62 SEXUAL SELECTION : BIRDS. Part IL 



"fallen tree," or, accordfno- to Audubon, against his own 

 body ; tbe sound thus produced is compared by some to 

 distant thunder, and by others to the quick roll of a 

 drum. The female never drums, "but flies directly to 

 "the place where the male is thus engaged." In the 

 Himalayas the male of the Kalij -pheasant " often makes 

 " a singular drumming noise with his wings, not ivnlike 

 " the sound produced by shaking a stiff piece of cloth." 

 On the west coast of Africa the little black-weavers 

 (Ploceus ?) congregate in a small party on the bushes 

 round a small open space, and sing and glide through 

 the air witli quivering wings, " which make a rajDid 

 " whirring sound like a child's rattle." One bird after 

 another thus performs for hours together, but only during 

 the courting-season. At this same season the males of 

 certain niglit-jars (Capri mulgus) make a most strange 

 noise w^ith their wings. The various species of wood- 

 peckers strike a sonorous branch with their beaks, witli 

 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 can- 

 not be described ; and I feel sure that its cause would 

 never be coniectured bv anv one who heard 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 

 (Upujnt ei^ops) combines vocal and instrumental music; 

 for during- the breeding-season this bird, as Mr. Sw^inhoe 

 saw, first draws in air and then taps the end of its 

 beak ]:>erpendicularly down against a stone or the trunk 

 of a tree, " when the breath being forced down the 

 " tubular bill produces the correct sound." When the 



