The Diseases and Parasites of Wild Ruffed Grouse 235 



the eight youngsters had minor infections and ". . . no apparent 

 harm had resulted to the birds." The adult, however, was ". . . cap- 

 tured alive in a weakened condition . . . There was an enormous 

 abundance of Hymenolepis in the duodenum and the bird would 

 probably have perished eventually from this cause." Erickson ( 1944) 

 found a single ". . . cestode fragment, possibly Hymenolepis sp. 

 in one bird" from Minnesota. 



Mueller (1941) reported the occurrence of H. carioca in New 

 Hampshire grouse, but gave no details. 



These parasites are thus occasionally pathogenic but are nor- 

 mally not a serious source of mortality as far as can now be deter- 

 mined. Considerable evidence indicates the group to be more preva- 

 lent in immature grouse than in adults. This may be because of the 

 young eating more insects, which undoubtedly act as intermediate 

 hosts. 



Davainea tetraoensis ( Fuhrmann, 1919 ) Staf seth and Kotlan, 1925 



Davainea pwglottina (Davaine, 1860) Blanchard, 1891 



These are almost-microscopic tapeworms that occur in the intes- 

 tinal tract, especially in the duodenal region. They have been found 

 in grouse from New England to Minnesota. 



Allen and Gross (1926) mentioned two specimens from New 

 York that contained unidentified species of Davainea. At about the 

 same time another species was described from Michigan, D. tetra- 

 oensis. Clarke ( 1936 ) found this in fifteen out of thirty-one young 

 grouse in Ontario in three out of five locations. At one site twelve 

 of thirteen chicks were infected. No serious lesions resulted and 

 Clarke concluded that this, together with its local distribution, ren- 

 ders it of no importance in connection with the die-off. 



Michigan grouse examined by Fisher ( 1939 ) proved to be com- 

 monly infected with D. tetraoensis. Of seventy-nine birds examined 

 in 1934, fourteen contained it. Only a single case in eighty autopsies 

 in 1935 and four out of eighty-six in 1936 completed this record. 

 No importance was attached to these cases by the author. 



Another species, D. proglottijia,^ was reported from three speci- 

 mens from Minnesota by Boughton (1937), also in three birds from 

 Minnesota by Erickson ( 1944 ) , and from New Hampshire by Muel- 

 ler (1941). It too is found in the small intestine and there is no 



^ See Boughton ( 1937) for complete description. 



