. The bird, its form and function . Fig. 184.—Bill of Oyster-catcher; used for prying open the shells of mollusks. the half-lemon rests before it is compressed. Whenthe mandibles of this bird are closely opposed the centralportion of the beak gapes slightly. In this cavity thebird firmly holds the shells of the land-snails upon whichit feeds, until it can bring the pressure of both mandiblesto bear and so crush the shell of the mollusk. The asymmetry of the bill—as seen in the Oyster-catcher—is not accidental, but constant, in the Crook-billed Plover of New Zealand. In this bird the bill is Be
. The bird, its form and function . Fig. 184.—Bill of Oyster-catcher; used for prying open the shells of mollusks. the half-lemon rests before it is compressed. Whenthe mandibles of this bird are closely opposed the centralportion of the beak gapes slightly. In this cavity thebird firmly holds the shells of the land-snails upon whichit feeds, until it can bring the pressure of both mandiblesto bear and so crush the shell of the mollusk. The asymmetry of the bill—as seen in the Oyster-catcher—is not accidental, but constant, in the Crook-billed Plover of New Zealand. In this bird the bill is Beaks and Bills 241 permanently bent to the right, a beautiful adaptationto help the bird in its search for insects, which, in thedry country that it inhabits, are found almost entirelyunder stones. As a rule, beaks are rather immovable throughouttheir length, but in the woodcock, and to a less extent. Fig. 185.—Bill of Crook-billed Plover, for probing under stones. in the Dowitcher Snipe, the extremity of the upper man-dible can be raised some distance (Figs. 159, 160). Thisextreme sensitiveness is especially necessary, as the eyesof the woodcock are placed very far back on the topof its head, and are of little or no use in seeking food. What an interesting study the various beaks of landbirds would offer, were we able to devote to them the 242 The Bird space which they deserve! They defy classification andrefuse to be arranged in any linear sequence. The ma-jority of those birds which have their beaks armed witha strong hook feed upon living prey,—from the greatmandible of the Golden Eagle to the tiny vireo, whichsnaps up the dancing gnats. The owls and the parrots, which, by the way, aremuch more closely related than most of our classificationswould indicate, have bills very much alike, and afford
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbirds, bookyear1906
