The Food of Birds 147 



masses of animate gelatine. But the fresh-water hydra, 

 belonging to the same division as the hydroids, is eaten 

 in myriads by ducks and geese. These and many other 

 birds are remarkably fond of duckweed, which they 

 devour with such evident pleasure that they must enjoy 

 it as much as cats do catnip, or canaries hempseed. As 

 the under surface of these small water plants is the fa- 



FIG. 113. Butterfly with wing torn by bird. 



vourite home of the hydra, they necessarily form a por- 

 tion of the food of these water birds. 



Roundworms, flatworms, and leeches are devoured 

 by many aquatic birds, while earthworms form a staple 

 article of diet with such different species as thrushes, 

 woodcocks, and cranes. A favourite morsel of the curi- 

 ous apteryx of New Zealand is a gigantic species of worm, 

 twelve to twenty inches in length, which is highly phospho- 

 rescent. The apteryx seeks its food by night, and when 



