PRODUCTIVITY OF POPULATIONS 



543 



though here the population was already relatively high when work was begun in 1932 and no 

 net gain was experienced until 1936. Considering the entire period covered on each tract, the 

 grouse population has just maintained itself. In fact, in spite of a greater average production 

 ratio on the northern area as of the end of the summer, there has been no significant differ- 

 ence in the corresponding values by the following spring. 



TABLE 92. PRODUCTION RATIO OF GROUSE BREEDING POPUL.\TIONS ON CONNECTI- 

 CUT HILL AND ADIRONDACK STUDY ARE.\S AS OF THE 

 FOLLOWING BREEDING SEASON— 1930-1942 



* Year stated is that of the beginning of each period (i.e. 1930=1930-31). 



A See footnote (*) of table 87. 



t April of the following year in each case. 



On the Pharsalia area the average over six years between 1931 and 1940 was 1.03 and for 

 eight years on the Catskill area during the same interval it was 1.05. On the latter the ratio 

 recorded in 1931-32 (3.27) was the highest observed throughout the study. 



In general the trend in the two production ratios (tables 87 and 92) has shown considera- 

 ble similarity over the period of study on both the Connecticut Hill and Adirondack areas, be- 

 ing stronger on the former. Obviously the value for the full year must be less than that for 

 only a part of that time. But when the two are examined with respect to the relationship of 

 specific values little correlation remains. It may be mentioned, however, that in no instance 

 did a net loss of breeders on Connecticut Hill follow a production ratio in September ex- 

 ceeding 2.0. 



With respect to the three life periods the distribution of the total loss of reproductive po- 

 tential has differed somewhat on the two main study areas (table 93). 



As has been pointed out productivity at the end of the brood period has averaged somewhat 

 lower on Connecticut Hill than on the other area chiefly as a result of higher breeding and 

 nesting losses. Accordingly, the role of overwinter mortality has been proportionately great- 

 er on the Adirondack tract. 



The data for individual years, however, have often varied considerably from the above pat- 

 tern. For example in 1930 and 1931, when the grouse population was low and increasing on 

 Connecticut Hill, less than 10 per cen' of the total loss of potential occurred during the over- 

 winter period. Similar values were associated with the low fall productivity experienced in 

 1933 and 1935. On the Adirondack area the proportion lost during this season rose to 46.0 



