236 The Bird 



bird at first feeds upon regurgitated food, taking it drop 

 by drop from the bill of the old bird, it of course has 

 no need of the curved beak of its parents. Later, when 

 its bill has increased in length and has begun to be marked 

 by the ultimately sharp angle, the birds begin to sift 

 from the coral mud the small mollusks of which their 

 food consists. 



Until its wings are full-feathered the young skimmer 

 is compelled to limit its wanderings to the sand-dunes 

 along the shore near its nest. Thus, although at birth 

 the lower mandible is a trifle longer than the upper, 3-et 

 even when the birds are half-grown the disparity in length 

 between the two mandibles is but slight. Later, when 

 the young bird is able to join its parents in their skimming 

 of the seas, the lower mandible quickly attains its full 

 development. The friction of the water upon the bill 

 must be considerable, as in a skimmer which I have had 

 for years in captivity, the lower mandible grew remark- 

 ably fast, measuring 6f inches from base to tip when 

 the bird was eighteen months old. 



Herons and ibises, through all the years, sought their 

 food in much the same places as have ducks; the straight- 

 billed herons seizing their living prey with a single light- 

 ning dart, as it swims past them; the spoonbills spatter- 

 ing in the shallows; and the curved-beaked ibises prob- 

 ing every crevice along shore. The spoonbills swing 

 their necks and heads from side to side, as thev walk 

 slowly through the water, gleaning their food with the 

 motion of a mower wielding his scythe. Two of the 

 herons are interesting enough to hold our attention for 



