SEXUAL SELECTION 477 



females are iDdiflferent to the charnja of the opposite sex, 

 or that they are invariably compelled to yield to the victori- 

 ous males. It is more probable that the females are excited, 

 either before or after the conflict, by certain males, and thus 

 unconsciously prefer them. In the case of Tetrao umbellvs, 

 a good observer*' goes so far as to believe that the battles 

 of the males "are all a sham, performed to show themselves 

 to the greatest advantage before the admiring females who 

 assemble around; for I have never been able to find a 

 maimed hero, and seldom more than a broken feather. ' ' I 

 shall have to recur to this subject, but I may here add that 

 with the Tetrao cupido of the United States, about a score of 

 males assemble at a particular spot, and, strutting about, 

 make the whole air resound with their extraordinary noises. 

 At the first answer from a female the males begin to fight 

 furiously, and the weaker give way ; but then, according to 

 Audubon, both the victors and vanquished search for the 

 female, so that the females must either then exert a choice, 

 or the battle must be renewed. So, again, with one of the 

 field starlings of the United States {Sturnella ludoviciand) 

 the males engage in fierce conflicts, "but at the sight of a 

 female they all fly after her as if mad." " 



Vocal and Instrumental Music. — With birds the voice 

 serves to express various emotions, such as distress, fear, 

 anger, triumph, or mere happiness. It is apparently some- 

 times used to excite terror, as in the case of the hissing 

 noise made by some nestling-birds. Audubon" relates that 

 a night-heron {Ardea nycticorax, Linn.) which he kept tame 

 used to hide itself when a cat approached, and then "sud- 

 denly start up uttering one of the most frightful cries, ap- 

 parently enjoying the cat's alarm and flight." The common 

 domestic cock clucks to the hen, and the hen to her chick- 



's "land and Water," July 25, 1868, p. 14. 



^ Audubon's "Omitholog. Biography"; on Tetrao oupido, vol. ii. p. 492; 

 on the Stumus, voL ii. p. 219. 



*• "Ornithological Biography," vol. v. p. 601. 

 Descent — Vol. n. — 3 



