An island-wide predator manipulation reveals immediate and long-lasting matching of risk by prey

Orrock, John L.; Fletcher, Robert J.

doi:10.1098/rspb.2014.0391

Cited by 27 publications

(29 citation statements)

References 47 publications

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“…Importantly, additional evidence supports the primacy of predation risk as a factor structuring prey activity timing. Overcast conditions reduce nocturnal predation risk on deer mice island‐wide (Orrock & Fletcher, ) and, consistent with expectations, our study shows that habitat‐specific patterns of P. maniculatus capture timing apparent on clear nights (Figure a) are not apparent during overcast conditions (Figure b). Overall, our work suggests that small mammal activity timing may be better understood by carefully considering how patterns of diel predation risk differ not only over small spatial scales (e.g., under shrub cover versus open, Kotler et al., ), but also between habitats with different dominant predators.…”

Section: Discussionsupporting

confidence: 90%

“…Observations of mouse activity during overcast conditions were limited to a single night. We cannot control for other factors possibly influencing behavior during that trapping session (e.g., rate of diurnal resource renewal, difference in insect prey availability or activity), but given that (i) our results are consistent with other independent and long‐term evaluations of island mouse behavior during overcast conditions (Orrock & Fletcher, ), (ii) mice were less active on clear nights (3.4 captures per transect) than on the overcast nights (6.0 captures per transect), and (iii) mouse capture timing responded similarly in two independent sites on the same overcast night (Figure b), we consider reduced nocturnal predation risk one of the most likely drivers of this change in small mammal behavior.…”

Section: Discussionsupporting

confidence: 61%

“…Islands are excellent natural systems to evaluate hypotheses regarding how predation risk shapes small mammal activity patterns, as predators clearly shape the behavior of island rodents (Orrock, 2010;Orrock & Fletcher, 2014;Thomsen & Green, 2016) just as they shape the behavior of mainland rodents (Brown & Kotler, 2004;Kotler, Brown, Mukherjee, Berger-Tal, & Bouskila, 2010;Verdolin, 2006). Importantly, islands may have small mammal communities with few or no interspecific competitors, making it possible to more clearly focus on the unique role of predation risk in shaping activity patterns.…”

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confidence: 99%

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Habitat‐specific capture timing of deer mice (Peromyscus maniculatus) suggests that predators structure temporal activity of prey

Connolly

Orrock

2017

Ethology

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Timing is an essential component of the choices that animals make: The likelihood of successful resource capture (and predator avoidance) depends not just on what an animal chooses to do, but when it chooses to do it. Despite the importance of activity timing, our ability to understand the forces that constrain activity timing has been limited because this aspect of animal behavior is shaped by several factors (e.g., interspecific competitors, predators, physical conditions), and it is difficult to examine activity timing in a setting where only a single factor is operating. Using an island system that makes it possible to focus on the effect of predation risk in the absence of interspecific competition, we examine how the onset of activity of the deer mouse (Peromyscus maniculatus) varies between habitats with unique predation risks (i.e., minimal‐shrub cover versus abundant‐shrub cover sites). Using capture time to assess the timing of mouse activity, we found that mice in habitats with minimal shrub cover were captured 1.7 hr earlier than mice in habitats with abundant shrub cover. This difference in timing between habitats was likely a direct response to differences in predation risk between the two habitats: There were no differences in thermal conditions between the two habitats, and the difference in activity timing disappeared during a night when overcast skies reduced island‐wide predation risk. Our results demonstrate that predation risk, independent of interspecific competition, can generate significant changes in animal activity timing. Our work suggests that habitat structure that provides safety (i.e., refuge habitats) plays a direct role in the timing of prey activity and that habitat modification that alters refuge availability (e.g., shrub dominance) may alter the timing of animal activity.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 61%

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confidence: 99%

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Habitat‐specific capture timing of deer mice (Peromyscus maniculatus) suggests that predators structure temporal activity of prey

Connolly

Orrock

2017

Ethology

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“…The rationale for this experiment was that where N. fuscus perceived greater risk of predation, they should forage more from 'safe 0 sheltered habitats than 'risky 0 open habitats [19,24]. To conduct our experiment, we established 18 pairs of 'risky 0 and 'safe 0 food patches across a gradient of predator activity (figures 1 and 3) and measured the difference in the GUD between 'risky 0 and 'safe 0 pairs, as well as the activity of predators and abundance of N. fuscus.…”

Section: Notomys Fuscusmentioning

confidence: 99%

“…First, because predation risk is expected to reduce the amount of time individuals allocate to foraging, we predicted that the GUD of N. fuscus will be lower in areas where dingoes are common because the risk of predation is lower owing to dingoes' suppressive effects on mesopredator populations and activity. Second, because risk of predation can reduce foraging animals' use of 'risky' habitats [24], we predicted that the breadth of habitat used by N. fuscus should be greater in areas where dingoes are common because the risk of predation is lower [25,26]. In addition to the above hypotheses, because conspecific density dependence can potentially increase animals' allocation of time to foraging and increase the range of habitats exploited owing to intra-specific competition and/or 'safety in numbers' effects [27,28], we also predicted that the GUD of N. fuscus should be lower and the breadth of habitat use greater in areas with higher N. fuscus population densities.…”

Section: Introductionmentioning

confidence: 99%

Mesopredator suppression by an apex predator alleviates the risk of predation perceived by small prey

et al. 2015

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Predators can impact their prey via consumptive effects that occur through direct killing, and via non-consumptive effects that arise when the behaviour and phenotypes of prey shift in response to the risk of predation. Although predators' consumptive effects can have cascading population-level effects on species at lower trophic levels there is less evidence that predators' non-consumptive effects propagate through ecosystems. Here we provide evidence that suppression of abundance and activity of a mesopredator (the feral cat) by an apex predator (the dingo) has positive effects on both abundance and foraging efficiency of a desert rodent. Then by manipulating predators' access to food patches we further the idea that apex predators provide small prey with refuge from predation by showing that rodents increased their habitat breadth and use of 'risky 0 food patches where an apex predator was common but mesopredators rare. Our study suggests that apex predators' suppressive effects on mesopredators extend to alleviate both mesopredators' consumptive and non-consumptive effects on prey.

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When perception reflects reality: Non‐native grass invasion alters small mammal risk landscapes and survival

Ceradini

Chalfoun

2017

Ecology and Evolution

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Modification of habitat structure due to invasive plants can alter the risk landscape for wildlife by, for example, changing the quality or availability of refuge habitat. Whether perceived risk corresponds with actual fitness outcomes, however, remains an important open question. We simultaneously measured how habitat changes due to a common invasive grass (cheatgrass, Bromus tectorum) affected the perceived risk, habitat selection, and apparent survival of a small mammal, enabling us to assess how well perceived risk influenced important behaviors and reflected actual risk. We measured perceived risk by nocturnal rodents using a giving‐up density foraging experiment with paired shrub (safe) and open (risky) foraging trays in cheatgrass and native habitats. We also evaluated microhabitat selection across a cheatgrass gradient as an additional assay of perceived risk and behavioral responses for deer mice (Peromyscus maniculatus) at two spatial scales of habitat availability. Finally, we used mark‐recapture analysis to quantify deer mouse apparent survival across a cheatgrass gradient while accounting for detection probability and other habitat features. In the foraging experiment, shrubs were more important as protective cover in cheatgrass‐dominated habitats, suggesting that cheatgrass increased perceived predation risk. Additionally, deer mice avoided cheatgrass and selected shrubs, and marginally avoided native grass, at two spatial scales. Deer mouse apparent survival varied with a cheatgrass–shrub interaction, corresponding with our foraging experiment results, and providing a rare example of a native plant mediating the effects of an invasive plant on wildlife. By synthesizing the results of three individual lines of evidence (foraging behavior, habitat selection, and apparent survival), we provide a rare example of linkage between behavioral responses of animals indicative of perceived predation risk and actual fitness outcomes. Moreover, our results suggest that exotic grass invasions can influence wildlife populations by altering risk landscapes and survival.

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An island-wide predator manipulation reveals immediate and long-lasting matching of risk by prey

Cited by 27 publications

References 47 publications

Habitat‐specific capture timing of deer mice (Peromyscus maniculatus) suggests that predators structure temporal activity of prey

Habitat‐specific capture timing of deer mice (Peromyscus maniculatus) suggests that predators structure temporal activity of prey

Mesopredator suppression by an apex predator alleviates the risk of predation perceived by small prey

When perception reflects reality: Non‐native grass invasion alters small mammal risk landscapes and survival

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