HORNBILLS. 175 



beaks, these birds lightly traverse the branches of 

 the forests and leap from one to another till the 

 highest is attained : they then often stop and 

 utter a loud roaring sound, which may be heard at 



a considerable distance The noise thus 



uttered, and which is most probably their call- 

 note, throws a light upon the design of the hol- 

 low protuberance surmounting the bill ; it acts as 

 a sounding-board, increasing the reverberations of 

 the air. With regard to the huge beak itself, 

 many conjectures have been entertained as to its 

 peculiar uses. It has been suggested as a reason 

 for its development, that it perhaps constitutes a 

 necessary weapon of defence against monkeys and 

 other animals, which may seek to assail its nest ; 

 while some have supposed that it might be em- 

 ployed in dragging snakes and lizards from their 

 lurking places, or young birds and eggs from the 

 recesses of the trunks of aged trees."* 



* Pict. Mus. i. 350. 



