376 The Descent of Man. Pakt II 



the air with quivering wings, " which make a rapid whirring 

 " sound like a child's rattle." One bird after another thus performs 

 for hours together, but only during the courting-season. At this 

 season and at no other time, the males of certain night-jars (Capri- 

 mulgus) make a strange booming noise with their wings. The 

 various species of wood-peckers strike a sonorous branch with 

 their beaks, with so rapid a vibratory movement that " the head 

 " appears to be in two places at once." The sound thus pro- 

 duced is audible at a considerable distance, but cannot be 

 described; and I feel sure that its source would never be con- 

 jectured by any one hearing it for the first time. As this jarring 

 sound is made chiefly during the breeding-season, it has been 

 considered as a love-song ; but it is perhaps more strictly a 

 love-call. The female, when driven from her nest, has been 

 observed thus to call her mate, who answered in the same 

 manner and soon appeared. Lastly, the male Hoopoe ( Upupa 

 ejjops) combines vocal and instrumental music ; for during the 

 breeding-season this bird, as Mr. Swinhoe observed, first draws 

 in air, and then taps the end of its beak perpendicularly down 

 against a stone or the trunk of a tree, " when the breath being 

 " forced down the tubular bill produces the correct sound." If 

 the beak is not thus struck against some object, the sound is 

 quite different. Air is at the same time swallowed, and the 

 oesophagus thus becomes much swollen ; and this probably acts 

 as a resonator, not only with the hoopoe, but with pigeons and 

 other birds. 52 



In the foregoing cases sounds are made by the aid of structures 

 already present and otherwise necessary ; but in the following 

 cases certain feathers have been specially modified for the express 

 purpose of producing sounds. The drumming, bleating, neigh- 

 ing, or thundering noise (as expressed by different observers) 

 made by the common snipe (Scolopax gallinagd) must have sur- 

 prised every one who has ever heard it. This bird, during the 

 pairing-season, flies to " perhaps a thousand feet in height," ana 



For the foregoing facts see, Weavers, 'Livingstone's Expeditior 



on Birds of Paradise, Brehm 



' T hierleben,' Band iii. s. 325. On Woodpeckers, Macgillivray, ' Hist 



Grouse, Richardson, ' Fauna Bor 

 Americ. : Birds,' pp. 343 and 359 



man in Canada,' 1866, p. 156; Mr 

 Haymond, in Prof. Cox's ' Geol 



to the Zambesi,' 1865, p. 425. Oi 



of British Birds,' vol. iii. 1840, pp 

 84, 88, 89, and 95. On the Hoopoe 



Major W. Ross King, ' The Sports- Mr. Swinhoe, in ' Proc. Zoolog. Soc, 



June 23, 1863 and 1871, p. 348. 

 On the Night-jar, Audubon, ibid. 



Survey of Indiana,' p. 227; Audu- vol. ii. p. 255, and 'American Natu- 



bon, * American Ornitholog. Bio- ralist,' 1873, p. 672. The English 



graph.' vol. i. p. 216. On the Night-jar likewise makes in the 



Kalij-pheasant, lerdon, ' Birds of spring a curious noise during its 



India,' vol. iii. p. 533. On the rapid flight. 



