or habitats. These populations can exist in a variety of 

 forms in some environments and not at all in many other 

 environments. This is true even within smaller areas such as 

 the State of Montana. Within the environments they occupy, 

 population characteristics and dynamics vary according to the 

 environment; some are relatively stable, some are relatively 

 variable, and most may function somewhere between the two 

 extremes. As Murdoch (1966) stated: "In attempting to 

 formulate general theories of population control, ecologists 

 are faced with the problem that every population is, in some 

 sense, unigue" . 



Our analysis, interpretation, and writing often focuses 

 on the importance of the individual animal. At times, this 

 makes both writing and reading unconventional and difficult. 

 A focus on the individual is sometimes necessary, however, to 

 understand and explain dynamics. A population is generally an 

 artificial entity; it has no life of its own. The dynamics of 

 a population are made up of the sums and interactions of the 

 histories and fates of individual animals. For variable 

 populations in variable environments, insight is often lost or 

 obscured by compressing data into means, even when measures of 

 deviation are included. In some cases, few if any animals 

 exhibit mathematically average behavior, performance, or 

 fates. The sum of this variability may lead to somewhat 

 predictable phenomena, but to understand it or to make 

 management adjustments, one must understand individual 

 histories . 



This variability also affected our data analysis and 

 presentation in other ways . Much of the data did not meet the 

 stability assumptions inherent in "classical" analytical 

 technigues of demographic investigation. Analysis and 

 presentation of data in those forms is necessarily missing 

 here. We also, by necessity, present few precise and 

 deterministic models. 



Because "there is nothing new under the sun", many or 

 most of our interpretations and conclusions have been hinted 

 at or boldly stated by others. The reader may find 

 similarities in our views and those of Thompson (1929), 

 Andrewartha and Birch (1954), Milne (1958), Ehrlich and Birch 

 (1967), Birch (1971), Sinclair (1974), White (1978), Murray 

 (1979), Botkin et al . (1981), Cockburn and Lidicker (1983), 

 Ostfeld et al . (1985), and Lidicker (1988) among others. 



The Population-Habitat Model 



We propose that the total, unigue environment each 

 population occupies establishes its characteristics and 

 dynamics. Further, no 2 populations on the same area, but at 

 different times, will exhibit exactly the same behavior, even 



17 



