Wings 



347 



spurs are not claws, but correspond in structure to the 

 ordinary spurs on tlie legs of a rooster. 



The great heavy-headed and heavy-bodied hornbills 

 fly with great effort, and it is said upon good authority 

 that when passing low overhead they make a noise like 

 a steam-engine. Although not strictly within the prov- 



FlG. 278. — Spur-winged Goose. 



ince of this volume, mention should be made of the inten- 

 tional use of the wings as instruments of sound, — to at- 

 tract the females, as in our Ruffed Grouse and other birds. 

 A little Bush Warbler of Africa has indeed never been heard 

 to utter a note, seeming to depend upon an occasional 

 whirr of wings, in Ueu even of the usual call-note or chirp. 



