494 



COLLEGE ZOOLOGY 



nancial return of any single fur-bearing ani- 

 mal. In certain states where marshland is 

 managed for the maximum production of 

 muskrats, the profit per acre is as much 

 as on surrounding farmland. Fox and mink 

 farming has developed into a fairly large 

 and profitable industry. Black and silver 

 foxes are color phases, or inherited varia- 

 tions of the red fox. New color muta- 

 tions of the red fox which are being ranch- 

 bred include platinum, pearl, and white face. 

 Some of the newer mutant furs have scarcity 

 value and sell for high prices. 



Figure 366. Mountain lion, Felis concolor, a 

 large predatory mammal; it kills calves, deer, and 

 other large animals. (Courtesy of N.Y. Zoological 

 Society.) 



Many, many mutations have occurred in 

 the mink to produce new fur colors. Some 

 of these are very beautiful and have a 

 scarcity value. 



The rat is the worst mammalian pest 

 known to man. The damage it does through- 

 out the world results in losses amounting to 

 hundreds of millions of dollars annually. 

 But these losses, great as they are, are of 

 less importance than the fact that rats carry 

 from house to house and from seaport to 

 seaport the germs of the terrible bubonic 

 plague or "black death." 



Predatory mammals feed upon the flesh of 

 other animals; if these animals preyed upon 

 are beneficial to man, the predatory mam- 

 mal may be considered injurious, but if the 

 animals preyed upon are harmful to man, 

 the predatory mammal is beneficial. The 

 harmful predatory mammals include the 



wolves and cougars, which subsist largely 

 upon big game, sheep, cattle, and horses; 

 and the house cat, which destroys millions 

 of birds in this country annually. Other 

 predatory mammals are occasionally harm- 

 ful, but usually beneficial. 



Figure 367. Ocelot, behs pardalis. This beauti- 

 fully colored cat is an inhabitant of Texas and 

 tropical America. (Courtesy of N.Y. Zoological So- 

 ciety. ) 



There is great danger in introducing a new 

 kind of mammal into this country. The 

 brown rat reached this country about 1775 

 and is now one of the worst mammalian 

 pests. Rabbits, which were introduced into 

 Australia about 1788, soon became so nu- 

 merous that legislative action was taken for 

 their destruction. By the middle of the 

 nineteenth century, rabbits were a menace 

 to sheep raising. In 1907, a one-thousand- 

 mile fence was built from north to south, 

 all the way across the continent, to stop 

 them from invading western Australia, The 

 mongoose of India destroys rats, lizards, and 

 snakes; it was introduced into Jamaica 

 and other tropical islands, and at first 

 proved very beneficial, but later it became a 

 great pest, destroying poultry, birds, young 

 domesticated animals, and even fruit. These 

 disastrous results led Congress to prohibit 

 importation of most birds and mammals, 

 unless special permission is obtained from 

 the government. 



