64 SEXUAL SELECTION: BIRDS. [Part II. 



The diver.'^ity of the sounds, both vocal and instrumen- 

 tal, made by the males of many species during the breed- 

 ing-season, and the diversity of the means for producing 

 such sounds, are highly remarkal)le. We thus gain a 

 high idea of their importance for sexual purposes, and are 

 reminded of the same conclusion with respect to insects. 

 It is not difficult to imagine the steps by which the notes 

 of a bird, primarily used as a mere call or for some other 

 purpose, might have been improved into a melodious love- 

 song. This is somewhat more difficult in the case of the 

 modified feathers, by which the drumming, whistling, or 

 roaring noises, are produced. But we have seen that some 

 birds during their courtship flutter, shake, or rattle their 

 unmodified feathers together; and, if the females were led 

 to select the best performers, the males whicli possessed 

 the strongest or thickest, or most attenuated feathers, 

 situated on any part of the body, would be the most suc- 

 cessful ; and thus by slow degrees the feathers might be 

 modified to almost any extent. The females, of course, 

 would not notice each slight successive alteration in shape, 

 but only the sounds thus produced. It is a curious fact 

 that, in the same class of animals, sounds so different as 

 the drumming of the snipe's tail, the tapping of the wood- 

 pecker's beak, the harsh trumpet-like cry of certain water- 

 fowl, the cooing of the turtle-dove, and the SQUg of the 

 nightingale, should all be pleasing to the females of the 

 several species. But we must not judge the tastes of dis- 

 tinct species by a uniform standard ; nor must we judge 

 by the standard of man's taste. Even with man, we 

 should remember what discordant noises, the beating of 

 tom-toms and the shrill notes of reeds, please the ears of 

 savages. Sir S. Baker remarks," that "as the stomach of 

 the Arab prefers the raw meat and reeking liver taken 



" -The Nile Tributaries of Abyssinia,' 1867, p. 203. 



