THE RELATIONS OF MAMMALS TO MAN 455 



are housed at night, and the fox necessarily turns his attention 

 to field mice, rabbits, ground squirrels, and insects, such as 

 grasshoppers, crickets, and May beetles, to the great benefit 

 of the farmer. Although it is true that the fox destroys a con- 

 siderable number of birds, yet a ruffed grouse has been known 

 to rear its young within 100 feet of a fox den, and the tracks of 

 the young birds have repeatedly been seen on the fresh earth 

 before the entrance. Among the food brought to the young of 

 this litter and left outside were rabbits, mice, and a half-grown 

 woodchuck, but no birds of any kind. 



The fur of the fox is a very valuable article of commerce. In 

 January, 1908, fox skins were quoted as follows: red fox, $1.50 to 

 $3.50 each; cross fox, $4 to $8; silver fox, $50 to $250; and 

 higher prices are sometimes paid for high-grade silver-fox skins. 

 The silver fox is a color variety of the common red fox. Its fur 

 is entirely black or more or less tipped with white. The rearing 

 of foxes for the sake of their fur is now carried on in several 

 localities, and undoubtedly fox farms will increase in number and 

 importance as the supply of skins from wild animals decreases. 



Fur-bearing Animals. — The majority of the fur-bearing ani- 

 mals of North America belong to the marten family. This 

 family includes the otter (Fig. 292), mink, weasel (Fig. 293), 

 marten, wolverine (Fig. 294), and badger. Most of these ani- 

 mals are now scarce, and furriers are forced to use the skins of 

 other species, such as the skunk, muskrat, raccoon, fox, lynx, 

 black bear, and rabbit. Of all the products derived from wild 

 animals, furs are the most useful and valuable. Indispensable 

 to primitive man, they are scarcely less important to the most 

 civilized, for in warmth, beauty, and durability no manufac- 

 tured fabrics excel them. But expanding civilization is steadily 

 diminishing the supply of furs, both by increasing the demand 

 and by encroaching upon the territory in which they are pro- 

 duced. Many furs, as well as ivory, whalebone, and other 

 natural commodities, are already so scarce that the demand for 

 them is met largely by the substitution of inferior products. 



