88 ANIMAL LIFE AND HUMAN PROGRESS 



5 Let us look at some illustrations of the same sort of 

 disturbance of the pattern of the web, but from the minus 

 side, when man eliminates instead of fostering. Without 

 pretending that this is the whole truth, we may safely say 

 that the over-destruction of certain birds of prey, such as 

 kestrels and owls, and of certain carnivores, such as weasels, 

 is in part to blame for the occasional occurrence of vole- 

 plagues, which turn fertile fields into deserts. Elimination 

 in the interests of game-preserving is thus apt to be at the 

 cost of the farmer. It seems likely enough that saving the 

 red grouse from Nature's sifting is one of the radical conditions 

 of an outbreak of so-called " grouse disease." 



There is an Australian story which reads as if written for 

 man's instruction. On certain Murray River swamps several 

 species of cormorants used to swarm in thousands, but ruth- 

 less massacres, based on the supposition that the cormorants 

 were spoiling the fishing, reduced them to hundreds. But 

 the fishing did not improve ; it grew worse. It was then 

 discovered that the cormorants feed largely on crabs, eels 

 and some other creatm-es which devour the spawn and fry 

 of the desirable fishes. Thus the ignorant massacre of the 

 cormorants made for the impoverishment, not for the improve- 

 ment, of the fishing. The obvious moral is that man should 

 get at the facts of the web of Hfe before, not after, he has 

 recourse to drastic measures of interference with the web of 

 hfe. 



It is not sentiment but science that warrants the strongest 

 disapprobation of the careless destruction of birds. For the 

 system of Nature depends on the check that birds keep on the 

 multiplication of insects. Perhaps six years without birds 

 would serve to bring our whole system of animate Nature to 

 an end. The destruction of the beautiful white heron or 

 egret for the sake of its scapular plumes has robbed nearly 

 half the world of a bird of high utihty to man. Its formerly 

 abundant presence in the rice-fields of China and India is 

 said to have been very beneficial : the bird has in great part 

 fallen a victim to ignorant or ruthless fashion. There is but 

 a short list of birds that are seriously injurious to the interests 



