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Predation's consequences can manifest through either consumptive or nonconsumptive effects, but the prey response may also vary depending on the predator hunting strategy. Considerable attention has been paid to coursing predators, whereas less information is available regarding responses to ambush predators. To remedy this paucity, we utilized a three‐dimensional tracking platform to record groups of Daphnia magna under predation risk from the ambush invertebrate predator red‐eyed damselfly, Erythromma najas. This design allowed us to test individual antipredator responses in multiple metrics of swimming behaviors. We demonstrate that predation risk was greatest for those that swam at 85% of the available depth and averaged 8.1 mm/s. Examining the swimming behavior of each individual separately showed that predation risk did not affect any of the prey response metrics. Interestingly, however, Daphnia did conform to one of two strategies while under predation risk: either swim fast high up in the water column or swim slowly close to the bottom. Hence, this dichotomous behavior is driven by strategies combining speed and depth in different constellations. In a broader context, our findings highlight the importance of considering both the spatial and temporal dimensions of predation events in order to correctly detect antipredator responses. [ABSTRACT FROM AUTHOR]

Reproduction of the pancake tortoise in the wild has remained poorly known over the decades. This study fills the knowledge gap by investigating the reproductive ecology of the species in its natural habitats in Kenya. Data were collected using the time‐constrained search‐and‐seize method, group‐level scan sampling, radio tracking, and camera‐trapping. Our observations revealed a total of 19 mating events that occurred between December and April, predominantly during the rainy seasons. Mating duration averaged 15.2 ± 2.4 min. Male–male aggression was observed during the mating season, with the dominant male keeping off all other males and mating with the resident females. Nest preparation events occurred between April and June. Nine nesting events were recorded, but in only five of them was an egg deposited. The nests were dug in loose soil, appeared almost circular, and measured 8.4 ± 0.9 cm wide and 7.0 ± 0.1 cm deep (n = 7). The average clutch size was one egg. The eggs were white, hard‐shelled, oval, and elongated measuring 4.4 ± 0.4 cm long, 2.7 ± 0.04 cm wide and weighed 17 ± 0.6 g (n = 3). Incubation period lasted 177 ± 5.7 days (n = 2), and hatching coincided with the onset of the short rainy season in November, aligned with the availability of abundant food for the tortoises. The hatchlings were minimally wider than long, having an average straight carapace length of 4.5 ± 0.6 cm, an average width of 4.5 ± 0.4 cm, and on average weighed 14.7 ± 3.7g, (n = 9). They remained near the nest site for 4–5 days before relocating to tiny rock crevices away from the adult tortoise crevices. Egg and hatchling predation was high, with four of the total of six eggs, observed after they were laid, being destroyed. Three juveniles, out of nine, were also eaten by predators. These findings contribute useful information for the formulation of effective conservation and management strategies for this critically endangered species. [ABSTRACT FROM AUTHOR]

Depredation (the partial or complete removal of a hooked species by a non‐target species) is a human–wildlife conflict as old as humans and the sea. In some ways, depredation is no different today than it was a century ago. But in many ways, this conflict has become more complicated. Following three decades of successful management, some US shark populations have begun to rebuild. However, many anglers attribute perceived increases in shark depredation to management measures, claiming they have led to 'overpopulation' of sharks and/or learned behaviour by sharks. We investigated whether these factors could explain the reported increases in depredation. Based on fishery‐independent surveys, neither shark population increases nor learned behaviour by sharks is evident. However, increases in angler effort provide an alternative explanation that is not often considered. While far from a smoking gun, at least four themes emerge from this thought exercise. First, it is important to understand historical predator baselines. Second, it is important to acknowledge lifting baselines, that is, instances where previously depleted populations are recovering. Third, it is important to remember that there are many instances when stakeholder observations were initially misaligned with traditional scientific observations but were ultimately recognized as pivotal for filling data gaps. Finally, and perhaps most important, is the acknowledgement that perceived conflict is as potent as real conflict. Arguably, it may not matter if depredation has increased or decreased; the overwhelming perception from stakeholders is an increase in depredation, and this is the perceived (or real) conflict that must be addressed. [ABSTRACT FROM AUTHOR]

Imagine the vast Palaeozoic oceans: graptolites (Pterobranchia, Graptolithina) appear as small and inconspicuous benthic faunal elements in the early Cambrian, later becoming one of the dominating planktic groups of macrofauna in Ordovician and Silurian marine environments. Their unusual organic housing secretions (tubaria) in the fossil record makes them one of the most important biostratigraphic markers for the Ordovician to early Devonian time intervals. The occurrence, especially of the planktic graptolites, in black shales led to the common notion of a life style that related them to anoxic or dysaerobic environments, but is merely a preservational aspect. Their demise in the early Devonian may be related to the origination and diversification of large plankton feeding organisms in the marine realm as the graptolites were unable to complete with the much faster growth and reproduction of smaller, non-colonial organisms that did not need to waste time producing a housing construction. Thus, from the later Devonian onwards, the graptolites were largely gone and the oceans were teeming with fast reproducing and growing micro-and macroplankton. Larger predatory animals evolved as plankton feeders, that may have preyed on the graptolites. Only a few cryptic benthic species survived into the modern world. [ABSTRACT FROM AUTHOR]

The main focus of this paper is to study some high codimension bifurcations of a predator-prey system with Michaelis-Menten type predator harvesting. In this paper, using the center manifold theorem, the cusp bifurcation of codimension two is discussed in detail. Furthermore, the Bautin bifurcation of codimension two and the Bogdanov-Takens bifurcation of codimension three are well studied by computing the second Lyapunov coefficient and using the normal form theory, respectively. Numerical simulations are provided to illustrate the theoretical results. The study of these bifurcations reveals the more complex dynamics of the system and may help us to better understand the complex interactions between predator and prey. [ABSTRACT FROM AUTHOR]

Consideration of generalist predators leads to relatively complex dynamics due to alternative food sources. Here, we propose and analyze a prey-predator model with a generalist predator. The availability of alternative food sources for the predator and a density-dependent growth rate induces not only bistability and tristability, but also more complicated dynamical behaviors. We have studied the possible number and geometric configurations of positive equilibria in detail. A systematic bifurcation analysis has revealed the existence of the degenerate Bogdanov-Takens bifurcation of codimension four and degenerate Hopf bifurcation of codimension three. We found that degenerate local bifurcations with a higher codimension are responsible for three limit cycles. Derivation of the analytical conditions for three limit cycles for a suitable range of parameters is a crucial finding of this work. [ABSTRACT FROM AUTHOR]

The impact of predator‐driven fear on ecosystems is significant and can encompass both trophic (direct) and nontrophic (indirect) effects. Previous studies have shown that nontrophic fear effects have an important role in predator–prey dynamics. This study investigates the nontrophic fear effect on prey caused by generalist predators and explores optimal harvesting. We assume that the reproduction rate of prey is reduced due to the fear effect, and generalist predator follows Holling type II foraging strategy for predation. Additionally, we assume that predators are commercially valuable and harvested proportionately to their density. We demonstrate the existence of equilibrium points, their local and global stability, and bifurcation analysis. We observe that the model system undergoes a sequence of codimension one and codimension two bifurcations. Our results show that in the absence of predator harvesting, increasing levels of fear destabilize the predator–prey system, and controlled harvesting is beneficial for the coexistence of both populations. Also, the harvesting of predators may produce hydra and multiple hydra effects. We identify different types of bistability phenomena, which emphasize the importance of initial population size. Further, an optimal harvesting policy is also explored by formulating an optimal control problem (OCP). The harvesting cost‐functional is designed by incorporating the bionomic equilibrium state. We use Pontryagin's maximum principle and solve the OCP numerically. It is observed that implementing optimal harvesting not only contributes to the ecological benefits by maintaining a sustainable balance of predator–prey evolution but also plays a significant role in maximizing the economic benefits. [ABSTRACT FROM AUTHOR]

It is widely recognized that predators can influence prey through both direct consumption and by inducing costly antipredator behaviours, the latter of which can produce nonconsumptive effects that cascade through trophic systems. Yet, determining how particular prey manage risk in natural settings remains challenging as empirical studies disproportionately focus on single predator–prey dyads. Here, we contrast foraging strategies within the context of a primary and secondary prey to explore how antipredator behaviours emerge as a product of predation intensity as well as the setting in which an encounter takes place. We studied the effects of spotted owls (Strix occidentalis) on two species experiencing asymmetrical risk: dusky‐footed woodrats (Neotoma fuscipes; primary prey) and deer mice (Peromyscus spp.; alternative prey). Woodrats are most abundant within young forests, but predominantly captured by owls foraging within mature forests; in contrast, deer mice occur in high densities across forest types and seral stages and are consumed at lower per‐capita rates overall. We deployed experimental foraging patches within areas of high and low spotted owl activity, created artificial risky and safe refuge treatments, and monitored behaviour throughout the entirety of prey foraging bouts. Woodrats were more vigilant and foraged less within mature forests and at riskier patches, although the effect of refuge treatment was contingent upon forest type. In contrast, deer mice only demonstrated consistent behavioural responses to riskier refuge treatments; forest type had little effect on perceived risk or the relative importance of refuge treatment. Thus, habitat can interact with predator activity to structure antipredator responses differently for primary versus secondary prey. Our findings show that asymmetrical predation can modulate both the magnitude of perceived risk and the strategies used to manage it, thus highlighting an important and understudied contingency in risk effects research. Evaluating the direct and indirect effects of predation through the paradigm of primary and secondary prey may improve our understanding of how nonconsumptive effects can extend to population‐ and community‐level responses. [ABSTRACT FROM AUTHOR]

In this paper, we consider a diffusive predator–prey model with spatial memory of prey and gestation delay of predator. For the system without delays, we study the stability of the positive equilibrium in the case of diffusion and no diffusion, respectively. For the delayed model without diffusions, the existence of Hopf bifurcation is discussed. Further, we investigate the stability switches of the model with delays and diffusions when two delays change simultaneously by calculating the stability switching curves and obtain the existence of Hopf bifurcation. We also calculate the normal form of Hopf bifurcation to determine the direction of Hopf bifurcation and the stability of bifurcation periodic solutions. Finally, numerical simulations verify the theoretical results. [ABSTRACT FROM AUTHOR]

Post-contact immobility (PCI) is a final attempt to avoid predation. Here, for the first time, we examine the pattern of movement and immobility when antlion larvae resume activity after PCI. To simulate contact with, and escape from, a predator we dropped the larvae onto three different substrates: Paper, Shallow sand (2.3mm-deep) and Deep sand (4.6mm-deep). The Paper lining a Petri dish represented a hard surface that antlion larvae could not penetrate to hide. The Shallow sand permitted the antlions to dig but not to submerge completely whereas the Deep sand allowed them both to dig and to submerge. We tracked their paths automatically and recorded alternating immobility and movement durations over 90min. On the impenetrable substrate, antlion larvae showed super-diffusive dispersal, their movement durations became longer, their immobility durations became shorter and their instantaneous speeds increased. This is consistent with the antlions needing to leave an area of hard substrate and quickly to find somewhere to hide. On Shallow sand, antlion larvae exhibited a modest increase in movement duration, a modest decrease in immobility duration and a concomitant diffusive dispersal. This is consistent with their use of a spiral search, presumably for a suitable depth of sand, to conceal themselves. On Deep sand, the movement and immobility durations of the antlion larvae did not change and their dispersal was sub-diffusive because they were able to bury themselves. On Paper, the distribution of immobility durations had a long tail, consistent with a log-normal distribution. On Shallow and Deep sand, most of the distribution was fitted better by a power law or a log-normal. Our results suggest that PCI in antlion larvae is a disruptive event and that post-PCI movement and immobility gradually return to the pattern typical of intermittent locomotion, depending on the scope for burying and hiding in the substrate. [ABSTRACT FROM AUTHOR]

In the Caribbean, reef-building scleractinian corals have declined precipitously and octocorals have emerged as one of their main successors. The success of octocorals and the formation of octocoral forests has been attributed to their continuing recruitment to reef habitats, as well as tolerance to pollution, reduced direct competition with scleractinians, and resistance and resilience to climatic events. Benthic grazers on coral reefs can facilitate the growth and recruitment of corals by reducing the abundance of competitive algal turfs and macroalgae. However, grazing can also hinder corals through sublethal damage to coral tissue and predation of recruits. We assessed the effects of grazing by fishes and the sea urchin Diadema antillarum as well as predation by mesofauna on octocoral recruitment through a series of manipulative in situ and ex situ experiments. Exposure to fish and urchin grazing significantly reduced the post-settlement survival of octocoral recruits, while turf-associated mesofauna did not significantly affect recruitment. We also found a positive relationship between octocoral recruitment and the abundance of turf algae, which may reflect the deleterious effect of grazing on both turf algae and octocoral recruits. These data suggest that grazers and predators mediate the bottleneck characteristic of recruitment, primarily through their effect on post-settlement survival. Thus, the declines in the abundance of grazing fishes and urchins throughout the Caribbean may have contributed to the increase in Caribbean octocoral abundance, concurrent with the loss of scleractinians. [ABSTRACT FROM AUTHOR]

In this paper, we propose a food chain model in which the primary predator moves directly toward areas of high prey density. Simultaneously, the primary predator, which serves as the prey for the secondary predator, indirectly influences the directional movements of the secondary predator through cues such as chemical signals, scents, or excretions. We investigate whether the distinct influences of direct taxis and indirect taxis, as observed in prey–predator dynamics, are also manifested in the proposed food chain model. Our study demonstrates that the model, which incorporates both direct and indirect prey‐taxis, possesses bounded and global solutions up to three‐dimensional space. [ABSTRACT FROM AUTHOR]

Interactions among predators can have cascading impacts on communities and ecosystems. These interactions often occur around carrion, where the carrion provides a food reward, but also a risk of encountering other, potentially dominant, predators. Understanding how predators balance risk and reward at carrion, and how perceived risk changes in response to carcass origins and conditions, provides valuable insight into intraguild interactions. We investigated Coyote (Canis latrans) behavior at carrion simulated as cache sites treated with Cougar (Puma concolor) scent versus carrion used as control sites to better understand how Coyotes assess risk while feeding on carrion. Coyotes displayed similar behavior between sites treated and untreated with Cougar scent, suggesting that the presence of Cougar scent did not alter perceived risk by Coyotes in our study. Instead, Coyote behavior responded to carcass age, elevation, and whether avian scavengers had visited the carcass. Coyotes spent more time feeding, more time on camera, and touched carcasses quicker as carcass age increased. Avian scavengers appeared to compete with Coyotes, and while the presence of avian scavengers reduced time to carcass detection by Coyotes, it also decreased time spent feeding. These results suggest that carcass condition is a more important indicator of risk and reward than the presence of dominant predator scent to Coyotes. Predator scent may be an unreliable cue of immediate predator presence. Alternatively, all carcasses may be risky because dominant predators also scavenge carrion, creating similar risk regardless of previous visitation by dominant predators. These results provide insights into predator interactions and can also inform the use of scent cues in wildlife management. [ABSTRACT FROM AUTHOR]

The sub-Antarctic terrestrial ecosystems survive on isolated oceanic islands in the path of circumpolar currents and winds that have raged for more than 30 million years and are shaped by climatic cycles that surpass the tolerance limits of many species. Surprisingly little is known about how these ecosystems assembled their native terrestrial fauna and how such processes have changed over time. Here, we demonstrate the patterns and timing of colonization and speciation in the largest and dominant arthropod predators in the eastern sub-Antarctic: spiders of the genus Myro. Our results indicate that this lineage originated from Australia before the Plio-Pleistocenic glacial cycles and underwent an adaptive radiation on the Crozet archipelago, from where one native species colonized multiple remote archipelagos via the Antarctic circumpolar current across thousands of kilometers. The results indicate limited natural connectivity between terrestrial macroinvertebrate faunas in the eastern sub-Antarctic and partial survival of repeated glaciations in the Plio-Pleistocene. Furthermore, our findings highlight that by integrating arthropod taxa from multiple continents, the climatically more stable volcanic Crozet archipelago played a critical role in the evolution and distribution of arthropod life in the sub-Antarctic. [ABSTRACT FROM AUTHOR]

The functions of bright bands in coral and other snakes have long been a puzzle. The most common opinion is that coral snakes display aposematic marks and that other red and black banded snakes in the Americas are mimics of coral snakes. I previously found that this prevailing opinion is weakly supported and unlikely, that red and bands had probably evolved independently or conjointly many times, and that a present selection for bands and red seems to exist in a significant fraction of the world. Here, I review the potential selective forces for red and bands in snakes. I find that snakes as predators are a priori plausible selective agents. I find that ophiophagy appears to be an exceptionally high risk in snakes that are themselves ophiophagous. Testing the working hypothesis that bands and red are protective against snake predators via their association with ophiophagy, as ophiophagous snakes are at higher risk, I find that the consumption of elongate vertebrates predicts band and red coloration with a very high level of confidence: red and bands are probably defensive against snake predators. Noting an apparent correlation of coloration with specific defensive behaviours and ontogenetic colour changes, I review both and find that ophiophagous snakes are remarkable for using stereotypical defences and not being aggressive, while ontogenetic colour changes seem to affect red and bands in snakes disproportionately. Defence against ophidian predators may be an unexpected natural selection shaping the appearance and behaviours of many snakes. [ABSTRACT FROM AUTHOR]

Studying the interactions between prey and predators is crucial for understanding the intricacies of predator-prey dynamics and for formulating effective conservation strategies. Yet there is almost no systematic analysis of pancake tortoise predation, and its consequences on the tortoise populations. Using camera trapping and visual encounter surveys, we recorded the animals visiting the crevices inhabited by pancake tortoises, as well as their surroundings. From our data, we propose which visitors were potential predators, and consider predator impacts on the species. We suggest ten species (21.3%) as potential predators, among the 47 visiting the tortoise crevices between July 2020 and November 2022. We encountered six adult pancake tortoises killed and eaten by unknown predators. Four of six eggs laid by pancake tortoises in May−June 2022 were also depredated. The white-tailed mongoose (Ichneumia albicauda) and the honey badger (Mellivora capensis) were recorded probing rock crevices inhabited by pancake tortoises, with their behaviour suggesting potential predation upon tortoises. We recorded the rock monitor lizard (Varanus albigularis) and common dwarf mongoose (Helogale parvula) digging pancake tortoise nest sites. This study significantly advances our understanding of the predation risk to the critically endangered pancake tortoise. [ABSTRACT FROM AUTHOR]

The recovery of mammalian predators of conservation concern in Europe is a success story, but their impact on some prey species of conservation concern may cause conservation dilemmas. This calls for effective intervention strategies that mitigate predator impacts without compromising their recovery.We evaluated diversionary feeding as a management intervention tool to reduce depredation on nests of rapidly declining Western capercaillies in Scotland. We studied the influence of diversionary feeding provision on the fates of artificial nests deployed using a replicated and representative randomised landscape‐scale experiment. This comprised 30 'paired' control (no diversionary feeding) and treatment (diversionary feeding applied) sites, 60 in total, each containing six artificial nests distributed across 600 km2. The experiment was replicated over 2 years, and in the second year, the control‐treatment pairs were reversed, yielding 60 treatment and 60 control sites and 720 artificial nests.Diversionary feeding substantially reduced depredation of artificial nests, translating into an 82.5% increase in predicted nest survival over 28 days of incubation. The increase in survival was mostly accounted for by a reduction in the probability that a pine marten, the main nest predator, consumed or cached eggs. Diversionary food also significantly reduced nest predation by badgers, although the magnitude of this effect varied by year.Synthesis and applications. Diversionary feeding is an easily employable method shown in this study to reduce predator impact (functional) without lethal (numerical) intervention. Managers should proceed with its application for conserving capercaillie in Scotland without delay. [ABSTRACT FROM AUTHOR]

Fish fins are remarkable devices of propulsion. Fin morphology is intimately linked to locomotor performance, and hence to behaviours that influence fitness, such as foraging and predator avoidance. This foreshadows a connection between fin morphology and variation in predation risk. Yet, whether prey can adjust fin morphology according to changes in perceived risk within their lifetime (a.k.a. predator‐induced plasticity) remains elusive.Here, we quantify the structural size of five focal fins in crucian carp (Carassius carassius) following controlled manipulations to perceived predation risk (presence/absence of pike Esox lucius). We also assess if crucian carp respond to increased predation risk by shifts in dorsal fin colouration, and test for differences in how fish actively use their dorsal fins by quantifying the area of the fin displayed in behavioural trials.We find that crucian carp show phenotypic plasticity with regards to fin size as predator‐exposed fish consistently have larger fins. Individuals exposed to perceived predation risk also increased dorsal fin darkness and actively displayed a larger area of the fin to potential predators.Our results thus provide compelling evidence for predator‐induced fin enlargement, which should result in enhanced escape swimming performance. Moreover, fin‐size plasticity may evolve synergistically with fin colouration and display behaviour, and we suggest that the adaptive value of this synergy is to enhance the silhouette of deep‐bodied and hard‐to‐capture prey to deter gape‐limited predators prior to attack. Together, our results provide new perspectives on the role of predation risk in development and evolution of fins. [ABSTRACT FROM AUTHOR]

Parental effects, or parental phenotypes affecting offspring phenotypes, are widespread across taxa, yet there is significant variation within species regarding which offspring traits are affected. One reason for this observed variation could be the type of sensory cues present in the parental environment. By exposing parents to sensory cues containing different information about the same ecological stressor, we can determine whether information is integrated differently by parents based on cue type, leading to differential trait development in offspring. In this study, we utilized predator cues, which can be found in isolation and in combination in natural settings, to test whether cue type plays a role in differential phenotype expression in Trinidadian guppies, Poecilia reticulata. Parents were exposed to predator cues (visual, olfactory or both combined) over 14 days, after which we assessed life history traits, morphology and activity. Offspring were then raised with no predator cues and tested for morphology and activity in adulthood. No differences in life history traits were observed across 10 weeks. In line with previous findings, behaviour differed in both the parent and F1 generations in response to predator cues; however, effects were dependent on cue type and sex. Our results suggest that exposure to even a single sensory cue is strong enough to initiate a cascade of responses both in parent and F1 generations, and that interacting factors such as cue type and sex lend importance to understanding consequences of parent risk perception for offspring. • Guppy adults were exposed to olfactory, visual or combined predator cues. • Offspring of adults exposed to different sensory cues were raised in freshwater. • Adults differed in behaviour but not life history based on sex and sensory cue type. • Offspring differed in morphology and behaviour based on sex and parental cue type. • Impact of sensory cues across generations may be linked to overall behavioural type. [ABSTRACT FROM AUTHOR]

Prey animals may lack appropriate predator avoidance behaviours to novel predators, which has contributed to the decline of many species worldwide following human introduction of novel predators. Excluding novel predators from conservation reserves has been used to attempt to recover naïve species with mixed success. However, in the absence of predators, prey naiveté can be exacerbated. Reintroducing native predators has been suggested as a solution to addressing this problem and may act as a stepping stone to improve behavioural responses to novel predators. We tested the behavioural responses of two prey species, the burrowing bettong, Bettongia lesueur , and spinifex hopping mouse, Notomys alexis , to the reintroduction of a native predator, the western quoll, Dasyurus geoffroii , and determined whether exposure to a native predator improved their antipredator responses to introduced feral cats, Felis catus. Quoll-exposed bettongs spent less time engaged in inattentive foraging behaviours compared to control (nonpredator exposed) bettongs but did not discriminate between predator and nonpredator visual or olfactory cues (native or novel). Quoll-exposed spinifex hopping mice modified their foraging in open habitats and increased wariness in the presence of quoll stimuli, whereas cat-exposed hopping mice only exhibited increased wariness in the presence of cat stimuli. Our results show that reintroductions of native predators improved general antipredator responses in native prey species, but there was only weak evidence that this led to an improved response to introduced predators. However, reintroducing native predators improved general antipredator behaviour in ontogenetically naïve populations which may make them more suitable for releases outside conservation fences where novel predators are present. • Reintroductions of native predators improve general antipredator responses in prey • Quoll-exposed bettongs spent less time in inattentive foraging than controls • Quoll-exposed hopping mice recognized foraging risk in open habitats • Limited evidence whether this improves discrimination towards novel predators [ABSTRACT FROM AUTHOR]

Reproductive allocation is often balanced between the quantity and quality of offspring. Ecological stresses, like exposure to predators, can cause organisms to shift their allocations along this continuum. While the consequences of such plastic shifts for offspring performance are often untested, they are critical to understanding the potential long‐term benefits of manipulating predation risk as an agricultural pest management technique. Predation risk induces reductions in egg production and increases in nutritional condition due to maternal provisioning in Colorado potato beetles (Leptinotarsa decemlineata, CPB). Here, we tested whether reductions in density or increases in offspring condition, which may increase per‐capita larval survival, can compensate for the reduction in total egg production, especially when offspring are exposed to predators. In two field trials, we manipulated density and condition of larval CPB and measured survival through development to adulthood in field cages with and without predaceous stink bugs (Podisus maculiventris). As expected, cages with the higher initial larval densities had more larvae and adults surviving in the treatments without predators – about 30%–50% survival across densities. When predators were present, this relationship did not hold because of density‐dependent predation. Larval condition interacted with density and impacted larval survival in both trials albeit in different ways. In trial 1, unprovisioned beetles had higher survival at the higher densities; in trial 2, provisioned beetles had higher survival across densities. Synthesis and Applications: Overall, our test of the effects of predation risk via manipulations of larval density and condition revealed few net compensatory benefits to the prey of reduced density and higher condition. Benefits to the prey of shifts in allocation from the quantity to quality of offspring may depend on factors that influence the strength of density dependence, including predation intensity. Our results suggest a new strategy of taking advantage of the reductions in prey density due to non‐consumptive effects of predators as a pest management approach to protect plants. [ABSTRACT FROM AUTHOR]

When describing Active Inference Agents (AIAs), the term "energy" can have two distinct meanings. One is the energy that is utilized by the AIA (e.g., electrical energy or chemical energy). The second meaning is so-called Variational Free Energy (VFE), a statistical quantity which provides an upper bound on surprisal. In this paper, we develop an account of the former quantity—the Thermodynamic Free Energy (TFE)—and its relationship with the latter. We highlight the necessary tradeoffs between these two in a generic, quantum information-theoretic formulation, and the macroscopic consequences of those tradeoffs for the ways that organisms approach their environments. By making this tradeoff explicit, we provide a theoretical basis for the different metabolic strategies that organisms from plants to predators use to survive. [ABSTRACT FROM AUTHOR]

Most species co-evolve with their predators and develop strategies to avoid predation. This is not possible when a novel predator invades an environment. Native residents must quickly adapt to their new predator or face local extinction. Intense competition for mating opportunities exerts significant selective pressure that can drive the evolution of exaggerated structures across taxa. However, these elaborate traits can elevate the risk of predation for some organisms. In the present study, we observe the effect that rats have had on a population of endemic New Zealand stag beetles, Geodorcus helmsi. Rats in Rakiura | Stewart Island often prey on stag beetles, taking them to a sheltered area to eat them and discard any uneaten parts of the beetle, namely the head and mandibles. We compared the head size, mandible size and numbers of predated and non-predated male and female beetles in three sites in Rakiura | Stewart Island that differ in their abundance of mammalian predators. We found that the population demography and the size of the beetles differed significantly between sites. Additionally, we determined whether predated beetles were larger than non-predated beetles, across multiple years, regardless of site. We found that overall the predated specimens were larger than the non-predated beetles. The trends found here suggest that exaggeration of the male mandibles increases the predation risk of these iconic beetles, acting as a limit to mandible size. Implications for insect conservation: Our results show for the first time the effect that novel predators can have on a population of animals with exaggerated sexually selected traits. The presence of novel predators can cause a shift in both population demography and trait distribution. [ABSTRACT FROM AUTHOR]

Chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) has emerged as a severe invasive pest of strawberry Fragaria × ananassa Duchesne in the United States. The objective of this study was to assess the field efficacy of a biopesticide and thrips predator, Amblyseius swirskii Athias-Henriot for S. dorsalis management in field grown strawberry compared to synthetic insecticide applications that are current industry standard (spinetoram) conducted at UF/IFAS GCREC, FL during 2021–2022 and 2022–2023 in a 2-year field study. The following treatments were applied in the field: (1) biopesticide, capsicum oleoresin extract + garlic oil + canola oil application at maximum label rate; (2) predatory mite of thrips, A. swirskii released at 30 predators per plot; (3) spinetoram applied at maximum label rate; and (4) biopesticide applied 24 h before release of A. swirskii. A control plot with no insecticide or predatory mite releases was maintained. Results show that the capsicum extract can be used for management of S. dorsalis , especially during the latter stages of strawberry field season when resistance to spinetoram is high. The field performance of A. swirskii was variable and extensive research is needed to highlight factors affecting field performance of predatory mites for thrips management. [ABSTRACT FROM AUTHOR]

The hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), is an invasive pest causing significant ecological and economic damage to certain hemlock tree (Tsuga (Endlicher) Carrière, Pinales:Pinaceae) species. In response to this invasive threat, biological control strategies have been implemented, introducing natural predators such as Laricobius nigrinus Fender (Coleoptera: Derodontidae) and, more recently, Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae), as specialist predators against A. tsugae. However, the genetic and morphological similarities between L. osakensis and both L. nigrinus and the native beetle, Laricobius rubidus LeConte (Coleoptera: Derodontidae), pose challenges in their identification. Effective monitoring of released predators is integral to evaluating the success of biological control measures. Environmental DNA (eDNA) holds potential for various detection applications, including species monitoring. In this study, we developed specific primers and probes targeting the mitochondrial cytochrome oxidase 1 gene sequences, achieving high specificity despite their 95% sequence similarity. With an optimal annealing temperature of 60 °C, our tools effectively differentiated L. osakensis from the other 2 beetles and demonstrated eDNA detection sensitivity down to 2 copies/µl. This research underscores the potential of precise molecular tools for advancing biological control and biodiversity assessment against invasive threats like A. tsugae. [ABSTRACT FROM AUTHOR]

Many wildlife species vary habitat selection across space, time, and behavior to maximize rewards and minimize risk. Multi‐scale research approaches that identify variation in wildlife habitat selection can highlight not only habitat preferences and risk tolerance but also movement strategies that afford coexistence or cause conflict with humans. Here, we examined how anthropogenic and natural features influenced coyote (Canis latrans) habitat selection in a mixed‐use, agricultural landscape in Mendocino County, California, USA. We used resource selection functions and hidden Markov models to test whether coyote selection for anthropogenic and natural features varied by time of day or by behavioral state (resting, foraging, and traveling). We found that coyotes avoided development, but, contrary to our expectations, coyotes selected for roads, agriculture, and areas with risk of human encounter and rifle use regardless of diel period or behavioral state. While traveling, coyotes increased selection for roads and avoided ruggedness, indicating that unpaved roads may enhance connectivity for coyotes in mixed‐use landscapes. Finally, we found that coyotes selected for mountain lion habitat when resting and at night, signifying that risk from natural predators was not a factor in habitat selection at coarse scales. Coyote habitat selection for places and times associated with human activity, without variation across scales, signals a potential for conflict if coyotes are perceived by people as a nuisance. [ABSTRACT FROM AUTHOR]

Understanding the drivers of food web community structure is a fundamental goal in ecology. While studies indicate that many coral reef predators depend on pelagic subsidies, the mechanism through which this occurs remains elusive. As many of these species are important fishery targets, a better understanding of their trophodynamics is needed. To address these gaps, we employed a comprehensive structural equation modelling approach using extensive surveys of the reef community to explore relationships between groupers and snappers, their prey, and the surrounding habitat in an oceanic coral reef system. There were significant positive relationships between site-attached and transient planktivores and grouper and snapper biomass, respectively, indicating that pelagic subsidies are transferred to upper trophic levels through planktivores. Contrary to previous studies, habitat complexity and depth were not important for predators or prey. Instead, corallivores and site-attached and transient planktivores were primarily associated with live habitat and coral cover. This indicates that a decline in coral cover could have severe direct and indirect impacts on the structure and functioning of multiple levels of the reef food web. While pelagic reliance may suggest that predators are resilient to bleaching-related habitat loss, the associations of their planktivorous prey with live coral suggest that both benthic and pelagic pathways should be preserved for continued resilience of these food webs and their fisheries. By considering direct and indirect relationships, our study generated insights not only on the complex dynamics of coral reef ecosystems, but also on how they may respond to environmental change. [ABSTRACT FROM AUTHOR]

Understanding and accounting for the slow–fast effect are crucial for accurately modeling and predicting the dynamics of predator–prey models, emphasizing the importance of considering the relative speeds of interacting populations in ecological research. This paper examines a predator–prey interaction to study its complex dynamics due to its slow–fast effect on predator populations. The occurrence and stability of equilibria are analyzed. The stability of positive fixed point is dependent on the slow–fast effect parameter ϵ$$ \epsilon $$, which must fall within a specific range when the generation gap is larger. The positive fixed point becomes unstable for bigger values of ϵ$$ \epsilon $$ because the growth of predators is faster, resulting in the extinction of all prey. Smaller values of ϵ$$ \epsilon $$ cause the positive fixed point to become unstable since the prey grows more quickly while the predator grows more slowly, ultimately causing the extinction of the predator. Moreover, it is shown that Leslie–Gower model experiences Neimark–Sacker and period‐doubling bifurcations at positive equilibrium point. In order to control bifurcation, hybrid control and feedback control methods are employed. Finally, analytical results are confirmed by numerical examples. [ABSTRACT FROM AUTHOR]

In this paper, we propose a Leslie–Gower predator–prey model in which the predator can only be captured when its population size exceeds a critical value; the mean growth rate of the prey in the absence of the predator is subject to a semi‐saturation rate that affects its birth curve, and the interaction between the two species is defined by a Holling II predation functional with alternative food for the predator. Since the proposed model is equivalent to a Filippov system, its mathematical analysis leads to a local study of the equilibria in each vector field corresponding to the proposed model, in addition to the study of the stability of its pseudo‐equilibria located on the curve separating the two vector fields. In particular, the model could have between one and three pseudo‐equilibria and at least one limit cycle surrounding one or two inner equilibria, locally unstable points. [ABSTRACT FROM AUTHOR]

Environmentally explicit models can improve model performance and our understanding of biological processes. However, these models must be retested over time, as the mechanisms influencing biological processes can change. The relationship between recently settled young‐of‐year (i.e., settlers) and pre‐recruit American lobsters was revisited to determine if our perception on post‐settlement lobster processes has changed. Analyses were focused within the southern region of the species' latitudinal range (Rhode Island, United States), where several environmental factors have been theorized to contribute to the Southern New England stock decline and continued depleted state. The inclusion of additional, recent years' data provided insight on how the density‐dependent nature of the settler–pre‐recruit lobster relationship has varied over time. Including both new and retested environmental drivers reaffirmed the importance of incorporating environmental data when describing this process. Specifically, modeling revealed the importance of epizootic shell disease, finfish predators, and Asian shore crabs in the settler–pre‐recruit relationship. Including disease, predation, and competition metrics in the lobster post‐settlement relationship has allowed for improved modeling and insight into settlement dynamics. This renewed analysis supports reevaluating environmentally explicit models over time and calls for further directed research regarding the biological processes we seek to model with time series data. [ABSTRACT FROM AUTHOR]

Predator-prey arms races have led to the evolution of finely tuned disguise strategies. While the theoretical benefits of predator camouflage are well established, no study has yet been able to quantify its consequences for hunting success in natural conditions. We used high-resolution movement data to quantify how barn owls (Tyto alba) conceal their approach when using a sit-and-wait strategy. We hypothesized that hunting barn owls would modulate their landing force, potentially reducing noise levels in the vicinity of prey. Analysing 87,957 landings by 163 individuals equipped with GPS tags and accelerometers, we show that barn owls reduce their landing force as they approach their prey, and that landing force predicts the success of the following hunting attempt. Landing force also varied with the substrate, being lowest on man-made poles in field boundaries. The physical environment, therefore, affects the capacity for sound camouflage, providing an unexpected link between predator-prey interactions and land use. Finally, hunting strike forces in barn owls were the highest recorded in any bird, relative to body mass, highlighting the range of selective pressures that act on landings and the capacity of these predators to modulate their landing force. Overall, our results provide the first measurements of landing force in a wild setting, revealing a new form of motion-induced sound camouflage and its link to hunting success. [ABSTRACT FROM AUTHOR]

Prey-predator interactions across time and space strongly influence many animal communities. This study unveils the first insights into the ecology of the Eurasian red squirrel (Sciurus vulgaris) in Mongolia, and specifically in Bogd Khan Mountain Strictly Protected Area. We used by-catch data obtained from camera traps to analyze activity patterns and potential interactions with mammalian predators. Red squirrels exhibited primarily diurnal activity with occasional nocturnal forays, while potential predators like foxes (Vulpes vulpes, Vulpes corsac) and martens (Martes foina, Martes zibellina) displayed cathemeral and nocturnal patterns, respectively. The diurnal Pallas’s cat (Otocolobus manul) showed the greatest activity overlap with squirrels. Suggesting predator avoidance behavior potentially mediated by olfactory cues, squirrel activity was negatively impacted by marten presence, which was in turn potentially affected by human disturbance. We highlight the need for further investigations, particularly regarding the dietary composition of Pallas’s cats in forested habitats and the broader ecological implications of human disturbance on predator–prey dynamics within this crucial conservation area. [ABSTRACT FROM AUTHOR]

Understanding how environmental factors affect the performance of predators can provide profound insights into predator–prey interactions from evolutionary and ecological perspectives and the global distributional patterns of each taxon. Almost all venomous predators are ectotherms, with muscle contraction properties depending on temperature. For predators having venom transportation systems driven by muscle contraction, temperature may have quite large effects on envenomation performance for prey subjugation. Here, we used videography and enzyme-linked immunosorbent assay to examine thermal effects on envenomation kinematics and venom expenditure in predatory strikes of a venomous snake, the Mamushi Gloydius blomhoffii, to its main rodent prey at various body temperatures under both field and laboratory experimental conditions. Unexpectedly, we found that the thermal effects on envenomation performance are limited over nearly the entire ecologically relevant range of temperature (from 13.2°C to 26.2°C). Although temperature statistically significantly affected the mass of venom injected under field conditions, temperature explained only a minor proportion of the variation in venom expenditure. These findings suggest that the Mamushi is able to maintain prey subjugation performance across a wide range of temperatures, which is highly advantageous for ectothermic predators. Further studies should examine the underlying mechanisms of the limited thermal effects and their ubiquity across venomous predators. [ABSTRACT FROM AUTHOR]

Assassin bugs (Hemiptera: Reduviidae Latreille) comprise not only one of the largest radiations of predatory animals (22 subfamilies; >6,800 spp.) but also include the medically important kissing bugs (Triatominae Jeannel). Reduviidae are morphologically diverse, engage in an astounding array of predatory strategies and have evolved some of the most unique anti‐predator and stealth techniques in the animal kingdom. While significant progress has been made to reveal the evolutionary history of assassin bugs and revise their taxonomy, the non‐monophyly of the second largest assassin bug subfamily, Reduviinae Latreille, remains to be addressed. Leveraging phylogenomic data (2,291 loci) and 112 morphological characters, we performed the first data‐ and taxon‐rich (195 reduvioid taxa) combined phylogenetic analysis across Reduvioidea and reconstructed morphological diagnostic features for major lineages. We corroborated the rampant polyphyly of Reduviinae that demands substantial revisions to the subfamilial and tribal classification of assassin bugs. Our new classification for Reduviidae reduces the number of subfamilies to 19 and recognizes 40 tribes. We describe three new subfamilies to accommodate distantly related taxa previously classified as Reduviinae (Heteropinae subfam. nov., Nanokeralinae subfam. nov., and Pasirinae subfam. nov.). Triatominae sensu nov. are expanded to include closely related predatory reduviine genera. Cetherinae Jeannel, Chryxinae Champion, Pseudocetherinae Villiers, Salyavatinae Amyot & Serville and Sphaeridopinae Amyot & Serville are treated as junior synonyms of Reduviinae sensu nov. Epiroderinae Distant are synonymized with Phimophorinae Handlirsch sensu nov. and Bactrodini Stål stat. nov. are reclassified as a tribe of Harpactorinae Amyot & Serville. Psophidinae Distant is treated as a valid subfamily. This new classification represents a robust framework for future taxonomic and evolutionary research on assassin bugs.Zoobank Registration: http://zoobank.org/urn:lsid:zoobank.org:pub:2310C9AA-0D53-4EF6-9E75-C2B3A98CE096 [ABSTRACT FROM AUTHOR]

Predation is a well-known factor that structures rotifer communities. However, the role of protists as predators is relatively understudied. Here, we investigated predatory behavior of Actinosphaerium sp., a freshwater heliozoan, on seven rotifer species. Predators and prey were collected from a local playa; except for Brachionus calyciflorus that served as a naive prey control. Prey included large species (≥ 175 µm mean length: Asplanchna sieboldii, B. calyciflorus, Platyias quadricornis, and Lacinularia flosculosa) and small species (< 175 µm: Cephalodella gibba, Euchlanis dilatata, and Lepadella patella). Four experiments were conducted. (1) Single prey items of varying size and motility. Larger prey types were ~ 1.7 to 3.0 times more likely to be ingested than small prey. No L. flosculosa were ingested, contrary to field observations. No correlation was found between swimming speed and predation risk. (2) Preference tests. Asplanchna sieboldii and B. calyciflorus were favored prey. (3) Growth rate of Actinosphaerium on mixed diets, with and without Asplanchna. Highest population growth of Actinosphaerium was observed in presence of A. sieboldii. (4) Prey defenses. Susceptibility of spined versus unspined B. calyciflorus resulted in no significant difference in predation risk. Thus, size and being mobile (compared to sessility) are the primary risk factors influencing rotifer predation vulnerability. [ABSTRACT FROM AUTHOR]

Predator-prey interactions in marine ecosystems control population sizes, maintain species richness, and provide intermediate disturbance. Such ecosystem structuring interactions may be rare in Antarctic epibenthic communities, which are unique among marine ecosystems worldwide for their dominance of soft bodied fauna (sponges, soft and hard corals, and echinoderms) and a simultaneous paucity of shell crushing predators (sharks, rays and durophagous decapods). In the shallow benthos, instead of durophagy, important Antarctic predators such as starfish, pycnogonids (sea spiders), nemertean worms, and nudibranchs employ grazing, scavenging, or sucking strategies. Far less is known about deep sea (>1000 m) Antarctic benthic communities due to the challenging nature of polar data collection, so that photographic surveys provide one of the only means of making in situ observations of these deep sea communities. We used seabed photographs of the deep (~2000m) slope of the Powell Basin, northwest Weddell Sea, taken by the Ocean Floor Observation and Bathymetry System on board the RV Polarstern (PS118, April 2019) to investigate the epibenthic community composition, and Bayesian Network Inference (BNI) to determine the ecological network, namely the ecological associations, including potential invertebrate predator-prey relationships between taxa. Photographs show that the rocky substrates of the basin slope support between 10-22 morphotaxa per photo, and highly abundant communities (density between 106 to 553 individuals/m2). BNI results reveal a network of associations between the sessile and mobile suspension and filter feeding organisms and their physical environment. However, associations between invertebrate predators like starfish, and other organisms, were not detected in the network. This lack of inclusion within the network suggests that, despite the presence of these normally important mobile predators, invertebrate predator-prey interactions on the rocky Powell Basin slope do not have the same ecosystem-regulating impact that they do on shallow Antarctic epibenthic communities. [ABSTRACT FROM AUTHOR]

In Brazil, the common earwig Doru luteipes (Scudder) (Dermaptera: Forficulidae) is considered an important biocontrol agent for the maize crop, consuming the fall armyworm Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) eggs and caterpillars from 1st to the 3rd instar. Despite this, several aspects of the interaction between these species have not yet been studied. We aim to evaluate the non‐consumptive effects of earwigs on the oviposition of moths, the earwig's predatory preference between eggs and neonates and its functional response to S. frugiperda eggs. In no‐choice tests between plants with or without the presence of the predator, S. frugiperda moths deposited a smaller number of eggs on plants with risk of predation. In choice‐based tests, earwigs initially attacked newborn caterpillars, but preferred to feed on eggs. Males and females fed more on eggs with increasing supply density and consumption was adjusted to the type II functional response curve. D. luteipes males were more efficient predators than females when exposed to higher egg densities. These findings clarify aspects of the predatory role of D. luteipes on S. frugiperda that had not yet been addressed and suggest that the earwig has potential for impacting the colonization and population growth of S. frugiperda in maize crops, if conditions are favourable to its early arrival. [ABSTRACT FROM AUTHOR]

The dorsal periaqueductal gray (dPAG) contains a tonically GABAergic network controlling defensive responses. Determining how this intrinsic dPAG inhibitory circuit functions might provide critical insights into how anti-predatory responses are organized. [ABSTRACT FROM AUTHOR]

Conservation havens free of invasive predators are increasingly relied upon for fauna conservation, although havened populations can lose anti‐predator traits, likely making them less suitable for life 'beyond the fence'. Sustaining low levels of mammalian predator pressure inside havens may prevent the loss of anti‐predator traits from havened populations. We opportunistically compared behavioural and morphological anti‐predator traits between four woylie (Bettongia penicillata ogilbyi) populations– one haven isolated from all mammalian predators, one haven containing a native mammalian predator (chuditch; Dasyurus geoffroii), and their respective non‐havened counterparts (each containing both chuditch and invasive predators). Havened woylies existing without mammalian predators were smaller (shorter hindfeet, smaller body weight) and less reactive (consumed more food from fox‐treated and control feeding stations, less agitated during human handling) than a non‐havened reference population. However, in the haven containing chuditch, we found no difference in behaviour or morphology compared to the adjacent non‐havened population. Across populations, anti‐predator responses tended to appear stronger at sites with higher predator activity, suggestive of an adaptive response across a gradient of predation pressure. Our findings suggest that maintaining mammalian predation pressure in conservation havens could be effective for preventing or slowing the loss of anti‐predator traits from these populations. [ABSTRACT FROM AUTHOR]

Gape‐limited predators (e.g., snakes, many fish) are not generally expected to pose a predation threat to prey that are too large for them to swallow. However, the extent to which snakes predate on prey that exceed their gape limitation remains largely unknown. We conducted the first study to investigate the influence of both prey and predator sizes on the frequency of ingestion success by snakes in a natural system. We combined survival monitoring of an avian prey species (Aplonis opaca) via radio‐telemetry with a survey of the size distribution of their major predator (Boiga irregularis) on Guam. This allowed us to assess (1) the frequency of unsuccessful ingestion by the predator, (2) whether the size of the prey predicts ingestion success, (3) whether the size of the predator predicts ingestion success, and (4) the relationship between prey and predator sizes in successful ingestion attempts. We found that nearly half (47.95%) of ingestion attempts by snakes on fledgling birds were unsuccessful, and no instances where unsuccessful ingestion caused the mortality of the snake. Attempts to consume smaller fledglings were as likely to be unsuccessful as attempts to swallow larger fledglings. However, snakes that successfully ingested fledglings were among the largest snakes in the population, and larger than average conspecifics attracted to endothermic prey. The smallest snakes that successfully ingested fledglings attained remarkably high relative prey mass values for their species, consuming prey weighing up to 79.9% of their own mass. Our study indicates that B. irregularis routinely predate prey that are too large for them to successfully ingest, which causes mortality to the prey but poses little risk to the predator. The potential reward for snakes in consuming oversized prey may outweigh the inherent risks, while instances of predation that do not result in consumption may have considerable impacts on prey populations. [ABSTRACT FROM AUTHOR]

Many Neotropical beetles present coloration patterns mimicking red-eyed flies, which are presumably evasive mimicry models. However, the role of predators in selecting for evasive mimics in nature remains untested. In a field experiment, we used nontoxic plasticine replicas of a specialized fly-mimicking beetle species, which we placed on the host plants of the beetles. We show that replicas painted with reddish patches simulating the eyes of flesh flies experienced a much lower predation rate than control replicas. We found that beak marks were the most frequent signs of attack on plasticine replicas, underlining the potential selective pressure exerted by birds. Replicas that matched the size of the beetles suffered higher predation than smaller or larger replicas. The predation rate was also higher for beetle replicas exposed during the warm and wet season, when adult beetles occur. Our results support predator-mediated selection of mimic beetles, highlighting that reddish spots resembling flies' eyes comprise an important trait in reducing attack by avian predators. [ABSTRACT FROM AUTHOR]

Trophic interaction modifications (TIM) are widespread in natural systems and occur when a third species indirectly alters the strength of a trophic interaction. Past studies have focused on documenting the existence and magnitude of TIMs; however, the underlying processes and long‐term consequences remain elusive. To address this gap, we experimentally quantified the density‐dependent effect of a third species on a predator's functional response. We conducted short‐term experiments with ciliate communities composed of a predator, prey and non‐consumable 'modifier' species. In both communities, increasing modifier density weakened the trophic interaction strength, due to a negative effect on the predator's space clearance rate. Simulated long‐term dynamics indicate quantitative differences between models that account for TIMs or include only pairwise interactions. Our study demonstrates that TIMs are important to understand and predict community dynamics and highlights the need to move beyond focal species pairs to understand the consequences of species interactions in communities. [ABSTRACT FROM AUTHOR]

Simple Summary: Many toxic animals display bright colour patterns to warn predators about their toxicity. Their colour patterns are sometimes mimicked by other non-toxic organisms to evade predation. These mimics, however, may not match their model organisms perfectly. It is unclear how much their colour patterns can vary away from the model before they become ineffective. In this study, we investigated how predation risk of the non-toxic Common Mormon butterfly (Papilio polytes) is affected by two progressive modifications of its wing pattern that make it more distinct from its toxic model, the Common Rose (Pachliopta aristolochiae). In the first modification, we exchanged the position of the red and white colour patches but kept the overall pattern constant. In the second modification, we created an eyespot-like shape from the pre-existing pattern elements by moving their positions in the wing, altering the overall wing pattern. We deployed butterfly paper models in the field, where all models displayed the same colours but had different patterns. Both modifications increased attack risk by predators relative to wildtype patterns, with the eyespot-like modification having the highest predation risk. Our results show that avian predators can distinguish between all three patterns tested, and that predators learn to avoid colours, not in isolation, but as part of specific patterns. Many toxic animals display bright colour patterns to warn predators about their toxicity. This sometimes leads other sympatric palatable organisms to evolve mimetic colour patterns to also evade predation. These mimics, however, are often imperfect, and it is unclear how much their colour patterns can vary away from the model before they become ineffective. In this study, we investigated how predation risk of the palatable Common Mormon butterfly (Papilio polytes) is affected by two alterations of its wing pattern that make it progressively more distinct from its model, the Common Rose (Pachliopta aristolochiae). We deployed butterfly paper models in the field, where all models displayed the same colours but had different patterns. In the first modification from the Wildtype pattern, we exchanged the position of the red and white colour patches but kept the overall pattern constant. In the second modification, we created an eyespot-like shape from the pre-existing pattern elements by moving their positions in the wing, altering the overall wing pattern. Both modifications increased attack risk from predators relative to Wildtype patterns, with the eyespot-like modification having the highest predation risk. Our results show that avian predators can distinguish between all three patterns tested, and that pattern is important in aposematic signals. Predators learn to avoid aposematic colours, not in isolation, but as part of specific patterns. [ABSTRACT FROM AUTHOR]

The behaviour of two benthic species, round goby (Neogobius melanostomus) and mottled sculpin (Cottus bairdii), were examined under natural relevant downwelling light during predatory attacks by Burbot (Lota lota) and Smallmouth Bass (Micropterus dolomieu). Population declines have been observed for mottled sculpin after round goby invaded the Laurentian Great Lakes, but no data exist on prey avoidance behaviours and success for either species. The activity levels of the prey species were measured in the presence and absence of predators. Predator–prey interactions were quantified for reaction, attack, capture and retention probabilities. In addition, flight initiation distance, turns per flee and a comparison between observed and optimal escape angles were used as escape metrics to examine differences in prey survival. Trials were run under downwelling irradiances calculated for Lake Superior that correlated with dark, civil twilight, and sunrise. The number of round goby movements decreased by 74% in the presence of predators while mottled sculpin movement declined by 95% compared to baselines established without predators. Round gobies were more successful at evading predation with 18.3% of mottled sculpins consumed compared to 8.5% of round gobies during a comparable number (n = 27) trials. Round gobies also fled closer to their theoretically calculated optimal angles than mottled sculpin. Greater variation in flight initiation distances at different light intensities, fleeing at optimum angles that avoid predation and a more erratic escape path led to increased escape success for round gobies. Greater success avoiding predators may be another compounding factor, combined with round goby aggression and competition, that has contributed to the success of the round goby invasion in the Laurentian Great Lakes. [ABSTRACT FROM AUTHOR]

Cooperative breeding occurs when individuals contribute parental care to offspring that are not their own. Numerous intra- and interspecific studies have aimed to explain the evolution of this behavior. Recent comparative work suggests that family living (i.e. when offspring remain with their parents beyond independence) is a critical stepping stone in the evolution of cooperative breeding. Thus, it is key to understand the factors that facilitate the evolution of family living. Within-species studies suggest that protection from predators is a critical function of group living, through both passive benefits such as dilution effects and active benefits such as prosocial antipredator behaviors in family groups. However, the association between predation risk and the formation and prevalence of family groups and cooperative breeding remains untested globally. Here, we use phylogenetic comparative analyses including 2,984 bird species to show that family living and cooperative breeding are associated with increased occurrence of avian predators. These cross-species findings lend support to previous suggestions based on intraspecific studies that social benefits of family living, such as protection against predation, could favor the evolution of delayed dispersal and cooperative breeding. [ABSTRACT FROM AUTHOR]

The temporal dynamics of insect populations in agroecosystems are influenced by numerous biotic and abiotic interactions, including trophic interactions in complex food webs. Predicting the regulation of herbivorous insect pests by arthropod predators and parasitoids would allow for rendering crop production less dependent on chemical pesticides.Curtsdotter et al. (2019) developed a food‐web model simulating the influences of naturally occurring arthropod predators on aphid population dynamics in cereal crop fields. The use of an allometric hypothesis based on the relative body masses of the prey and various predator guilds reduced the number of estimated parameters to just five, albeit field‐specific.Here, we extend this model and test its applicability and predictive capacity. We first parameterized the original model with a dataset with the dynamic arthropod community compositions in 54 fields in six regions in France. We then integrated three additional biological functions to the model: parasitism, aphid carrying capacity and suboptimal high temperatures that reduce aphid growth rates. We developed a multi‐field calibration approach to estimate a single set of generic allometric parameters for a given group of fields, which would increase model generality needed for predictions.The original and revised models, when using field‐specific parameterization, achieved quantitatively good fits to observed aphid population dynamics for 59% and 53% of the fields, respectively, with pseudo‐R2 up to 0.99. But the multi‐field calibration showed that increased model generality came at the cost of reduced model reliability (goodness‐of‐fit).Our study highlights the need to further improve our understanding of how body size and other traits affect trophic interactions in food webs. It also points up the need to acquire high‐resolution data to use this type of modelling approach. We propose that a hypothesis‐driven strategy of model improvement based on the integration of additional biological functions and additional functional traits beyond body size (e.g., predator space search or prey defences) into the food‐web matrix can improve model reliability. [ABSTRACT FROM AUTHOR]

Symbiotic relationships shape ecological communities and often involve more than two species. Yet few experimental studies examine the impact of symbioses involving three species, particularly any mediating role of third parties, and none involving symbioses of predators.We investigated experimentally the synergistic and antagonistic fitness effects of three symbiotic spider predators across a broad latitudinal range and involving different species combinations.The three‐dimensional web complex of Cyrtophora spiders is a habitat patch to different associates—species of Argyrodes and web‐building Leucauge spider guests. Our field experiments, which manipulated the presence of each guest species and determined the subsequent host weight change, revealed a remarkable consistency in fitness outcomes across the three populations, with the consequences of the interactions between two species depending upon the services provided by a third.Cyrtophora hosts intercepted more prey when web‐building Leucauge guests were present and thus gained more weight. In contrast, Argyrodes guests exerted a fitness cost on their Cyrtophora host, but only when Leucauge guests were absent. A comparison of the prey consumed by Cyrtophora hosts and Argyrodes guests revealed that their diets (reflected in the size of prey) overlapped less in the presence of Leucauge web‐building guests.Our novel experimental study highlights the importance of exploring synergistic effects in multi‐species symbioses. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Tonatia bidens is listed as 'Data Deficient' in the IUCN Red List. Our research, conducted in the Brazilian Caatinga dry forest between 2016 and 2022, aimed to shed light on the diet of this little-known species. Thirty-eight taxa were identified among insect remains beneath T. bidens' feeding perch. Notably, certain insects such as hawkmoths and cerambycid beetles are agricultural pests with significant negative impacts on crops, including cassava, corn, tomato, papaya, and cashew plantations. These results underscore bats' crucial role in insect pest consumption, emphasizing the need for further studies to fully understand their diet and ecosystem contributions. [ABSTRACT FROM AUTHOR]

Mimicry, the superficial resemblance between organisms of two or more species, is considered a textbook example for natural selection, for which it is assumed that predators are important selective agents. Ant mimicking spiders have received considerable attention in studies on mimicry because they include examples with remarkable, species‐specific morphological adaptations. Ant‐like behaviours such as erratic locomotory patterns, abdomen bobbing and vertical movements of the first or second pair of legs to imitate antennal movements, are assumed to have evolved before morphological mimicry and may be considered adaptations to general ant resemblance. Species‐specific behavioural ant mimicry (behaviour that is only observed in specific ants and imitated by their mimics) was very rarely documented and ant resembling behaviour that repels predator attacks has not been confirmed yet. In this study we report and discuss such species‐specific behaviour, a spray display (SD), in the castianeirine spiders Myrmecotypus iguazu (a morphologically accurate mimic of the carpenter ant Camponotus sericeiventris), and M. tahyinandu (a morphologically accurate mimic of C. crassus). The SD consisted of the raising of the cephalothorax and moving of the abdomen ventrally under the cephalothorax, pointing the apex forward, and holding the antennae (ant) or first pair of legs (spiders) at an angle of about 45°–120°. The morphological adaptations that are required to perform the SD and the lack of an alternative explanation for the purpose of this display suggest that the SD has evolved to enhance both general behavioural and morphologically accurate ant resemblance. The two observed Myrmecotypus species may be considered the behaviorally most accurate ant‐resembling spiders known to date, as the SD may provide protection against spider‐ and ant‐eating predators at a point in predator interactions where other myrmecomorph spiders may abandon their ant‐resembling behaviour. [ABSTRACT FROM AUTHOR]

In this paper, focusing on individualistic generalist predators and prey living in herds which coexist in a common area, we propose a generalization of a previous model, namely, a two-population system that accounts for the prey response to predator attacks. In particular, we suggest a new prey-predator interaction term with a denominator of the Beddington-DeAngelis form and a function in the numerator that behaves as N for small values of N, and as N α for large values of N, where N denotes the number of prey. We can take the savanna biome as a reference example, concentrating on large herbivores inhabiting it and some predators that feed on them. Only two conditionally stable equilibrium points have emerged from the model analysis: the predator-only equilibrium and the coexistence one. Transcritical bifurcations from the former to the latter type of equilibrium, as well as saddle-node bifurcations of the coexistence equilibrium have been identified numerically by using MATLAB. In addition, the model was found to exhibit bistability. Bistability is studied by using the MATLAB toolbox bSTAB, paying particular attention to the basin stability values. Comparison of coexistence equilibria with other prey-predator models in the literature essentially shows that, in this case, prey thrive in greater numbers and predators in smaller numbers. The population changes due to parameter variations were found to be significantly less pronounced. [ABSTRACT FROM AUTHOR]