CHAPTER X 



PARASITISM AND DISEASE 



By P. P. Levine and Frans C. Goble 



DISEASE AND ITS CAUSES 



The So-called "Grouse Disease" — Fa 



ical Injuries — Chemical Poisons — NutricTORs Which May Cause Disease — Mechan- 



Parasites — Filterable Viruses tional Deficiencies — Animal Parasites — Plant 



PARASITISM AND DISEASE IN WILD GROUSE 



Factors Affecting Different Age Classes — Yearly Variations — Seasonal Vari- 

 ations — Regional Distribution — Relation of Other Animal Diseases to Grouse 



— Poultry Diseases in Grouse — Parasites of Other Wild Birds — Diseases of Wild 

 Mammals — Relation of Disease to Predation 



PARASITES OF WILD GROUSE 



In the Respiratory System — Gape Worm — In the Digestive Tract — Crop Worm 



— Stomach Worm — Gizzard Worm — Large Roundworm — Large Tapeworm — Small 

 Tapeworm — Cecal Worms — Coccidia — Blood Parasites — Microfilaria External 

 Parasites — Ticks — Louse Fly — Parasites Not Encountered During the Inves- 

 tigation 



DISEASE IN HAND-REARED GROUSE 



Quail Disease — Blackhead — Tuberculosis — Aspergillosis — Air-Sac Mites — 

 Perosis 



THE ROLE OF DISEASE 



SUMMARY 



No evidence has been uncovered pointing to a strong causative relationship between disease 

 and periodic fluctuations in grouse abundance, (p. 442). 



No significant variation in the incidence of parasitism and disease occurred from year to year 

 during the period of the Investigation, (p. 413). 



No one malady can rightly be termed "the grouse disease". Specific diseases responsible for 

 deaths among grouse in one locality are not found in other parts of the grouse range, 

 while those parasites which have a wide distribution appear largely to be innocuous, (p. 

 404). 



