Song Birds and Water Fowl 



and subsist largely upon animal food which 

 they find in the water. The nature of their 

 diet makes their flesh rank and usually unpal- 

 atable, although the "canvas-back" is a not- 

 able exception. These rarely breed as far south 

 as the United States, but commonly far north, 

 one of the largest and handsomest, the king 

 eider, being circumpolar. Sea ducks differ 

 from river ducks in having larger feet and 

 broader webs, enabling them to swim and 

 dive more easily. I will mention one curious 

 and significant distinction between the two 

 groups, although it touches upon the anatomi- 

 cal side of the subject. In all sea ducks the 

 hind toe is bordered by a narrow band or lobe, 

 which is never the case in river ducks. This 

 increases the area of the webbed foot, and the 

 relation of this fact to the different degrees of 

 propulsive power possessed by the two groups, 

 which in turn so largely determines their habi- 

 tat and diet, and thus their serviceableness to 

 man, justifies an allusion to what might other- 

 wise be called a dry, scientific fact. The field 

 ornithologist ignores nothing in the physique 

 of a bird that has an evident relation to the 

 special habits of the species ; but the intricate 

 details of an insignificant bone in the body that 



86 



