Persistence Of Prey Research Articles

Dynamics of a stochastic delay predator-prey model with fear effect and diffusion for prey

We establish a stochastic delay predator-prey model with fear effect and prey diffusion, and investigate the dynamic behavior of the model. Initially, we use Itô's formula to prove the existence and uniqueness of a global positive solution and the stochastic ultimate boundedness of the system. Subsequently, we provide sufficient conditions for the extinction and persistence of prey and predator, and discuss three possible scenarios. Beside, we construct a suitable Lyapunov function and obtain the conditions for the existence of an ergodic stationary distribution. Finally, we present some numerical simulations to verify the analytical results.

Global dynamics of a Leslie–Gower predator–prey model in open advective environments

This paper investigates the global dynamics of a reaction–diffusion–advection Leslie–Gower predator–prey model in open advective environments. We find that there exist critical advection rates, intrinsic growth rates, diffusion rates and length of the domain, which classify the global dynamics of the Leslie–Gower predator–prey system into three scenarios: coexistence, persistence of prey only and extinction of both species. The results reveal some significant differences with the classical specialist and generalist predator–prey systems. In particular, it is found that the critical advection rates of prey and predator are independent of each other and the parameters about predation rate have no influence on the dynamics of system. The theoretical results provide some interesting highlights in ecological protection in streams or rivers.

Mesopredator release among invasive predators: Controlling red foxes can increase feral cat density and alter their behaviour

Abstract1. The mesopredator release theory predicts that the density of subordinate predators will increase as dominant predators decline. Persistent debate around mesopredator release in part reflects the lack of robust, replicated experiments that test this theory, and the use of population indices that confound changes in mesopredator density and detectability. This uncertainty has immediate impacts for conservationists who are faced with managing sympatric invasive predators.2. We used replicated experimental designs and spatially explicit models to examine whether mesopredator release of the feral cat Felis catus occurs in response to targeted control of the introduced red fox Vulpes vulpes. We surveyed three Control‐Impact paired landscapes in a region with long‐term fox control (1080 poison baiting) and conducted a Before‐After Control‐Impact Paired‐Series experiment in another region. We used fox occurrence as a simple metric of fox populations and estimated feral cat density with spatial mark–resight models.3. Lethal fox control had varying effects on fox occurrence, consistent with variation in the duration and intensity of poison baiting. Correspondingly, responses in feral cat density ranged from negligible to a 3.7‐fold higher density in fox‐baited landscapes. At a fine spatial scale (200 m2), feral cat density was negatively associated with fox occurrence probability across both regions. These results were consistent with mesopredator release, although uncertainty was high in the region where fox control had only recently commenced.4. Feral cat detectability also varied across the (artificially manipulated) gradients of fox occurrence probability. In one region, nonlinear models indicated that feral cats had lower detection and increased movement rates when foxes were uncommon, giving way to density suppression at high fox occurrence probabilities.5. Synthesis and applications. Our study provides replicated, experimental evidence that dominant predator suppression can be associated with a higher mesopredator density. Mesopredator release can manifest as changes in both behaviour and density, distorting inference if these processes are not distinguished. Our results may help explain why fox control does not consistently improve native prey persistence, suggesting integrated pest management may be necessary to improve conservation outcomes.

The effect of advection on a predator–prey model in open advective environments

This paper deals with a reaction–diffusion–advection system that characterizes the interactions between predators and prey in open advective environments, subject to an unidirectional flow, such as streams or rivers. To explore the influence of advection rates on the dynamics of this system, we study its dynamical classification by taking advection rates of two species as the variable parameters. It turns out that there exist some critical curves in the parameter plane of advection rates, which classify the dynamics of this system into several scenarios: (i) coexistence, (ii) persistence of prey only, (iii) persistence of predators only, (iv) extinction of both species. Furthermore, some qualitative properties of these critical curves are given by rigorous mathematical analysis and numerical computations. Our analytical and numerical results show that predators can invade successfully when they take relatively small advection rates. Especially, specialist predators always coexist with the prey when they invade successfully because they must keep pace with the prey for food. Nevertheless, generalist predators can take over the habitats when the prey’s advection rate is suitably large, which implies that the prey’s advection can facilitate the invasion of generalist predators. In addition, we numerically observe that the boundary loss rate has a significant influence on the dynamical classification. All of these results provide us with some deep insights into the dynamics of this system.

Global dynamics of a generalist predator–prey model in open advective environments

This paper deals with a system of reaction-diffusion-advection equations for a generalist predator-prey model in open advective environments, subject to an unidirectional flow. In contrast to the specialist predator-prey model, the dynamics of this system is more complex. It turns out that there exist some critical advection rates and predation rates, which classify the global dynamics of the generalist predator-prey system into three or four scenarios: (1) coexistence; (2) persistence of prey only; (3) persistence of predators only; and (4) extinction of both species. Moreover, the results reveal significant differences between the specialist predator-prey system and the generalist predator-prey system, including the evolution of the critical predation rates with respect to the ratio of the flow speeds; the take-over of the generalist predator; and the reduction in parameter range for the persistence of prey species alone. These findings may have important biological implications on the invasion of generalist predators in open advective environments.

CHAOS IN A NONAUTONOMOUS MODEL FOR THE INTERACTIONS OF PREY AND PREDATOR WITH EFFECT OF WATER LEVEL FLUCTUATION

Water level regulates the dynamics of different populations residing in water bodies. The increase/decrease in the level of water leads to an increase/decrease in the volume of water, which influences the interactions of fishes and catching capability. We examine how seasonal variations in water level and harvesting affect the outcome of prey–predator interactions in an artificial lake. A seasonal variation of the water level is introduced in the predation rate. We derive conditions for the persistence and extinction of the populations. Using the continuation theorem, we determine the conditions for which the system has a positive periodic solution. The existence of a unique globally stable periodic solution is also presented. Moreover, we obtain conditions for the existence, uniqueness and stability of a positive almost periodic solution. We find that if the autonomous system has a stable focus, the corresponding nonautonomous system exhibits a unique stable positive periodic solution. But, whenever the autonomous system shows limit cycle oscillations, the corresponding nonautonomous system exhibits chaotic dynamics. The chaotic behavior of system is confirmed by the positivity of the maximal Lyapunov exponent. For higher values of the assimilation fraction of prey population, the persistent oscillations of the autonomous system are eliminated and this system becomes stable. On the other hand, chaotic nature of the nonautonomous system is converted into periodicity if the assimilation fraction of prey is large. Moreover, populations behave almost periodically if the seasonally varied rate parameters are almost periodic functions of time. Our findings show that water level plays an important role in the persistence of prey–predator system.

Predator type influences the frequency of functional responses to prey in marine habitats.

The functional response of a consumer to a gradient of resource density is a widespread and consistent framework used to quantify the importance of consumption to population dynamics and stability. Within benthic marine ecosystems, both crustaceans and fishes can provide strong top-down pressure on prey populations. Taxon-specific differences in biomechanics or habitat use, among other factors, may lead to variable functional response forms or parameter values (attack rate, handling time). Based on a review of 189 individual functional response fits, we find that these predator guilds differ in their frequency distribution of functional response types, with crustaceans exhibiting nearly double the proportion of sigmoidal, density-dependent functional responses (Holling type III) as predatory fishes. The implications of this finding for prey population stability are significant because type III responses allow prey persistence while type II responses are de-stabilizing and can lead to extinction. Comparing per capita predation rates across diverse taxa can provide integrative insights into predatory effects and the ability of predation to drive community structure.

Stationary distribution and extinction of a stochastic one-prey two-predator model with Holling type II functional response

In this article, we investigate a stochastic one-prey two-predator model with Holling type II functional response. We first establish sufficient conditions for persistence and extinction of prey and predator populations, then by constructing a suitable stochastic Lyapunov function, we establish sharp sufficient criteria for the existence of a unique ergodic stationary distribution of the positive solutions to the model. The results show that the smaller white noise can ensure the persistence of prey and predator populations while the larger white noise can lead to the extinction of prey and predator populations.

Stochastic prey–predator model with additional food for predator

In this work we have studied a predator–prey model where the prey grows logistically in the absence of predator and the functional response of predator towards prey and additional food that are derived in the text. Prey’s growth rate and the predator’s death rate have been perturbed with Gaussian white noises which has been proved extremely useful to model rapidly fluctuating phenomena. These two parameters are the main terms subject to coupling of a prey–predator pair with its environment Dimentberg (1988). Existence and uniqueness of global positive solution of the system have been established under environmental noise. Then the conditions under which extinction of predator and prey populations occur have been established. In our analysis, it is found that the environmental noise plays an important role in extinction as well as persistence of prey and predator populations. We have also discussed about the persistence of the system under obtained conditions and how the solution of the underlying system is globally attractive in mean. To derive the theorems we have shown the uniform continuous behavior of the solutions. Although we have considered a prey–predator model, the survival of predator population is possible in absence of prey population, since the additional food is provided to predator. But it is found that the extinction of prey population drive predator population to extinction. Our analytical findings are explained through numerical simulation which show the reliability of our model from the ecological point of view. It is shown in numerical simulation that if the effectual food level of additional food which is provided to the predator is high, then the predator dominates the prey population.

Predators indirectly induce stronger prey through a trophic cascade.

Many prey species induce defences in direct response to predation cues. However, prey defences could also be enhanced by predators indirectly via mechanisms that increase resource availability to prey, e.g. trophic cascades. We evaluated the relative impacts of these direct and indirect effects on the mechanical strength of the New Zealand sea urchin Evechinus chloroticus We measured crush-resistance of sea urchin tests (skeletons) in (i) two marine reserves, where predators of sea urchins are relatively common and have initiated a trophic cascade resulting in abundant food for surviving urchins in the form of kelp, and (ii) two adjacent fished areas where predators and kelps are rare. Sea urchins inhabiting protected rocky reefs with abundant predators and food had more crush-resistant tests than individuals on nearby fished reefs where predators and food were relatively rare. A six-month long mesocosm experiment showed that while both food supply and predator cues increased crush-resistance, the positive effect of food supply on crush-resistance was greater. Our results demonstrate a novel mechanism whereby a putative morphological defence in a prey species is indirectly strengthened by predators via cascading predator effects on resource availability. This potentially represents an important mechanism that promotes prey persistence in the presence of predators.

Spatial extinction or persistence: landscape‐temperature interactions perturb predator–prey dynamics

Recognising that species interact across a range of spatial scales, we explore how landscape structure interacts with temperature to influence persistence. Specifically, we recognise that few studies indicate thermal shifts as the proximal cause of species extinctions; rather, species interactions exacerbated by temperature result in extinctions. Using microcosm‐based experiments, as models of larger landscape processes, we test hypotheses that would be problematic to address through field work. A text‐book predator–prey system (the ciliatesDidiniumandParamecium) was used to compare three landscapes: an unfragmented landscape subjected to uniform temperatures (10, 20, 30°C); a fragmented landscape (potentially hosting metapopulations) subjected to these three temperatures; and a fragmented landscape subjected to a spatial temperature gradient (∼ 10 to 30°C) – despite the prevalence of natural temperature ecoclines this is the first time such an analysis has been conducted. Initial thermal response‐analysis (growth, mortality, and movement measured between 10 and 30°C) suggested that as temperature increased, the predator might drive the prey to extinction. Thermal preferences (measured at 5 temperatures between 10 and 30°C), indicated that both predator and prey preferred warmer temperatures, with the predator exhibiting the stronger preference, suggesting that cooler regions might act as a prey‐refuge. The landscape level observations, however, did not entirely support the predictions. First, in the unfragmented landscape, increased temperature led to extinctions, but at the highest temperature (where the predator growth can be reduced) the prey survived. Second, at high temperatures the fragmented landscape failed to host metapopulations that would allow predator–prey persistence. Third, the thermal ecocline did not provide heterogeneity that improved stability; rather it forced both species to occupy a smaller realized space, leading toward extinctions. These findings reveal that temperature‐impacted rates and temperature preferences combine to drive predator–prey dynamics and persistence across landscapes.

Lionfish cause increased mortality rates and drive local extirpation of native prey

As predators play a central role in prey population regulation, predicting the impact of a novel predator requires determining how the invader affects the compensatory dynamics that underlie native prey persistence. The Indo-Pacific lionfish Pterois volitans is an invasive meso- predator that voraciously consumes native coral-reef fishes of the tropical western Atlantic and Caribbean. The fairy basslet Gramma loreto is a common prey of lionfish, and pre-invasion research has demonstrated that basslet populations undergo regulating density-dependent mor- tality due to predation. To unequivocally measure lionfish effects on prey mortality and to test whether prey survival remained density-dependent when exposed to predation by the invader, a controlled field experiment was conducted wherein both fairy basslet settlement density and lion- fish presence were manipulated by divers on natural coral reefs. On reefs with and without lion- fish, fairy basslet populations were repeatedly censused over the 28 d experimental period and mortality rates across a gradient of prey densities were quantified. Per capita loss of fairy basslet was density-dependent on reefs with and without introduced lionfish; however, the magnitude of this loss was significantly higher on reefs with the invader present. High mortality rates at low prey density resulted in local extinction of 2 of 14 fairy basslet populations exposed to the invader, a phenomenon observed only on lionfish reefs. Further, 9 out of 14 lionfish-exposed prey popula- tions showed loss rates of >50% compared with just 3 prey populations with such rates on native- only reefs.

Amphibians breeding in refuge habitats have larvae with stronger antipredator responses

Antipredator responses are a key determinant of the successful persistence of prey, and behavioural modifications are a frequent antipredator strategy. However, conspecific populations often inhabit heterogeneous environments. This can determine local adaptations, and might also induce variation in antipredator responses. Nevertheless, there is limited information on whether heterogeneity of predation risk among populations determines variation in antipredator response. Here we studied the fire salamander, Salamandra salamandra, a species that can breed in both surface streams and caves, habitats that are predator-rich and predator-free, respectively, and measured differences in antipredator responses across populations with different predation risk. We combined field surveys and laboratory experiments to understand the role of predation risk on the activity patterns of larvae, while measuring behavioural differences between populations. We reared larvae from different habitats in safe and risky conditions and tested their response to predator cues before and after rearing. In the field, predation risk was much higher in surface streams than in caves; larvae moved more in the absence of predators and when the light intensity was low. During laboratory experiments, larvae were less active if reared in risky conditions, but cave larvae showed a stronger response to risk than stream larvae. Therefore, larvae from sites without predators showed higher antipredator responses than those from risky habitats. This response fits the predictions of the risk allocation model, in which prey from habitats with a high background level of risk need to be active even when predators are present, to satisfy their energetic demands. Our findings show that antipredator behaviour may differ strongly between populations and stress the importance of integrating this variability in studies on predatory responses.

Food web persistence is enhanced by non-trophic interactions.

The strength of interspecific interactions is often proposed to affect food web stability, with weaker interactions increasing the persistence of species, and food webs as a whole. However, the mechanisms that modify interaction strengths, and their effects on food web persistence are not fully understood. Using food webs containing different combinations of predator, prey, and nonprey species, we investigated how predation risk of susceptible prey is affected by the presence of species not directly trophically linked to either predators or prey. We predicted that indirect alterations to the strength of trophic interactions translate to changes in persistence time of extinction-prone species. We assembled interaction webs of protist consumers and turbellarian predators with eight different combinations of prey, predators and nonprey species, and recorded abundances for over 130 prey generations. Persistence of predation-susceptible species was increased by the presence of nonprey. Furthermore, multiple nonprey species acted synergistically to increase prey persistence, such that persistence was greater than would be predicted from the dynamics of simpler food webs. We also found evidence suggesting increased food web complexity may weaken interspecific competition, increasing persistence of poorer competitors. Our results demonstrate that persistence times in complex food webs cannot be predicted from the dynamics of simplified systems, and that species not directly involved in consumptive interactions likely play key roles in maintaining persistence. Global species diversity is currently declining at an unprecedented rate and our findings reveal that concurrent loss of species that modify trophic interactions may have unpredictable consequences for food web stability.

Functional responses of the intertidal amphipod Echinogammarus marinus: effects of prey supply, model selection and habitat complexity

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 468:191-202 (2012) - DOI: https://doi.org/10.3354/meps09978 Functional responses of the intertidal amphipod Echinogammarus marinus: effects of prey supply, model selection and habitat complexity Mhairi E. Alexander1,*, Jaimie T. A. Dick1, Nessa E. O’Connor1, Neal R. Haddaway2, Keith D. Farnsworth1 1School of Biological Sciences, Queen’s University Belfast, MBC, 97 Lisburn Road, Belfast BT9 7BL, UK 2School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, UK *Email: malexander06@qub.ac.uk ABSTRACT: The influence of predation in structuring ecological communities can be informed by examining the shape and magnitude of the functional response of predators towards prey. We derived functional responses of the ubiquitous intertidal amphipod Echinogammarus marinus towards one of its preferred prey species, the isopod Jaera nordmanni. First, we examined the form of the functional response where prey were replaced following consumption, as compared to the usual experimental design where prey density in each replicate is allowed to deplete. E. marinus exhibited Type II functional responses, i.e. inversely density-dependent predation of J. nordmanni that increased linearly with prey availability at low densities, but decreased with further prey supply. In both prey replacement and non-replacement experiments, handling times and maximum feeding rates were similar. The non-replacement design underestimated attack rates compared to when prey were replaced. We then compared the use of Holling’s disc equation (assuming constant prey density) with the more appropriate Rogers’ random predator equation (accounting for prey depletion) using the prey non-replacement data. Rogers’ equation returned significantly greater attack rates but lower maximum feeding rates, indicating that model choice has significant implications for parameter estimates. We then manipulated habitat complexity and found significantly reduced predation by the amphipod in complex as opposed to simple habitat structure. Further, the functional response changed from a Type II in simple habitats to a sigmoidal, density-dependent Type III response in complex habitats, which may impart stability on the predator−prey interaction. Enhanced habitat complexity returned significantly lower attack rates, higher handling times and lower maximum feeding rates. These findings illustrate the sensitivity of the functional response to variations in prey supply, model selection and habitat complexity and, further, that E. marinus could potentially determine the local exclusion and persistence of prey through habitat-mediated changes in its predatory functional responses. KEY WORDS: Functional response · Predation · Prey replacement · Habitat complexity · Marine amphipod Full text in pdf format PreviousNextCite this article as: Alexander ME, Dick JTA, O’Connor NE, Haddaway NR, Farnsworth KD (2012) Functional responses of the intertidal amphipod Echinogammarus marinus: effects of prey supply, model selection and habitat complexity. Mar Ecol Prog Ser 468:191-202. https://doi.org/10.3354/meps09978 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 468. Online publication date: November 14, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Marine predators and persistent prey in the southeast Bering Sea

Predictable prey locations reduce search time and energetic costs of foraging; thus marine predators often exploit locations where prey concentrations persist. In our study, we examined whether this association is influenced by differences among predator species in foraging modes (travel cost, surface feeder or diver) or whether the predator species is a central place forager or not. We examined distributions of two seabird species during their nesting period, the surface-feeding black-legged kittiwake (Rissa tridactyla) and the pursuit-diving thick-billed murre (Uria lomvia), and two baleen whale species, the humpback whale (Megaptera novaeangliae) and the fin whale (Balaenoptera physalus), in relation to two key prey, age-1 walleye pollock (Theragra chalcogramma) and euphausiids (Euphausiidae). Prey surveys were conducted once each year during 2004 and 2006–2010. Concurrent predator surveys were conducted in 2006–2010 (seabirds) and 2008 and 2010 (whales). We compared the seabird and whale foraging locations to where age-1 pollock and euphausiids were concentrated and considered the persistence of these concentrations, where the time-scale of persistence is year (i.e., a comparison among surveys that are conducted once each year). Euphausiids were widespread and concentrations often were reliably found within specific 37km×37km blocks (‘persistent hot spots of prey’). In contrast, age-1 pollock were more concentrated and their hot spots were persistent only on coarser scales (>37km). Both seabird species, regardless of foraging mode, were associated with age-1 pollock but not with euphausiids, even though age-1 pollock were less persistent than euphausiids. The higher travel cost central place foragers, thick-billed murres, foraged at prey concentrations nearer their island colonies than black-legged kittiwakes, which were more widespread foragers. Humpback whales were not tied to a central place and mostly were located only where euphausiids were concentrated, and further, often in locations where these concentrations were persistent. Fin whales were associated with locations where age-1 pollock were more likely, similar to black-legged kittiwakes and thick-billed murres, but their association with euphausiids was unclear. Our results suggest that a predator's foraging mode and their restrictions during breeding affect their response to prey persistence.

Spatial connectivity moderates the effect of predatory fish on salamander metapopulation dynamics

In predator-prey metapopulations, persistence of prey in patches with predators may depend on the rescue effect in which immigration from nearby sources prevents local extinction. Thus, constraints on spatial connectivity may have important implications for predator-prey coexistence. We tested the hypothesis that metapopulation dynamics of Ambystoma tigrinum (tiger salamander) depend on combined effects of predatory fish and spatial connectivity. Because matrix heterogeneity can influence dispersal, we also considered how a proximate constraint on amphibian dispersal—desiccation risk—scales up to influence metapopulation dynamics for A. tigrinum. Occupancy and subsequent turnover patterns were quantified in a network of 90 wetlands for three years in an agricultural landscape in Illinois. Our previous field experiments demonstrated that desiccation risk varies among matrix habitats, and that individuals orient movements towards habitat with low desiccation risk. We used cost-distance modeling to generate a connectivity metric that accounted for desiccation risk. Occupancy and colonization probabilities were related negatively to fish occupancy and positively to connectivity. Matrix structure had a strong influence on colonization, and the connectivity metric based on desiccation risk was a better predictor of colonization than alternative metrics. The positive effect of desiccation-informed connectivity on colonization was strongest in wetlands with fish, indicating matrix composition can moderate the effects of predation on amphibians. We detected a rescue effect in which extinction probability was related negatively to connectivity, and this effect was strongest in sites with fish. The matrix did not have a strong effect on occupancy or extinction probabilities, and we discuss why matrix effects may vary for different aspects of population turnover. Our results suggest effects of fish predators on metapopulation dynamics of amphibians depend on spatial connectivity, and that immigration may be essential for maintaining persistence of amphibians in systems with fish. This study also demonstrates that the mechanisms underlying dispersal limitation for A. tigrinum may include desiccation risk.

Prey persistence and abundance in systems with intraguild predation and type-2 functional responses

The apparent prevalence of intraguild predation in productive environments has been regarded as puzzling because some simple models suggest that the intraguild prey species is often either reduced in abundance or driven extinct at high resource productivity. While various theoretical mechanisms that avoid this prediction have been uncovered, they have often been viewed as being narrowly applicable. This article examines the fate of the intraguild prey in models in which consumer species may have type-2 functional responses; these are usually characterized by sustained fluctuations in population density at high enough resource productivities. The models also include adaptive, but imperfect diet choice by the top predator. We concentrate on two situations: (1) the prey exhibits less saturation in its functional response to the resource than does the predator and (2) the predator is unable to persist on the basal resource alone. The reasons given by previous studies for discounting these cases are re-examined. The present analysis shows that prey abundance often increases with increasing productivity in both cases, as does the range of prey parameters that allows prey persistence. It is also possible for the prey to coexist with the predator in spite of having a larger equilibrium requirement for the resource. Different assumptions about the dynamics of diet choice can have a large impact on population responses to enrichment. We argue that the persistence and/or increase in abundance of intraguild prey at higher productivity should not be regarded as puzzling because observations are consistent with a range of theoretical models that reflect commonly observed mechanisms.

Predator–prey systems in streams and rivers

Many predator–prey systems are found in environments with a predominantly unidirectional flow such as streams and rivers. Alterations of natural flow regimes (e.g., due to human management or global warming) put biological populations at risk. The aim of this paper is to devise a simple method that links flow speeds (currents) with population retention (persistence) and wash-out (extinction). We consider systems of prey and specialist, as well as generalist, predators, for which we distinguish the following flow speed scenarios: (a) coexistence, (b) persistence of prey only or (c) predators only (provided they are generalists), and (d) extinction of both populations. The method is based on a reaction–advection–diffusion model and traveling wave speed approximations. We show that this approach matches well spread rates observed in numerical simulations. The results from this paper can provide a useful tool in the assessment of instream flow needs, estimating the flow speed necessary for preserving riverine populations.

Quantifying a dynamic risk landscape: heterogeneous predator activity and implications for prey persistence

Spatial heterogeneity in predation risk can ameliorate impacts on prey populations, particularly for prey of generalists. Spatially heterogeneous risk implies the existence of refugia, and the spatial scale of those refugia and their persistence over time affect whether prey can avoid predation by aggregating therein. Our objective was to quantify the magnitude, spatial scale, and temporal persistence of heterogeneity in risk of predation by white-footed mice (Peromyscus leucopus), an abundant generalist predator of gypsy moths (Lymantria dispar) and songbirds. We used track plates to measure white-footed mouse activity at > 170 trees in each of three forest plots in upstate New York during summers of 2003-2005. We quantified the mean and coefficient of variation of track activity among trees by fitting the beta-binomial distribution to data from each plot and study period. We measured temporal persistence by disattenuated autocorrelation, and spatial scale by fitting exponential variograms. Mice were much less abundant in 2005 than the other two years, leading to lower overall track activity but higher coefficient of variation among trees. Mouse track activity at individual trees was positively autocorrelated between monthly study periods in 2003 and 2004, and even between the two years, whereas temporal autocorrelation in 2005 was much weaker. Track activity showed positive spatial autocorrelation over lag distances from approximately 30 to > 1000 m. These findings indicate that mouse activity, and hence risk to their prey, varies substantially in space at spatial and temporal scales that appear responsive to mouse population dynamics. The spatial scale and temporal persistence of that variation imply that prey may benefit from returning to, or failing to disperse from, refugia.