An alternative way of viewing population dynamics in 

 variable environments is that "carrying capacity" (in whatever 

 manner it is defined) fluctuates widely and unpredictably. 

 Thus, some may assert that although measurements using 

 absolute density may not show predictable density-dependent 

 relationships, population dynamics may respond to relative 

 density. Our data did not show a response to relative density 

 for the Missouri River Breaks mule deer population. 

 Furthermore, if fluctuation in "carrying capacity" is 

 primarily caused by density-independent factors (as we 

 observed) , then there is no feedback loop, hence no 

 regulation . 



Why was this population limited by "random" or chaotic 

 extrinsic factors rather than density-dependent regulation? 

 Actually, our results are not unusual for free-ranging 

 populations. There has been no substantial evidence presented 

 to "prove" density-dependent regulation for free-ranging 

 "natural" populations (see Chapter 1). The only substantial 

 evidence for density-dependent regulation has come from 

 laboratory, penned, introduced, or island populations and 

 possibly from populations for which predators had been 

 eliminated. Cohen et al . (1980) recognized this when they 

 stated (p. xv) : 



"Laboratory studies ... tend to present a picture of 

 populations well regulated and largely self- 

 regulated. .. Because food, predation, and disease 

 [also weather and emigration] are not allowed to 

 act as limiting factors, exogenous controls appear 

 unimportant, and since random environmental events 

 are prevented from impinging, eguilibrium states 

 are readily observed." 



They further stated (p.x): 



"In fact, an informed consensus of the participants 

 in the symposium, pre-selected in large part for 

 their interest in internal regulation, was that 

 there is enormous variation both among species and 

 among habitats in the relative importance of self- 

 regulation; that .. .mechanisms of self-regulation 

 are at some level probably fairly common among 

 animal species; but that for most species they may 

 only rarely come into play in periods when 

 exogenous forces do not first intervene." 



Similarly, Botkin et al . (1981:373) state: 



"One of the problems with much existing population 

 theory for large mammals is its failure to view the 

 animals within an ecosystem context. Standard 



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