. The bird; its form and function . Fig. 177.—Young in gray plumage, later Fig. 178.—Adult living bird. 235 236 The Bird bird at first feeds upon regurgitated food, taking it dropby drop from the bill of the old bird, it of course hasno need of the curved beak of its parents. Later, whenits bill has increased in length and has begun to be markedby the ultimately sharp angle, the birds begin to siftfrom the coral mud the small mollusks of which theirfood consists. Until its wings are full-feathered the young skimmeris compelled to limit its wanderings to the sand-dunesalong the shore ne


. The bird; its form and function . Fig. 177.—Young in gray plumage, later Fig. 178.—Adult living bird. 235 236 The Bird bird at first feeds upon regurgitated food, taking it dropby drop from the bill of the old bird, it of course hasno need of the curved beak of its parents. Later, whenits bill has increased in length and has begun to be markedby the ultimately sharp angle, the birds begin to siftfrom the coral mud the small mollusks of which theirfood consists. Until its wings are full-feathered the young skimmeris compelled to limit its wanderings to the sand-dunesalong the shore near its nest. Thus, although at birththe lower mandible is a trifle longer than the upper, yeteven when the birds are half-grown the disparity in lengthbetween the two mandibles is but slight. Later, whenthe young bird is able to join its parents in their skimmingof the seas, the lower mandible quickly attains its fulldevelopment. The friction of the water upon the billmust be considerable, as in a skimmer which I have hadfor years in captivity, the lower mandible grew remark-


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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbirds, bookyear1906