14 



THE OOLOGIST. 



The Bills of Birds. 



In order to seize food quickly and easil}^ 

 and to reach every part of the plumage 

 ■with oil, a bird must have somew^here in 

 its body quite freedom of motion ; the 

 back and breast must be firm and strong 

 for.tlie attachment of the muscles of flight, 

 but in the neck, with its ten to twenty-three 

 vertebrae freely moving, we have this de- 

 mand supplied. The neck is like a long, 

 bony spring, at the end of which are the 

 two mandibles of bone, covered usually 

 with horny, sometimes with skin-iike mem- 

 brane. The lower mandible is freely artic- 

 ulated with the skull, and in parrots, the 

 upper also, but in most birds the latter is 

 joined to the skull by elaitic bony plates, 

 which break the force of shocks caused by 

 pecking. 



There is a very curious arrangement by 

 which the lowering of the under mandible 

 raises the upper. A small bone rests with 

 one end on the palate and the other on the 

 bone articulating the lower jaw with the 

 skull. When the lower jaw falls this small 

 bone acts as a lever, is pushed forward 

 against the palate and lifts it. 



The horu}' bill covering answers partiall}' 

 the place of teeth, and is homologous to the 

 whalebone of whales, and the nails and 

 claws of mammals. It is sometimes ridged 

 and creased strongl}' on the outside, as in 

 Auks, the depressions sometimes going 

 through into the bone. In Anatides the 

 covering is ridged on the inside, and so 

 forms a sort of strainer, very needful for 

 Ducks and Geese, who fill their bills with 

 muddy water, and strain it, leaving the 

 food "high and dry" between the "teeth." 

 But this family also eats vegetation, and it 

 .seems to me these ridges ar^ useful in 

 bruising and cutting grass, although I have 

 never seen this opinion given. 



Some authorities say that nostrils are 

 always present in birds, though sometimes 

 rudimentary or obsolete. Others deny this. 

 In most cases, however, there are two 

 nostrils .situated near the base of the upper 

 mandil)le. In the Apteryx of New Zea- 

 land, the nostrils are at the tip. These 



external organs of smell are of very vari- 

 ous size and shape, and are often protected, 

 either by a scale or close-lying, bristly 

 feathers. The Woodpeckers characteristi- 

 cally have the latter, to furnish protection 

 from dust and falling chips, occa.sioned by 

 their chiseling, hammering habits. 



Audubon proved that sight, not smell, is 

 the strong sense in Vultures, but in Snipes 

 the bill is covered with a sensitive, nervous 

 membrane, and in typical Snipe the lower 

 jaw bone is perforated to receive blood- 

 ves.sels and nerves. The bill is thus made 

 a tit instrument for finding food in the 

 mud. The nostrils sometimes opsn in the 

 cere — a dense, fleshy substance at the base 

 of the bill of some birds, which serves as 

 a touch organ, but whose full function is, 

 I believe, unknown. 



The large bills of Toucans and Hornbills 

 are supplied with air from the lungs, by 

 means of "air cells," and so made more 

 easilj^ supportable. 



The use of the bill are various, and there 

 is a wonderful adaptability of the shape, 

 size, strength and structure of bills to indi- 

 vidual needs. In Woodpeckers, for in- 

 stance, it is interesting to note the loss of 

 strength, size, and acuteness, from the 

 immense gleaming ivor}^ of Campephilus 

 down to the slender curved bill of the 

 flicker, used largely in eating insects from 

 the ground. In birds of prey the bill is a 

 veritable butcher's knife; in Ducks a neat 

 strainer and grater; in Kingfishers a spear; 

 in Humming Birds a pump, and in Swal- 

 lows and Goatsuckers, a broad, deep fly- 

 trap, well guarded with bristles. 



Most birds use the bill in nidification, 

 noticeably Woodpeckers and Orioles, all 

 use it in lubricating and cleansing the 

 plumage; Parrots to climb by; Swifts to 

 break olf twigs in flying; Woodpeckers to 

 sound their love call, both sexes; and most 

 land birds to carry the ordure of the young 

 from the nest. Swallows are exceptions to 

 this last rule. Their bill being exceedingly 

 short it would be very disagreeable for 

 them to perform this function, even if their 

 nesting habits required it. 



I hope I have said enough to show you 

 that the study of this imi)ortanl and primal 

 member of Aves ofl:er rich reward in its 

 variety and discoveries of wonderful adap- 

 tation. S. L. W. 



