38 BIRD BEHAVIOUR 



manner the water in the roadside gutters, filled 

 with dead leaves, on a wet afternoon in Hyde Park. 

 The Magpie-Goose, however, also grazes at times, 

 but is particularly fond of digging and tearing with 

 its bill at mud and roots, though I have so far not 

 been able quite to make out what it gets when thus 

 engaged. 



It will be noticed that the Common Duck, with 

 its specialized bill, keeps up the varied methods of 

 feeding noted in this primitive-looking relative, 

 though the Shoveller has practically become a 

 sifter pure and simple. The diving Ducks, al- 

 though having a sifting beak, seem to use it very 

 little, for when one watches them feeding in clear 

 water they seem to simply pick up theii; food from 

 the bottom, darting hither and thither, and not 

 working away in the same place. Small portions 

 they can swallow below the surface, but have to 

 come up with a large mouthful, such as a water- 

 snail. Such molluscs form a large proportion of 

 the food of Ducks and other water-birds, and 

 land-shells, as all know, are eaten by land-birds, 

 though generally these are small specimens which 

 are eaten whole, the Song-Thrush being exceptional 

 in its habit of dashing large specimens on stones 

 in order to chip off their shells and prepare them 

 for food. 



There are several other kinds of specialized 

 mollusc-eaters, notably the shell-eating Storks of 

 the genus Anastomus, called " Open-bills " from 

 the fact that their beaks gape in the middle in 



