200 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. . . .' Ina 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 
cehtury 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 
