XX LNTRODUCTION. 



we wish to do the same for this practical problem of the 

 economic value of birds. 



One thing is certain, that birds should always get the 

 benefit of the doubt, and that an order for destruction 

 should be preceded by an order for examination. In 

 illustration of this, I may be allowed to quote a very 

 instructive instance which I owe to my friend Mr W. P. 

 Pycraft of the British Museum. In the Emu for 

 1908, Mr A. H. F, Mattingley tells that on the Murray 

 River swamps and ' billabongs,' and on certain lakes, 

 Cormorants are now found nesting in hundreds, where 

 they were formerly in thousands. Owing to ruthless 

 destruction by persons seized with the idea that they 

 were benefiting fishing by destroying 'shags,' but a 

 tithe remain. Bitter complaints are now made of the 

 scarcity of fish. This is due to the fact that the areas 

 in question are the spawning-grounds of the food-fishes, 

 and this spawn is now devoured by myriads of crabs and 

 other crustaceans, by turtles, and by eels and other 

 fishes. Later on these creatures batten on the fish-fry. 

 The Cormorants, it is now discovered, fed on the crabs 

 and eels; hence the destruction of the Cormorants has 

 meant the removal of two checks on the increase of these 

 undesirables. During the time the Cormorants were breed- 

 ing the bulk of their food consisted of crabs, the 

 spawning -fish being too large to swallow. In these 

 swamps Phalacrocorax melanoleucas, P. carbo, and Plotus 

 novcehollandicc swarmed, sure of a rich food-supply for 

 their young. In proportion as the ranks of the 

 Cormorants were thinned, the ranks of the crabs, eels, 

 and other spawn-eaters increased. This case seems to us 

 to point with great clearness to the obvious conclusion 

 that before we seek to control nature by drastic measures 

 we should first of all get a grip of the facts, and that 



