FORM AND llAIUT: TllK IlILI.. 31 



perforni tlicir toilet, iiiid, pii'ssiii^ ii drop <»f oil from the 

 gland at the root of the tail, thev dros their feathers 

 with their hill. Tarruts use the hill in cliiuhing, and 

 its hawklike shape in these birds is an unusual instance 

 of similarity in structure accompanying different habits. 



I)irds which do not strike with their feet may use 

 tlie hill as a weapon, but the manner in which it is em- 

 ])lo\ed corresi^onds so closely with the method, by which 

 a bird secures its food, that as a weapon the bill pre- 

 sents no special modifications. In constructing the nest 

 the hill may be used as a trowel, an auger, a needle, a 

 chisel, and as several other tools. 



But as a hand the bill's most important office is that 

 of procuring food ; and wonderful indeed are the forms 

 it a-sumes to supply the appetites of birds who may 

 re<piire a drop of nectar or a tiny insect fr(jm the heart 

 of a Hower, a snake from the marshes, a clam or mussel 

 from the ocean's beach, or a fish from its waters. The 

 bill, therefore, becomes a forceps, lever, chisel, hook, 

 hammer, awl, probe, spoon, spear, sieve, net, and knife — 

 in short, there is almost no limit to its sbaj^e and uses. 



With Hummingbirds the shape of the bill is appar- 

 ently related to the flowers from which the bird most 

 frecpiently procures its food. It ranges in length from 

 a quarter of an inch in the 

 Small-billed Hummer (Micro- 

 rhynchus) to five inches in 

 the Siphon-bill {D()c'naa.st('>i\ 

 which has a bill longer than ^ _ ^ , i •„ ^ c- 1 1 



^ Fig. 17.— Becurved bill of Siokle- 



itS body, and is said to feed HU Iluinniingbird. (Natural 



from the hjng-tubed trumpet 



flowers. The Avocet Hummer (Avfyyift/I//) has a bill 

 curved slightly upward, hut in tlie Sickle-hilled Hummer 

 (Kf/tfKceres) it is curved downward to form half a circle, 

 and the bird feeds on flowers having a similarly curved 



