if their initial numbers are the same (see Petrusewicz 1963). 

 This is due to both the unique nature of individuals and the 

 environment over time. Heterogeneity of the environment in 

 both space and time is an important concept in our 

 interpretations . 



We also support a multi-factorial model of population 

 dynamics. The importance of each factor, the intensity and 

 frequency at which it operates, and the interaction of factors 

 all vary with the species, population, and environment. There 

 are elements of all previous theories within our alternative. 

 A principal difference is that we do not emphasize one aspect 

 to the extent of excluding others. 



The habitat portion of the model (Fig. 1.4) contains both 

 a relatively fixed-stable component and a dynamic-variable 

 component. The fixed-stable component of the habitat model 

 includes the following factors: location (latitude, 

 longitude, altitude) , general climate zone, topography, soil 

 fertility, vegetation, and habitat structure and 

 heterogeneity. To the extent that these factors can change, 

 they generally do so over a long period of time. 



The dynamic-variable component of the habitat model 

 includes the following factors: weather and forage 

 variability, predation, hunting, inter- and intraspecif ic 

 competition, and the effects of man's activities on the 

 habitat. In some cases, man's activities can also impact the 

 fixed-stable habitat base. Variability of weather affects the 

 length and amplitude of periods of positive and negative 

 energy balance, forage production and quality, and the 

 operation of other variable components of the model such as 

 predation, hunting, and interspecific competition. 



The animal component of the model (Fig. 1.4) contains the 

 genetic, morphological, physiological, and behavioral 

 characteristics of animals that determines their resource 

 requirements. The interaction of resource requirements with 

 resource outputs and availability determines individual animal 

 strategy. 



The submodel of individual animal strategy (Fig. 1.4) has 

 both behavioral and physiological components. Behavioral 

 responses to the interaction of resource requirements and 

 resource outputs include: parturition territoriality, 

 dispersion or home range location, habitat use patterns, 

 emigration-immigration, activity patterns, food habits, and 

 movement patterns. These all have physiological consequences 

 including: animal size, condition, and reproductive strategy. 

 Behavioral and physiological responses to the interaction of 

 habitat and animal components determines recruitment and 



18 



