Landscapes of Fear: Spatial Patterns of Risk Perception and Response

Abstract

Animals experience varying levels of predation risk as they navigate heterogeneous landscapes, and behavioral responses to perceived risk can structure ecosystems. The concept of the landscape of fear has recently become central to describing this spatial variation in risk, perception, and response. We present a framework linking the landscape of fear, defined as spatial variation in prey perception of risk, to the underlying physical landscape and predation risk, and to resulting patterns of prey distribution and antipredator behavior. By disambiguating the mechanisms through which prey perceive risk and incorporate fear into decision making, we can better quantify the nonlinear relationship between risk and response and evaluate the relative importance of the landscape of fear across taxa and ecosystems. HighlightsBehavioral and Population Ecology Behavioral ecologists have long recognized the importance of spatially variable predation risk and prey responses in stabilizing predator-prey population dynamics [76][77][78]. Charnov introduced the concept of 'behavioral resource depression' to describe changes in prey microhabitat selection in response to predation risk, which made prey less accessible to predators [79]. Early studies of the 'ecology of fear' [80] combined mass action models (in which the lethal effects of predators drive numeric responses in prey populations), with optimal foraging theory [81]. These conceptual models provided the theoretical framework for empirical studies of free-ranging predators and prey on complex landscapes.Subsequent studies linked antipredator strategies to physiological outcomes, including stress and reproduction [82,83]. Mesocosm experiments have demonstrated that in some contexts, these risk effects of predation have a greater influence on prey population dynamics than the consumptive effects [84]. While the study of risk effects has proven challenging in heterogeneous natural landscapes, patterns of spatial variation in predation risk and response likely have important consequences for spatial demographic patterns [85,86]. Community EcologyMeanwhile, community ecologists observed that foraging behavior of fearful grazers structured the distribution of primary producers. Spatial variation in predation risk was hypothesized as a mechanism behind the formation of 'grazing halos', denuded areas at the edge of coral reefs where urchins sought refuge from predatory fish [87]. Similar patterns were observed in terrestrial systems; for example, the effects of pika (Ochotona princeps) on vegetation were strongest near rocks that provided refuge [88]. Through experiments, ecologists linked the structural complexity of the habitat back to predator efficiency, with refuges from predators reducing prey mortality rates and transforming prey communities [89]. Spatial variation in predation risk and accompanying patterns of prey foraging activity have been found to shape lower trophic levels via 'predator-induced resource avoidance' [90].The indirect effects of predators on lower trop...

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