Family CRICETIDAE 167 



arranged in two longitudinal rows, whereas in the Norway rat 

 thev are arranged in three rows, fig. 74a, c. Dental formula: 

 I 1/1, C 0/0, Pm 0, M 3/3. 



Life History. — The rice rat is nearly as much at home in the 

 water as the muskrat and almost as good a trail-maker as the 

 meadow vole; its runw^ays thread the dense vegetation of 

 marshes and swamp margins, fig. 3. The rice rat readily takes 

 to water when disturbed, and in many cases it is necessary for 

 it to go through water to reach its nest. 



The nest of the rice rat is a globular structure of dry grasses 

 and leaves. It may be constructed in an oval chamber at the 

 end of a burrow, in one of the highest, driest objects in a swamp 

 or bottomland, such as a stump or hollow log or a pile of debris, 

 or on the top of a fence post which is well covered with vines; 

 or it may be suspended on a bunch of interlaced marsh grass or 

 embedded in a tangled mass of blue flags or marsh grasses. 



Breeding may extend from March to October. Three to 

 eight young are produced in a single litter. The young are help- 

 less at birth but grow" and mature rapidly. Females may begin 

 bearing young when they are about 2 months old. 



The rice rat is active during daylight hours as well as at 

 night. In this regard, it resembles the meadow vole. It feeds 

 principally on green plants, but also on young turtles, snails, 

 and crayfish. Apparently this rat acquired its currently used 

 common name because, in parts of its range, individuals of this 

 species w^ere found invading rice fields to feed on newly planted 

 and also maturing grain. Each rat normally eats approximately 

 25 per cent of its own weight in food every day. The rice rat 

 is fed upon by swampland predators, including snakes, owls, 

 haw^ks, minks, and raccoons. 



Signs. — The runways of the rice rat resemble those of the 

 meadow vole but they are more open and without the numerous 

 cut sections of vegetation lying in them. Feeding platforms of 

 freshly cut grass stems near such runways are almost certain 

 signs of the rice rat. These may be as large as dinner plates, but 

 smaller than those of the muskrat. The burrow of the rice rat 

 is seldom more than a foot deep, and the entrance is commonly 

 a few inches above the high water level usual for the area in 

 which it is located. 



Footprints in soft mud near water may be those of a rice rat, 

 especially if they lead to a nest or a feeding platform. The 



