Prey Types Research Articles

Selection for evasive mimicry imposed by an arthropod predator.

It has long been hypothesized that a species that is relatively easy to catch by predators may face selection to resemble a species that is harder to catch. Several experiments using avian predators have since supported this 'evasive mimicry' hypothesis. However, the sudden movement of artificial evasive prey in each of the above experiments may have startled the predators, generating an avoidance response unrelated to difficulty of capture. Additionally in the above experiments the catchability of prey was all or nothing, while in nature predators may occasionally catch evasive prey or fail to catch slower species, which might inhibit learning. Here, using mantids as predators, we conducted an experimental test of the evasive mimicry hypothesis that circumvents these limitations, using live painted calyptrate flies with modified evasive capabilities as prey. We found that mantids readily learned to avoid pursuing the more evasive prey types. Warning signals based on evasiveness and their associated mimicry may be widespread phenomena in nature. These findings not only further support its plausibility but demonstrate that even arthropod predators can select for it.

Unveiling the diets of Eurasian Curlew and Bar-tailed Godwit through droppings analysis on the west coast of India

This study examines the population dynamics and dietary patterns of the near-threatened Eurasian Curlew and Bar-tailed Godwit along west coast of India, underscoring critical conservation issues. From 2010 to 2023, both species experienced significant declines, with peak abundances observed on sandy beaches, deviating from their usual mudflat and mangrove habitats. Analysing 231 droppings identified seven key prey types, with polychaetes and small crabs being most common in mangroves and mudflats, while Cosmonotus crabs were predominantly found on sand beaches. Species-specific prey preferences were evident, with Bar-tailed Godwits showing a significant association with polychaetes and medium crabs. The findings highlight the urgent need for habitat restoration, pollution reduction, and focused conservation efforts to ensure the resilience and survival of these critical shorebird species.

Social Dynamics and Intelligence of Killer Whales (Orcinus Orca)

The present study undertakes a comprehensive investigation into the behavioral and social complexity of Orcinus orca, commonly referred to as killer whales. Utilizing a multimodal approach that combines acoustic analysis, behavioral observation, and social network mapping, this research addresses four primary dimensions: the species' specialized communication techniques, intricate social structures, cooperative hunting strategies, and evidence for cultural transmission. Our analysis reveals that killer whales employ diverse acoustic and non-acoustic signals, enabling intricate communication networks essential for social bonding and collaborative behaviors. Social structures within pods are observed to be highly hierarchical, often influenced by matrilineal lineages, thereby indicating advanced social organization. Cooperative hunting strategies differ depending on prey type and local environmental conditions, reflecting a high degree of behavioral adaptability and specialization. The study also furnishes compelling evidence for the cultural transmission of learned behaviors across generations, suggesting a complexity often attributed solely to primates. Understanding these multidimensional characteristics holds substantial implications for the broader marine biology animal cognition field, especially for conserving this apex predator. However, it is essential to note the limitations of this study, including potential observer bias, restricted sample size due to observational limitations, and the inconclusive nature of some findings on cultural transmission. Further research is imperative, both to validate and extend these results. Advancements in remote sensing technologies and machine learning algorithms offer promising avenues for future research, which is pivotal for developing nuanced and effective conservation strategies for Orcinus orca in an era of rapidly changing oceanic ecosystems.

Predatory Responses and Feeding Behaviour of Three Elasmobranch Species in an Aquarium Setting

Many progressive aquariums worldwide house various elasmobranch species as part of their commitment to conservation awareness and the long-term well-being of these creatures. These aquariums face the challenge of enabling these natural predators to live harmoniously with other fish without triggering natural predation. This research, conducted at Zoomarine Algarve in Southern Portugal, aimed to investigate the behaviour of three elasmobranch species (Carcharhinus melanopterus (1:1:0), Triaenodon obesus (1:0:0), and Pteroplatytrygon violacea (0:3:0)) when exposed to different feeding mechanisms. The goal was to provide them with opportunities for alternative predatory behaviours beyond their typical feeding techniques and to reduce the likelihood of natural predation. The study took place under controlled conditions within a community habitat. Four feeding methods (pole, short buoy, long buoy, and PVC) were tested during morning, afternoon, and evening periods, using five different prey species. The results shed light on which feeding method aligns best with each species’ distinct physiological standards and predatory tendencies and revealed their prey preferences. All three species interacted with all feeding methods, with P. violacea showing a strong preference for the pole method. T. obesus favoured bony fish, while C. melanopterus showed a preference for cephalopods. P. violacea interacted with all prey types but displayed no marked preference. These various feeding methods and prey options also function as environmental enrichment strategies, enhancing the complexity of the habitat and providing the animals with more choices and control, ultimately promoting their welfare in captivity.

Dynamics of a Leslie-Gower type predation model with non-monotonic functional response and weak Allee effect on prey

This research concerns with analysis of a class of modified predator- prey type Leslie-Gower models. The model is described by an autonomous nonlinear ordinary differential equation system. The functional response of predators is Holling IV type or non-monotone, and the growth of prey is affected by the Allee effect. An important aspect is the study of the point (0, 0) since it has a strong influence on the behavior of the system being essential for the existence and extinction of both species, although the proposed system is not define there.

Comparative Trophic Levels of Phragmocone-Bearing Cephalopods (Nautiloids, Ammonoids, and Sepiids).

Cephalopods are among many marine animals that through some combination of habit and/or habitat have proven difficult to study, especially understanding their trophic positions in marine communities. Stable isotope analyses have provided powerful tools for discovering quantitative aspects about the ecology and food sources of many cephalopod species. Here, we present new gut content and isotopic data (carbon and nitrogen isotopes) from phragmocone-bearing cephalopods (both ectocochleates, as well as those with internal, hard part buoyancy maintenance apparatuses). To this, we also include observations from baited remote underwater video systems to describe feeding habits and potential prey types to correlate with gut contents analyses. These data come from extant Allonautilus, Nautilus, and Sepia species, as well as from extinct nautiloids and ammonites. Extant nautiloids occupy a different isotopic niche than all other cephalopod groups where such data have been published to date. We conclude that these species are obligate scavengers rather than predators on any living species in their environments. Extant Nautilus and Allonautilus also demonstrate different patterns of functional allometry of nitrogen isotope values over ontogeny than do most other cephalopods (or animals in general), by showing decreasing nitrogen isotope levels during ontogeny. This pattern is shown to be different in Sepia and the yet small number of ammonite cephalopods studied to date, supporting the increasingly accepted view that ammonites were far closer to coleoids in basic biology than nautiloids. Overall, phragmocone-bearing cephalopods appear fundamentally different ecologically than cephalopods without this kind of buoyancy system. Of these groups, nautiloids appear to live a low-energy existence that allows them to subsist on energy-poor food sources, such as crustacean molts, as well as being able to scavenge in low oxygen basins where rare food falls, such as dead fish, remain unobtainable by most other animals.

An eco-epidemiological model with predator switching behavior

AbstractSwitching mechanism is adopted by predator populations when they are provided with two types of prey: susceptible and infected. In this study, we propose a modification of an eco-epidemiological model with the predator switching mechanism. In the presence of switching behavior, the existence of steady states and their stability have been discussed. The qualitative changes in the proposed model have been observed by the existence of transcritical and Hopf bifurcation. Numerical simulations are performed to support our numerical findings. In the context of species’ survival when disease is present in the system, it gives some theoretical views for eco-managers to understand the dynamics.

Differences in the Diet of Reproductively Isolated Ecotypes of Killer Whales (<i>Orcinus orca</i> Linnaeus, 1758) in the Seas of the Russian Far East

A systematic analysis of the species composition of the prey of killer whale Orcinus orca Linnaeus, 1758 was carried out. The results of observations of killer whales hunting for different types of prey and the data from an analysis of the contents of their stomachs were summarized; the species affiliation of the prey was compared with the affiliation of predators to the R- or T-type based on a genetic analysis. It has been shown that killer whales of the Far Eastern seas of Russia have a pronounced foraging specialization, which correlates with the haplotype of the mitochondrial DNA control region. Killer whales with the NT1 and GAT haplotypes previously described for mammal-eating T-type killer whales from the northeast Pacific (also called Bigg’s killer whales) have been observed preying on marine mammals but not on fish. Killer whales with the SR haplotype, previously described for fish-eating R-type killer whales from the northeastern Pacific, preyed only on fish. Two new T-type killer whale haplotypes have been discovered; animals with these haplotypes have been observed preying on large baleen whales. The importance of traditions and social learning in the differentiation of ecological niches in cetaceans has been noted. The specialization to hunt certain prey transmitted from mother to calves allows killer whales of different ecotypes to avoid food competition and acquire morphological and behavioral adaptations that facilitate hunting for a particular type of prey.

Segregation in diet composition of two syntopic tree frog species, Hyla simplex and Polypedates megacephalus, in Ben En National Park, Vietnam

Abstract The segregation in one trophic niche of n-dimensional niches can allow many species to coexist in the same habitat. In this study, we conducted surveys in Ben En National Park, Thanh Hoa Province, Vietnam to examine stomach contents of two syntopic tree frog species, Hyla simplex and Polypedates megacephalus, using the stomach-flushing method. A total of 21 individuals of H. simplex and 32 individuals of P. megacephalus were sampled revealing 352 food items (H. simplex: 131 invertebrates belonging to 20 prey types of seven orders; P. megacephalus: 215 invertebrates belonging to 22 prey types of 11 orders). Generally, both species consumed slightly diverse and equal prey types. However, ants (Formicidae) and termites (Rhinotermitidae) were identified as the most dominant and important prey for the two tree frog species. With only 38.95% overlap, it is evident that there is tropic segregation between the two syntopic species.

Bacteriovory of enteric bacteria by soil isolated amoeba depends on both temperature and salinity

Recycling of wastewater for agricultural irrigation is an important means for sustainable reuse practices, but a major concern of such practice is the introduction of pathogens and antibiotic determinants. Previous attempts to mitigate contaminants focused on water treatment, yet the growing appreciation of the soil microbial food web brings into focus its potential to mitigate pathogens introduced by recycled effluent. We hypothesized that effluent-introduced bacteria serve as prey to soil-free living amoeba (FLA), but predation is interfered with by environmental conditions such as temperature and/or salinity. To test our hypothesis, we first demonstrated that an enteric bacterium model, Escherichia coli, is preyed on by soil FLA. We then isolated 12 FLA from three soil types (loamy-sand, loam, and clay) and followed the predation dynamics in three prey types: E. coli, Serratia marsescens, and Enterococcus mundtii. Predation was simulated in an unstructured environment at various temperatures (20, 25, 30 °C), mimicking changing climatic conditions and salinities (2, 10, 30 mM NaCl), mimicking the relative ionic strength and conductivity applied by irrigation effluent. We found that the predation efficiency of the amoeba strains increased significantly increased (p < 0.01) at both low temperature (20 °C) and high salinity (30 mM NaCl) regardless of the types of prey. We suggest that increased salinity applied by effluent irrigation may benefit micropredators, while high temperatures may increase resistance to predation. Our results demonstrate the importance of understanding the effects of environmental conditions on soil trophic interactions and their potential benefits for agricultural practices.

Skeletal convergence in thunniform sharks, ichthyosaurs, whales, and tunas, and its possible ecological links through the marine ecosystem evolution

Tunas, lamnid sharks, modern whales, and derived ichthyosaurs converged on the thunniform body plan, with a fusiform body, lunate caudal fin, compressed peduncle, and peduncle joint. This evolutionary convergence has been studied for a long time but little is known about whether all four clades share any skeletal characteristics. Comparisons of vertebral centrum dimensions along the body reveal that the four clades indeed share three skeletal characteristics (e.g., thick vertebral column for its length), while an additional feature is shared by cetaceans, lamnid sharks, and ichthyosaurs and two more by lamnid sharks and ichthyosaurs alone. These vertebral features are all related to the mechanics of thunniform swimming through contributions to posterior concentration of tail-stem oscillation, tail stem stabilization, peduncle joint flexibility, and caudal fin angle fixation. Quantitative identifications of these features in fossil vertebrates would allow an inference of whether they were a thunniform swimmer. Based on measurements in the literature, mosasaurs lacked these features and were probably not thunniform swimmers, whereas a Cretaceous lamniform shark had a mosaic of thunniform and non-thunniform features. The evolution of thunniform swimming appears to be linked with the evolution of prey types and, in part, niche availability through geologic time.

Study on a fractional order delayed predator-prey model including prey refuge and type II functional response

The fractional-order delayed predator-prey dynamical scheme studied here includes a prey refuge with Holling type-II functional response. The existence and uniqueness of a solution for our scheme are explored. Hopf bifurcation with respect to delay is reconnoitered, besides local and global stability of existing steady states of fractional order0 < q ≤ 1. It is discovered that the delay passes through a series of crucial values when Hopf bifurcation takes place. Additionally, both theoretically and statistically, the impacts of prey refuge effects and fractional order on system stability are investigated. The delayed differential scheme's dynamics and results durability are improved by fractional order. Fractional order enhances the stability of the solutions and enriches the dynamics of the delayed differential model. Additionally, both theoretically and by the use of numerical simulations, the effects of fractional order and the prey refuge effects on the stability of the system are investigated.

Preliminary Studies on the Predation of the Mite Blattisocius mali (Acari: Blattisociidae) on Various Life Stages of Spider Mite, Thrips and Fruit Fly.

Research in recent years has shown that some species of predatory mites, considered to be typically associated with soil and litter, can also be found on plants. Such species include Blattisocius mali, which is an effective predator of acarid mites, nematodes and the eggs of moths and which can disperse by means of drosophilid fruit flies. Apart from soil and litter or storage, it has also been recorded on the bark of apple trees and the leaves of strawberries, thus suggesting its possible predation of/feeding on herbivorous mites and insects. Our goal was to examine whether B. mali could consume different development stages of two polyphagous herbivores, the two-spotted spider mite, Tetranychus urticae, and the western flower thrips, Frankliniella occidentalis, as well as the drosophilid fruit fly Drosophila hydei. In 24 h cage tests, single, starved B. mali females consumed all types of prey offered, i.e., the eggs, males and females of spider mites; the first-instar larvae and prepupae of thrips; and the eggs and first-instar larvae of fruit flies. The potential for B. mali to prey upon these insects and mites was confirmed. However, to estimate whether it can also effectively reduce their population, additional tests on the predator's survival, fecundity and prey preference are needed.

Prey consumption does not restore hydration state but mitigates the energetic costs of water deprivation in an insectivorous lizard.

To cope with limited availability of drinking water in their environment, terrestrial animals have developed numerous behavioral and physiological strategies including maintaining an optimal hydration state through dietary water intake. Recent studies performed in snakes, which are generalist carnivorous reptiles, suggest that the benefits of dietary water intake are negated by hydric costs of digestion. Most lizards are generalist insectivores that can shift their prey types, but firm experimental demonstration of dietary water intake is currently missing in these organisms. Here, we performed an experimental study in the common lizard Zootoca vivipara, a keystone mesopredator from temperate climates exhibiting a great diversity of prey in its mesic habitats, in order to investigate the effects of food consumption and prey type on physiological responses to water deprivation. Our results indicate that common lizards cannot improve their hydration state through prey consumption, irrespective of prey type, suggesting that they are primarily dependent upon drinking water. Yet, high-quality prey consumption reduced the energetic costs of water deprivation, potentially helping lizards to conserve a better body condition during periods of limited water availability. These findings have important implications for understanding the physiological responses of ectotherms to water stress, and highlight the complex interactions between hydration status, energy metabolism and feeding behavior in insectivorous lizards.

Golf course living leads to a diet shift for American alligators.

Human-driven land use change can fundamentally alter ecological communities, especially the diversity and abundance of large-bodied predators. Yet, despite the important roles large-bodied predators play in structuring communities through feeding, there have been only a few investigations of how the feeding patterns of large-bodied predators change in human-dominated landscapes. One group of large-bodied predators that has been largely overlooked in the context of land use change is the crocodilians. To help fill these gaps, we studied the feeding patterns of juvenile American alligators (Alligator mississippiensis) on neighboring barrier islands on the southeast coast of Georgia, USA. Jekyll Island has multiple golf courses and substantial amounts of human activity, while Sapelo Island does not have any golf courses and a much smaller amount of human activity. We found that juvenile alligator populations on both islands ate the same types of prey but in vastly different quantities. Sapelo Island alligators primarily consumed crustaceans while alligators that lived on Jekyll Island's golf courses ate mostly insects/arachnids. Furthermore, the Jekyll Island alligators exhibited a much more generalist feeding pattern (individuals mostly ate the same types of prey in the same quantities) than the more specialized Sapelo Island alligators (diets were more varied across individuals). The most likely explanation for our results is that alligators living on golf courses have different habitat use patterns and have access to different prey communities relative to alligators in more natural habitats. Thus, land use change can strongly alter the feeding patterns of large-bodied predators and, as a result, may affect their body condition, exposure to human-made chemicals, and role within ecological communities.

Comparative prey predation ability of big-eyed bug Geocoris ochropterus (Fieber) (Hemiptera: Geocoridae)

We investigated the predation ability of big-eyed bugs Geocoris ochropterus on different single prey species of thrips, whiteflies, and aphids. Results indicated that G. ochropterus adults consumed the highest number of aphids per day (33.6 ± 3.35). First instar nymphs of G. ochropterus showed low ability to consume prey, while from second to fifth instar nymphs showed high ability to consume prey with significant differences. The number of eggs deposited per female fed on whiteflies was significantly different larger than other prey types. In addition, development time of Geocoris ochropterus nymphs first to fourth instar was longest when fed on aphids and significantly different among prey types. Results suggest that G. ochropterus consumed the highest numbers of aphids, with the order of preference aphids &gt; whiteflies &gt; thrips.

The tailless gecko gets the worm: prey type alters the effects of caudal autotomy on prey capture and subjugation kinematics.

Prey capture and subjugation are complex behaviors affected by many factors including physiological and behavioral traits of both the predator and the prey. The western banded gecko (Coleonyx variegatus) is a small generalist predator that consumes both evasive prey items, such as spiders, wasps, and orthopterans, and non-evasive prey items, including larvae, pupae, and isopterans. When consuming certain prey (e.g., scorpions), banded geckos will capture and then rapidly oscillate, or shake, their head and anterior part of their body. Banded geckos also have large, active tails that can account for over 20% of their body weight and can be voluntarily severed through the process of caudal autotomy. However, how autotomy influences prey capture behavior in geckos is poorly understood. Using high-speed 3D videography, we studied the effects of both prey type (mealworms and crickets) and tail autotomy on prey capture and subjugation performance in banded geckos. Performance metrics included maximum velocity and distance of prey capture, as well as velocity and frequency of post-capture shaking. Maximum velocity and distance of prey capture were lower for mealworms than crickets regardless of tail state. However, after autotomy, maximum velocity increased for strikes on mealworms but significantly decreased for crickets. After capture, geckos always shook mealworms, but never crickets. The frequency of shaking mealworms decreased after autotomy and additional qualitative differences were observed. Our results highlight the complex and interactive effects of prey type and caudal autotomy on prey capture biomechanics.

Increasing landscape heterogeneity as a win–win solution to manage trade-offs in biological control of crop and woodland pests

Agriculture and forestry cover more than 75% of Europe, and invertebrate pests are a costly challenge for these two economic sectors. Landscape management is increasingly promoted as a solution to enhance biological pest control, but little is known on its effects on adjacent crop fields and woodlands. This study aims to explore the effect of the proportion of woodlands and permanent grasslands as well as crop diversity on biological pest control simultaneously in cereals fields and woodland patches, in south-western France. We used different types of sentinel prey as well as bird and carabid community metrics to assess biological pest control potential in these two ecosystems. We first show that land cover variables influence biological pest control both in cereal fields and woodland patches, but have antagonistic effects in the two ecosystems. Although results vary according to the biological control indicator considered, we show that increasing landscape heterogeneity represents a valuable solution to manage trade-offs and promote higher average predation rates across forests and cereal fields. Our study therefore calls for more integrative studies to identify landscape management strategies that enable nature-based solutions across ecosystems.

Helminth parasitic ecology in Gymnodactylus geckoides Spix, 1825 (Squamata: Phyllodactylidae) from Caatinga domain, north-eastern Brazil

ABSTRACT Gymnodactylus geckoides is an endemic lizard from the Caatinga domain. However, the relationship of G. geckoides with its parasites remains largely unknown. Therefore, the present study aimed to identify the helminth fauna of G. geckoides in a Caatinga fragment and determine the influence of factors such as host morphology, sex, diet and seasonality on parasite load. The study was conducted at the Conservation Unit (CU) of the Catimbau National Park located in Catimbau, Pernambuco, north-eastern Brazil. In total, 83 individuals were captured, among which 43 (51.8%) were infected by the following helminths: Acanthocephala cystacanths (prevalence, 47%; mean intensity, 2 ± 3.99; mean abundance, 1.61 ± 3.25) and the nematodes Parapharyngodon alvarengai (prevalence, 15.7%; mean intensity, 1 ± 0.74; mean abundance, 0.25 ± 0.66), Physaloptera lutzi (prevalence, 2.4%; mean intensity, 4 ± 1.00; mean abundance, 0.10 ± 0.64) Physaloptera sp. (prevalence, 4.8%; mean intensity, 1 ± 0.00; mean abundance, 0.05 ± 0.24), and Spauligodon oxkutzcabiensis (prevalence, 3.6%; mean intensity, 1 ± 0.94; mean abundance, 0.06 ± 0.36). A significantly positive relationship was found between the intensity of infection by the most prevalent helminth (which belonged to Acanthocephala) and host morphology (snoutvent length) (β ± SE = 6.421 ± 1.555, z = 4.128, p < .001), as well as prey type (β ± SE = 0.256 ± 0.078, z = 3.251, p < .001). Acanthocephala infection had a higher intensity during the rainy season (Analysis of Variance1,81: p < .01) in both female and male hosts (ANOVA1,73: p = 0.21). The present study is the first to identify the ecological patterns of the host–parasite relationships of G. geckoides. The results of this study contribute to the knowledge of the parasitic fauna of lizards in the Neotropical region. http://www.zoobank.org/urn:lsid:zoobank.org:pub:0C037904-257A-40E1-9460-487B9FAFE786

Scaling relationships of maximal gape and prey size of snakes for an egg‐eating specialist (Dasypeltis gansi) and a dietary generalist (Pantherophis obsoletus)

AbstractThe size of both predators and prey can profoundly affect the foraging ecology of animals. This is especially true for snakes which consume prey whole. Although their gape imposes an anatomical limit on prey size, different snake species have a wide variety of prey types, prey sizes, and dietary breadth. To test whether a dietary specialist that only consumes bird eggs (Dasypeltis gansi) differed from a generalist that occasionally eats eggs (Pantherophis obsoletus), I quantified and compared the scaling relationships between overall size, cranial dimensions, and maximal gape and the orientation and mobility of relevant bones. Compared to P. obsoletus with a given overall size, D. gansi had maximal gape areas approximately 3–4 times greater and a significantly larger relative contribution to gape by the intermandibular (IM) soft tissues (50% vs. 19%). The greater distensibility of the IM soft tissues also allowed much greater lateral displacement of the distal end of the lower jaw in D. gansi versus P. obsoletus, but at maximal gape, the bones of these species had unexpectedly similar orientations in lateral view. The large gape of D. gansi was attained despite having a significantly shorter head than P obsoletus for a given snout–vent length. As a result of their large gape and more slender build, the predicted values of relative prey masses (RPM) for D. gansi at maximal gape vastly exceeded those of P. obsoletus for a given prey type. Although eggs are much stouter than rats, values of RPM at maximal gape for D. gansi eating eggs greatly exceeded those for P. obsoletus eating rats. Perhaps, Dasypeltis has the greatest size‐corrected gape and potential values of RPM (for a given prey shape) of any snake taxon as these values of D. gansi exceed those from all previously studied species with similar data.