FORM AND HABIT: THE BILL. 31 



perform tlieir toilet, and, pressing a drop of oil from the 

 gland at the root of the tail, they dress their feathers 

 with their bill. Parrots use the bill in climbing, and 

 its hawklike shape in these birds is an nnnsual instance 

 of similarity in structure accompanying different habits. 



Birds whicli do not strike with their feet may use 

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

 ployed corresponds so closely with the method by whicli 

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

 sents no special modifications. In constructing the nest 

 the bill 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 assumes to supply the appetites of birds who may 

 require a drop of nectar or a tiny insect from the heart 

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

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

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

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

 in short, there is almost no limit to its shape and uses. 



With Hummingbirds the shape of the l)ill is appar- 

 ently related to the flowers from which the bird most 

 frequently procures its food. It ranges in length from 

 a quarter of an inch in the 

 Small-l)illed Hummer {Micro- 

 7'/tf/nckfcs) to five inches in 

 the Siphon-bill {Docimastes), 

 which has a bill longer than i t,, ^ c- 1 1 



"^^ Fig. 17.— Decurved lull of Siekle- 



itS body, and is said to feed l>ill Hummingbird. (Natural 



from the long-tubed trumpet 



flowers. The Avocet Hummer (AvoceUula) has a bill 

 curved slightly upward, but in the Sickle-billed Hummer 

 {Eutoxereii) it is curved downward to form half a circle, 

 and the bird feeds on flowers having a similarly curved 



