506 
Wherever there is a bit of waste ground where grass and weeds 
can grow undisturbed the prairie-vole and, more rarely, the Penn- 
sylvania meadow-mouse (Microtus pennsylvanicus) are present, and 
together with the short-tailed shrew will invade the fields soon after 
cultivation ceases. These and the house-mouse are always taken 
in fall, unless the ground is quite cleared of standing or shocked corn 
or grain. In clover fields, meadow-lands, pastures, and alfalfa 
fields, especially when these crops have grown on the same land for 
several successive years, the prairie-vole becomes the dominant form, 
with the mole a close second, especially around the margin. 
Wherever there are piles of rubbish, old ricks, compost heaps, 
etc., these serve as homes of house-mice, and, if large, of rats, Mus 
norvegicus. From these centers the former spread out into the 
adjoining territory. Along the small streams—mere drainage 
ditches usually—so long as they contain a trace of water, muskrats 
are really abundant. These ditches serve, too, as highways for 
minks and weasels. The former especially take refuge in the open 
mouths of the tile drains. When the ditches are a little larger and 
their banks are bordered by a rank growth of grass and weeds, this 
furnishes shelter for rabbits the whole year through. Rabbits are 
abundant, too, during fall and early winter, finding a precarious 
shelter under clods and fallen stalks during the hght winter snows 
- On this*pant or the state: 
Where the till plains are devoted to pasture, or where they border 
the moraines, the striped gopher, C7itellus tridecemlineatus, and the 
gray gopher, C. franklinu, are present, and enter corn and grain 
fields during summer and fall. The latter, so far as my own obser- 
vations go, seems to spread out farther into fields of alfalfa and 
clover, while the striped gopher often takes up its residence in corn 
fields immediately after planting—to the exasperation of the farmer. 
Under usual conditions, the white-footed wood-mouse, Peromys- 
cus leucopus, is not found in this type of locality. If, however, there 
be present anywhere a small grove, a neglected thicket, or an old 
hedge, one is almost sure to find this mouse. It is surprising how 
little of such shelter suffices for it, and yet it is almost never found 
without any shelter at all. 
Skunks are occasionally seen in the fields in these plains, but 
they are not common. 
