. The bird; its form and function . Fig. 286.—Nuthatch on tree,cHnging upside down. Fig. 287.—Nuthatch clinging to a glovedhand. (Bowdish, photographer.) The creepers. Fig. 240, are passerine woodpeckersin habit and forever wind their spiral paths about thetree-trunks. But the nuthatch is the marvel of thewhole Class of birds in this climbing ability. With nosupport whatever from the tail, and without specialadaptation of toes, it defies all laws of gravitation andcreeps up and down or around the vertical trunks, as ifon a level surface. Never a misstep, never a slip, but 360 The Bird each foo
. The bird; its form and function . Fig. 286.—Nuthatch on tree,cHnging upside down. Fig. 287.—Nuthatch clinging to a glovedhand. (Bowdish, photographer.) The creepers. Fig. 240, are passerine woodpeckersin habit and forever wind their spiral paths about thetree-trunks. But the nuthatch is the marvel of thewhole Class of birds in this climbing ability. With nosupport whatever from the tail, and without specialadaptation of toes, it defies all laws of gravitation andcreeps up and down or around the vertical trunks, as ifon a level surface. Never a misstep, never a slip, but 360 The Bird each foothold as secure as if its feet were vacuum-cupped. In the swallows the feet are very small, having falleninto disuse with the great increase of the power of and weaver-birds make occasional use of theirfeet to hold a strand of grass or string which they areweaving with their beaks into their elaborate nests, andcertain flycatchers pounce upon and hold their insect. Fig. 2<S8.—Swallow, showing small size of feet. prey as an owl grips a bird, or a jay clings to a nut; butwith the exception of a few such cases, the feet of perchingbirds serve principally the function of locomotion. As variation in habitat or haunt depends so much uponthe power of locomotion, it will not be out of place tomention here, in rather more detail than usual, a splendidexample of adaptive radiation which we can all verify forourselves. There is no more wonderful fact in Nature than the way Feet and Legs -761 in which birds have inherited the earth. When we reahzethe immense advantage which the power of flight givesto them, we do not marvel at this remarkable distribu-tion, but the more we think about it the more wondersappear. The utmost efforts which man has made toreach the North Pole have shown flocks of birds wingingtheir way still farther to the North, heedless of the ter-rible cold. In the heat of deserts and the swelteringjungles of the tropics, birds find cong
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbirds, bookyear1906
