irrupt ive, overused their forage resources, and temporarily or 

 permanently reduced the carrying capacity (K) of their range. 

 Caughley (1976a, 1979) modified this somewhat by indicating 

 that generally an equilibrium population results from the 

 dynamics of ungulates interacting with the dynamics of the 

 plants on which they feed. Populations of both herbivores and 

 plants fluctuate and each affects the other. Ungulates are 

 the major or only factor affecting forage production in these 

 models, at least in the way they are generally presented. 



For wildlife managers, the concept of deer irrupting, 

 exceeding their forage base, and then abruptly declining to 

 lower levels probably has its roots in the Kaibab deer 

 incident (Rasmussen 1941). In textbooks and classrooms, the 

 Kaibab story is the "classic" example used to indicate that, 

 at least in the absence of predators, deer will "overuse" 

 their forage and reduce carrying capacity. Interpretations 

 have varied in their emphasis on the importance of predation 

 and interspecific competition (livestock grazing) in the 

 process, but the Kaibab story has generally been viewed as a 

 typical example of intraspecif ic competition and delayed 

 density-dependent mortality (Lack 1954). More recently, 

 Caughley (1970) questioned the reliability of the data on the 

 Kaibab deer herd and Burk (1973) termed the Kaibab incident "a 

 myth. " 



The predator-ungulate interaction theory of ungulate 

 population regulation (Peek 1980) was supported by indications 

 that most irruptions of ungulates took place in the absence of 

 predators. This theory holds that, in the presence of 

 predators, herbivore populations seldom approach limits 

 imposed by food. Hairston et al. (1960) and Slobodkin et al . 

 (1967) provided a theoretical framework arguing that predation 

 regulates the dominant members of the herbivore trophic level. 

 Recent work (Bergerud 1971, Keith 1974, Beasom 1974, Bergerud 

 1978, Stout 1982, and Gasaway et al . 1983) indicated that, at 

 least in some circumstances, predation can have a significant 

 impact on ungulate population dynamics . According to Gasaway 

 et al . (1983): "One of the most significant lessons to be 

 learned from the patterns observed in Minnesota, Alaska, and 

 on Isle Royale is that a combination of controlling factors 

 can initiate a decline in ungulates, which may then continue 

 to very low densities as wolf predation becomes an 

 increasingly important controlling factor." 



The predator-ungulate interaction model is basically a 

 modification of the ungulate-habitat interaction model, and 

 most adherents of the former seem to believe that in the 

 absence of predators, the latter is applicable. There are 

 also those, however, who believe the predators cannot regulate 

 populations even when they are present and abundant; thus, the 

 ungulate-habitat interaction model is always applicable. 



