544 PRODUCTIl IT) OF GliOLSE POPULATIONS 



per cent in 1934 as a result of a very high fall population and a severe scarcity of buffers. 

 Then following the nearly complete lack of a crop of young birds in 1935 it fell to 2.0 per 

 cent. 



That the per cent of mortality based on the number of individuals entering a given life 

 period is frequently a poor indication of the relative weight of the losses during that period 

 with respect to the total reduction of potential each year must be borne in mind. For in- 

 stance, in 1936, 76.7 per cent of the chicks hatched on Connecticut Hill failed to survive un- 

 til fall. Yet because of unusually high losses during the breeding and nesting season this 

 represented only 18.1 per cent of the total drop in potential. 



TABLE 93. AVERAGE ANNUAL LOSS OF REPRODUCTIVE POTENTIAL ASSOCIATED WITH 

 EACH LIFE PERIOD ON CONNECTICUT HILL AND ADIRONDACK AREAS 



—1930-1912 



* Includes only period through winter of 1937-38. 



Using the breeding population each year as a starting point the data have been tabulated 

 for the Connecticut Hill and Adirondack areas*. The relationships of greatest interest to 

 the sportsman and game manager are illustrated graphically in figure 51. 



As has been pointed ouf^ the basic attributes of reproduction — sex ratio, breeding, and the 

 number, fertility and viability of eggs — have remained quite constant. Thus the potential num- 

 ber of chicks each year has been closely correlated with the breeding population. But be- 

 yond this point the varying vicissitudes of the nest, brood and adult jieriods have resulted in 

 lironounced fluctuations in produilix il\ . 



On Connecticut Hill the breeding population gained steadiK frdin 1 930 through the spring 

 of 1933 in spite of increasing overwinter mortality. Then, as a result of unusually high 

 losses throughout the breeding, nesting and rearing seasons, a net loss had taken place by 

 the fall of the latter year which was reflected the following spring. Productivity was slightly 

 above average in 1934, however, and next to the highest September population observed was 

 recorded. But brood losses the following summer were abnormal due to the flood in early 

 July and another failure in the crop of young occurred which, although the ensuing winter 

 mortality was average, resulted in the second net reduction in lirceding stock. A further re- 

 duction in 1936-37 was associated with the highest overwinter mortality noted. This was cor- 

 iflated with a marked scarcity aiming buffer species. .After this the po[)ulatii)n gained steadily 

 until the spring of 1940 when a liigh rate of loss during the nesting period brought about a 

 fourth set-back. Nevertheless. reci)\erv again cummenccd in 1912. although a high brood 

 mortality brought the Se|)tcinl)cr pojiulation to a level very little above that of the spring. 



On the Adiroiulaik area the number of grouse was comparatively high when work was 



* See Appendix, p. 862. 

 A See Chipler VIII. 



