CONTENTS, 



PAGE 



Introduction, ...... . 7 



Natural enemies regulate the numbers of animals, . 7 



Natural enemies preserve the fitness of the animals on which they prey, 8 



Some natural enemies regulate others, . . 9 



Useful species may become harmful if not held in check by natural enemies, . 10 



Natural enemies supplement and check one another, . . 12 



Natural enemies tend to keep the numbers of birds at their normal limit, . 13 



Natural enemies oppose man's attempts to secure abnormal increase, . 15 

 When man must reduce natural enemies, ..... .16 



Man the only exterminator, ..... 16 



Man's satellites and assistants in extermination, ... 17 



Introduced domesticated enemies, ....... 18 



Cat, . 18 



Dog, . 18 



Hog, . . 19 



Grazing animals, ....... 19 



Brown rat, . . ..... 20 



Feral enemies, ........... 20 



Mammals, ..... ... 20 



Red fox, . . 20 



Minks, . 22 



Weasels, . 22 



Skunk, . 24 



Raccoon, . ......... 24 



Squirrels, . . ........ 25 



Red squirrel, ......... 25 



Gray squirrel, . . . . . ■ . . . .26 



Flying squirrel, ......... 28 



Chipmunk, ......... 28 



Muskrat, . 29 



Mice 29 



Field mouse or meadow mouse, ...... 32 



Deer mouse, ......... 32 



Deer, . ......... 33 



Birds 33 



Shrikes, ........... 33 



Grackles or crow blackbirds, ....... 34 



