The Diseases and Parasites of Wild Rutfed Grouse 229 



The records of the autopsies performed by the New York study 

 from 1932 to 1942 on 2,059 adult grouse showed a great variation 

 in incidence of Ascaridia, ranging from nine to seventy-one per cent 

 in different years and averaging forty-one per cent. The incidence of 

 twenty-five per cent in 1932 ( and probably less in the preceding two 

 or more years) increased to the highest rate in 1935 and then de- 

 creased steadily each year to the lowest rate in 1942. This steady 

 trend may have some significance as an indicator of population re- 

 lationships. 



These worms are commonly found in grouse chicks too, but are not 

 nearly as prevalent in them as in the adults. The average incidence 

 in nine hundred and thirty-two chicks reported by the New York 

 study in their annual reports from 1933 to 1941 was ten and four- 

 tenths per cent, with variations of from zero to twenty-five per cent 

 in different years. The highest incidence of infection with this para- 

 site in the chicks occurred in the same year that it reached a high in 

 the adults, a year of high grouse density ( 1935 ) . 



Thus, while its distribution is general and its incidence high, 

 Ascaridia is not normally a parasite of much consequence. However, 

 as several authors have indicated, it might conceivably cause serious 

 trouble, and may be one of the numerous parasitisms of the grouse 

 that are associated with high population densities and may con- 

 tribute to their decimation. 



Hcterakis honasae (Cram, 1927). This parasite infects the caeca, or 

 blind gut, that forms an appendage to the intestine. It is a little less 

 than half an inch in length. Its development is direct, eggs dis- 

 charged from the host embryonating and infecting other birds. 



The occurrence of this worm has been recorded most commonly 

 from New York and the species found here and named H. honasae 

 is somewhat different from the species, H. gallinae, reported as com- 

 mon to many domestic and wild gallinaceous birds and certain 

 others throughout the world. 



It was found in one bird from Rhode Island and one from Nova 

 Scotia among four hundred and seventeen examined by Dr. E. E. 

 Tyzzer and in ten per cent of the birds from New York and fifty 

 per cent of those from Pennsylvania studied at Ithaca (Allen and 

 Gross, 1926). Neither Fisher nor Clarke reported any occurrences 

 from their studies but Boughton (1937) reported three from among 



