9 



sitive. and serve well to guide them in the dark, but if too 

 closely pursued by nocturnal enemies they can easily change 

 their habits, feeding in daylight and sleeping at night. The 

 brown rat may be seen abroad at any hour, especially at morn- 

 ing and evening. It never likes to go far from some hole or 

 hiding place to which it can retreat at the first sign of danger, 

 and if it has to cross wide fields, it prefers to go through bushes, 

 grass or grain, along some wall or fence, or through or near a 

 ditch, where it can find shelter. In many cases it burrows in 

 the earth in fields, either near water, where it goes to drink, or 

 near its food supplies. Sometimes these burrows are used only 

 as places in which to hide from its enemies, but it often lives 

 all summer (and under some circumstances all winter) in 

 burrows in well-drained banks of rivers or small streams, or 

 along the shores of islands in the sea. The brown rat drinks 

 large quantities of water, and must have water, snow, rain or 

 dew in plenty at all times, hence its preference for banks of 

 streams, ditches, pools and springs. Also it is perfectly at 

 home in water, and can swim rapidly and easily for half a mile 

 or more, and it dives and swims readily under water. It nests 

 and rears its young in burrows in and under buildings and under 

 rubbish piles, and there it also stores more or less food for use 

 in times of want or danger. 



Rats live outdoors more in the south than in the north. In 

 rural New England, especially where grain is grown, the brown 

 rat lives chiefly in fields in summer and in and around buildings 

 in winter. In villages and cities rats stay much about buildings 

 all the year, but some migrate into the open in spring and 

 return to the buildings in autumn. Rats migrate in large num- 

 bers whenever food fails, crossing deserts and rivers that may 

 lie in their path. Hunger thus accounts for the great invasions 

 of rats that sometimes occur. It is a well-known fact that rats 

 catch and eat mice, but they never can exterminate mice, for 

 the same reason that cats cannot extirpate rats. Mice are so 

 much smaller than rats that they can run into holes where the 

 latter cannot follow. Therefore rats and mice are commonly 

 found in the same buildings or fields. It is not generally 

 known, however, that brown rats are cannibals. The adult 

 male will search out and eat its own offspring; but, on the 



