240 The Ruffed Grouse 



have caused local dying-off in the areas studied, but it is certain 

 that they are not responsible for grouse declines in a broad geo- 

 graphical sense. As species of this genus are known to be peculiarly 

 pathogenic to the young of turkeys, ducks, geese, and ostriches 

 ". . . this fact, together with the high incidence of the disease, 

 especially in the single case of ... (a) sick bird ... (he men- 

 tions ) . . . and the lack of evidence of any other disease-producing 

 organism or parasite . . ." ( Clarke, 1936 ) led him to conclude that 

 it was the organism responsible for sudden grouse declines. Even 

 the assumption that the cause of grouse dying-off is some pathogenic 

 organism is not known to be valid, even in restricted areas. 



Regardless of any cyclic significance this disease might have, 

 Clarke did find it in twenty-one out of twenty-four specimens exam- 

 ined for blood parasites ^ in the areas of dying-off in 1934. The previ- 

 ous year, the gametocytes of the Leucoctozoon were found in four 

 of five grouse ". . . in which they might be expected." One of these 

 was a sick youngster, half underweight, which apparently was a re- 

 sult of this disease. No other serious cases were noted. 



The only other areas from which this organism has been reported 

 are Michigan and Minnesota. Fisher (1939) records that five 

 grouse out of seventy-nine examined in 1934 from Michigan showed 

 its presence in blood samples. In July, 1935, two five-weeks-old 

 chicks out of seven collected by Dr. O'Roke contained the parasite 

 (Fisher, 1939). Erickson (1944) found the parasite prevalent in 

 Minnesota. The incidence among 30 specimens in 1941 was sixty- 

 three and three-tenths per cent; of 48 specimens examined in 1942, 

 sixty and four-tenths per cent were infected; and of twenty-four 

 grouse taken in 1943, eighty-three and three-tenths per cent had 

 these protozoons present. These birds were collected from Sep- 

 tember to November. 



Subsequent to Clarke's pronouncement on the importance of this 

 protozoan in 1936, others conducted a diligent search for it in other 

 areas. None at all was found by the New York study. 



The Flagellates 



Trypanosoma gallinarum Bruce et al. 



Trypanosoma sp. 



^ Examination for blood parasites requires the preparation of fresh blood smears in 

 the field at the time the bird is killed. 



