Effort and the Functional Response of Deer Hunters

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Abstract
Managers of overabundant deer have failed to incorporate relevant predator-prey theory into management research. In particular, understanding the functional response of deer hunters (deer encountered/time) to declining deer density is important because functional responses determine relative effort (time/deer encountered) required to harvest a deer and may, in turn, influence hunter perceptions of deer density and costs associated with deer removal. We used information-theoretic techniques and nonlinear regression to reanalyze data from controlled hunts in Illinois, Michigan, Wisconsin, and Ontario. Alternate models include killing rates or sighting rates as Type 1 (linear), Type 2 (hyperbolic), or Type 3 (sigmoidal) functions of deer density. Akaike's information criteria suggested that optimal models for most data sets were Type 1, although this may have been a artifact of small sample sizes. Nonetheless, effort curves derived from fitted functional responses indicated that relative effort accelerates as deer density declines. Accelerating effort requirements on the part of deer hunters likely hinders agency efforts to reduce overabundant deer populations and may be a source of hunter perceptions of unrealistically reduced deer herds. If general, this relation-ship (1) may determine what levels of harvest/removal are realistic, (2) is a potential source of bias in population estimation, and (3) may contribute to hunter distrust of agency efforts to reduce population size.