C'OLOK AN!) Si;.\. 



45 



o\!ict valiK' rc^inaiiis to he (letermiiicd hy cluser oljser- 

 viitinn. 



CJnr (iinJ Stw."^ — It is not possible here to discuss at 

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

 means of directing observation, I present a synopsis of 

 the princi])al 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. 



Size. 



PIuiii;i>'0. 



I. STRUCTURAL. 



iVrale larf]:er than female (usiinl). 

 Female lar<2:er than male (rare). 



{ ^lale l»ri<;hter than female. 



I Female brii^hter than male (rare). 



Vssumption (if ]»lumes, ruffs, erests, ti'ains, 

 etc. : si)ecial modification of wing and tail 

 feathers. 

 I a. Worn by male alone. 

 [^ h. ^Vorn 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 lleshy or horny ajipendages. 

 Sole or greater development in male of spurs. 

 Male with more highly colored or larger bill than 

 female. 



Col( 



Foi 



Of the 

 Of the 



feet, 

 bill. 



Pursuit. 



Display. 

 Battle. 



Music. 



Special 

 habits 



n. FUNCTIONAL. 



j By male when similar to or Ijrightcr than female. 

 ( By female when brighter than male. 



I>y male of accessory plumes and other ai»pendages. 



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, 

 -I strutting, etc. 

 I a. By n)ale l)efore the female, 

 l^ b. Among the males alone. 



* Kcad Darwin, "llw Descent of .Man and Selection in Relation to 

 Sex (1). Appleton iV: Co.). Wallace, Darwinism (Macmillan Co.). 



