THE MUSKKAT. 



15 



mud. Such a nest is placed above the reach of tides in a brush pile 

 or a bunch of growing plants. Mr. Slacum states that he has often 

 found young muskrats in these nests, which are far less bulky than 

 the winter houses. He is uncertain as to the duration of pregnancy 

 in the female, but thinks it must be less than a month. 



All this testimony shows that in their breeding habits muskrats 

 are not unlike field mice. This conclusion is further strengthened 

 by the remarkable way in which the marshes, depleted by vigorous 

 winter trapping, are replenished before the opening of another season. 

 The known facts may be thus summarized: Normally the animals 

 mate in March and the first litter is born in April ; a second litter is 

 due in June or early July, and a third in August or September. In 

 favorable seasons a fourth or even a fifth litter may be produced. 

 The period of gestation is possibly no longer than twenty-one days, 

 as with the common rat and probably with the field mouse. The 

 young are blind and naked when born but develop rapidly. Outside 

 of low marshes, muskrats are usually born in the underground 

 burrows. 



MIGRATIONS. 



Muskrats often wander over fields and along highw^ays far from 

 water. This occurs in late fall, early spring, or during severe 

 droughts in late summer. The causes are not understood, although 

 the spring movement has been generally attributed to sexual excite- 

 ment. When met away from water, muskrats sometimes show con- 

 siderable ferocity and have been known to attack persons savagely 

 without apparent provocation. 



Whether general migrations of muskrats occasionally occur is 

 doubtful, although the trader at Lake Traverse, Minnesota, informed 

 Featherstonhaugh that such movements take place, and that at times 

 the animals were seen on the prairies in incredible numbers.*^ 



The local movements of muskrats from place to place, both over- 

 land and along streams, make it difficult to protect canals and arti- 

 ficial ponds from the animals. They promptly find their way to new 

 ponds built several miles from their former known haunts. Irriga- 

 tion canals and ditches are likewise invaded throughout their entire 

 length so nearly simultaneously that it is hard to believe that all the 

 animals could have reached them through the head gates. 



FOOD. 



Like nearly all rodents the muskrat is chiefly herbivorous, but it 

 sometimes indulges in animal food, a habit which it shares with 



« Featherstonhaugh's Canoe Voyage, I, 384, 1847. 



396 



