Game Cycle 137 



Per Cent Mortality by Species. 



(a) Four Wisconsin samples of ruffed grouse population seem to have been 

 3, 30, 15, and 51 times as abundant in a high or medium year, as in the next suc- 

 ceeding low one of the last cycle. 



(b) It is believed that the fluctuation from "normal" or average population 

 density runs as high as 95 per cent in ruffed grouse and snowshoes, and as high 

 as 75 per cent in prairie chickens. 



That the per cent of mortality is higher in ruffed grouse than in prairie 

 chickens is corroborated by an independent investigation made by W. B. Grange, 

 who compiled the recollections of 70 State game observers. This compilation is 

 presented graphically in Chart 9- 



Lag Between Localities. 



(a) In 33 selected localities studied during the survey and scattered over 

 Wisconsin, ruffed grouse were hit by the last cycle in 30 localities between 1925 

 and 1927, and in none later than 1927. Some were hit as nearly as 1922. The 

 year 1927 was the most frequent date of the first severe mortality. 



Expressed in percentages, the lag in point of time is: 



1922 3 per cent of total localities 1925 15 per cent of total localities 



1923 per cent of total localities 1926 36 per cent of total localities 



1924 6 per cent of total localities 1927 40 per cent of total localities 



Grange's game observers likewise reported the bulk of the mortality in 

 both ruffed grouse and prairie chickens as falling in 1925, 1926, and 1927, with 

 some evidence of continuance (in prairie chickens) in 1928. The bulk of the 

 lag, as indicated by the horizontal recession of figures from the curves in Chart 

 9, lies mostly within a period beginning two years before and ending one year 

 after the median curve or "most frequent" date. 



(b) Since the last cycle shows a lag of at least three years within Wisconsin, 

 with the most frequent date toward the end of the three-year period, and since 

 fragmentary information from other States indicates a similar dispersion of dates, 

 it may be said as a working assumption that the lag is so great as to almost ob- 

 scure the cycle. It is only during the year when the median shows a peak that 

 some localities are not low, and only during the year when the median shows a 

 trough that some localities are not high. 



Order of Mortality by Species. 



(a) No clear evidence of any fixed order of mortality as between species was 

 found during the survey. 



(b) Of 15 cases in which mortality in two or more species was dated in the 

 same locality, ruffed grouse fell off first in eight and prairie chickens first in five. 

 Rabbits were never first, but cottontails in one case fell off simultaneously with 

 ruffed grouse. The earliest species to fall off seems usually to be only one year 

 ahead of the last. The order of recovery seems to be the same as the order of 

 mortality. 



Grange's independent investigation (Chart 9) indicates that prairie chickens 

 began to decrease slightly before ruffed grouse began to decrease slightly, but 



