ECONOMIC RELATIONS OF MAMMALS 13 



It is doubtful whether we are justified in the complete extermination 

 of any species, even the predatory mammals. In addition to the fact 

 that they destroy some injurious animals, they are of scientific, educa- 

 tional and recreational value, which should be placed in the balance in 

 weighing their good and bad qualities. We are not yet fully enough 

 informed as to all of the interrelations and interactions of various 

 species to determine the wisdom of the total extermination of any of 

 them. Man may kill, but he cannot re-create. 2 



Certain burrowing rodents do some good by stirring the soil and 

 bringing subsoil to the surface; but, to offset this, their holes, tunnels 

 and mounds are in various ways a nuisance and sometimes dangerous. 

 Wolves and coyotes kill harmful rodents, but also kill very useful 

 animals. Beavers are valuable fur-bearers, but sometimes cut down 

 trees of very much greater value than their pelts. Minks and weasels, 

 also valuable as fur-bearers, and as enemies of injurious rodents, 

 sometimes make raids upon the poultry houses, though they can be 

 "built out" by proper construction of the pens and houses. Rabbits 

 furnish us with great quantities of meat and fur, but do much damage 

 to orchards, gardens and farm crops. Cats catch some mice, but are not 

 as good mousers as some of the predatory birds, and do considerable 

 harm by catching insectivorous and other useful birds. It is therefore 

 very evident that it is often difficult to strike a balance and decide with 

 certainty whether a given species should be listed with the injurious, 

 neutral or beneficial species. 



There are, however, many species of mammals of very great and 

 beneficent importance to the welfare of mankind, particularly those 

 that have been domesticated, of which there are many kinds, discussed 

 more at length in other chapters. Especially valuable are those that 

 furnish us with large quantities of meat, milk, butter, cheese, wool, 

 lard, furs, leather, oil and other commodities of great aggregate value, 

 the beasts of burden, and the dogs that guard our homes and help 

 herd and drive our sheep and cattle. 



The branches of business of the modern world that revolve around 

 mammals and mammalian products are numerous and aggregate in 

 value billions of dollars per annum. In the succeeding chapters we shall 

 consider some of the esthetic relations of mammals. Then, turning to 

 the practical phases of mammalogy, we shall see, on one hand, the 



2 See Adams, The conservation of predatory mammals, Journ. Mammalogy, vi, 

 83-96, 1925. Compare Goldman, ibid., pp. 28-33. 



