524 



Life-histories of Northern Animals 



of Grass to the Island of Carnivores. Indeed, the flesh-eaters, 

 in Canada at least, are far more dependent on the Muridae than 

 they are even on the great ruminants. These may furnish an 

 occasional meal, but the Mice are the ever-present and reliable 

 hunger-stay, and without them our carnivorous birds and 

 beasts would speedily cease to exist. 



What the archaean rocks are in geology, then, our rodents 

 are in the mammal kingdom. Near the bottom of the system- 



Fig. 151 — Midden-heap of Microius drummondi, with 2 back doors contributory. The pile contained about 

 10,000 pellets. Whitewater, Manitoba, April 29, 1904. 



atic scale, and not only great in aggregate bulk among forma- 

 tions, but also the raw material of which most others are 

 made. 



SOCIABIL 

 ITY 



This species commonly lives in crowded colonies, the 

 members of which, to a considerable extent, profit by each 

 other's labours and presence. Their tunnels, runways, midden- 

 heaps, and stores are apparently common property. The 

 species is therefore sociable as well as gregarious. 



