fore they are weaned at about 4 

 weeks of age. By that time the in- 

 cisors are well developed and can 

 inflict pain. Growth is remarkably 

 rapid but depends on the abundance 

 and quality of their food, on water 

 and temperature conditions, and on 

 racial characteristics (fig. 16). In 

 Maryland, a total length of nearly 

 18 inches and a weight of about I14 

 pounds may be reached at 7 months. 

 Size of the muskrat at maturity 

 may differ considerably between re- 

 gions and between races. By the 

 end of the trapping season, young 

 of the first spring litter of the Vir- 

 ginia muskrat may not weigh more 

 than 2 pounds 3 ounces, whereas in 

 central New York those of the com- 

 mon eastern muskrat may reach 

 slightly more than 3 pounds. 



In spite of the belief of many 

 trappers to the contrary, young 

 muskrats do not mature sufficiently 

 to breed during the year of their 

 birth. By the next spring breeding 

 season, however, young of the early 

 spring litters have reached matur- 

 ity. In Louisiana, where young 

 have been found in every month of 

 the year, it is possible that kits born 

 early in January may mature and 

 breed by the end of December ; but 

 confirmatory data on this are lack- 

 ing. 



DEVELOPING THE MUSKRAT 

 RESOURCE 



Large areas, formerly considered 

 worthless except as waterfowl 

 marshes are today being used to 

 produce muskrats. With the in- 

 crease in the value of muskrat fur, 

 many areas totally unsuited for 

 farming, even when drained, are 



Figure 16. — A 2-months-old Maryland 

 muskrat. 



yielding a greater income than ad- 

 joining, cultivated fields. A better 

 understanding of the application of 

 modern management practices to 

 such properties has helped to stabi- 

 lize muskrat production at a high 

 level. 



Good muskrat habitat is usually 

 good waterfowl marsh. Both for 

 waterfowl and for muskrats, tight 

 or solid marshes are undesirable. 

 The effect of muskrats on a water- 

 fowl marsh is important. In their 

 normal activities muskrats create 

 ponds and keep channels open, but 

 allowed to increase uncontrolled 

 they deplete the vegetation and ruin 

 the habitat both for waterfowl and 

 for themselves. 



Improving the Habitat 

 Controlling water levels 



Maintenance of proper water 

 levels is very important as muskrat 

 populations are affected more by 

 rapid changes in water levels than 

 by changes in the type of marsh 

 vegetation. Extreme fluctuation is 

 damaging both to muskrats and to 

 their food plants. A freshet, or 

 sudden rise of water in the spring, 

 often results in heavy mortality of 

 the very young. Again, lowered 

 water levels in late spring followed 

 by intense and prolonged summer 

 drought and high temperatures can 

 stop breeding and lower the rate of 

 survival of the young. 



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