Interrelationships of Rutfed Grouse 211 



THE EFFECT OF PREDATOR CONTROL ON RUFFED 

 GROUSE POPULATIONS ' 



We have aheady observed that any discussion covering the rela- 

 tions of predators and game is most delicate. That phase of the sub- 

 ject dealing with control of the predators, and its value, is probably 

 the most delicate of all. Our object, therefore, must be to evaluate 

 dispassionately the efiFectiveness of control on the prevalence of the 

 predatoiy species themselves and the resulting efiFects on the ruffed 

 grouse populations. 



Predator control studies were made on the Connecticut Hill area. 

 New York, in 1930-32, and continued in 1933-35. Two types of con- 

 trol experiments were made: complete control, where all predatory 

 species were taken; and selective control, under which foxes (two 

 species ) and weasels ( two species ) were taken. 



The initial experiment in 1930-32 was designed to appraise the 

 effects of complete predator elimination. Of course this was far from 

 accomplished, the degiee of success with any species depending 

 upon its mobility and its susceptibility to trapping. The trapped 

 area consisted of one thousand, four hundred and twenty-five acres 

 of giouse coverts while the untrapped check-area covered one thou- 

 sand, two hundred and twenty-three acres. The fact that these two 

 tracts lay adjacent to each other, one being the northern, the other 

 the southern part of the whole study area, unquestionably acted to 

 reduce differentials in both grouse populations and mortality. Hence, 

 any conclusions as to positive effectiveness of predator control in 

 improving grouse numbers would probably be conservative. 



A total of five hundred and fifty-seven predators were taken by 

 trap and shot during the first two-year period, three hundred and 

 twenty-one the first year (October 1, 1930-September 30, 1931) and 

 two hundred and thirty-six the second year (October 1, 1931-August 

 31, 1932), including fifty-six homed owls, twenty-five foxes, sixty-six 

 skunks, forty-three weasels and twenty-two accipitrine hawks. 



Records of the numbers taken the second year indicate that re- 

 duction was markedly successful with respect to the long-eared owl, 

 red-tailed hawk, and small brown weasel; and moderately success- 



^ This account is taken largely from an article of the same title, by the author, in 

 the Journal of Wildlife Management, October, 1939. 



