The Diseases and Parasites of Wild Ruffed Grouse 243 



1926; N. Y. S. Cons. Dept. Ann. Rep., 1933-42), but is also known 

 to occur in wild individuals. Dr. Tyzzer found it in two such speci- 

 mens in 1925 (Allen and Gross, 1926). The New York study re- 

 ported twenty-seven cases in adult wild grouse from 1,816 specimens 

 examined from 1935 to 1942 {N. Y. S. Cons. Dept. Ann. Rep. 1935- 

 42). No cases were listed among birds examined from 1932 to 1934, 

 although one bird found dead by the author on Connecticut Hill, 

 N. Y., in 1933 after decapitation by a predator, proved to have suf- 

 fered from aspergillosis. 



Tularemia. This disease is caused by a bacterial organism, Pasteurella 

 tuhrense. It has been found in wild ruffed grouse only in the Mid- 

 west, primarily in Minnesota. Green and Shillinger (1934) reported 

 one case among eighty-seven birds (including some sharp-tails) 

 collected in northern Minnesota in 1932; two instances were found 

 among seventy-one grouse taken in September 1933 (again the 

 total included some sharp-tails); in October 1933 three cases of 

 tularemia were noted in ruffed grouse from among twenty-six grouse 

 of three species. They concluded ". . . that tularemia is a common 

 disease of both ruffed and sharp-tailed grouse." They could not 

 "... however, give any decisive judgment as to the significance 

 of the occurrence of tularemia in grouse as a mortality factor." These 

 birds were all collected for the study by game wardens, were all 

 able to fly, and showed no symptoms of disease, with a single ex- 

 ception. One of the infected birds was found in a dying condition. 

 However, it was noted that there was little opportunity to locate 

 sick or dead birds, hence the disease might well have been more 

 prevalent than indicated. 



The tularemia organism is spread by its alternate host, the tick 

 ( Haemaphy salts cinnaharina ) , and probably by other species of the 

 same genus. These ticks infest numerous other birds and mammals 

 and in some are known to spread tularemia, notably in the snow- 

 shoe hare. The number of ticks per animal varies greatly both by 

 season and in different years, and may well be correlated with 

 population fluctuations. As tick numbers rise, the disease increases 

 until finally an epizootic occurs. This reduces the host population 

 and with it the disease, and from there the cycle builds again. 



This hypothesis is still just that— a theory so far as grouse are con- 



