"I" carrying capacity is the definition generally 

 recognized by range managers for domestic livestock. When 

 applied to wild ungulate populations and combined with the 

 concept that a high proportion of climax forage species is 

 good, this definition has led to heavy cropping of ungulates 

 in many locations. In commenting on this application, 

 Sinclair (1981), citing Caughley (1976b), stated "Range 

 managers have misguidedly used these plant criteria 

 (decreasers, increasers, and invaders) to determine whether 

 herbivores were overabundant or not by declaring arbitrarily 

 that a high proportion of decreasers was good while a high 

 proportion of invaders was bad." He (Sinclair 1981) added 

 "Unfortunately, this led to management decisions that there 

 were always too many animals (the reason for 30 years of elk 

 culling in Yellowstone [National Park]). These criteria 

 result in the ridiculous conclusion that the only good 

 herbivore population is one vanishingly small." 



For practical purposes, intraspecif ic density-dependent 

 competition for a finite forage resource is the major 

 consideration inherent in most definitions of ungulate 

 carrying capacity. Despite giving at least some "lip service" 

 to other possible environmental variation, the models and 

 graphs of most theorists display a herbivore-forage 

 interaction where the only factor influencing forage 

 production is the degree of use by the herbivores. Models 

 proposed by Caughley (1976b, 1977, and 1979) and McCullough 

 (1979) are typical of widely held views assuming a more or 

 less determinate carrying capacity. Generally, competition 

 for other resources (space, cover, water) has not been 

 considered for ungulates. 



The typical density-dependent logistic model (Fig 1.1A) 

 indicates that recruitment rate declines linearly as 

 population density approaches K. Yield, in terms of number 

 of animals that may be harvested while maintaining a stable 

 population, typically peaks around . 5K (Fig 1.1B). In 

 theory, this occurs because as population numbers approach K, 

 the quantity and quality of food available per capita 

 decreases. Lag effects of a population increase may result 

 in "overuse" of the forage, thereby lowering K. 



Fowler (1981) has modified typical logistic models by 

 indicating that most density-dependent change for large 

 mammals occurs at population levels quite close to carrying 

 capacity (Figs. 1 . 2A and 1.2B). Nevertheless his models in 

 this form retain a fixed carrying capacity (K) influenced only 

 by the herbivore . 



In fairness to the modelers, we must point out that, to 

 illustrate a point, they often present a simpler model than 

 they know to be the case. Most realize that environmental 



