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 tlie 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 OP THE SECONDARY SEXUAL CHARACTERS 

 OF BIRDS. 



Size. 



I. STRUCTURAL. 



j Male larger than female (usual). 



\ Female larger than male (rare). 



f p , . j i\Iale brighter than female. 



I o 01. ^ x^emale brighter than male (rare). 



I C Assumption of plumes, ruffs, crests, trains, 



Plumage. \ etc. : special modification of wing and tail 



I Form. \ feathers. 



I I a. Worn by male alone. 



[ yb. Worn by both sexes. 



( Sole or greater development in male of brightly col- 

 Of the body. \ ored bare tracts of skin, combs, wattles, caruncles, 



( and other fleshy or horny appendages. 



Of the feet. Sole or greater development in male of spurs. 



/vr^i 1-11 ( Male with more highly colored or larger bill than 

 Of the bill, -j f^,j^^^i^_ . - ^ 



II. FUNCTIONAL. 



r) •. S P'X male when similar to or brighter than female. 



i ursuit. ^ j^y female when brighter than male. 



Display. By male of accessory plumes and other appendages. 



Battle. By male using spurs, wings, bill, etc. 



,, . \ Vocal, by male and, rarely, female. 



Music. ^ Mechanical, by male and sometimes female. 



f Dances, mock fights, aerial evolutions, construction of 

 o . , I bowers, decoration of playgrounds, attitudinizing, 



^^rivt \ strutting, etc. 



naoits. I ^ -gy j^^jg h^ioxQ the female. 



[ b. Among the males alone. 



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

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



