316 The RufiFed Grouse 



lease, October 18, 1933), and 'up to the present time it has affected 

 ruffed grouse principally, and on areas where the birds were most 

 plentfful ... In many instances (it) is affecting only townships 

 ... In other counties practically the whole grouse population seems 

 to be affected . . ." Out of thirty-four counties submitting reports, 

 grouse were seriously affected in eleven, but were normally plentfful 

 or better in twenty-three. 



Experience in New York indicates great local variation in popu- 

 lation trends. One portion of Connecticut HiU had a high popula- 

 tion in 1927 when most coverts in the region were at a low ebb. 

 Throughout the years of the detailed studies in several areas in 

 New York, some cover units would be at a peak while others were 

 low. Broad effects result from the cumulative effects of local condi- 

 tions. When the majority of coverts aie up, there is a pronounced 

 peak; when the greater proportion are down, there is a trough in 

 the general curve of population. But at any time there will be some 

 coverts, and some areas or regions, that are contrary to the general 

 condition. 



Clarke (1936) concluded: "Periodically, ruffed grouse popula- 

 tions in Canada suffer serious diminutions in numbers. They do 

 not occur simultaneously throughout the whole country. Even in 

 Ontario there are local differences of at least three years in the 

 time at which diminution begins." Fisher (1939) says: "The fluctua- 

 tion in abundance of ruffed grouse is not uniform throughout its 

 range in Michigan. The birds may be increasing in some localities 

 while decreasing in others." 



This evidence is supported by recent writings on the irregular 

 nature of mammalian cycles too. MacLulich (1937) found cycles in 

 varying hares to be regional phenomena arising from changing 

 local conditions. Cross (1940) concluded that ". . . periods of 

 maximum abundance in the nmnbers of (red) foxes in Ontario are 

 regional phenomena and not province-wide . . ." 



5. Severity Varies with Location and Species. 



The typical cyclic surges are most severe in the North and West, 

 less severe to the South and East, with any given species. Likewise, 

 the severity, that is the degree of loss in the die-off periods, is con- 

 sistently greater with some species than others, as for example with 

 the voles and lemmings in the north. It is most severe on range ex- 

 tended from its indigenous range. 



