Probably no mammal is more numerous in the eastern United States than the short-tailed shrew. It occurs everywhere--in forests, in brushy areas, in old fields, and along grassy banks. Within the city of Washington it is common in Rock Creek Park, where it lives in covered runs which it makes among the grass and fallen leaves. These shrews drink frequently, and this may in part account for their abundance near streams or other water, although it may be the desirable moist soil conditions which draw them to such situations. [Illustration: THE TRACK OF A COMMON COW (A SMALL ONE) It is well to take the tracks of domestic animals as standards in identifying tracks of wild big game. The roundness of the front foot and the narrowness of the hind are general characteristics, though not always so pronounced as here. But note that the hind foot is set ahead, beside, or behind the trail of the front foot, but rarely exactly on it. This peculiarity is commonly seen in animals that are accustomed to walk on bogs. Note also the toes are set pointing a little outward, not straight forward. The clouts, or accessory hoofs, rarely show; only in deep, soft ground.] The runways of these shrews are scarcely half an inch wide, usually partly sunken in the mold or rotting surface vegetation. These are not made by digging, but by pushing aside the loose mold, and they cross and re-cross in an irregular network. They lead to the entrances to burrows which generally drop nearly straight down. The burrows are sometimes amid the leaves, but usually under the shelter of a root, stump, old log, or other cover. In addition to their own runways, the shrews make free use of the runs of meadow mice and even traverse the tunnels of the pine mice and moles in their restless search for prey. Small rounded chambers opening off their underground runways are filled with fine grass, pieces of leaves, and other soft matter for a nest. One nest examined was made entirely from the hair of meadow mice, probably the spoils of war from the bodies of victims. As a rule, shrews are extremely unsocial, but a pair of this species is sometimes found occupying the same nest, no doubt a temporary arrangement. Several litters, containing from four to six each, appear to be born through the summer and fall, usually beginning in June.