242 The Ruffed Grouse 



the disease. Chickens especially are likely to be carriers. Any grouse 

 walking over infected range may pick up the organisms from the 

 ground. Being exceedingly susceptible, the bird would die in a 

 short time. 



The organism first affects the ceca and later the liver, causing 

 destruction of the liver parenchyma. According to Allen and Gross 

 (1926) "One or both ceca gradually become filled with cheesy, 

 necrotic material which is more or less bloodshot. Sometimes the 

 young grouse and occasionally the old birds die at this stage be- 

 fore the typical lesions appear on the liver. These lesions on the 

 liver appear as dark depressed areas with a central light area and an 

 outer light fringe, at first appearing as watermarks but later the 

 white areas giow until the dark portion is entirely obliterated. There 

 is usually also a thick straw-colored fluid in the loose tissue about 

 the heart and sometimes in the peritoneum covering the viscera." 



Again it should be emphasized that this very serious disease has 

 not yet been proved to occur in wild grouse, but the circumstances 

 indicate that its occurrence is likely where grouse range borders 

 the farm poultry yard. Any statement linking this disease with 

 grouse declines would be purely conjectural. 



Trichomonas, species. A protozoan parasite reported by Allen and 

 Gross ( 1926 ) as "occasionally found in small numbers by Dr. Tyz- 

 zer." No significance was attached to its presence, nor any details 

 given concerning its status as a grouse parasite. 



Infectious Diseases. The grouse is occasionally subject to infectious 

 disease of several sorts. The disease of captive grouse called "black- 

 head" ( and likely to occur in wild birds ) is caused by a protozoan 

 parasite and has been discussed above. Several others known to 

 occur in grouse are covered below. All are capable of causing death 

 and some, as tularemia, blackhead, and aspergillosis, are potentially 

 agents of serious epizootics. 



Aspergillosis. This is a disease of the lungs and air sacs caused by 

 a fungus, Aspergillus fumigatus. Its spores generally are distributed 

 in the soff and in such material as moldy straw. The conditions re- 

 quired for its growth in the bird are not well understood. 



It has been most prevalent in captive grouse (Allen and Gross, 



