The concept of maximum sustained yield assumes that 

 populations maintained below maximum density are more 

 productive and yield greater sustained harvests than high 

 density populations. We observed 2 major problems with 

 application of this concept in management. First, net 

 recruitment may not be related to population density; for the 

 MRBMD population it certainly couldn't be predicted from 

 density. Thus, yield was not predictable (and sustainable) at 

 any population level. Second, even if density-relationships 

 applied, forage-based "carrying capacity" fluctuated so much 

 that attempts to achieve stable population levels and 

 sustainable yields were impractical. Yields were not 

 sustainable at any population level, but tended to be higher 

 at higher population densities (Chapter 5). 



The " law" of diminishing returns also needs further 

 discussion. At times, we have heard this concept confused 

 with compensatory mortality. The statement usually goes 

 something like this: "There is compensatory mortality because 

 if deer become too scarce in one area, hunters compensate by 

 moving to another area, thereby lowering mortality in the 

 former area." The concept of diminishing returns and the 

 extent to which it may be operative need to be updated. Long 

 ago, Aldo Leopold (1933) recognized that the level of 

 operation of "diminishing returns" and hunter effectiveness 

 are variable when he stated: "gasoline has not lengthened the 

 tether of the bobwhite". Habitat security is much more than 

 vegetation composition, interspersion, and topography. 

 Changes in access, hunter affluence, mobility, leisure time, 

 equipment, and desire can alter habitat security as surely as 

 changes in vegetation composition. What was "secure" habitat 

 yesterday may be insecure today even without environmental 

 change. Reliance on the "law of diminishing returns" to 

 affect changes in hunter distribution and hunting pressure can 

 result in hunter dissatisfaction (Wood et al . 1989). Use of 

 the "law of diminishing returns" as a management tool will 

 result in unhappy customers and would not be employed in 

 competitive businesses. 



Finally, we address concepts of habitat management. 

 Because of the overriding influence of the concept of a 

 forage-based carrying capacity, most habitat management for 

 ungulates has focused on practices that "improve" forage 

 conditions, particularly on winter range. Indeed, the 

 philosophy of reducing deer populations to at least somewhat 

 below "carrying capacity" has been considered habitat 

 management because it is intended to improve forage production 

 and the condition of forage plants. The U.S. Forest Service 

 often justifies timber cutting on the basis that it improves 

 forage production for ungulates. Many State Game Departments 

 buy land (especially winter range) for the purpose of 

 preserving and enhancing forage for ungulates. Although 



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