COLOR AND SEX 89 



more commonly than is generally supposed, and by species which do 

 not possess pronounced sexual characters of color or plume), will doubt 

 the ardor or objects of the suitor; but it seems probable that the effect 

 of such display is to stimulate the female to the point of accepting 

 rather than of selecting a mate. It should not be forgotten, however, 

 that if this theory be true the male which breeds in immature plumage 

 (e. g. Orchard Oriole; Redstart) is placed at a distinct disadvantage. 



Wallace ('91) attributes gay colors and showy plumes to the action 

 of the surplus vital energy which, because of a bird's perfect adaptation 

 to its environment, can expend itself in the production of brilliant 

 colors and ornamental appendages without endangering their owner; 

 but in this connection we should recall that when, as with the Phalar- 

 opes, the male plays the part of the female, incubating unaided by her, 

 then it is the female that wears the brighter colors. 



Thayer, without positively committing himself on the subject of 

 sexual coloration, contends that, whatever be the minor uses of the 

 distinctively male costumes, their main function is for the purposes of 

 concealment; but it is difficult to believe that the male of the Red- 

 winged Blackbird, Bobolink, Scarlet Tanager or Lark Bunting, for 

 example, is as protectively colored as his dull-plumaged mate, which 

 lives in the same environment. If, however, his brighter colors increase 

 his chances of death, there must be born a greater number of males than 

 females, to offset the higher mortality. 



Again, it has been suggested that it is only the female's plumage 

 which has an especial significance, the task of incubation requiring in 

 her a concealing coloration which will protect the contents of the nest 

 as well as herself. The whole subject is as attractive as it is difficult. 

 It should be studied in connection with other secondary sexual char- 

 acters of which a^synopsis from " Bird-Life" is appended: 



SYNOPSIS OF THE SECONDARY SEXUAL CHARACTERS OF BIRDS 

 I. STRUCTURAL 



gj ze ( Male larger than female (usual). 



1 " ( Female larger than male (rare). 



Color I Male brighter than female. 



( Female brighter than male (rare). 



Plumage . . . f Assumption of plumes, ruffs, crests, trains, etc. ; 



Form J special modification of wing- and tail-feathers. 

 I a. Worn by male alone. 

 [ b. Worn by both sexes. 



{Sole or greater development in male of brightly colored 

 bare tracts of skin, combs, wattles, caruncles, and other 

 fleshy or horny appendages. 



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



Of the bill. . . . Male with more highly colored or larger bill than female. 



