CONSERVATION OF GAME BIRDS. 501 



thus assisting other forces to maintain the biologic balance 

 in the waters of bays, estuaries and lakes. 



Dr. George W. Field, chairman of the Massachusetts 

 Commission on Fisheries and Game, informs me that mussels, 

 which are the principal food of Scoters, or "Coots," and 

 Eiders, are among the chief enemies of the common clam. 

 They occupy clam flats to the exclusion of the clams, and 

 are difficult to eradicate. The Scoters feed on starfish also, 

 and Dr. Field says that they destroy the oyster drill (Uro- 

 salpinx cinerea). The starfish and the drill are the most de- 

 structive enemies of the oyster and the scallop, and are dreaded 

 by the oyster growers. Dr. Field declares that these animals 

 are certainly a hundred times as destructive to the oyster and 

 scallop industries as are all species of water-fowl combined. 



While the Scoters feed on sea clams {Mactra solidissima) , 

 quahaugs {Venus mercenaria) and scallops (Pecten irradians), 

 they take only the young or very small shell-fish,^ and Dr. 

 Field states his belief that, other things being equal, these 

 birds select mainly those places where such shell-fish are most 

 abundant. Young shell-fish in their beds are so crowded that 

 were they not thinned out many would die from overcrowding 

 or lack of food. Dr. Field states that he has found young 

 clams set as thickly as two thousand to the square foot. In 

 such cases the removal of all but a dozen or twenty to the square 

 foot will be succeeded usually by a rapid increase in growth. 

 Thus the thinning done by the birds saves shell-fish from the 

 evils of overcrowding, and benefits the shell-fish industry 

 by inducing a quicker and better growth of the marketable 

 product. It seems probable that these birds are essential to 

 the success of the shell-fisheries, and that any serious reduction 

 in their numbers would be detrimental to the industry. 



River Ducks require a large quantity of animal food in 

 spring, and devour such destructive insects as army worms, 

 cutworms* marsh caterpillars, grasshoppers and locusts. 

 Aughey in his report on Locust-feeding Birds, made to the 

 United States Entomological Commission in 1877, gives the 



> A small bivalve commonly eaten by these birds is very similar to the quahaug and usually is 

 mistaken for it. This is Gemma gemma, a favorite food of the Black Duck, which never grows 

 to a marketable size. 



