^5 A GROUSE HUNTER 379 



This ratio, being based on total birds flushed, is considerably smaller than the ratio of 

 birds bagged to birds shot at which is the correct test of success in terms of shooting skill. 

 This ratio was not determined on the 1930 and 1931 check areas but in 1936 it proved to 

 be 27.1 per cent or about one bird bagged for every four shot at. 



Effect on Grouse Abundance of Man's Hunting 



Whether the hunters harvest 10 or 20 per cent of the grouse is of importance from the 

 game management point of view, mainly as it affects the continuing abundance of the species. 

 Under ideal conditions, the hunting loss should be the maximum that would leave an 

 optimum breeding stock for the succeeding year. To illustrate, assuming an area with a 

 good grouse population in the fall, there might be two birds of the year for every pair of 

 breeders existing on the area the previous spring. In such a case, if there were no other 

 sources of mortality from October through the next breeding season, the hunters could 

 harvest two birds of every four, or 50 per cent, and still leave the optimum breeding stock. 

 Actually, however, this figure represents the percentage from which must be deducted the 

 anticipated winter loss due to other causes, in order to get the maximum allowable harvest 

 by hunting. 



Examining the record in retrospect, the deductible figure has varied in different years from 

 11 to 60 per cent (the winter loss on the Connecticut Hill study area). Again assuming a 

 fall population to which the above mentioned 50 ])er cent is aj)plicable, the theoretical permis- 

 sible harvest would vary from 39 to per cent of the pre-hunting season level. But pro- 

 ductivity is not constant. On this area it has varied from year to year so that, instead of .50 

 per cent, the total allowable overwinter loss with respect to what may be considered an ade- 

 quate breeding population has ranged from 17 per cent to 70 per cent. This variability is to 

 a large extent compensated for. however, by the fact that high overwinter losses have tended 

 to be associated with high fall densities and vice versa. 



Fortunately, too, there is substantial evidence which indicates that these figures may run 

 much higher without danger*. The above "deductible figures" are based on an area where 

 no hunting was allowed. Many of the birds that might have been taken by hunters were lost 

 through other causes. If the) had been taken by hunters, it is improbable that in every 

 case other birds would have been lost in their place. One may then fairly conclude that 

 the 17 per cent hunting loss estimated does not endanger the continued abundance of the 

 species in well-stocked coverts. 



That modern hunting is seldom an important factor in altering the natural course of 

 grouse abundance is further indicated by the record in New York in recent years. Following 

 two years of closed seasons during the low-abundance period of 1928 and 1929, the season 

 was re-opened in 1930 when the abundance curve had recovered to about 30 per cent of its 

 ultimate peak. Many were the disapproving cries of anxious sportsmen who, having become 

 thoroughly alarmed by the "disappearance" of the birds in 1927, felt that it was not yet safe 

 to allow an open season. But in spite of this and succeeding open seasons, the grouse 

 continued to increase until a high level of abundance was reached, which, in general, has 

 been maintained until the present (1942). 



To further indicate the part played by decimation from hunting, it is helpful to examine 

 the relative importance of the various sources of loss by which the potential productivity 

 of a spring grouse population is reduced. The charts included under the discussion of Net 



» See Chapter XII. p. 538. 



