Family CRICETIDAE 173 



The bog lemming is preyed upon by foxes, as well as hawks, 

 owls, weasels, and most other Illinois predators. When lem- 

 mings are at the peak of their population cycle, there may be 30 

 or 40 per acre in suitable habitat, but, at the bottom of the 

 cycle, there may be only 2 or 3 per acre. 



Signs. — Fresh piles of grass, cut in pieces about an inch long, 

 and bright green droppings in small, grass-covered runways 

 may indicate the presence of bog lemmings. Only when other 

 voles feed as exclusively on bluegrass as do lemmings, and this 

 is rarely the case, are their droppings bright green. When there 

 are many bog lemmings present, the greenish fecal pellets form 

 a solid mass on the floor of much of the runway network. 



Distribution. — The bog lemming, sporadic in occurrence and 

 usually not abundant in Illinois, has been taken in only the 

 southern two-thirds of the state. The subspecies in Illinois is 

 Synaptomys cooperi gossii (Coues). The range of the species 

 extends from eastern Quebec to southwestern Ontario, and 

 southward to northern Arkansas and the southern Appalachian 

 Mountains, with an extension into western Kansas. 



MICROTUS PENNSYLVANICUS (Ord) 

 Meadow Vole Meadow Mouse 



Description. — The meadow vole, fig. 96, is a stout-bodied, 

 short-tailed, dark-colored mouse that lives in meadow-like 

 places. Its back is dark brown or chestnut brown; the under 

 parts are grayish, tipped with silver (never tipped or washed 

 with fulvous or ochraceous) ; the under side of the tail is nearly 

 the same color as the belly. The hind foot usually has six pads 

 or tubercles. The tail is nearly twice as long as the hind foot. 

 The female has four pairs of mammary glands. 



Length measurements: head and body S^/g-A^ inches (93-120 

 mm.) ; tail 1^-1^ inches (35-42 mm.) ; over-all 5-6^ inches 

 (128-162 mm.) ; hind foot about ^ inch (18-22 mm.). 



The skull is 25-29 mm. (l-li/^ inches) long. The front sur- 

 face of each upper incisor is not grooved, and each of the last 

 upper molars has five or six enamel triangles or loops, fig. 74d, 

 not four as in the prairie vole, fig. 74e. Dental formula: I 1/1, 

 C 0/0, Pm 0/0, M 3/3. 



Life History. — The meadow vole lives in damp, grassy 

 places. If the dense vegetation of such places is parted, surface 



