Inter-Relations of Living Creatures 657 



several species of cormorants used to swarm in thousands, 

 but ruthless massacres, ordered on the supposition that the 

 birds were spoiling the fishing, reduced them to hundreds. 

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

 discovered that the cormorants fed largely on crabs, eels, and 

 some other creatures which devour the spawn and fry of the 

 desirable fishes. Thus the ignorant massacre of the cor- 

 morants 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 life before, not after, he has had 

 recourse to drastic measures of interference with the webs of 

 life. 1 



The Importance of Birds 



One of the risks to which the Balance of Nature is exposed is 

 the multiplication of insects. There are so many of them and they 

 are so prolific. Their over-population is often disastrous for a 

 time in a limited area, as is familiar in an invasion of locusts ; but 

 this is obviated as a worldwide catastrophe by the changeable 

 weather and by insectivorous animals. Among these the place of 

 first importance must be given to insect-eating birds. It is not 

 possible to make precise calculations, but some experts have said 

 that six to ten years without birds would suffice to bring our 

 whole system of Animate Nature to an inglorious end a vast 

 hecatomb of insects devouring and smothering one another. 

 This is the biological reason for opposing the destruction of insect- 

 eating birds except under careful scrutiny. That they are irre- 

 placeable masterpieces of beauty is another reason of a different 

 order but not less cogent. 



One cannot pretend that the question of elimination is easy; 

 one can only plead that wholesale massacres should not be 

 permitted without the most careful consideration. Poisonous 

 snakes are proscribed, but is it clearly understood that their 

 destruction implies a multiplication of mice and other "vermin" 



1 Thomson in Dendy's Animal Life and Human Progress, 1919, p. 88. 



