Predator and Prey Models with Flexible Individual Behavior and Imperfect Information

Abstract

To begin identifying what behavioral details might be needed to characterize community dynamics and stability, we examined the effect of prey behavioral responses to predation risk on community dynamics and stability. We considered the case of prey altering their foraging effort to trade off energy gain and predation risk. We used state-dependent dynamic optimization to calculate the optimal trade-off for four models of prey behaviorally responding to predation risk. We consider a fixed behavior model in which prey use constant levels of foraging effort and three flexible behavior models in which prey change their foraging effort according to their physiological state and their perceived level of predation risk. Flexible behavior was destabilizing at the community level as evidenced by higher predator-prey oscillations and lower community persistence times. The mechanisms by which prey estimated predation risk also affected community stability. We found that community dynamics resulting from prey with flexible behavior and fixed perception of risk approximated community dynamics resulting from prey with flexible behavior and perfect information about predation risk, however neither approximated the community dynamics resulting from prey with flexible behavior and flexible perception of risk. Thus, whether it might be possible to abstract complex behavior with simpler rules when modeling community dynamics depends on the prey's behavioral mechanisms, which are empirically poorly known.

Prey State and Experimental Design Affect Relative Size of Trait- And Density-Mediated Indirect Effects

“…In addition, the reliability of information that prey receive about current predation risk should affect their behavioral reactions to changes in predation risk, with behavioral reactions being strongest when prey have reliable information (Luttbeg and Schmitz 2000). However, we have made several assumptions that may affect the relative impact of resources on indirect effects, and thus deserve further theoretical and empirical testing.…”

“…There is less evidence from direct comparisons of the strength of trait-and density-mediated effects (Soluk and Collins 1988, Huang and Sih 1990, Wissinger and McGrady 1993, Diehl et al 2000, Peacor and Werner 2001. For example, the foraging literature suggests that prey behavior should depend on the temporal pattern and predictability of predation risk (Lima and Bednekoff 1999), and the clarity of information that prey have about current predation risk (Luttbeg and Schmitz 2000). While doing these tests, we should look to the large theoretical and empirical studies of foraging behavior to guide our experiments.…”

Phenotypic modifications to conspecific density arising from predation risk assessment

“…Long‐term population dynamics of a species could be affected by the predictions made here concerning adaptive modifications of phenotype in response to conspecific density. Whereas most population and community level models that include phenotypic responses to predators are based on the assumption that species have perfect knowledge of predation risk, a recent theoretical study of Luttbeg and Schmitz (2000) indicates that accuracy of predation risk evaluation can strongly affect long‐term dynamics. Luttbeg and Schmitz therefore call for increased attention to the manner and ability of species to assess predation risk.…”

Connecting Theoretical and Empirical Studies of Trait-Mediated Interactions

“…Ecology,Vol. 5 namic optimization model (Werner and Anholt 1993, Crowley and Hopper 1994, Luttbeg and Schmitz 2000, Luttbeg et al 2003. 5 namic optimization model (Werner and Anholt 1993, Crowley and Hopper 1994, Luttbeg and Schmitz 2000, Luttbeg et al 2003.…”