Plumage. 



Of the body. 



Of the feet. 

 Of the bill 



l ar er th an female (usual). 

 Female larger than male (rare). 



Color ! ^ a ^ e bl> ih. ter than female. 



' ( Female brighter than male (rare). 

 f Assumption of plumes, ruffs, crests, trains, 

 etc. : special modification of wing and tail 

 Form. <{ feathers. 



I a. Worn by male alone. 

 ^ b. Worn by both sexes. 



Sole or greater development in male of brightly col- 

 ored bare tracts of skin, combs, wattles, caruncles, 

 and other fleshy or horny appendages. 

 Sole or greater development in male of spurs. 



Male with more ^^ly colored or larger bill than 

 female. 



Pursuit. 



Display. 

 Battle. 



Music. 



Special 

 habits. 



II. FUNCTIONAL. 



( By male when similar to or brighter than female. 

 \ By female when brighter than male. 



By male of accessory plumes and other appendages. 



By male using spurs, wings, bill, etc. 

 ( Vocal, by male and, rarely, female. 

 \ Mechanical, by male and sometimes female. 



{Dances, mock fights, aerial evolutions, construction of 

 bowers, decoration of playgrounds, attitudinizing, 

 strutting, etc. 

 . By male before the female. 

 6. Among the males alone. 



* Read Darwin, The Descent of Man and Selection in Relation to 

 Sex (D. Appleton & Co.). Wallace, Darwinism (Macmillan Co.). 



