The Diseases and Parasites of Wild Ruffed Grouse 231 



impaired. His records showed no pronounced variation from year 

 to year and he concluded that the parasite has no relation whatever 

 with the cyclic dying-off. 



Boughton ( 1937 ) recorded an infection rate of twenty-three per 

 cent in Minnesota grouse with an average infection of three and 

 eight-tenths worms and a maximum of thirty. Erickson (1944) re- 

 ported four instances among twenty-six birds also taken in Minne- 

 sota. Boughton included this parasite among those that are poten- 

 tially dangerous to the ruffed grouse but found no very serious cases 

 among those examined. The grouse from Michigan reported upon by 

 Fisher ( 1939 ) were more heavily infected than any recorded, except 

 the Michigan specimens earlier examined by Allen and Gross. In the 

 four years from 1933 to 1936 the rate of infection varied from 

 twenty-eight per cent to fifty-one per cent. Fisher indicates that the 

 species may be quite significant, for not only was it the most preva- 

 lent parasite but "many of the grouse were so heavily infected with 

 these parasites that part of the lining of the gizzard had been de- 

 stroyed and there was destruction of the surrounding tissue." 



The autopsies of the New York study over the eleven-year period, 

 1932-1942, show it to have very minor importance in that state. 

 The average infection rate for adult birds was eight per cent and for 

 chicks two and six-tenths per cent. The annual extremes were two 

 per cent (1932) to sixteen per cent (1941) for the adults and zero 

 ( 1933, 38, 39) to four and five-tenths per cent ( 1941 ) for the young 

 birds. This parasite cannot be considered to be of significance to 

 grouse in New York on the basis of present evidence, but may be so 

 locally, and possibly quite generally, in Michigan in some years. 



Capillaria annulata (Molin). A haii'-thin worm found beneath the 

 epithelial lining in the bird's crop and gullet, this parasite is about 

 two to three inches long. It can do serious damage by causing the 

 walls of the crop and gullet to thicken. An anemia in a grouse para- 

 sitized by C. annulata was described by Allen and Gross (1926). 



The specimens examined by these authors did not reveal this 

 species commonly for they say "Fortunately these are apparently 

 comparatively rare parasites, only five wild birds, all from southern 

 New England and Columbia County, New York, were found with 

 them." 



The species was not common in the birds examined during the 



