22 EXTINCT AND VANISHING MAMMALS 



and Felidae) , because of their competition with man for food in the 

 shape of the ungulate mammals, both wild and domesticated, such 

 as cattle, sheep, goats, antelopes, horses, asses, swine, and deer. 

 In the case of such formidable carnivores as wolves, bears, lions, 

 tigers, and leopards, the matter of outright self-defense on man's 

 part may also be involved. Moreover, it is natural that the large 

 game species of the cattle and deer families, which require extensive 

 feeding grounds and are eagerly sought by mankind for food, 

 should have suffered some of the principal losses. 



SUMMARY AND CONCLUSIONS 



During the past 2,000 years the world has lost, through extinc- 

 tion, about 106 forms (species or subspecies) of mammals. They 

 are distributed by regions as follows: Australia, 11; Malay Archi- 

 pelago, 3; Asia, 3; Europe, 6; Africa, 9; Madagascar, 1; North 

 America, 27; West Indies, 41; South America, 1; Falkland Is- 

 lands, 1; Galapagos Islands, 2; oceans, 1. Approximately 67 per- 

 cent of these losses have occurred during the past century, and 38 

 percent during the past half-century. Thus the rate of extinction 

 is being steadily accelerated. 



In addition to the mammals already extinct, more than 600 others 

 require consideration as vanishing or threatened forms. 



Insular faunas, partly by reason of their circumscribed nature 

 and partly by reason of a certain lack of adaptability or self- 

 defense, are particularly vulnerable to attack or competition by man 

 and by certain mammalian pests introduced by him. There may be 

 a further reason for the decadence of insular faunas in some cases, 

 such as that of the West Indies, in the virtually total lack of native 

 mammalian predators; these would doubtless have played a bene- 

 ficial role by eliminating the less fit individuals, and thereby con- 

 tributing to the survival of the fittest individuals, among the species 

 preyed upon. 



In general, it is fairly obvious that species of restricted distribu- 

 tion and specialized habits have less chance of survival than those 

 of wide distribution and generalized habits. 



The primary factor in the depletion of the world's mammalian 

 faunas is civilized man, operating either directly through excessive 

 hunting and poisoning, or indirectly through invading or destroying 

 natural habitats, placing firearms in the hands of primitive peoples, 

 or subjecting the primitive faunas of Australia and of various 

 islands to the introduction of aggressive foreign mammals, including 

 fox, mongoose, cat, rat, mouse, and rabbit. Except in the West 

 Indies, comparatively few species seem to have died out within the 

 past 2,000 years from natural causes, such as evolutionary senility, 

 disease, or climatic change. 



