THE BALANCE OF NATURE 17 



them nor to permit them to become overabundant. Then white men 

 moved into the region and introduced large flocks of sheep and herds 

 of cattle, to which more abundant and easily obtained food the preda- 

 tors turned, causing great losses to stockmen, who have been compelled 

 to declare war upon the enemies of their flocks. It is surely quite 

 necessary to keep predatory animals within reasonable bounds, but no 

 human being yet has sufficient knowledge of all the complexities of 

 nature to determine with absolute certainty whether any of the 

 predators should be entirely exterminated. One thing that is quite 

 certain is that though man may destroy a species, he can never bring 

 back into existence one that he has exterminated. 



As a necessary result of the destruction of the coyote, man will have to face the 

 problem of accounting for the thousands of ground squirrels which the animals 

 destroy each year, as Dixon clearly points out. Control measures breed control 

 measures. Control in one direction throws nature out of balance and often gives 

 rise to troublesome consequences which must be dealt with through additional 

 control measures. The case has recently been well stated by two British authori- 

 ties. Watt cited herbivorous animals as a chief cause of failure of natural re- 

 generation of the oak in Britain. As a result of the reduction in numbers of 

 carnivorous animals there has been a general increase in rabbits, mice, moles and 

 certain birds. "Man, by upsetting the balance of nature and assuming control of 

 what directly affected his own interests, is now paying the penalty in other ways, 

 and must, having killed or suppressed the controllers, either assume total con- 

 trol himself or assist in such by a judicious encouragement of those animals he 

 once considered his inveterate foes." The same point is made by Lankester, quoted 

 by Watt, ". . . civilized man has proceeded so far in his interference with extra- 

 human nature, has produced for himself and the living organisms associated with 

 him such a special state of things by his rebellion against natural selection and 

 his defiance of nature's pre-human dispositions, that he must either go on and 

 acquire firmer control of the conditions or perish miserably by the vengeance 

 certain to fall on the half-hearted meddler in great affairs. We may indeed com- 

 pare civilized man to a successful rebel against nature who by every step forward 

 renders himself liable to greater and greater penalties, and so cannot afford to 

 pause or fail in one single step." 2 



Thorough investigation has shown that most species of wild birds 

 are more useful than harmful. Though not so fully investigated, the 

 same is true of a considerable proportion of mammals, but unfortu- 

 nately among mammals the most abundant and prolific species are those 

 whose food habits render them particularly destructive the rodents. 

 However, it is highly probable that no species is entirely harmful, and 

 quite possible that no species is entirely harmless. 



2 Taylor, Journ. Mammalogy, n, 177, 1921, quoting Dixon, California College Agric. 

 Bull, No. 20, pp. 379-397, 1920; Watt, Journ. Ecology, vn, 201-202, 1919; Lankester, 

 Kingdom of Man, pp. 31-32, 1911. 



