56 Order INSECTIVORA 



tail and longer hind feet, and has five instead of four unicuspids 

 (three visible in lateral view) on each side of the upper jaw. 



Life History. — Little is known about the masked shrew in 

 Illinois. Elsewhere an adult female of this species produces 

 about five young in April. Her ball-shaped nest, 4 or 5 inches in 

 diameter and lined with fine grass and rootlets, is hidden in a 

 cavity of an old log or stump. 



The masked shrew is generally found under a dense growth of 

 weeds or in woods, fig. 1. This tiny mammal, like all other 

 shrews, is a scurrying, vibrating mite of energy, driving narrow 

 tunnels in leaf mold and darting swiftly about in search of food 

 day or night, summer or winter. It is a prodigious eater. In a 

 single day a shrew may eat one, two, or even three times as 

 much as its own weight in food. Its diet consists chiefly of in- 

 sects, snails, and worms. 



This shrew, like others in Illinois, possesses scent glands that 

 secrete a musky fluid which renders the animal undesirable as 

 food for some predators and may account for the fact that cats 

 sometimes leave shrews uneaten after catching and killing them. 



Signs. — Curious parallel tracks in snow (tracks similar to 

 but smaller than those of the short-tailed shrew), and often 

 accompanied by a tail mark, may indicate the presence of the 

 masked shrew. This animal may make small ridged runways 

 in the snow similar to those of the mole in soil, but the shrew 

 runways are only about ^ inch across as seen from the surface. 

 The burrow the masked shrew makes in snow, and probably also 

 in loose soil, has an inside diameter of about half an inch. 



Distribution. — The masked shrew is uncommon and in Illi- 

 nois is restricted to the northern fourth of the state, fig. 43. 

 The subspecies occurring in this state is Sorex cinereus lesueurii 

 (Duvernoy). The range of this species includes most of Can- 

 ada and much of the northern United States, \yith southern ex- 

 tensions in the Rocky Mountains to northerii New Mexico, in 

 the Great Lakes region to the Wabash River valley, and in 

 the Appalachian Mountains to western North Carolina. 



SOREX LONGIROSTRIS Bachman 



Southeastern Shrew Bachman's Shrew 



Description. — The southeastern shrew, fig. 47, is of about 

 the same size and proportions as the masked shrew and can be 



