32 



FORM AND HABIT: THE BILL. 



corolla. In tlie Tooth-billed Hummer {A?idrod(m) both 

 mandibles arc finely serrate at the end, the upper one 

 being also hooked, and the bird feeds on insects which it 

 captures on the surface of leaves and other places. 



Among the Woodhewers {DendroeolajMidw) of South 

 America there is fully as much variability, which reflects 



equally variable feeding 

 habits. Some sjDecies have 

 short, stout, straight bills, 

 others exceedingly long, 

 slender, curved ones. 



Fig. 18.— Serrate bill of Merganser, a fish- MergauSCrS, Ganucts, Au- 

 eating bird, ('/a natural size.) . . ° ' t . t 



hingas, and other birds 

 that catch fish by pursuing them under water, have 

 sharply serrate mandibles, which aid them in holding 

 their slippery prey. 



Some shore birds (Limicolce) use the bill as a probe, 



Fio. 19. — Probelike bill of Woodcock, showing extent to which upper mandi- 

 ble can be moved, (^/s natural size.) 



when it may be six inches in length and straight, or 

 curved downward. It has recently been learned that 



Fig. 20. — Recurved bill of Avocet. (2/3 natural size.) 



several of these probing Snipe, notably the Woodcock, 

 have the power of moving the end of the upper mandi- 



