6 OUR HUMBLE HELPERS 



don't see how little stones that have been swallowed 

 can be used as teeth. " 



"A short digression on the digestive organs of 

 birds/' replied Uncle Paul, "will give you the in- 

 formation you ask for. 



"Birds do not chew their food; they swallow it 

 just as they seize it, or nearly so. The beak, lacking 

 teeth, is for that very reason unsuited for the work 

 of grinding. It merely seizes; it strikes, picks up, 

 digs, pierces, breaks, tears, according to the kind of 

 food adapted to the bird's needs. A solid horn cov- 

 ers the bony framework of the two mandibles and 

 makes their edges sharp and very well fitted for dis- 

 membering if necessary, but not for triturating. 



"Rapacious birds that feed on live prey have the 

 upper mandible short, strong, hooked, and terminat- 

 ing in a sharp point, sometimes with serrate edges. 

 With this weapon the hunting bird kills its prey, and 

 tears it to pieces while holding it with its vigorous 

 talons armed with sharp, curved nails. 



"Fish-eating birds that tear the fish to pieces in 

 order to swallow it have the hooked beak of the ra- 

 pacious birds ; those that swallow the fish whole have 

 a straight beak with long, wide mandibles. Some 

 throw it into the air to catch it in their beak a second 

 time, head first, and swallow it without any difficulty 

 in spite of the fin-bones, which lie flat from front to 

 back while the fish is passing through the narrow gul- 

 let. A great fishing bird, the pelican, has in its lower 

 mandible a large membranous pouch, a sort of fish- 

 pond, where it stores the fish as long as the catch 



