BIRDS AND THE WEB OF LIFE 399 



admit that it is merely anthropomorphism to regard the 

 numerical ascendancy of poor-brained and almost spawning 

 rodents as a faunal retrogression, A thousand mice will 

 not compensate for the death of one mole. 



No doubt some birds devour other birds ; and when 

 these " other birds " are insectivorous, so much the worse 

 for man. It is difficult to over-emphasise the persistent 

 insect-peril, for a few years of super-abundance among 

 such insects as plant-bugs (Rhynchota or Hemiptera) would 

 ruin the vegetation of the earth. And that would mean the 

 degradation of the fauna and the rapid decline of man. 

 We do not know whether the possibility is more than a 

 theoretical one, for the foundations of Animate Nature 

 have been well laid. But it is surely practical wisdom to 

 lean one's weight against interferences which bring the insect 

 peril nearer. The issues are so complicated that we doubt 

 the wisdom of every big interference with birds, whether in 

 the way of fostering or in the way of elimination, but if we 

 had to choose between protecting a carrion-crow or a black- 

 headed gull, we should vote for the latter. For the carrion- 

 crow destroys many an insectivorous bird — we are not 

 inclined to black-list or exterminate him on that account — 

 whereas the black-headed gull eats huge numbers of 

 " leather-jackets " and other injurious insect larvae in the 

 fields around the gullery. 



When we come to birds that devour snakes, it is difficult 

 to shunt off human prejudice. The fact is that the issue 

 is mixed. We cannot get a clear bill. From the point 

 of view of man and his stock (a narrow anthropocentric 

 one) we praise the Secretary Bird — one of the masterpieces 

 of creation — because it often kills snakes, which are hostile 

 to human interests. But we must face the corollary that 

 the elimination of certain kinds of snakes means the increase 

 of rats and mice and other pests. Who is sufficient for 

 these things ? We cannot accept an entirely laissez-faire 

 policy, first because no vigorous organisms that have 

 achieved any success have ever done so, and second because 

 man is rapidly making all Nature artificial, and he must 



