Predator Type Research Articles

How cunning is the puppet-master? Cestode-infected fish appear generally fearless

Trophically transmitted parasites have life cycles that require the infected host to be eaten by the correct type of predator. Such parasites should benefit from an ability to suppress the host’s fear of predators, but if the manipulation is imprecise the consequence may be increased predation by non-hosts, to the detriment of the parasite. Three-spined sticklebacks (Gasterosteus aculeatus) infected by the cestode Schistocephalus solidus express reduced antipredator behaviours, but it is unknown whether this is an example of a highly precise manipulation, a more general manipulation, or if it can even be attributed to mere side effects of disease. In a series of experiments, we investigated several behaviours of infected and uninfected sticklebacks. As expected, they had weak responses to simulated predatory attacks compared to uninfected fish. However, our results suggest that the parasite induced a general fearlessness, rather than a precise manipulation aimed at the correct predators (birds). Infected fish had reduced responses also when attacked from the side and when exposed to odour from a fish predator, which is a “dead-end” for this parasite. We also tested whether the reduced anti-predator behaviours were mere symptoms of a decreased overall vigour, or due to parasite-induced hunger, but we found no support for these ideas. We propose that even imprecise manipulations of anti-predator behaviours may benefit parasites, for example, if other behaviours are altered in a way that increases the exposure to the correct predator.

Hunting from the air: A new record of predation of Agelaia testacea (Fabricius, 1804) (Vespidae: Polistinae) on a katydid Parascudderia sp. (Orthoptera: Tettigoniidae: Phaneropterinae) in the Peruvian Amazon

Social wasps capture adult and/or immature insects to feed their larvae. Frequent observations indicate mainly small or immature insects as their prey. However, there are very few records of social wasps as predators of larger living insects. Herein, we report a predation event carried out by an understory social wasp Agelaia testacea (Fabricius, 1804) (Vespidae: Polistinae) on an adult katydid Parascudderia sp. (Orthoptera: Tettigoniidae: Phaneropterinae), visibly larger than the wasp. This fact is added to a previous internet record of the same type of predation (Agelaia testacea in Tettigoniidae) for French Guiana in the Parc amazonien de Guyane. Studies like this contribute to understanding the trophic networks and hunting behavior of social wasps.

Evaluating the taphonomic consistency of microvertebrate assemblages at Natural Trap Cave, Wyoming, USA

Paleontological sites composed of small vertebrate specimens can contain hundreds-of-thousands of identifiable fossils, which can reveal community responses to environmental and trophic changes. However, the composition of these communities may be skewed if the taphonomic signatures of the deposits change over time and across strata. Here, we discuss the taphonomic processes that led to dense deposits of microvertebrate fossils at Natural Trap Cave, Wyoming, USA. We then evaluate the nature and consistency of the taphonomic signature across stratigraphic layers using bone breakage rates and bone processing information. Natural Trap Cave is a pitfall cave that has an excellent record of vertebrate communities over the last 35,000 years. Along the North Wall of the excavation site, microvertebrate fossils form a dense accumulation, raining down from a packrat (Neotoma) nest located ∼20 m above the floor of the cave. Using the breakage rates of micromammal limb bones, we evaluate whether the accumulation mechanism appears consistent across strata. We demonstrate that the variation in breakage rates from Natural Trap Cave's strata cluster together when compared to breakage rates for different predator types (mammalian carnivores, raptors, and owls). We then demonstrate that the variation in breakage rates from the three strata is less than would be expected if it were the result of a change in major predator type across the strata. Our analysis of depositional taphonomy at Natural Trap Cave provides confidence in the reliability of the microvertebrate community record, paving the way for future paleoecological analyses.

Effects of individual differences in the locomotor activity of assassin bugs on predator–prey interactions

AbstractPredator–prey interactions affect ecological communities. Consistent individual differences in the behavior, or animal personality, of predators and/or prey can influence inter‐specific interactions. For example, high activity predators may have increased foraging success on low activity prey (i.e., the locomotor crossover hypothesis). On the other hand, the foraging style of predators can be categorized as “active hunting” or “sit‐and‐wait”; this difference impacts the selection pressure on prey and may thus also affect predator–prey interactions. Although some studies have evaluated the joint effect of the personality types of both active hunting predators and prey, few studies have focused on sit‐and‐wait predators with respect to the locomotor crossover hypothesis. Here we tested the locomotor crossover hypothesis using assassin bugs (Amphibolus venator) as a sit‐and‐wait predator and red flour beetles (Tribolium castaneum) as prey. There was no relationship between the personalities of A. venator and T. castaneum with respect to foraging rate; therefore, the present study did not support the locomotor crossover hypothesis. This result suggests that the locomotor crossover hypothesis may be supported in active hunting predators, but not in sit‐and‐wait predators. This study highlights the importance of focusing on predator foraging styles in predator–prey interactions when studying the evolution of animal personality.

Exposure to fire affects acorn removal by altering consumer preference

Prescribed fire has been encouraged as a management tool to increase oak regeneration across the southeastern United States. The least utilized part of the burn window in this region is during fall, but burning in this season with the objective of oak regeneration has been discouraged because of the potential negative consequences on subsequent germination. While exposure to fire decreases acorn viability, acorns cached in recently burned areas increases their survival. By following the fate of unburned acorns added to those areas, previous studies identified post-fire habitat characteristics (e.g., altering vegetation structure, decreased leaf litter, etc.) as a cause of increased acorn establishment success. However, exposing acorns to fire may also contribute to fate of surviving acorns by changing consumer removal rates. We exposed acorns to fire and established cafeteria-style experiments in unburned forests to compare burned and unburned acorn selection and removal rate of eight oak species by caching and non-caching consumers (i.e., predator type). Exposing acorns to fire did not appear to affect selection of oak species but affected overall removal risk for acorns differently by species of consumers. For example, while one important non-caching consumer (white-tailed deer, Odocoileus virginianus) and caching consumer (southern flying squirrel, Glaucomys Volans) showed strong selection of burned acorns, other important consumers in each predator type showed little discrimination or strong selection of unburned acorns (e.g., southern fox squirrel Sciurus niger). Exposure to fire reduced the overall rate of removal of acorns and when an acorn was removed, fire significantly reduced the probability that it would be removed by a caching consumer. Overall, our experiment demonstrates that shifts in consumer removal for exposed acorns may play an important role in the net effects of fall burning on oak regeneration.

Freezing or death feigning? Beetles selected for long death feigning showed different tactics against different predators.

Prey evolve antipredator strategies against multiple enemies in nature. We examined how a prey species adopts different predation avoidance tactics against pursuit or sit‐and‐wait predators. As prey, we used three strains of Tribolium beetles artificially selected for short (short strain) or long (long strain) duration of death feigning, and a stock culture (base population). Death feigning is known to be effective for evading a jumping spider in the case of the long strains, while the present study showed that the long‐strain beetles used freezing against a sit‐and‐wait type predator, Amphibolus venator, in this study. The short‐ strain beetles were more easily oriented toward predators. The time to predation was also shorter in the short strains compared to the long strains. The results showed that, as prey, the short strains displayed the same behavior, escaping, against both types of predators. Traditionally, death feigning has been thought to be the last resort in a series of antipredator avoidance behaviors. However, our results showed that freezing and death feigning were not parts of a series of behaviors, but independent strategies against different predators, at least for long‐strain beetles. We also examined the relationship between a predator's starvation level and its predatory behavior. In addition, the orientation behavior toward and predation rate on the prey were observed to determine how often the predatory insect attacked the beetles.

Effect of Isolation on the Recognition of Context-Specific Alarm Calls in a Captive Vervet Monkey (Chlorocebus pygeryhrus)

In contrast to many animal signals that share limited information, context-specific signals communicate referential and/or situational information that is consistently interpreted by a group. Wild Vervet monkeys (Chlorocebus pygerythrus) use context-specific alarm calls to communicate predator type (e.g., eagle, leopard, snake), which causes receivers to respond in predator-specific ways. Captive Vervets use and respond to context-specific alarm calls, though these calls can be applied to novel stimuli such as when eagle calls signal an airplane, another flying entity. Context-specific calls may require a social structure to be produced and understood, where isolated individuals may not understand the information contained within calls. This experiment evaluated the response of a socially-isolated captive Vervet monkey to the context-specific calls that he presumably heard for the first time during the study. The subject, Ross, was exposed to three types of Vervet monkey predator-specific alarm calls, a Vervet monkey social signal, and a control signal (i.e., European Starling). Ross showed behavioral differences after the Vervet calls, suggesting he could recognize conspecific vocalizations. Ross demonstrated an ability to recognize the “alarm” nature of alarm calls with increased scanning behavior displayed after the calls. However, Ross was unable to distinguish between the predator type that the calls communicated. He failed to show the predator-specific responses to alarm calls. Ross’ inability to recognize the information communicated within predator-specific alarm calls suggests the importance of social learning in understanding the context-specific nature of these signals. The overall interpretation of the results should be treated with caution because the study was based on the response of a single animal who lived in an extraordinary situation of social isolation.

Shadows into Light: The Potential Investigative Utility of Voice Analysis with Two Types of Online Child-Sex Predators

ABSTRACT Over 390,000 child sexual abuse victims in the United States have not yet been identified. Due to the increased prevalence of Internet-driven child-sex offenders (e.g., child pornographers and travelers), detection becomes more elusive, and disclosure elicitations are more challenging for law enforcement. The current retrospective study examines an innovative, investigative method of voice stress analysis use, and describes its possible utility in identifying previously undetected sexual offending within these two offender populations. In the total sample of 82 arrestees with no known history of “hands-on” sexual offending, 0% initially admitted to sexually abusing at least one child. However, coinciding with voice stress analysis procedures, 40.2% of the suspect pool (57.1% of child pornographers and 36.7% of travelers) provided admissions to hands-on offenses. Also, 80.5% admitted to at least one sex crime offense during the pre and posttest stages of the investigation. All voice stress analysis “Stress Indicated” examinations resulted in verifiable disclosures (of victims and sex crimes). Critically, as a result of voice stress analysis procedures, 87 previously undiscovered live victims were identified. Finally, this study’s description of specific characteristics and predictive qualities of victimizers vs. non-victimizers in each offender-type should benefit future investigators, researchers, and therapists alike.

Stability and bifurcations analysis in an ecoepidemic system with prey group defense and two infectious routes

In this paper, we explore an ecoepidemic model of a prey–predator type in which the prey population is infected by an SI type disease with two infectious routes (horizontal and vertical). Specifically, we consider that both susceptible and infected preys have emergent carrying capacities, which implies that both preys are involved in intraspecific and interclass competitions. In addition, we assume that the susceptible prey gathers together to defend the predator. It is found that the proposed system exhibits abundant dynamics and admits nine equilibria: three boundary equilibria, three plane equilibria, and three interior equilibria. At least one of the three populations can be eliminated from the ecosystem based on the stability of the previous two types of equilibria. According to the stability of the interior equilibria, the given ecosystem can allow the coexistence of susceptible prey–infected prey–predator. We then investigate the stability and direction of Hopf bifurcation. A sensitivity analysis is also conducted to show the effects of the six parameters which are relevant to the emergent carrying capacity and infectious routes on the studied system. Numerical simulations are conducted to verify our theoretical conclusions.

Effects of Colony Disturbance on Reproductive Success and Nest Defense Behaviors in Caribbean Roseate Terns

Heterospecific disturbance in seabird colonies can negatively influence reproductive success both through direct effects, such as predation, and through indirect effects, such as increasing parental energy expenditure via defense behaviors. Here, remote nest cameras were used to evaluate the effects of intrusion on early nest survival and predation risk in Roseate Tern (Sterna dougallii) colonies in the U.S. and British Virgin Islands. Effects of colony traits such as colony size on parental nest defense were also investigated to assess individual response to predator presence in colonies. We counted 141 intrusion events at 118 nests and found that frequency of heterospecific disturbance did not influence nest survival, but did have a positive association with predation rate. Disturbance decreased significantly with colony size and % cover, and disturbance increased with nest density, indicating that concealed, isolated nests within large colonies were less likely to be disturbed. Parental nest defense decreased significantly with colony size and nest density. Results were likely driven by the dominant predator types in our system—large predatory birds and invasive rats—as parents were more likely to leave nests with intrusion from these predator types.

Diet of the little Athene noctua (Scopoli, 1769) on the territory of Berehovo district (Transcarpathian region)

Objectives. The Little Owl is the most common owl in the Western Palearctic and its population is declining significantly in Europe. Therefore, conservation and study of this owl is an important issue in most European countries. Analysis of trophic patterns at the local level provides interesting and valuable information about the predator’s eating habits. The owl’s diet investigation allows us to analyze their potential adaptations to habitats with different levels of environmental transformation. Materials and Methods. We studied nutrition of the Little Owl Athene noctua, in agricultural lands of Berehove district of Transcarpathian region in Ukraine. In total, 1446 pellets were collected at 15 pellet stations in 2002–2020 and 2506 prey items were identified. The prey items represented 18 vertebrate species (16 species of small mammals of three orders Rodentia, Soricomorpha, Carnivora, as well as reptiles of the family Lacertidae and birds of the order Passeriformes and arthropods. Results. Vertebrates play a major role in feeding the Little Owl (over 99 % of total prey biomass in all of the studied sites). The common vole is the most common prey in the owl’s diet (52.1 % of the total prey number and 67.5 % of the biomass of the prey caught), as well as a high proportion of mice of the genus Apodemus and Sylvaemus. The contribution of invertebrates to total prey biomass is insignificant (0.3 %). A large number of invertebrates were observed in the diet of the Owl in summer and were almost completely absent in winter. Conclusions. According to our data, the Little Owl is a typical predator generalist in Transcarpathia. The 28 taxa found in the pellets show a wide range of food objects in a relatively small area, and high level adaptations to habitats with different levels of environmental transformation (agrosystems and anthropogenic areas).

Inter-individual differences of calling and exploratory behaviour in a lebinthine cricket species hint at different mate-finding strategies

Abstract Individual fitness can be boosted by behavioural strategies that maximise mate-finding probability while minimising predation risk. Animals that use acoustics to find mates may benefit from using both stationary calling and active exploration, but these also expose them to different types of predators. Studying calling and searching behaviours concurrently allows us to understand their evolutionary trade-offs between survival and reproduction. Unlike most other crickets, lebinthine males alternate between singing and exploration to find females, which offer a unique and excellent opportunity to test for inter-individual differences and behavioural syndrome between call properties and exploratory behaviours. Our data demonstrate that call properties and exploratory behaviour were repeatable. We did not, however, find that call properties correlate with exploration as some consistently exploratory individuals produce longer calls while others produce shorter calls. Our study suggests that lebinthine males use different combinations of calling and exploratory behaviours to cope with unpredictable risk–benefit scenarios.

Risk-Induced Foraging Behavior in a Free-Living Small Mammal Depends on the Interactive Effects of Habitat, Refuge Availability, and Predator Type

Predators have a major influence on prey populations and broader ecosystem dynamics through both their consumptive and non-consumptive effects. Prey employ risk-induced trait responses such as shifts in habitat use or changes in foraging behavior in response to the presence of predators. Risk-induced changes in foraging depend upon both the predator community and the environmental context; however, the influence of these factors have rarely been concurrently examined in free-living animals. We investigated the interactive effects of habitat, refuge availability, and predator type on the foraging behavior of free-living white-footed mice, accounting for the abiotic factor moonlight. We used auditory calls of a local terrestrial cursorial predator and a local avian ambush predator to simulate predation risk in both a forest edge and a forest interior habitat, and measured the foraging of mice under different experimental refuge types. We found that, while mice had reduced foraging when exposed to predation risk, the degree of this response depended on an interaction among habitat, refuge use, and type of predator. Prey had the greatest reduction in foraging and used refuges the most when exposed to cursorial-hunting foxes at the open forest edge. The risk-induced reduction in foraging and the use of refuges was much weaker in the forest interior, but even here foxes elicited a greater response as compared to owls. Generally, foraging tended to decrease with increasing moonlight, but this was not significant. We suggest that it is the temporal nature of cursorial vs. ambush predators in our system that drives such effects as opposed to their hunting mode, and that prey responses to temporal hotspots of risk need further examination. Generally, our results show that wild small-mammal prey species have variable responses to predation risk depending on the environmental context in which risk occurs.

Anti-predator behaviour of Rhinella major (Müller and Hellmich 1936), with insights into the Rhinella granulosa group

In anurans, the different types of anti-predator behaviour have been documented in isolation, but some species have shown synergistic strategies in different situations. The display of these types of behaviour may be related to the types of predators in the habitat, which boost defensive responses in their prey. However, most reports are mostly opportunistic and punctual observations, not systematic. Here, we report the occurrence of anti-predator behaviour in the toadRhinella major(Müller and Hellmich 1936) (Amphibia, Anura, Bufonidae) in the face of different handling modes. Probably the disturbance caused by handling had elicited a predator deterrence response in the individual, causing it to rapidly exhibit such behaviour. These conditions are discussed along with an overview of anti-predator behaviour in species of theR. granulosagroup and we re-interpreted these strategies for two species in the group.

Keep calm and carry on: reactive indifference to predator encounters by a gregarious prey species

Strategies that mitigate predation, whether proactive or reactive, can nevertheless impose significant ‘nonconsumptive’ costs on prey species. Here we used data from two wild vervet monkey, Chlorocebus pygerythru,s groups to assess whether the detection of predators affected their subsequent behaviour to the detriment of their short-term foraging effort. Encounters with the three predator classes present at our study site were frequent and there was evidence that animals were more likely to shift to predator-focused vigilance, which was modulated by alarm call intensity, but not predator type, in the hour following detection. Nevertheless, and against expectation, there was no detectable shift in overall levels of vigilance, which remained low, interindividual distances, travel bearing and, consequently, effort put into foraging. We consider this surprising imperturbability by our study groups in the context of population group size, as our groups are large and have correspondingly lower levels of individual vigilance, as well as in terms of the constraints imposed by small, overlapping territories and frequent predator encounters. Finally, we advocate for increased consideration of the responses of the predators themselves to detection by their prey. • We observed vervet monkeys to assess whether predators affect vigilance and foraging. • Vervets were as likely to forage after predator encounters as they were before. • While female vervets were more vigilant, both sexes were generally unperturbed. • Predator type did not affect the likelihood of vigilance. • We explain this surprising indifference to predators in terms of large group size.

Stochastic Analysis of Predator-Prey Models under Combined Gaussian and Poisson White Noise via Stochastic Averaging Method.

In the present paper, the statistical responses of two-special prey–predator type ecosystem models excited by combined Gaussian and Poisson white noise are investigated by generalizing the stochastic averaging method. First, we unify the deterministic models for the two cases where preys are abundant and the predator population is large, respectively. Then, under some natural assumptions of small perturbations and system parameters, the stochastic models are introduced. The stochastic averaging method is generalized to compute the statistical responses described by stationary probability density functions (PDFs) and moments for population densities in the ecosystems using a perturbation technique. Based on these statistical responses, the effects of ecosystem parameters and the noise parameters on the stationary PDFs and moments are discussed. Additionally, we also calculate the Gaussian approximate solution to illustrate the effectiveness of the perturbation results. The results show that the larger the mean arrival rate, the smaller the difference between the perturbation solution and Gaussian approximation solution. In addition, direct Monte Carlo simulation is performed to validate the above results.

The behavioural ecology behind anti-predator mechanisms: diversity, ontogenetic changes and sexual differences in anuran defence behaviours

Anti-predator mechanisms play a key role in the survival of any animal in nature. Anurans exhibit a great diversity of defensive behaviours and interact with the widest range of predators of any vertebrates. However, there are few systematic and experimental studies of anuran defensive behaviours, which are generally opportunistic. Here, we deploy a range of methods to investigate various facets of anuran defensive behaviour using the cane toad Rhinella marina as a model organism. This originally Amazonian anuran is now widely distributed across the globe and has caused several predators to decline at introduction sites where this species is not native, a direct result of its anti-predation defenses. First, we compiled previously published data on anuran predation events to assess the relationship between predator/anuran size and predator size and type. We then performed a systematic experiment to test the hypothesis that there is an ontogenetic variation in cane toad behavioural defense displays, as well as a variation in these displays between males and females. In total, we tested 173 individuals including juveniles, adult males and adult females. We show that the size and type of the predator is related to the size of the anuran as prey and that this, in turn, has led to the adoption of different predation-avoiding behavioural defensive strategies during ontogeny. Our results also indicate that both the sex and the size of anurans influence the adoption of defensive strategies.

Beneath the Leaf-Litter: Can Salamander Personality Influence Forest-Floor Dynamics?

Ecological research demonstrates how intraspecific phenotypic variation can have consequences for community dynamics. However, the effects of animal personalities (i.e., intraspecific behavioral variation) on ecological processes remains relatively understudied. Using Red-backed Salamanders (Plethodon cinereus) and the detrital food web as a model system, we conducted a laboratory mesocosm experiment to explore whether or not the personality type of a top-level predator could affect the community structure within a complex, terrestrial food web. We used behavioral assays to investigate the repeatability of salamander behaviors, and classified individuals as either active or inactive. We then subjected laboratory mesocosms to one of four treatments for 3 mo: one active salamander, one inactive salamander, control (no salamander), and a pre-experimental reference. Our results indicate that the effect of P. cinereus on the detrital food web might be behaviorally mediated, with only the most active salamanders affecting community structure. Specifically, mesocosms housing active salamanders contained less diverse invertebrate communities than all other treatments. This difference was primarily driven by springtails, which were more abundant within mesocosms housing active salamanders. We also found that salamander personality was associated with cover board use inside mesocosms, with inactive salamanders exhibiting a more philopatric use of cover objects than active individuals. Leaf-litter degradation did not differ between treatments, indicating that the ecological effects of salamanders were too weak to influence basal resources within the detrital food web. Our study prompts further questions regarding the potential for animal personalities to influence ecological processes within terrestrial communities.

Inferring species interactions from ecological survey data: A mechanistic approach to predict quantitative food webs of seed feeding by carabid beetles.

Ecological networks are valuable for ecosystem analysis but their use is often limited by a lack of data because many types of ecological interaction, for example, predation, are short‐lived and difficult to observe or detect. While there are different methods for inferring the presence of interactions, they have rarely been used to predict the interaction strengths that are required to construct weighted, or quantitative, ecological networks.Here, we develop a trait‐based approach suitable for inferring weighted networks, that is, with varying interaction strengths. We developed the method for seed‐feeding carabid ground beetles (Coleoptera: Carabidae) although the principles can be applied to other species and types of interaction.Using existing literature data from experimental seed‐feeding trials, we predicted a per‐individual interaction cost index based on carabid and seed size. This was scaled up to the population level to create inferred weighted networks using the abundance of carabids and seeds from empirical samples and energetic intake rates of carabids from the literature. From these weighted networks, we also derived a novel measure of expected predation pressure per seed type per network.This method was applied to existing ecological survey data from 255 arable fields with carabid data from pitfall traps and plant seeds from seed rain traps. Analysis of these inferred networks led to testable hypotheses about how network structure and predation pressure varied among fields.Inferred networks are valuable because (a) they provide null models for the structuring of food webs to test against empirical species interaction data, for example, DNA analysis of carabid gut regurgitates and (b) they allow weighted networks to be constructed whenever we can estimate interactions between species and have ecological census data available. This permits ecological network analysis even at times and in places when interactions were not directly assessed.

La relación de depredación entre humanos y no-humanos en la ontología de los q’ero de la cordillera de Vilcanota, Perú

The anatomy of human and non-human (apus, pachamamas, the dead etc.) relations and dependencies manifests itself in different types of daily practices and rituals (agri-culture and herding, mobility, alimentation, ritual songs, shamanic and medicinal practices) and reveals ontological schemes of exchange and predation. Interestingly, both schemes can be expressed through the idiomatic expression of “feeding”. This implies that the purpose of relationships between personal beings is to feed each other through reciprocal practices (exchange) or feed on others (predation). In this paper, we analyze the scheme of predation among the Q’eros, which takes the forms of seduction, sexual intercourse, cannibalism and kidnapping. Different types of predation were grouped into three modalities (oblivion, breaking the taboo and otherness) that constitute the axis of the narrative and, at the same time, represent the origins or causes of these relations.