234 Studies in Animal Behavior 



evidence from the behavior of birds that the sense 

 of smell is relied upon in this matter to any degree. 

 In those birds in which the two sexes are much 

 alike, as in most pigeons, differences in behavior ap- 

 parently afford the chief means by which each sex 

 distinguishes the other. Craig in his interesting ac- 

 count of the expressions of emotions in pigeons 1 says 

 that "If a cage containing an unmated male ring- 

 dove be suddenly brought alongside another 

 cage containing another ring-dove, of unknown sex, 

 the male becomes highly excited at once, and gives 

 vent to his excitement in all possible ways. First 

 he bows and coos with all his might, and he con- 

 tinues to do so for a long time. Then he charges 

 about the cage, assuming the attitude peculiar to 

 the charge, and frequently repeating the loud kah- 

 of-excitement. At intervals, he stops to glare at 

 the strange bird and sometimes to peck at it through 

 the bars, but soon he starts again to bow-and-coo 

 and charge. . . . 



"If left beside the stranger's cage for some hours, 

 the male must sometimes rest and be silent; but 

 even the intervals of rest and silence are broken fre- 

 quently by series of perch-coos. This behavior on 

 the part of the male is useful in that it stimulates 

 the strange bird to respond, and, in responding, to 

 reveal its sex. 



"If the strange bird be a male, it shows similar 



1 Journal of Comparative Neurology and Psychology, Vol. 19, 

 p. 29, 1909. 



