Ruffed Grouse 153 



During the low year 1929, R. T. King, the institute fellow at the University 

 of Minnesota, made a census showing about one bird per 80 acres on a large 

 tract in Pine County, Minnesota. This census is relatively accurate, but being 

 made during a low year, it throws no light on the crucial point of maximum 

 density. 



Rough measurements of fluctuation between years are obtainable without a 

 determination of density, and hence are more numerous. The findings are sum- 

 marized in the Table 27. 



The first three observers counted grouse on the same tract or route in dif- 

 ferent years. The last is a bag record, but must be interpreted in the light of the 

 legal season limit of 25 birds, which prevents the kill figures for the high years, 

 192345, from showing the full difference in population as compared with low 

 years. 



The Hornberg count shows three times as many birds on the same road in a 

 high year as in a low one, the Burr count 30 times as many on the same tract, 

 and Prof. Moore's count as 15 times as many in a medium year as in a low one. 

 The Kinziger journal shows 51 times as many birds killed in a high year (1914) 

 as in a low one when hunting was done (1916), although it is improbable that 

 the hunting was as intensive in the latter case. 



These counts, taken in conjunction with a great number of general impres- 

 sions gathered from less compete evidence, convince me that the cyclic fluctuation 

 in ruffed grouse runs in excess of 90 per cent above and below normal or average, 

 in high and low years respectively. 



The vital question of whether or not the species has a saturation point must 

 go unanswered as far as evidence is concerned. Mershon's statement, however, 

 that market hunters saw as high as 1,000 birds per man per day, plus a good many 

 other mental impressions, leads me to suspect that this species, which fluctuates 

 the most violently in abundance, is the least subject, at least in the Forest Belt, 

 to that limit of density which has elsewhere been called the saturation point. 



Symptoms Associated with Mortality. The symptoms listed in Table 

 28 were observed by laymen, and are therefore not to be accepted as establishing 

 the identity of any parasite or disease. The table is nevertheless valuable in 

 indicating that diseased birds occur at all seasons of the year, and that parasites are 

 conspicuous before heavy mortality has set in. 



One other significant observation could not be expressed in tabular form: 

 Prof. R. A. Moore, head of agronomy in the Wisconsin Agriculture College, states 

 that during the mortality years 1925 and 1926, near his cottage at Armstrong 

 Creek, Forest County, Wisconsin, such young birds as he saw during the summer 

 had not grown to normal she. In short, he claims a stunted growth. 



Peculiarities of Distribution. The cause of cyclic fluctuation in ruffed 

 grouse is still such a total enigma that it seems worth while to set down any 



