100 RODENTS OP IOWA 



one occasion when the horses of a farmer broke through one of 

 these houses on the edge of a pond near Marengo (Iowa county) 

 at least a bushel of corn was found within. This may have been 

 surplus food, which is to be found in some quantity at almost 

 any time. When the streams and ponds are frozen over, these 

 animals are able to obtain air in spaces under the ice and fre- 

 quently air holes are to be found which are kept open through use. 



Not much exact and definite information is available concerning 

 the breeding habits of the muskrat, but the facts so far as known 

 may be stated in the words' of Lantz : ' ' Normally the animals mate 

 in March and the first litter is bom 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 pro- 

 duced. 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. ' ' 21 



The food of the muskrat consists, for the most part, of vegetable 

 matter, but occasionally animal food is taken. In winter its staple 

 articles of diet are the roots of aquatic plants. Carp and other 

 mud-loving fishes as well as clams also are eaten. Robert Kenni- 

 cott in speaking of the food habits of this animal says : ' ' The musk- 

 rat is active in winter, seeking its food under the ice, and carrying 

 it into its burrow, or house to be eaten. Though roots are some- 

 times found in a nest in winter, they are only such as have re- 

 cently been brought in, no considerable stores of food being col- 

 lected. The food, in winter, appears to .consist of aquatic plants. 

 In summer, it also feeds upon the leaves of various plants, as 

 well as upon mussels, (TJmo anodonta and 77. plicatus, etc.), of 

 which they consume great quantities in some of our rivers. Col- 

 lecting them at the bottom it carries them in its teeth to a log or 

 stone, where, sitting upon its haunches and grasping them in the 

 fore-paws, it opens the shell with the incisors as skillfully as it 

 could be done with an oyster-knife. In this way, large piles of 

 shells are collected around stones and logs, by examining which 

 the conchologist may often find rare species brought from the 



Lantz, D. E., The Muskrat: U. S'. I>ept. Agr., Farmers' Bull. No. 396, 15, 

 1910. 



