250 ANIMAL COMPETITORS 



uttermost ends of their burrows if necessary. 

 Mr. Osgood says of the small Arizona weasels : 

 "They are the most effective enemy of pocket- 

 gophers. ... In a narrow valley where an 

 old weasel had her young I found it impos- 

 sible to secure a single pocket-gopher. A 

 single weasel will effectually keep down the go- 

 phers and meadow-mice on a field or small 

 ranch. Except in very rare cases they should 

 be protected with the greatest care." The 

 black-footed "ferret" (a true weasel) is rarely 

 found away from prairie-dog towns, where it 

 plays the bandit unceasingly. The writings 

 of naturalists abound in evidence of the same 

 sort. A notable instance may be found in the 

 great work on American mammals, The Quad- 

 rupeds of North America, published half a 

 century ago by Audubon and Bachman, a few 

 paragraphs from which may well be quoted : 



"Whenever an ermine has taken up its residence 

 the mice in its vicinity for half a mile around have 

 been found rapidly to diminish in number. Their 

 active little enemy is able to force its thin vermiform 

 body into the burrows, it follows them to the end 

 of their galleries, and destroys whole families. We 

 have on several occasions, after a light snow, followed 



