Number Of Prey Research Articles

Abundance of Eurasian lynx in the mountain taiga of the Southern Urals

The study aims to analyze the dynamics of the Eurasian lynx in the mountain taiga, and to search for the factors affecting the numbers of this predator. The study was conducted in the Southern Urals (Russia) from 2008 to 2019. The dynamics of lynx and its main prey numbers Capreolus pygargus, Lepus timidus and L. europaeus, Tetrao urogallus and Bonasa bonasia is based on the data obtained during the complex winter census (CWC). Annual CWCs were performed in Chelyabinsk Oblast with total area of 23.445.5 km². The hypotheses on the influence of snow depth on the number of lynx and the relationship between the dynamics of the predator and prey abundances were tested using regression method. The relationship between the number of lynx and snow depth were obtained using Spearman's coefficient. The number of lynxes varied from 51 to 281 individuals, population density - from 0.09 lynx/100 km2 to 0.48 lynx/100 km2 . The lowest abundances were recorded in 2013 and 2016. In the winters of 2013 and 2016, the snow depth was 2.0-2.5 times greater than on average for long-term observations. However, no significant decrease in the number of the Siberian roe deer was observed in these years, while the number of lynxes decreased by 2 times compared to the previous years. No significant correlation was found between the abundance of lynxes and the Siberian roe deer, r = 0.25 ± 0.3. A negative relationship was found between the amount of precipitation and the winter number of lynxes (r = -0.717 ± 0.22; p ˂ 0.05). The amount of snow cover in the Southern Ural Mountains is an important factor affecting the distribution of ungulates. The snow depth may determine the lynx presence both directly and through the changes in the number of its main prey.

First data on the consumed prey by Speleomantes italicus from the Republic of San Marino

We here present the first study on the consumed prey by an epigean population of the Italian cave salamander (Speleomantes italicus) from the Republic of San Marino. Using the harmless technique of stomach flushing, we aimed to provide the first data on the diet and on the degree of individual specialization that characterizes the studied population. We performed two-night surveys (one in autumn 2022 and one in spring 2023) in which we opportunistically searched for salamanders in forested areas and dry walls. Captured salamanders were sexed, weighed, photographed, measured and stomach flushed. Overall, we inspected the stomach contents of 67 individuals, recognizing 1,018 prey items belonging to 28 different prey categories. The examined population was mainly composed by generalist individuals, and no differences in number and diversity of prey consumed were observed among salamanders. Contrarily to what has been observed in other Speleomantes species, flying prey provided a minor contribution to the diet of the investigated population. Our study produced the first information on the diet of Speleomantes italicus from the Republic of San Marino, representing the starting point for future assessments on the dietary habits of this specific population.

The impact of global warming on polar bears' diet and habitat

Conventional fuels produce large amounts of greenhouse gases leading to global warming and with it dramatic changes in the Arctic, especially for its top predator, the polar bear. The environment of polar bears will gradually be more affected and challenged. This literature review explores how climate change has impacted the diets and reproduction of polar bears, along with potential solutions to mitigate these effects. The loss of sea ice due to rising temperatures has led to a decline in the number of primary prey, forcing polar bears to hunt alternative prey, including reindeer, to survive. Furthermore, reduced sea ice is affecting the reproduction and survival of the polar bear population, with the decline in genetic diversity posing a threat to their long-term survival. To mitigate these effects, reducing greenhouse gas emissions, protecting critical polar bear habitats, restoring and managing their habitats, and international collaboration and legal interventions are necessary. The implementation of these solutions will help to ensure the continued existence and thriving of this magnificent animal in the Arctic ecosystem.

Morphology and diet are decoupled in nearshore notothenoids from King George Island, West Antarctica.

Antarctic notothenioid fishes show wide adaptive morphological radiation, linked to habitat preferences and food composition. However, direct comparisons of phenotypic variability and feeding habits are still lacking, particularly in stages inhabiting nearshore areas. To assess these relationships, we collected juveniles and adults of the most common benthic species inhabiting shallow waters off the South Shetland Islands within a similar size range, the plunderfish Harpagifer antarcticus, the black rockcod Notothenia coriiceps, and the marbled rockcod Notothenia rossii. Individual size ranges varied from 44.0 to 98.9 mm standard length (LS) (H. antarcticus), from 95.8 to 109.3 mm LS (N. coriiceps), and from 63.0 to 113.0 mm LS (N. rossii). Notothenioid fish showed different morphospace variability, being larger for H. antarcticus than the other Notothenia species and associated with the position of the posterior end of the operculum, along with the location and relative size of the eye. The evolutionary allometry was low, but the static allometry was much higher, especially for H. antarcticus and N. rossii. The diet was mainly carnivorous, consisting of amphipods and euphausiids. Macroalgae were scarce or totally absent in the gut contents of all species. Only H. antarcticus showed an increase in the prey number and ingested prey volume with fish size. Finally, there was a significant covariation between shape changes and LS in all species (allometric effects), however, not with prey composition, probably due to the small size range or ontogenetic stage and the relative similarity (or lack of contrast) in the benthic environment that they utilized.

Diet of Engystomops pustulosus (Anura: Leptodactylidae) from Colombia and current knowledge of its dietary


 
 
 
 We investigated the diet of Engystomops pustulosus from a population in the Middle Magdalena River valley, including an evaluation of theeffect of body and head size on prey number and volume. We present the current state of knowledge of the diet of E. pustulosus from published information in addition to our data. We found a total of 400 prey items representing two phyla, Arthropoda and Mollusca; seven orders and nine families were detected. Arthropods, mainly insects, were the most frequent prey in the diet. Among arthropods, Acari and Isoptera were numerically dominant. We did not observe effects of body and head size on prey number and volume. The published literature of the diet of E. pustulosus included 66 prey items, among which Isoptera (termites), Acari, and Formicidae were the most common groups, suggesting dietary specialization. Prey items consumed by E. pustulosus varied among different localities; Blattodea, Orthoptera, and Thysanoptera were unique at certain localities. Further study of prey availability and diets associated with land-use changes across majorgeographic localities will contribute to a better understanding of the predator-prey interactions in these anthropogenic environments.
 
 
 

An analysis of predatory bugs (Orius spp., Hemiptera: Anthocoridae) and pest insects on some crop plants: Their distributions, abundance and population developments

Seasonal distributions and population dynamics of predatory bugs, Orius (Hemiptera: Anthocoridae) species with some harmful insects in crop plants in 2019-2020 Turkey were investigated in Turkey. A total of four Orius species were identified, these are; Orius laevigatus,(Fieber) Orius niger (Wollf) Orius albidipennis (Reuter) and Orius vicinus (Ribaut). The most common species was O. laevigatus, constituting 78.36% of the total adult individuals. Both O. laevigatus and O. niger were relatively more abundant on broad beans and beans than those numbers found in fruit trees and field crops. Very few Orius individuals were recorded on the fruit trees. Orius and thrips individuals were collected mainly from the flowers of the plants, and their population patterns depended on the flowering phenology patterns of the plants. Orius individuals were recorded together with the pest thrips on plants particularly summer and winter vegetables sampled. The total prey (thrips, aphids and leafhoppers) numbers per Orius were lower on broad bean and bean plants. Finally, the number of prey per Orius was 5.83 in the broad bean and 14.33 in the bean plant, indicating thrips in particular had high predation risks due to Orius attacks in these two plant species.

Spatiotemporal and Individual Patterns of Domestic Cat (Felis catus) Hunting Behaviour in France.

Domestic cats (Felis catus), one of the most popular pets, are widespread worldwide. This medium-sized carnivore has well-known negative effects on biodiversity, but there is still a need to better understand the approximate causes of their predation. Based on a citizen science project, we assessed the role of spatiotemporal (i.e., latitude, longitude, and seasons), climatic (i.e., rainfall), anthropogenic (i.e., human footprint, HFI), and individual (i.e., sex and age) variables on the number of preys returned home by cats in metropolitan France. Over the 5048 cats monitored between 2015 and 2022, prey from 12 different classes (n = 36,568) were returned home: 68% mammals, 21% birds, and 8% squamates. Shrews brought home by cats peaked during summer, while rodents were recorded during summer-autumn. Birds brought home by cats peaked in spring-summer and in autumn, and lizards peaked in spring and in late summer. Lower HFI was associated with more voles and mice brought home, and the opposite trend was observed for lizards and birds. Younger cats were more prone to bring home shrews, birds, and reptiles. Although environmental factors play a minor role in prey brought home by cats, some geographical characteristics of prey species distribution partly explains the hunting behaviour of cats.

Dynamics of Zooplankton Consumption by the Three-speed Stickleleback <i>Gasterosteus aculeatus</i> (Linnaeus, 1758) at Different Densities of the Predator

An experiment was set up to estimate the rate of zooplankton consumption by the three-spined stickleback Gasterosteus aculeatus (Linnaeus, 1758) at different predator densities. A differential equation describes the dynamics of zooplankton abundance depending on duration of predator feeding. The derived function accurately characterizes the rate of zooplankton consumption by stickleback in the experiment, demonstrating a good agreement between the theoretical prerequisites and the experimental results. The relationship between changing a number of prey during predation, its mortality and consumption rate was revealed. The hypothesis of consumption rate proportional to the number of predators was tested. A comparative analysis of ingestion rate as a function of time and a function of prey density was performed.

Threshold dynamics and probability density functions of a stochastic predator–prey model with general distributed delay

Predator–prey interactions are among the most complicated interactions between biological species, in which there may be both delay digestion and stochastic fluctuation. In the literature, due to the computational complexity and the lack of available methods, few papers have directly considered the predator–prey model for the combination of general infinite time delays with stochasticity. In this sense, this work is devoted to studying the long-term qualitative behavior of a stochastic predator–prey system with general infinite distributed delay. First, we establish sufficient and necessary conditions for exponential extinction and persistence of species. Notably, not only do our results cover the predator–prey model without stochastic noises and time delays, but also reveal the impact of environmental noises on population dynamics. Moreover, there are some challenges to analyze the stationary distribution of the numbers of prey and predator under species persistence. Based on the recent work (Zhou et al., 2020) where the density function of a three-dimensional avian influenza model with non-degenerate diffusion is concerned, we further generalize the relevant theories to a five-dimensional population system with degenerate diffusion. Via solving the corresponding Fokker–Planck equations, several approximate expressions of the density function of the stochastic predator–prey system with special distribution delay kernels are obtained. Finally, we provide some numerical simulations to supplement the analytical results and study the impact of stochastic noises.

High order sliding mode control for restoration of a population of predators in a Lotka-Volterra system.

Human-induced extinction and rapid ecological changes require the development of techniques that can help avoid extinction of endangered species. The most used strategy to avoid extinction is reintroduction of the endangered species, but only 31% of these attempts are successful and they require up to 15 years for their results to be evaluated. In this research, we propose a novel strategy that improves the chances of survival of endangered predators, like lynx, by controlling only the availability of prey. To simulate the prey-predator relationship we used a Lotka-Volterra model to analyze the effects of varying prey availability on the size of the predator population. We calculate the number of prey necessary to support the predator population using a high-order sliding mode control (HOSMC) that maintains the predator population at the desired level. In the wild, nature introduces significant and complex uncertainties that affect species' survival. This complexity suggests that HOSMC is a good choice of controller because it is robust to variability and does not require prior knowledge of system parameters. These parameters can also be time varying. The output measurement required by the HOSMC is the number of predators. It can be obtained using continuous monitoring of environmental DNA that measures the number of lynxes and prey in a specific geographic area. The controller efficiency in the presence of these parametric uncertainties was demonstrated with a numerical simulation, where random perturbations were forced in all four model parameters at each simulation step, and the controller provides the specific prey input that will maintain the predator population. The simulation demonstrates how HOSMC can increase and maintain an endangered population (lynx) in just 21-26 months by regulating the food supply (hares), with an acceptable maximal steady-state error of 3%.

Modelling of Carrying Capacity at Komodo National Park: System Dynamics Approach (Case Study: Komodo Island and Padar Island, East Nusa Tenggara Province)

Komodo (Varanus komodoensis) with its wildlife is the only one in the world that lives in the Komodo National Park (KNP), East Nusa Tenggara, Indonesia. The conservation efforts are carried out by considering the carrying capacity to remain in line with the principles of sustainable tourism management. This study aims to analyze the carrying capacity of the visits carrying capacity on Komodo Island and Padar Island. The method used in this research is system dynamics analysis. The number of Komodo dragons in 2045 is estimated to increase to 4000-4500 Komodo dragons in KNP or around 2500 Komodo dragons in Komodo Island and Padar Island since the number of preys is still quite available in their habitat. However, without the implementation of low carbon development, there will be pressure on its population, which can drop to 800-900 Komodo dragons both on Komodo Island and Padar Island. Meanwhile, the temperature increase occurs until the year 2045 which reaches 0.8°C. In terms of the ideal number of visits on Komodo Island based on the carrying capacity calculation of 219,000 visits/year, on Padar Island the ideal number of visits is 39,420 visits/year and it can be still increased up to 2-2.5 times

Behavioral and demographic responses of the predatory rotifer Asplanchna sieboldii (Leydig, 1854) fed prey (Plationus patulus (Müller, 1786)) previously exposed to cadmium and microplastics

We quantified the feeding behavior (encounter, attack, capture and ingestion) and demographic parameters (survival and reproduction) of the predatory rotifer Asplanchna sieboldii fed on the prey Plationus patulus previously exposed to microplastics (MPs), Cd or their combination. As compared to controls, capture and ingestion rates of P. patulus by A. sieboldii decreased by 71 and 61%, respectively, with prey previously exposed to mixed MPs and Cd treatment. Life table data showed that the predator died earlier in controls than when fed on prey exposed to both Cd and microplastics. Regardless of the prey treatment, the offspring production by A. sieboldii increased as the available prey numbers increased (from 1 to 4 ind. ml−1). Compared to controls, the fecundity rate of the predator decreased when contaminated prey was offered as food.

Temperature-dependent feeding behavior in the brown box crab, Lopholithodes foraminatus

IntroductionGrowing fishing pressures and ocean warming are potential concerns for populations of brown box crabs, Lopholithodes foraminatus, at the southern end of their geographic distribution. In Southern California, brown box crabs are thought to occupy a broad depth gradient (intertidal zone - 547 m), which exposes them to temperatures ranging from 8°C - 24°C. This large temperature span presents challenges for these ectothermic animals because the rates of their physiological processes, and ultimately their dietary needs, behavior, and health, vary with temperature. Here we examined how temperature affects the feeding behavior of brown box crabs to better understand their ecology in warmer regions of their distribution.MethodsAdult crabs were exposed to one of three temperature treatments (8°C, 15°C, and 20°C, N=10) for 2 months. Weekly throughout the exposure period, crabs were given two similar-sized prey items of different crushing strength (clam and mussel). Claw pinch force, prey preference, time to consume prey, and number of prey consumed were recorded prior to the start of the experiment and weekly for the duration of the study, with the exception of pinch force, which was recorded bi-weekly. We hypothesized that crabs will have a stronger pinch force at warmer temperatures, prefer prey items that require less breaking force at the coldest temperature, consume prey faster at warmer temperatures, and consume more prey at warmer temperatures.ResultsOur results confirm that pinch force is consistently greater at 15°C compared to 8°C, however, crabs at 8°C consumed more clams (higher strength) while those at 15°C consumed more mussels. Crabs at 8°C also consumed prey items faster than crabs at 15°C but ate a similar number of prey. Furthermore, there was 100% mortality at 20°C within 8 days of exposure, indicating their proximity to lethal limits within Southern California.DiscussionThese results show that brown box crab feeding behavior exhibits temperature thresholds, which may alter their nutritional state, community interactions, and distribution under both short-term and long-term changes in ocean temperature.

What constrains food webs? A maximum entropy framework for predicting their structure with minimal biases.

Food webs are complex ecological networks whose structure is both ecologically and statistically constrained, with many network properties being correlated with each other. Despite the recognition of these invariable relationships in food webs, the use of the principle of maximum entropy (MaxEnt) in network ecology is still rare. This is surprising considering that MaxEnt is a statistical tool precisely designed for understanding and predicting many types of constrained systems. This principle asserts that the least-biased probability distribution of a system's property, constrained by prior knowledge about that system, is the one with maximum information entropy. MaxEnt has been proven useful in many ecological modeling problems, but its application in food webs and other ecological networks is limited. Here we show how MaxEnt can be used to derive many food-web properties both analytically and heuristically. First, we show how the joint degree distribution (the joint probability distribution of the numbers of prey and predators for each species in the network) can be derived analytically using the number of species and the number of interactions in food webs. Second, we present a heuristic and flexible approach of finding a network's adjacency matrix (the network's representation in matrix format) based on simulated annealing and SVD entropy. We built two heuristic models using the connectance and the joint degree sequence as statistical constraints, respectively. We compared both models' predictions against corresponding null and neutral models commonly used in network ecology using open access data of terrestrial and aquatic food webs sampled globally (N = 257). We found that the heuristic model constrained by the joint degree sequence was a good predictor of many measures of food-web structure, especially the nestedness and motifs distribution. Specifically, our results suggest that the structure of terrestrial and aquatic food webs is mainly driven by their joint degree distribution.

A hybrid model of population dynamics with refuge-regime: regularization and self-organization

A mathematical model of the dynamics of the predator and prey populations in the form of a hybrid dynamical system consisting of two two-dimensional systems switching between each other is proposed. Switching of the systems allows us to reproduce a special refuge-regime when the prey number is very small and predators have complications to find preys. The sliding modes are studied using Filippov approach. Regularization of the system by using two switching lines to avoid chattering is provided. For the regularized model the limit sets are established. A scenario of the system self-organization preventing the unbounded populations' growth is proposed. A sensitivity study is carried out with respect to a parameter defining the switching lines. An important result of the research is that sufficiently small changing of the switching lines does not change the qualitative behavior of the system.

Labral tooth loss in the carnivorous gastropod Acanthina monodon: Recovery capacity and incidence in the feeding process

The temporary loss of an animal feeding structure can often be replaced by a new one. During that replacement period, however, the animal can be limited in its ability to feed. The muricid gastropod Acanthina monodon can sometimes lose its labral tooth naturally; recovering the tooth will typically take between 14 and 21 days. Our studies show that the volume, length and area of the recovered tooth are equal to or greater than the characteristics of the original tooth. However, the recovered teeth were seen to grow differently and have different shapes than those of the original teeth. Moreover, less force was required to break the newly formed teeth, to an extent based on the shape of the new tooth. Although the toothless snails continued to feed in our study, the absence of the labral tooth had a negative impact on the size of attacked prey, although not on the number of prey attacked. Thus, the ingestion rate was lower in specimens with recovered teeth than in snails with the original intact teeth. Snails that lost the labral tooth also displayed alterations in the feeding process, including lower energy income and potential energetic repercussions, at least during the recovery period of the lost structure.

Potential prey and conservation implications of the Algerian Nuthatch Sitta ledanti (Vielliard 1976)

The Algerian Nuthatch ( Sitta ledanti), which is mentioned on the Red List of threatened species, is one of the first protected birds in Algeria. The species’ populations are distributed with low numbers in Babors’ Kabyliain northeastern Algeria. The diet composition of the species has been studied on a large scale in five large forests. The diet analysis method is based on the identification of the different prey items found in the fecal sacs of the nestlings. We divided the 89 identified prey into 81 insects, 7 arachnids and 1 gastropod, giving 88 arthropods and 1 mollusc. According to both the Cluster Dendrogram and the Costello graph, the Algerian Nuthatch becomes a specialist species while searching for prey to feed its nestlings. This supply of specific prey for nestlings has been observed in both evergreen (Atlas cedar or Algerian fir) and deciduous (Algerian or African oaks) forests. Only the relative abundances (RA) of each prey consumed, prey number per fecal sac, and prey diversity by forest type showed differences. The low proportion of gastropods found in the fecal sacs of Algerian Nuthatch nestlings may explain the low nutritional value of this prey or may also be due to its low abundance. The species’ nestlings consumed a lot of European Earwig ( Forficula auricularia) and White spotted rose beetle ( Oxythyrea funesta) which could be due to their high energy intake and abundance in the area near the nests. Repeated fires and other anthropogenic activity constitute direct threats to the species’ habitat, and its specialised diet on certain prey weakens the survival of this species with endangered conservation status.

Native predators can learn new prey cues to overcome naivete and hunt novel alien prey

Biological invasions continue to rise globally, increasing the frequency of novel ecological interactions and the potential for naivete. Native predators can defend against invasion by alien prey species through biotic resistance, but initial predator naivete towards novel alien prey can allow prey to establish. Here we test if predator naivete can be overcome via a learned association between novel prey cues and a food reward, and if this conditioning increases predator motivation to hunt novel alien prey. We exposed free-living native bush rats (Rattus fuscipes) to repeated bouts of novel alien cockroach (Nauphoeta cinerea) odour and food rewards over an 11-day training period. We then conducted a simulated invasion, comparing the survival rates of sentinel cockroach prey in sites with trained and untrained rats. Cockroaches in sites with trained rats were 46 % more likely to be found and consumed over the invasion period than prey in sites with untrained rats. Also, the number of food rewards taken during training was correlated with the number of prey consumed on the first night of the invasion. Our results suggest that predators can overcome their naivete to novel prey through learning and that pre-exposing free-living predators to novel prey cues can subsequently increase predation rates on novel alien prey.

Diet analyses of the pelagic thresher shark, Alopias pelagicus (Lamniformes: Alopiidae), from the Lombok Strait waters, Indonesia

Abstract. Alghozali FA, Salsabila R, Gustianto MWD, Putri HMIH, Himawan MR, Yuneni RR, Hatmoro CK, Rezkiani M. 2023. Diet analyses of the pelagic thresher shark, Alopias pelagicus (Lamniformes: Alopiidae), from the Lombok Strait waters, Indonesia. Biodiversitas 24: 3708-3714. The pelagic thresher shark, Alopias pelagicus, is an endangered shark species estimated to be declining in the Pacific and Indian Oceans because of overexploitation, including from target fisheries and bycatch. Despite its importance in providing better information for species management, the ecological aspects of this species are still rarely studied. This study aims to provide information on the feeding ecology of the pelagic thresher sharks from the Lombok Strait. Stomach samples from 178 specimens were sampled from 2020-2021, and 149 stomachs that contained food contents were analyzed for species diet characterization. Prey Species Accumulation Curve slope values are <0.1 and the percentage of prey coverage for all sharks combined is 92.1%, suggesting reliable inventory in the number of prey represented. The resulting diet indexes suggest that A. pelagicus in Lombok Strait waters is a specialist predator (Ba=0.3) with few prey variations (H=2.21) and no competition between sexes and maturity stages of the species (C=0.64 and 0.81, respectively). The top three prey species found for A. pelagicus in the study area are the Auxis thazard (85.8 %IRI), Sthenoteuthis oualaniensis (8.5 %IRI), and Dasyscopelus spinosus (1.11 %IRI). A better understanding of the overlap of A. pelagicus and its diet, which includes economic fish commodities, will inform authorities to develop better fisheries and conservation management for the species in Indonesia.

Daily vertical distribution and diet of Cyclothone braueri (Gonostomatidae) in the Polcevera submarine canyon (Ligurian Sea, north-western Mediterranean)

Despite its abundance, the role of Cyclothone braueri in intermediate mesopelagic food webs has been poorly investigated, notably its trophic behaviour in areas characterized by peculiar oceanographic and ecological features, such as submarine canyons. In this study, we investigated the diel feeding pattern of C. braueri in the Polcevera submarine canyon, in the Ligurian Sea. Stratified sampling from the surface to 1300 m was undertaken with a BIONESS every 6 h during a 24 h period. Stomach contents of 244 C. braueri specimens from 11.6 to 27.5 mm SL were examined. Calanoid copepods were the dominant taxa in the fish stomachs (98% of all copepods), with Pleuromamma abdominalis, Neocalanus gracilis, Pleuromamma gracilis and Euchaeta acuta being the main preys. Among the 20 identified copepod prey species, about 20% were typical of the epipelagic zone, while the remaining 80% usually live in mesopelagic waters. The low number of prey per stomach (average = 1.4) and high vacuity index (53%) indicated that this species had very low metabolic requirements (trophic level in this study was 3.03). Most of the full stomachs were found during the morning and afternoon in the upper mesopelagic zone (200–400 m), indicating two main periods of feeding activity per day. This study confirmed high abundance and biomass of C. braueri in Polcevera canyon compared to those of open ocean waters and raised the question of how the presence of the canyon affects migratory and trophic behaviours of this mesopelagic fish. Further analyses aimed at investigating the link between the hydrodynamic regime of the Polcevera canyon and the behaviour and trophic ecology of C. braueri are needed to address this question.