DISEASE AND ITS CAUSES 405 



Although a few cases have been observed in which recovery has been made from minor in- 

 juries, in most cases death ensues sooner or later as a resuh of the structural and functional 

 changes produced. Occasionally shooting or other trauma will result in the perforation of the 

 intestine without serious injury to blood vessels or other vital organs. Death from peritonitis 

 results sometime later. 



Observations on captive birds have shown that even comparatively minor injuries may 

 cause a disinclination to eat and that death from malnutrition may result a week or so follow- 

 ing injury. As small an injury as the loss of a toenail may lead to severe bleeding and death. 

 On the other hand, birds so severely scalped that their skulls are laid bare, may recover. 



Chemical Poisons 



Contacts with the chemical poisons which have come to be of importance in connection with 

 other species of wildlife are of rare occurrence in grouse. During this Investigation one grouse 

 chick, collected for routine examination, presented pathological findings indicative of lead poi- 

 soning, the result of eating and harboring one small lead pellet in its gizzard. The conditions 

 associated with grouse hunting as well as the habits of the birds would logically minimize 

 the occurrence of this disorder. 



No other instances of either chemical or organic poisoning have been observed. 



That grouse are remarkably resistant to some of the poisons commonly used in insect or 

 rodent control seems to be indicated by the experiments reported in the chapter on Food 

 Habits fp. 195). 



Nutritional Deficiencies 



For the most part, Nature has provided for the adequate nutrition of wildlife in its natural 

 habitat. It is only when broad natural changes or man's activity disturbs the habitat that diffi- 

 culties due to inadequate nutrition are likely to occur. 



No evidence of malnutrition has been encountered in wild grouse during the course of the 

 Investigation except in birds which were suffering from mechanical injuries or parasitism 

 which interfered with their normal feeding activities. 



On the other hand, at least one abnormality due to inadequate diet has been produced in 

 grouse reared in captivity. This condition, known as perosis, slipped tendon or big hock 

 disease, has been encountered in young grouse chicks. 



Animal Parasites 



The group of organisms most frequently observed by sportsmen and others interested in 

 grouse are the animal parasites. As the hunter picks up a freshly shot bird, he may see among 

 the feathers, winged insects with flattened bodies which scurry about and soon leave the dead 

 game. If he observes more closely, ticks of various sizes may be apparent, closely attached 

 to the skin. 



Later, when he cleans the bird, he may discover thick white worms a couple of inches long 

 in the body cavity. Or. if the gizzard lining is stripped off preparatory to cooking, thin pink 

 worms may be found lying between the lining and the muscle. 



These are the comparatively harmless grouse dwellers that are commonly seen. Other 

 animal parasites live in the blood, some actually within the red blood cells, others in the cells 

 lining the intestine. Still others are small flat worms not readily observed with the naked eye. 



