Preface 



The ruffed grouse is a creature that has evolved over milHons of 

 years along with thousands of contemporaries in the animal and 

 plant world of today. The fact that the species exists at all is evi- 

 dence of its ability to compete successfully in a world of constant 

 strife. Like all other creatures it developed certain innate reproduc- 

 tive abilities, together with skills of escape and concealment that 

 enabled it to increase and maintain its numbers. Also, other condi- 

 tions developed to offset these increases. These opposing forces that 

 play on each species tend to preserve the status of each. In discussing 

 this mechanics of ecology for game species these forces have come to 

 be called the factors of abundance. 



These elements, or factors, that control the numbers of a species 

 are essentially the same for all. But the different factors assume 

 vastly different degrees of importance with different species and 

 under varying circumstances with each species. Under any set of 

 conditions, some one of the factors will keep grouse from increasing 

 beyond the level it actually does; or, stated another way, will reduce 

 grouse to the minimum numbers they decline to prior to the breed- 

 ing season. This limiting factor does not cause all the mortality; 

 merely the ultimate part. But if the limiting factor is reduced or 

 eliminated, some other will take its place at a somewhat improved 

 level of population. There will always be some factor to set the 

 actual limit of survival for each species. And other factors, no matter 

 what their importance or how man may affect them, cannot change 

 the survival level of our game species. The limiting factor deter- 

 mines the greatest number that will survive on a particular area. 



The eight major factors that control grouse populations may be 

 divided into two types, as shown graphically in Fig. 1, page 3. The 

 ones that compose the environment are in one group, while those 

 that are inherently a part of the species are in the other. These we 

 will describe briefly. 



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