508 



REPORT OP STATE GEOLOOTST. 



not hesitate to take to water. I have found their runways else- 

 Avliere in boggy places, running along under the dry grass for 

 some distance, then going through underground tunnels filled with 

 water, and perhaps leading to a nest under some upraised hum- 

 mock. I have never found the mice at home in such a place, but 

 there is strong evidence that they do at times occupy nests that 

 can be reached only by swimming through tunnels that are filled 

 with water. 



In the southern part of the State, where there are fewer marshes, 

 they often live along the grassy banks that line the smaller streams. 

 They are sometimes found under corn and wheat shocks also, being 

 therefore independent of the swamps; but they are not the most 

 common mice in such situations. 



Their food is principally grass blades. In winter when green 

 grass is scarce they can subsist on the dried blades that they find 

 under the snow, although tender green blades are not entirely 

 lacking even then. The grass is cut away in a path just large 

 enough for the animal to pass through comfortably and care is 

 taken that it shall be where the long stems have fallen over so that 

 they form a roof for the runway. These paths are extended nightly 

 and often ramify and reunite in a bewildering maze of endless 

 passages. However, the animals do not depend altogether on elon- 

 gations of these pathways for their food. Often they find a bunch 

 of particularly juicy grass and there they sit and eat their fill. 

 Usually they are not ' ' clean eaters, ' ' but leave sections of the grass 

 blades, either because they are too tough or because it does not 

 seem to the creatures profitable to pick up dropped food when 

 there is so much at hand. 



These mice will also eat grains and seeds, as their occasional 

 presence under corn and wheat shocks testifies. However, I have 

 examined the stomachs of a number of individuals, principally in 

 August when both seeds and grass are plentiful, and have found 

 that about 80 per cent of the contents was grass. 



Butler and Quick state that this species breeds from February 

 to December and that they never saw more than four young at a 

 time. The only two pregnant females that I have taken contained 

 two and four fetuses respectively. However it is known that six 

 or more young are sometimes produced in a litter. The nest is made 

 of dry grass and is often, though not always, placed underground. 



Economic status. — This species is less injurious to farmers in 

 Indiana than either of the other voles or the common white-footed 

 mouse. Its habits of staying about marshy places renders it com- 



