The landscape of fear conceptual framework: definition and review of current applications and misuses

Bleicher, Sonny S.

doi:10.7717/peerj.3772

Cited by 119 publications

(80 citation statements)

References 81 publications

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“…Predators can alter herbivore ensemble composition, population abundances and individual behaviour [17,18]. A byproduct of these effects is reduced herbivory, particularly in areas where herbivores perceive themselves to be at greater risk of predation [19,20]. These predator-prey interactions are size dependent as energetic and mechanical constraints limit predators' ability to hunt very large herbivores [21,22].…”

Section: Introductionmentioning

confidence: 99%

Trophic rewilding presents regionally specific opportunities for mitigating climate change

Sandom

Middleton

Lundgren

et al. 2020

Phil. Trans. R. Soc. B

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Large-bodied mammalian herbivores can influence processes that exacerbate or mitigate climate change. Herbivore impacts are, in turn, influenced by predators that place top-down forcing on prey species within a given body size range. Here, we explore how the functional composition of terrestrial large-herbivore and -carnivore guilds varies between three mammal distribution scenarios: Present-Natural, Current-Day and Extant-Native Trophic (ENT) Rewilding. Considering the effects of herbivore species weakly influenced by top-down forcing, we quantify the relative influence keystone large-herbivore guilds have on methane emissions, woody vegetation expansion, fire dynamics, large-seed dispersal, and nitrogen and phosphorus transport potential. We find strong regional differences in the number of herbivores under weak top-down regulation between our three scenarios, with important implications for how they will influence climate change relevant processes. Under the Present-Natural non-ruminant, megaherbivore, browsers were a particularly important guild across much of the world. Megaherbivore extinction and range contraction and the arrival of livestock mean large, ruminant, grazers have become more dominant. ENT Rewilding can restore the Afrotropics and the Indo-Malay realm to the Present-Natural benchmark, but causes top-down forcing of the largest herbivores to become commonplace elsewhere. ENT Rewilding will reduce methane emissions, but does not maximize natural climate solution potential. This article is part of the theme issue ‘Climate change and ecosystems: threats, opportunities and solutions'.

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Section: Introductionmentioning

confidence: 99%

Trophic rewilding presents regionally specific opportunities for mitigating climate change

Sandom

Middleton

Lundgren

et al. 2020

Phil. Trans. R. Soc. B

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“…The information a forager gains from olfactory cues varies based on a number of environmental and temporal variables (Sih 1992; Lima and Bednekoff 1999; Gonzalo et al 2009). The interpretation of the cues clearly impact the strategic behaviors of the foragers and the way the animals will balance the tradeoffs of food and safety (Brown et al 1999; Bytheway et al 2013; Bleicher 2017). This experiment provides a clear example of how the same cues vary in the information they provide over a short period of time.…”

Section: Discussionmentioning

confidence: 99%

Olfactory cues and the value of information: voles interpret cues based on recent predator encounters

Bleicher

Ylönen

Käpylä

et al. 2018

Behav Ecol Sociobiol

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Prey strategically respond to the risk of predation by varying their behavior while balancing the tradeoffs of food and safety. We present here an experiment that tests the way the same indirect cues of predation risk are interpreted by bank voles, Myodes glareolus, as the game changes through exposure to a caged weasel. Using optimal patch use, we asked wild-caught voles to rank the risk they perceived. We measured their response to olfactory cues in the form of weasel bedding, a sham control in the form of rabbit bedding, and an odor-free control. We repeated the interviews in a chronological order to test the change in response, i.e., the changes in the value of the information. We found that the voles did not differentiate strongly between treatments pre-exposure to the weasel. During the exposure, vole foraging activity was reduced in all treatments, but proportionally increased in the vicinity to the rabbit odor. Post-exposure, the voles focused their foraging in the control, while the value of exposure to the predator explained the majority of variation in response. Our data also suggested a sex bias in interpretation of the cues. Given how the foragers changed their interpretation of the same cues based on external information, we suggest that applying predator olfactory cues as a simulation of predation risk needs further testing. For instance, what are the possible effective compounds and how they change “fear” response over time. The major conclusion is that however effective olfactory cues may be, the presence of live predators overwhelmingly affects the information voles gained from these cues.Significance statementIn ecology, “fear” is the strategic response to cues of risk an animal senses in its environment. The cues suggesting the existence of a predator in the vicinity are weighed by an individual against the probability of encounter with the predator and the perceived lethality of an encounter with the predator. The best documented such response is variation in foraging tenacity as measured by a giving-up density. In this paper, we show that an olfactory predator cue and the smell of an interspecific competitor result in different responses based on experience with a live-caged predator. This work provides a cautionary example of the risk in making assumptions regarding olfactory cues devoid of environmental context.Electronic supplementary materialThe online version of this article (10.1007/s00265-018-2600-9) contains supplementary material, which is available to authorized users.

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“…Consequently, predators are forced to consume herbivores that 445 deviate from their preferred optimal size. Furthermore, we should note that movement of herbivores 446 in our model is only influenced by the basal resource and not the predator, so non-lethal effects 447 acting in landscapes of fear are not considered (Bleicher, 2017;Schmitz et al, 2017). Moreover, we 448…”

Section: Pressure 397mentioning

confidence: 99%

Habitat loss and fragmentation increase realized predator-prey body size ratios

Hillaert

Vandegehuchte

Hovestadt

et al. 2018

Preprint

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In the absence of predators, habitat fragmentation favours large body sizes to facilitate gap crossing. The size of primary consumers is, however, also shaped by top‐down effects as predators select prey of a certain size. Therefore, higher trophic levels should be taken into consideration when studying the effect of habitat loss and fragmentation on size distributions of herbivores. We built a model to study the effect of habitat loss and fragmentation within a tri‐trophic food chain. Body size is directly linked to movement capacity and metabolic processes and considered as a master trait under selection. We show that basal resources accumulate locally if a predator causes top‐down control of the herbivore. Due to this increasing spatiotemporal variability in resource availability, larger herbivores are selected than in scenarios without predator as they are able to move further. As predators cause herbivores to be intrinsically much larger than the optimal sizes selected by habitat fragmentation in the absence of predators, habitat fragmentation is no longer a significant driver of herbivore size. However, there is selection for increased predator size with habitat fragmentation as herbivores become less abundant, hence favouring gap‐crossing ability of the predator. Since herbivore and predator body size respond differently to habitat loss and fragmentation, realized predator–herbivore body size ratios increase along this fragmentation gradient. Our model demonstrates how feedbacks between the abundance, body size and mobility of predators and prey ultimately determine body size distributions in food webs. These new insights shed light on the impact of habitat destruction and fragmentation on overall food web structure. A free Plain Language Summary can be found within the Supporting Information of this article.

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The landscape of fear conceptual framework: definition and review of current applications and misuses

Cited by 119 publications

References 81 publications

Trophic rewilding presents regionally specific opportunities for mitigating climate change

Trophic rewilding presents regionally specific opportunities for mitigating climate change

Olfactory cues and the value of information: voles interpret cues based on recent predator encounters

Habitat loss and fragmentation increase realized predator-prey body size ratios

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