PRODUCTIVITY OF POPULATIONS 



531 



TABLE 83. RELATIONSHIP OF DENSITY OF BREEDING POPULATIONS TO SURVIVAL 

 DURING THE BROOD PERIOD ON CONNECTICUT HILL AND ADIRONDACK 



STUDY AREAS— 1930-1942 



* Group I — years having a breeding population density, on Connecticut Hill ol under 6 per 100 acres, on the Adirondack area 



of under 4. 



Group 11 — years having densities between 6 and 10, and over 4 respectively. 



Group HI — years on Connecticut Hill with densities over 10. 

 A Analysis by chi-square shous that on Connecticut Hill Group 11 was very close to the total average while Groups i and 11! 



were signiBcantly different. 



Adult Period 



In appraising adult survival, September 1 each year has been taken as a starting point be- 

 cause this is the time the voung of the year are considered to "come of age". By the same 

 date the following year slightly less than half have been left as an average, most of the loss 

 having taken place prior to the breeding season (table 84). On Connecticut Hill, however, 

 a much higher survival followed the low fall populations of 1930 and 19.31. A similar rela- 

 tionship was observed on the Adirondack area in 193.5-36. 



TABLE 8t. 



ADULT SURVIVAL RECORDED ON CONNECTICUT MILL AND ADIRONDACK 

 STUDY AREAS^193(i-19H* 



*Year indicated is that of the beginning of each September 1 to August 31 period. 



Alti 1933 on the Adirondack area and in 1937 on Connecticut Hill the number of birds moving into the area during the summer 



e.\ceoded the iiilliiher k)Sl. 

 tl^stimate made in Jtinuary 19.'i2 and therefore somewhat below September level. 

 jSpring censuses were discontinued on this area after 1938. 



As has been discussed in Chapter VII, some 80 per cent of the losses during this period 

 have been attributable to predation, the remainder resulting largely from accident and disease. 

 Just what the relative importance of these minor causes has been, however, is difficult to judge 

 because few of the dead grouse located during the survey have been found in a thoroughly 

 fresh condition that would permit recognition of disease. On the other hand, field experi- 

 ence indicates that accidents are infrequent and the collection of specimens for pathological 

 examination has revealed a very low incidence of disease. At the same time one must re- 



