Game Cycle 14 1 



sonal experience or public event of known date. Such "association datings" un- 

 doubtedly carry a probable error of one or two years, but this error probably does 

 not increase greatly with the lapse of time. About one third of the numbered 

 curves on Chart A are association datings. 



Of the total of 119 observers, 17 based their observations on shooting 

 journals, personal records as ornithologists or taxidermists, or published works. 

 This constitutes about one sixth of the total. 



The remainder, comprising about half of the total, are based on mere 

 recollection. Such observations were not accepted, however, without checking the 

 observer's statements against each other. It was found that many country people 

 maintain a surprisingly complete mental chronology, based not on years, but on 

 the number of years ago. The probable error in such recollections of course in- 

 creases with elapsed time. 



Chart 7 is divided horizontally into 15 geographic units, each consisting of a 

 group of counties. The vertical position of any species symbol in any geographic 

 unit indicates the status of that species during the year indicated by the vertical 

 line. Thus a hollow square near the top of the 1912 line in the first (upper) 

 unit means that ruffed grouse were "high" in the year 1912, while a hollow square 

 near the bottom of the 1917 line means that ruffed grouse were low in 1917. 

 "High" and "low" are not based on any numerical value or measurement, but 

 rather on a general judgment of how the observer considered abundance during 

 any certain year to compare with normal or average abundance for his locality. 

 This is of course inaccurate, but the only way I could think of to use the recol- 

 lections of observers. The scientific reader should not forget that the woodsman's 

 daily observations at all seasons build up a much more reliable "standard" than 

 his own sporadic "field trips." The hope was to get a sufficient quantity of 

 observations to counterbalance the lack of a numerical scale. 



Where symbols are connected by lines for a series of years, it represents 

 consecutive observations in a single locality, either by a single observer or by 

 several observers in agreement about that locality. 



The number opposite each species symbol refers to an index giving names 

 of observers and exact locality within the geographic unit. This index appears 

 in the appendix, item (C). Thus the number "22" which appears on the graph 

 above used as an example means (see Index) that Haskell Noyes is authority for 

 it, and that it refers to the Brule River in Douglas County. 



Where two or more symbols show high and low respectively in the same 

 year in the same geographic unit, reference to the numbers will show that each 

 pertains to a separate locality. There are any number of cases where various de- 

 grees of both high and low occurred simultaneously in the same unit or group of 

 counties. 



Where a graph begins or ends with a line having no species symbol at the 

 end of it, it means that the observer remembered a rise or fall, but could not 

 exactly place the time of its beginning or end. 



