. The bird, its form and function . Fig. 186.—Bill of Golden Eagle, hooked for tearing prey. a striking example of two large related groups of birdswhose diet has become radically unlike, although evenin this case blood will tell and the Kea Parrot slipsback into carnivorous habits with ease. Owls tear their prey apart with their beaks, or swallowit entire, but parrots gnaw and gnaw upon their nutsand seeds, reducing their food to powder. This grind-ing and rasping is aided by several file-like ridges whichmany parrots have within their beaks. The hingingof the upper mandible with the skull is
. The bird, its form and function . Fig. 186.—Bill of Golden Eagle, hooked for tearing prey. a striking example of two large related groups of birdswhose diet has become radically unlike, although evenin this case blood will tell and the Kea Parrot slipsback into carnivorous habits with ease. Owls tear their prey apart with their beaks, or swallowit entire, but parrots gnaw and gnaw upon their nutsand seeds, reducing their food to powder. This grind-ing and rasping is aided by several file-like ridges whichmany parrots have within their beaks. The hingingof the upper mandible with the skull is more evident in a Beaks and Bills 243 parrot than in any other bird. This arrangement allowsmuch freedom of motion. It is not clearly known what use the immense beaksof toucans may serve, although there seems little excusefor this ignorance in those who know the birds in theirnative haunts. The delicate, spongy texture renders the. Fig. 187.—Toucan, showing enormous bill used perhaps for reaching fruit onthe tips of branches. clumsy-looking appendages exceedingly light, and theyare usually banded or marked with brilliant hues,—blue,yellow, red, brown, green, or black. But light as thebeaks are in these birds, in the unrelated but similarlymonstrous-beaked hornbills the weight must be con-siderable, for the first two vertebrae of the neck in these 244 The Bird latter birds are fused together, to yield a firmer supportfor the muscles of the neck. Chimney Swifts and hummingbirds both feed uponinsects and are rather closely related to each other, buthere again the most decided difference is to be found intheir bills. The broad, flattened mandibles of the swifts
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbirds, bookyear1906
