VOL. VIII.] LAND-RAIL INQUIRY REPORT. 91 



we are too apt to explain things as the direct result 

 of human instrumentaMt3^ I do not doubt that 

 civihzation has had a vast effect on the whole of nature 

 in this and all other civilized countries ; but this effect 

 is brought about much less by actual destruction of 

 species than by indirect means : when man reclaims 

 virgin ground he changes the balance of nature far 

 more even than when he becomes an inveterate collector 

 of specimens. If it could be shown that any of the 

 changes in agriculture in the last fifty years had in- 

 directly affected either the food-supply or the supply 

 of nesting-sites of the Land-Rail we should soon know 

 the cause of its decrease ; but at present I doubt if 

 enough is known of the bird's requisites to permit 

 even of speculation on the subject. 



The decrease of the Land-Rail, however, is no mere 

 isolated phenomenon, and it must not be treated as if it 

 were. Many other species show a marked tendency 

 either to decrease or to increase, and we know no more 

 why the Redpoll and Hawfinch have increased than 

 why the Land-Rail and Martin have decreased. I 

 am incUned to think that ornithologists, in common 

 perhaps with other naturahsts, have been too much 

 disposed to regard evolution as a process which 

 works so slowly that no natural change can be 

 expected to show itself in any period short of a 

 million years ; and consequently, when they see an 

 evolutionary change (even of distribution) taking place 

 rapidly under their own eyes, they resort to the 

 explanation that man is upsetting nature. How- 

 ever this may be, it is clear that a proper com- 

 prehension of the problems of distribution, in particular 

 those of changing distribution, can only be gained by 

 a study of ecology ; and from the ornithological point 

 of view ecology is still in its infancy. If this Land- 

 Rail inquiry should serve to stimulate a further study 

 of ornithological ecology it wiU have had some value ; 

 and in any case I hope it may make it easier for 



