PARASITES OF WILD GROUSE 417 



Although Green and Shillinger"' mention only the genus Haemaphy salts with the implication 

 that the rabbit tick is the only one involved with the transmission of tularemia to grouse, 

 Parker, Philip and Davis""" present evidence pointing to the probability that the bird tick (H. 

 ch-ordeilis) acted as a vector in an outbreak of this disease on sage grouse. 



The rarity of tularemia in New York may be indicated by the fact that, during the decade 

 1932 through 1941, there were only eight cases of tularemia among persons which could be 

 traced definitely to animals having their origin within the State. Of these, the species impli- 

 cated were as follows: cottontails — 4, muskrats — 2, fox — 1, deerfly — 1. In two of the cases 

 where the infection was suspected of having been contracted from cottontails, a collector from 

 the Conservation Department immediately went into the field and trapped or shot all the rabbits 

 which could be contacted in the vicinity in which the original suspect was taken. Blood sam- 

 ples from these were subjected to agglutination tests by the Department of Public Health and 

 the animals were sent to the Research Center for post-mortem examination. F'.ighty-seven rab- 

 bits were taken from one locality and 27 from the other. In all instances blood tests and 

 autopsy findings were negative for tularemia. 



It seems probable that further observations on the inter-relation of tularemia, wild birds and 

 mammals, and ticks will come from areas where tularemia is more prevalent. 



Whether the presence on grouse of certain miles, ordinarily found on small rcidents (Laelap- 

 tinae, Trombicula microti), is accidental or significant is a matter for speculation. It has been 

 suggested that rodent mites related to these may be involved in the dissemination of tularemia 

 among meadow mice"'". 



Relation of Disease to Predation 



The relation of predators to the elimination of diseased animals has been the subject of 

 many discussions. During the course of the Investigation, a number of grouse were received 

 which had been killed by predatory mammals or birds. Of these, 33 were satisfactory for 

 post-mortem examination. In none of these was parasitism or disease present to a degree 

 which suggested that either might be a factor in the susceptibility of the bird to predation. 

 Nineteen cases were completely negative and the parasitism in the others differed neither in 

 incidence nor degree from that found in a normal population. 



We have, however, a number of records of birds which were weakened by a result of stom- 

 ach worm infection and were readily shot or picked up by dogs. It can be inferred that these 

 diseased grouse would also have been available to other predators. 



PARASITES OF WILD GROUSE 

 In the Respiratory System 



Gape worms were the only animal parasites encountered in the respiratory tracts of wild 

 ruffed grouse during the Investigation. The occurrence of the fungus infection, aspergillosis, 

 in both wild and hand-reared birds has already been mentioned. Discussion of this disorder, 

 which is more likely to be found in captive grouse than in the wild, has been relegated to the 

 section on disease in hand-reared birds. Air-sac mites, also discussed later, were found only in 

 captive grouse in association with poultry. 



Gape Worm (Syngamus trachea) 

 Distribution. This parasite is found in most parts of the world. It has been re- 



