Part II.] NATURAL ENEMIES OF BIRDS. 221 



brings her destructive forces to bear against the project. The 

 natural enemies of game and poultry, finding in the crowded 

 birds a numerous, easily accessible source of food, attack eggs, 

 young and adults, and unless every resource is used to pro- 

 tect them, the poultryman, the sportsman or the gamekeeper 

 will reap neither pleasure nor profit from bis venture in propa- 

 gation. 



Bearing in mind that only when man steps in and in some 

 way disturbs the biologic balance does it become necessary for 

 him to destroy the natural enemies of birds, let us inquire 

 under what circumstances this destruction may be proper. 



WHEN MAN MUST REDUCE NATURAL ENEMIES. 



]Man must reduce (not exterminate) certain natural enemies 

 of birds: (1) when he attempts to rear poultry or game birds 

 in excessive numbers; (2) when, because of the disturbance of 

 the biologic balance caused by extensive agricultural opera- 

 tions, he needs to increase the number of insectivorous birds 

 beyond what the land naturally would support; (3) when the 

 most sagacious natural enemies of birds, like the fox and the 

 crow, — their own enemies having been reduced or exterminated 

 by man himself, — take advantage of the extra protection and 

 food afforded them in civilized communities and thus become 

 too numerous and too destructive: (4) wherever man hunts 

 and destroys wild game he may also reduce somewhat the 

 numbers of the enemies of the game and thereby relieve the 

 game of a part of the pressure brought to bear against its 

 increase. In all such cases discrimination must be used, and it 

 is unsafe to reduce too far the numbers of any but the most 

 powerful predatory animals. 



MAN THE ONLY EXTERMINATOR. 



It is now believed that even before historic times man be- 

 came the greatest natural enemy of birds and the chief exter- 

 minator of species. There is every probability' that giant Pleis- 

 tocene birds, such as the moas of New Zealand (the largest 

 being able to reach a height of twelve feet) and the iEpyornis 

 of Madagascar, were exterminated by primitive man. 



There is no evidence, however, to sustain the belief that 



