PHYSIOLOGICAL STUDIES OF THE RUFFED GROUSE* 



By William H. Long 



Commenting on some of the causes for variation in the behavior and distribution of wild 

 animals living under natural conditions, Charles Elton, the well-known English ecologist. 

 states''^: 



"most animals are, in practice, limited in their direct distribution by their habits and 

 reactions, the latter being so adjusted that they choose places to live in which are suit- 

 able to their particular physiological requirements . . . every animal has a certain range 

 of external conditions in which it can live successfully, ultimate limits of the environ- 

 ment are set by its physiological make-up, if these limits are reached the animal will die." 



A knowledge of the physiological limits of tolerance and susceptibility to normal and 

 abnormal influences is an important objective in wildlife research. Yet the physiology and 

 physiological needs of wild animals, particularly upland game birds, are practically unknown. 

 Therefore, a study of the interaction of vital processes and environmental conditions, as well 

 as of the role which specific factors or cf)mi)iiiati(>ns of factors such as temperature, food and 

 water play in regulating the distribution and beha\ ior of a species, is valuable as a supple- 

 ment to ecological investigation. 



Through direct or indirect effect on the internal \ital processes and external physical reac- 

 tions of an animal, variations in air temperature, air movement, radiation, evaporation, humid- 

 ity and light govern to a large extent the daily and seasonal activity of the animal in its nat- 

 ural habitat. When unfavorable conditions exist, physiological resistance and mortality 

 increase. On the other hand, when favorable living conditions are maintained, both mortality 

 and physiological resistance decrease, with the result that wild game species have a better 

 opportunity to survive, reproduce, and increase in number. 



An individual bird is not an entity isolated from the habitat. Rather, there is a continual 

 exchange of energy between it and the environment. The habitat, in the form of vegetative. 

 cover and its by-products (food, minerals, water) furnishes the potential energy. The bird, 

 through processes of internal metabolism, absorbs and assimilates the energy, the waste 

 material (carbon dioxide, water, heat, etc.) being returned to the environment. If the habitat 

 does not furnish an adequate supply of potential energy to meet daily requirements for 

 maintenance of physical activity and vital processes, and suflTicient protection against adverse 

 weather conditions and animals of prey, then the inherited ability of the bird to support 

 bodily functions at normal levels is weakened and survival time is shortened. When there 

 exists a condition of stable physiological equilibrium with the habitat, the bird will be ener- 

 getic and better able to resist unfavorable change. 



When we know more exactly how much of the behavior of a game species is based on the 

 interaction between vital processes and environmental conditions and how each physical factor 

 or combination of factors regulates internal and external activities, including the utilization 

 of food and water, then the game manager will be far better equipped to handle important 

 wildlife problems. 



* Tlie studiL's iiiMiii Hhicli this paper is basrd wrrp I'onilucU'd by the author in the Physiological Wildlite Research Labora- 

 tory located at Cornell University. Ithaca. New York, and established jointly by the New York State Conservation Department, 

 the United States Fish .ind Wildlife Service, and the New York State College of Agriculture. Acknowledgment is due Cuilfor<l 

 K. Woodward for precise, conscientious and untiring assistance rendered throughout these investigations. 



