Wings 347 
spurs are not claws, but correspond in structure to the 
ordinary spurs on the 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- 
Fic. 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 lieu even of the usual call-note or chirp. 
