Aquatic Mammals 241 



there, and commit local and intermittent depredations. 

 The water birds nest mainly on land, and in their 

 nesting and brooding habits they differ little from their 

 terrestrial relatives. 



The aquatic mammals of inland waters fall mainly in 

 two groups, the carnivores and the rodents. Here 

 again, the carnivores that are more expert swimmers 

 and divers, such as fisher, martin, otter and mink are 

 all fish-eating animals. They have become fitted to 



FIG. 148. A muskrat, Fiber zibethicus. 



utilize the chief animal product of the water. Of these 

 four the mink alone has withstood the "march of 

 progress," and retains its former wide distribution. 



Of rodents there are two fur-bearers of much import- 

 ance, the beaver, now driven to the far frontier, and the 

 muskrat. The muskrat has become under modern 

 agricultural conditions the most important aquatic mam- 

 mal remaining. By reason of its rapid rate of repro- 

 duction, its ability to find a living in any cat-tail marsh, 

 big or little, and its hardiness, it has been able to main- 

 tain its place. 



