COLOR AND SEX. 



45 



exact value remains to be determined by closer obser- 

 vation. 



Color and Sex.^ — It is not possible bere 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. 



Pluiiia<!:e. 



j Male larjjer than female (usual). 

 ( Female larger than male (rare). 



Color. 



j Male lirighter than female. 

 \ Female brighter than male (rare), 

 f Assumption of plumes, ruffs, crests, trains, 

 I etc. : special modification of wing and tail 

 Form. -{ feathers. 



I a. Worn by male alone. 



l^ b. Worn by both sexes. 



( Sole or greater development in male of brightly col- 



Of the body. -; oi-ed bare tracts of skin, combs, wattles, caruncles, 



( and other fleshy or horny appendages. 



Sole or greater development in male of spurs. 

 ( Male with more highly colored or larger l>ill than 

 ( female. 



Of the feet. 

 Of the bill. 



Pursuit. 



Display. 

 Battle. 



Music. 



Special 

 habits. 



II. FUXCTIONAL. 



\ By male when similar to or brighter than female. 

 ] By female when brighter than male. 



By male of accessory plumes and other ap[iendages. 



By male using spurs, wings, bill, etc. 

 j Vocal, by male and, rarely, female. 

 ( Mechanical, by male and sometimes female, 

 f Dances, mock fights, aei'-ial evolutions, construction of 

 I bowers, decoration of playgrounds, attitudinizing, 

 -{ strutting, etc. 

 I a. By male before the female. 

 [ b. Among the males alone. 



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

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



