. The bird, its form and function . Fig. 324.—Tail of Pelican alighting. Fig. 325.—Tail of Tern in flight. the air, it can keep on only in a straight line and is atthe mercy of every cross-current of air. A more familiarcase, which any one may observe, is a Song Sparrow, orother small bird, which, from accident or from some irregu-larity of moult, has lost all or most of its of rismg with the strong, darting flight withwhich such a bird is accustomed to make its escape fromour path, its flight under such conditions is weak anddirect, like the trial efforts of a young bird
. The bird, its form and function . Fig. 324.—Tail of Pelican alighting. Fig. 325.—Tail of Tern in flight. the air, it can keep on only in a straight line and is atthe mercy of every cross-current of air. A more familiarcase, which any one may observe, is a Song Sparrow, orother small bird, which, from accident or from some irregu-larity of moult, has lost all or most of its of rismg with the strong, darting flight withwhich such a bird is accustomed to make its escape fromour path, its flight under such conditions is weak anddirect, like the trial efforts of a young bird. 410 The Bird Reserving the mention of partly ornamental tails untilthe last, we may now consider the use of this member asa prop or support to the bird as it clings to or makes itsway up vertical surfaces. Four groups of birds whichare thus distinguished are the woodhewers—a tropical. Fig. 326.—Chimney Swift clinging To wall, resting upon tail. family,—the creepers, woodpeckers, and swifts. Thesebirds really sit upon their tails, the feathers of which areadapted for this special use, while retaining perfectly therudder function in flight. The tail-feathers of the Chim-ney Swift are peculiar in having the ends, for a short dis- Tails 411 tance, free of barbs, the tips being thus composed of a num-ber of bare spines which are admirably adapted to catchin the irregularities of hollow trees, or, as now in theirrecently adopted homes, in the roughness of chimney-bricks. I one day caught a Chimney Swift and placedit against a varnished wall composed of compositionbricks; and, smooth though the surface w^as, the birdstail and toes held it firmly, not slipping even a quarterof an inch. After photographing it, I watched it forsome minutes and saw the bird shift its position severaltimes, moving always with a certainty and surety ofgrasp most inexplicable. The tails of w
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1906
