THE EAGLE AS ELIMINATOR 345 



an idea lingered that the Great Auk might he re- 

 discovered in the Arctic regions, an area which it, 

 as a matter of fact, never reached. When not in- 

 sular in habitat, birds have generally become exti-nct 

 through the habit of colony-breeding, a useful one 

 in wild nature, because fighters like Terns and 

 Weavers may beat oflE an enemy ; and in any case 

 the enemy, if always successful in raiding, is never- 

 theless likely to get tired of eating the same food, 

 a change of diet being acceptable and generally 

 essential to vertebrates. 



When an Eagle used to alight on one of the trees 

 inhabited by our free colony of Night-Herons and 

 Ij)warf CoTmoT3Lnis(Phalacrocorax javanicus) in the 

 Calcutta Zoo, a roar went up from the combined 

 cries of the terrified birds like a train entering a 

 lailway-station ; yet I have not the slightest 

 doubt that, though they made no attempts to 

 mob him, he would not have broken up the colooy 

 even had he not been very unnecessarily shot. 

 But then no human inroad was being made on these 

 fishing-birds as well; when man wants birds and 

 their eggs for his own use, to say nothing of other 

 animals such as sheep, to which, for instance, Eagks 

 are enemies, he must inevitably make war on the 

 birds of prey; though there is no need to exter- 

 minate them completely, and as a matter of fact 

 no bird of prey has been eiterminated as yet, 

 though many have been driven from districts they 

 once occupied. Several Parrots have, however, 

 been exterminated from islands, Parrots being both 



