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 FORM AXD HABIT: THE BILL. 31 le perform their toilet, and, pressing a drop of oil from tl gland at the root of the tail, they dress their feathers with their bill. Parrots use the bill in chmbing, and its hawklike shape in these birds is an mmsnal instance of similarity in stnicture accompanying different habits. Birds which 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 which 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 fish from its waters. The bill, therefore, becomes a forceps, lever, chisel, hook, hammer, awl, probe, spoon, spear, sieve, net, and knife — in sliort, there is almost no limit to its shape and uses. With Hummingbirds the shape of the bill 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-billed Hummer {Micro- rhijnchus) to five inches in the Siphon-bill {Docimastes which has a bill longer than ^ _ ^ ,,.,, „^.,, ^ ■ Fig. 17.— Decurved bill of Sickle- itS body, and is said to feed bill Hummingbird. (Natural from the long-tubed trumpet flowers. The Avocet Hummer {AvocetUda) has a bill curved slightly upward, but in the Sickle-billed Hummer {Eutoxeres) it is curved downward to form half a circle, and the bird feeds on flowers havinof a similarlv curved