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232 ANIMALS UNDERGROUND 



mine until the superincumbent earth collapsed and 

 buried the greater number. A young prairie-dog let 

 loose in a small gravel-floored house instantly dug a 

 hole large enough to sit in, turned round in it, and bit 

 the first person who attempted to touch him. Property 

 gave him courage, for before he had been as meek as a 

 mouse. 



It is noticeable that the two weakest and least 

 numerous of our mice, the dormouse and the harvest- 

 mouse, do not burrow, but make nests ; and that these 

 do not multiply or maintain their numbers like the 

 burrowing mice and voles. But the fact that there are 

 members of very closely allied species, some of which 

 do burrow, while others do not, seems to indicate that 

 the habit is an acquired one. In this connection it is 

 worth noting that many animals which do not burrow 

 at other times form burrows in which to conceal and 

 protect their young, or, if they do burrow, make a 

 different kind, of a more elaborate character. Among 

 these nursery burrows are those of the dog, the fox, the 

 sand-martin, the kingfisher, and the sheldrake. Fox- 

 hound litters never do so well as when the mother is 

 allowed to make a burrow on the sunny side of a straw- 

 stack. In time she will work this five feet or six feet 

 into the stack, and keep the puppies at the far end, 

 while she lies in the entrance. Vixens either dig or 

 appropriate a clean burrow for their cubs, which is a 



