568 FLUCTUATIONS IN GROUSE ABUNDANCE 



spite of this lack of harmony throughout the range of the species in the onset of major declines 

 in abundance, in most instances there have been a year or two during which grouse have been 

 generally scarce. 



To analyze the problem further it may be pointed out that the average status of grouse abun- 

 dance throughout a regional unit of range represents the sum of conditions on the many local 

 areas involved. Moreover, while it is obvious that if the average abundance over a region 

 fluctuates the populations of individual areas must also fluctuate, it does not follow that they 

 all exhibit the same pattern. That in actuality they have not done so is evident from the rec- 

 ords in the literature. In these accounts one finds all degrees of variation from agreement to 

 direct opposition within the same region at the same time. 



As Bump°° commented "it is a rare year in which there does not occur some apparently 

 reliable report indicating both abundance and marked scarcity in the same part of this range". 

 Leopold"'^ in assembling data relative to the onset of the decline of the '20s in Wisconsin, found 

 "a completely irregular incidence, such as moths would make in invading a carpet". Simi- 

 larly Green and Shillinger"" observed that pojiulations "may become abundant at the same time 

 and die off at the same time in widely separated areas, whereas in two closely adjacent areas 

 an abundant population may develop in the one while animals* are dying off in the other". 

 In correlating the available information for Ontario and other provinces in Canada. Clarke'' 

 found "local differences of at least three years in the time at which diminution begins". The 

 same author, in describing his method of summarizing questionnaire information'' indicates 

 that reports of both abundance and scarcity were received from the same region during most 

 years. Gross'" recorded a parallel situation for New England. In 1937 Connecticut" reported 

 "islands of abundance in a fairly general scarcity". A great many other accounts also attest 

 the fact that such dis])arity among local grouse populations lias been of frequent occurrence. 



During the most recent jjcriod of severe grouse shortage in New York (1927-28) Allen" 

 reported that the birds were "still apparently in normal numbers" in a few places in the cen- 

 tral and northeastern parts of the State. In fact the ]jo])ulatioii of one compartment of the 

 Connecticut Hill study area is known to have been high in 192f). Likewise W oodruff"' quoted 

 a State game protector to the effect that in Allegany County (N. Y.) in 1907. when grouse in 

 the Northeast generally were at a very low level, "Partridge seem to be more numerous than 

 last year — fifty birds seen a day". 



During the present Investigation the grouse populations of the two princi])al study areas 

 have followed similar courses during some years and at other times have been divergent (fig- 

 ure ,S8)^. In 1931. while the Coinieclicut Hill area was still recovering from the scarcitv of 

 a few years before, the numl>cr of birds on the Adirondack area was at as high or higher a 

 level as at any time after that. From 1932 to 1939 both areas exhibited generally similar trends 

 althr)ugh the low point reached on the northern tract in 193.'i was relatively much lower than 

 the depression of 1936-37 on Coimecticut Hill. Since 1939 tlie trend on the latter area has been 

 steadily downward while this has not been the case on the other. In this connection it may 

 be noted that the minor trough on (^.onnecticut Hill in 1936-37 coincided with the status of 

 grouse reported at that time for New York as a wlnilc iiiul the Northeast in general. 



Fisher's data for Michigan"' afford another example of a lack of synchronism because, al- 



* The tenn animal wat used here as applyini; to both the {rouse and varying hare. 



A "The etrpss o! the percentage rrportlng 'abundant* over those rcporlinf 'scarce* was the figure used in plotting the graphs.** 

 T It is reroRni/ri) that llicse imto arfiis difTrr holh in sire atiit in rhararler, the Ctmnri'lii-ul Hill trmt hring madr up <>( a num- 

 ber nf separated coverts while on the Adirondack unit. the gniuse cover is continuous. In the absence of more extensile data, 

 however, their comparison seems warranted. 



