POPULATION CHARACTERISTICS 



523 



inated in some other way. Game managers have used the term carrying capacity to denote 

 this limitation. 



Carrying capacity is a property of the environment and accordingly differs in various habi- 

 tats. Basically the determining factors are food and shelter, as is most clearly seen among 

 the hoofed mammals which exhibit no apparent psychological intolerance of crowding. With 

 respect to grouse it is associated primarily with shelter values, no indication of food scarcity 

 having been observed*. Furthermore, its effect is ultimately limited by the saturation point 

 of the species'^ although few of the coverts surveyed in this study have evidenced such high 

 quality. Whatever the variations, however, any area of range has a fundamental capability 

 of supporting only a certain number of birds. 



The most significant measurement of this relationship is the number of individuals remain- 

 ing after the critical period each year. For the ruffed grouse in the Northeast this falls at 

 the end of the winter season. Other things being equal, the population of a given area should, 

 in theory, return to about the same level each spring regardless of the extent to which the 

 density of the -preceding fall may have exceeded it. 



But, although this concept seems fundamentally sound, the number of grouse recorded from 

 year to year at this time on the areas studied by the Investigation has not been constant. 

 Rather they have fluctuated considerably as shown in table 79. 



TABLE 79. Ut';iATIVE SECURITY OF FALL GUUUSE POPULATIONS ON CONNECTICUT 



HILL AND ADIRONDACK AREAS— 1930-19H 



* Represents fall of eacfi overwinter period. 



A Figures in parenthesis computed from number of adults remaining the following 



September on basis of average summer losses fur preceding years since no spring 



census was made on this area after 1938, 



Considering the average of the two highest survivals on Connecticut Hill as an index, the 

 carrying capacity of this area must be at least 270. This level was associated with the high 

 fall densities of 1932 and 1934. Yet in 1931, 1933, 1937 and 1940 populations exceeding it 

 only slightly suffered substantial mortality. On the other hand, the low number present in 

 1930 lost few birds. 



The less densely populated Adirondack area at first glance appears to have maintained 

 a more stable level, especially from 1933 to 1936. But the residual number of grouse during 

 these years cannot be considered to represent carrying capacity as nearly twice that many have 



* See Chapter IV, p, 229. 



A See discussion of Saturation Point, p, 521. 



