CHARACTERISTICS 563 



More recently grouse in Pennsylvania. Maine and much of eastern Canada variously 

 dropped to low levels of abundance in 1943 or 1944* although in Ontario the decline of 1943 

 was minor. Again the intervals involved were of eight to ten years in length. In New York, 

 Connecticut, Massachusetts, Vermont, and New Hampshire there has still (1944) been no 

 significant general decrease in the present decade. It may be noted, however, that in these 

 states 1944 was only the eighth year since the last depression although, as has already been 

 pointed out, the latter was not marked in New York. 



In the Lake States (Minnesota. Wisconsin and Michigan), these fluctuations have exhibited 

 an even greater degree of regularity. There, considering only records since 1900. a condition 

 of general scarcity was reached in the years 1907-08, 1916-17, 1924-26, 1934-3.5, and 1943-14 

 (figure 59). The intei"val involved has varied from eight to ten years with nine the most 

 frequenf^. The fact that so high a degree of periodicity has now been recorded for four suc- 

 cessive lows in this territory seems especially significant. 



The intervals which have elapsed between recurrent times of high abundance are not so 

 clear as those between lows. The records are frequently indefinite as to just when the grouse 

 populations of different regions reached a high level following the various periods of scarcity. 

 The same is true, although to a lesser degree, with respect to peak numbers. A better criterion, 

 in view of the available data, seems to be the last year of high abundance preceding a major 

 decline. 



In New York, according to Conservation Department records and other data, 1906, 1914, 

 and 1923 seem to have been such vears. So was 1935. although it was followed by only a 

 minor depression. Thus, in this State, three inter\als of eight, nine and twelve years, respec- 

 tively, have been experienced since 1900. In lite fall of 1944. eight years after 1935. the 

 grouse population over the State as a whole was still at a high level. 



Elsewhere in the northeastern United States and eastern Canada intervals of eight to ten 

 years have predominated. In much of the East, however. 12-year periods occurred between 

 1923 and 1935. In Pennsylvania this was followed bv one of seven years associated with the 

 minor low of 1936-37 after which the population fell off sharply in 1943. In New Bruns- 

 wick a short-lived decline occurred in 1940 but the birds were again numerous in 1942 before 

 the scarcity of 1943. Throughout most of this region the records cover four periods since 

 the beginning of the century, but in southern New England, as in New York, only three are 

 involved, although grouse numbers have recently been at a high level for several years. 



As in the case of scarcity a remarkable degree of regularity has existed in the Lake States 

 throughout four successive periods with respect to the recurrence of grouse abundance. The 

 interval has varied from eight to ten years in length, nine years being the most frequent. 



These data thus lead to the conclusion that the general abundance of grouse over the major 

 regions of its range in eastern Canada and the northeastern and north-central United States 

 has, during the present century at least, exhibited recurrent fluctuations between high and low 

 levels, the intervals between which have varied from eight to ten years in the case of lows and 

 from seven to twelve years in the case of highs; that in both cases nine years has been the 

 most frequent^: but that, in spite of these narrow limits, there is no evidence of a precise 

 periodicity. 



* Peraonal corii'si>oudence with State anil Provincial officials. 



A Leop.ild^sr. suinniari7p(i data taken principally from the north-iciitral states for the year* 1902-27 as indicating two intervals of 



ten tn eleien years hetween peaks of ahiindance and two intervals, one of twelve years and one of nine years, between troughs. 



giving; "an average period of a fraction over ten years". But he lumped the several species of grouse together while the data 



used ahove apply to the ruflcd grouse only. 

 t The means of the records for tlie intervals between high ao.i low abundance as shown in figure S9 are 9.3 and 9.2 years re. 



speclively. 



