The Diseases and Parasites of Wild Ruffed Grouse 245 



about the head, mouth, and tongue. Recovery probably takes place 

 unless feeding is so interfered with as to result in starvation. 



Green and Shillinger ( 1936 ) have reported the occurrence of the 

 bacterium, Fasteurella aviseptica, in wild grouse. This organism is 

 the cause of fowl cholera in chickens. The discoverers note that "if 

 this organism is as destructive in grouse as it is in domestic fowl, it 

 may well be an important factor in grouse mortality." No evidence 

 of its widespread occurrence has as yet been demonstrated. 



External Parasites. Ruffed grouse are known to be infested by five 

 different types of ectoparasites, creatures which live on the body 

 surface and mostly derive their sustenance from biting or pierc- 

 ing the bird's skin to take its blood. An exception are the feather 

 mites which live on the feather substance. The other four types are 

 ticks, fleas, lice, and flies. It is also likely that grouse are attacked 

 by "bite-and-run" insects such as mosquitoes that remain on the 

 body only long enough to take one load of blood. 



These external parasites are not normally a serious threat to the 

 bird's health. However, some carry other diseases which may be 

 serious (see under tularemia, p. 243), and occasionally the infesta- 

 tion may be so heavy as to be a serious drain on the vitality. In these 

 instances it is commonly found that the bird has been weakened by 

 other afflictions as well as the ectoparasites. 



Ticks ( Ixodoidea ) . Four species of ticks of the genus Haemaphy- 

 salis are known to infest ruffed grouse. They are found on the bird 

 in aU three stages: larva, nymph, and adult. The degree of preva- 

 lence decreases with each older stage, the larvae being most abun- 

 dant, n\Tnphs next, and the adults relatively scarce. The reason for 

 this is not wholly clear but is probably due to reduction in numbers 

 of ticks with each stage from mortality and progressively increased 

 difficulty in locating hosts. Ticks drop off a grouse quickly upon the 

 bird's death. The adults probably leave most quickly, due to greater 

 agflity, and this helps to explain the difference in numbers of each 

 stage of ticks found on birds freshly killed. 



They are foimd on the host from spring to fall, and pass the winter 

 in the ground in the egg stage. Abundance seems to be greatest in 

 late summer. Further, there is apparently a marked geographic vari- 

 ation in abundance, the ticks being most prevalent in midwestem 

 lake states, less in the East. 



