Productivity aiid Populations 317 



Testing these hypotheses with ruffed grouse is difficult owing 

 to the lack of adequate quantitative data. There is some indication 

 that grouse de<:imations may be more severe in the North and West 

 than in the East. Both King (1937) and Fisher (1939) have re- 

 corded losses exceeding ninety per cent for early fall populations 

 in Minnesota and Michigan respectively. The New York State hunt- 

 ing statistics between 1923 and 1935 indicate a decline of about 

 seventy-five per cent although this may be lower than the actual 

 drop, since no hunting was permitted in 1928 and 1929, years of 

 lowest abundance. No such severe declines have occurred in the 

 Northeast in the 1930's to correspond with the records from the 

 North-central states. 



How the ruffed grouse die-offs compare with those of other species 

 as to severity is not wholly clear. There is little doubt but that they 

 are less violent than the decimations of some of the rodents, such as 

 the lemmings, the red and gray squirrels, and the snowshoe hare. 

 There is some evidence (Criddle, 19^30) that sharp-tailed grouse 

 fluctuations are more \iolent than those of the ruffed grouse. Other 

 species, as the bobwhite quail (in its northern range), the red fox, 

 and some other predatory species exhibit fluctuations alleged to be 

 cyclic in nature that are less severely marked than those of ruffed 

 grouse. 



The contention that a cyclic species exhibits its most violent 

 changes in population at the periphery of its range, a doubtful 

 attribute at best, does not hold with grouse. The species is notably 

 stable in its southern Appalachian range. Chapman (1939) says: 

 "There is no evidence of a grouse cycle in Southern Ohio." 



6. Cyclic Mortahty Primarily Affects Young Birds. 



It is believed that all, or practically all, the losses of grouse in a 

 cyclic dechne are birds of the year. King indicates this to be true of 

 ruffed grouse and Green and Evans (1940) come to essentially 

 the same conclusion for snowshoe hares. This is likely to be true 

 whether the losses are cyclic or not. There are normally more young 

 birds than old, and the resistance to all decimating agencies is lower 

 with the young ones. This is truer when the birds are mere chicks 

 in the brood period. Abnormally high losses on the Connecticut 

 Hill area in 1933 and 1935 were both the result of losses in young 

 birds. This may not always be the case, however. The 1937 spring 

 population fell to the lowest level since 1931 as the result of winter 



