Predator Type Research Articles

Predation risk and herd position influence the proportional use of antipredator and social vigilance by impala

Vigilance is just one of the many fitness-enhancing activities that animals do each day. However, as vigilance is used for both predator detection and obtaining social information, individuals must decide how to divide their time between these two vigilance types. Yet, it is unclear (1) how prey species living in the centre and edge of groups prioritize their use of these different vigilance types and (2) how this prioritization varies with increasing risk. To explore this, we focused on the degree to which impala, Aepyceros melampus, a herd-living antelope, adjusted their antipredator (looking out from the herd) and social (looking at herd members) vigilance across three sites with different predator guilds and predator densities. We found that as predator types and densities increased, herd size increased, but that impala did not adjust the total time they spent vigilant (antipredator plus social vigilance). Thus, they did not sacrifice other fitness-enhancing activities (e.g. foraging) to increase vigilance. Yet, overall, within the herds, edge individuals displayed greater total vigilance (antipredator plus social) and showed a greater proportional use of antipredator vigilance compared to central individuals. With increasing predator numbers, edge individuals maintained and ultimately increased their proportional use of antipredator vigilance. In contrast, central individuals reduced their use of antipredator vigilance and increased social vigilance. As suggested elsewhere, this adjustment might have been related to these individuals trying to increase foraging efficiency and cohesion benefits. However, they may have also monitored conspecifics to detect threats, while obtaining both short- (e.g. less time spent in a vulnerable head-down position) and long-term (e.g. reduced daily foraging time allowing more time for less vulnerable activities) antipredator benefits. Ultimately, our results highlight that herd position and predator differences can influence overall vigilance levels and how individuals adjust their use of antipredator and social vigilance.

Insight into occupancy determinants and conflict dynamics of grey wolf (Canis lupus) in the dry temperate zone of Hindukush Range

The grey wolf (Canis lupus) is a widespread but locally endangered species across Pakistan. The current study investigates the occupancy of grey wolf and conflict with humans in Khanbari Valley Gilgit Baltistan. The study was conducted from the 5th of December 2014 to the 11th of January 2015. The study area was delineated into blocks following natural watersheds, and overall 47 motion-triggered cameras were installed in various locations encompassing an area of 810 km2 with an effort of 1428 trap nights. A human-wolf conflict survey was carried out through questionnaires, where 57 respondents were randomly chosen from 08 villages in the valley. Grey wolf was photo-captured at 11 different camera stations, occupancy estimated at 0.37 ± 0.22 S.E., and detection probability of 0.29 ± 0.19 S.E was obtained. A total of 166 livestock were killed which incurred an economic loss of USD 17,046 (USD 299 per household) in five years. Predation on goat was highest, though consumed as per availability. Sheep predation indicates selection for this animal because predation was much higher than availability. Cattle was predated as per availability and accounts for the least part of the livestock loss. Predation of livestock was greatly influenced by four factors: habitat, prey type, prey age, and time of predation. We recommend conservation initiatives like compensation for economic losses, construction of predator-proof corrals, and awareness campaigns to promote human-wolf co-existence in the area.

Frequency of Occurrence and Ingested Biomass of Different Prey of the Barn Owl Tyto alba in an Island Ecosystem

The Barn Owl Tyto alba is commonly reported as a non-selective predator of small mammals, and its diet has been thoroughly analyzed also to assess the small mammal assembly composition in many study areas. The aim of this work was to analyze the diet of the Barn Owl in the Elba island through the analysis of 161 pellets collected in September 2020. Undigested fragments were isolated and compared with reference collections. We confirmed that the Barn Owl is a typical predator of field mice (62% of relative frequency), with synanthropic murid rodents as the second category of prey. The frequency of consumption of shrews increased by 9% with respect to the previous work, suggesting that the natural environment of Elba island is still in a good health status. Moreover, fragments of two newborn hares were detected, increasing the knowledge on the local trophic spectrum of the Barn Owl. Finally, the skull of a Geoffroy’s Myotis Myotis emarginatus confirmed the presence of this species in Elba island after over 60 years from the first unconfirmed record. Repeated studies conducted in the same study site may provide useful information on prey population trends and local environmental status.

Environmental controls on African herbivore responses to landscapes of fear

Herbivores balance forage acquisition with the need to avoid predation, often leading to tradeoffs between forgoing resources to avoid areas of high predation risk, or tolerating increased risk in exchange for improved forage. The outcome of these decisions is likely to change with varying resource levels, with herbivores altering their response to predation risk across heterogeneous landscapes. Such contrasting responses will alter the strength of non‐consumptive predation effects, but are poorly understood in multiple‐predator/multiple‐prey systems. We combined fine‐scaled spatial information on two predator and 11 herbivore species with remotely‐sensed measurements of forage quantity and vegetation structure to assess variation in herbivore response to predation risk with changing environmental context, herbivore body size, herbivore foraging strategy (browsers versus grazers), predator type (ambush versus coursing hunters) and group size across a South African savanna landscape. Medium‐sized herbivore species were more likely to adjust their response to risk with a changing resource landscape: warthog, nyala and wildebeest tolerated increased long‐term predator encounter risk in exchange for abundant (warthog and nyala) or preferred (wildebeest) forage, and nyala selected areas with higher visibility only in landscapes where food was abundant. Impala were more likely to be observed in areas of high visibility where wild dog risk was high. In addition, although buffalo did not avoid areas of high lion encounter risk, large buffalo groups were more frequently observed in open areas where lion encounter risk was high, whereas small groups did not alter their space use across varying levels of risk. Our findings suggest that risk effects are not uniform across landscapes for medium‐sized herbivores and large buffalo groups, instead varying with environmental context and leading to a dynamic landscape of fear. However, responses among these and other prey species were variable and not consistent, highlighting the complexities inherent to multi‐predator/multi‐prey systems.

Protective effect of predator species richness on human hantavirus infection incidence

Are predators of rodents beneficial for public health? This question focuses on whether predators regulate the spillover transmission of rodent-borne diseases. No clear answer has emerged because of the complex linkages across multiple trophic levels and the lack of accessible data. Although previous empirical findings have suggested ecological mechanisms, such as resource partitioning, which implies protective effects from predator species richness, epidemiological evidence is needed to bolster these arguments. Thus, we investigated the association between predator species richness and incidence of rodent-borne haemorrhagic fever with renal syndrome in the human population using district-level longitudinal data of 13 years for South Korea. With the exception of districts with low species richness, we found a significant negative association between the incidence of haemorrhagic fever with renal syndrome and the species richness of both avian and mammalian predators; the trends for both predator types were similar. Thus, biodiversity conservation may benefit public health.

Evolutionary trade‐offs may interact with physiological constraints to maintain color variation

AbstractAnimal coloration is a multifaceted trait with many ecological roles and related to a variety of developmental and physiological processes. Consequently, coloration is often subject to a variety of selective pressures, leading to the evolutionary maintenance of variation. In this study, we investigated hypotheses related to the maintenance of dorsal color variation in wood frogs (Rana sylvatica). First, we tested for multimodality, and whether color correlates with body size or condition or varies by sex or age class. We combined behavioral trials with visual modeling to test for sex recognition. We also considered visual models for predators and tested for an interaction between discriminability indexes (JND) of color channel (chromatic vs. achromatic) and predator type (birds vs. snakes), as well as for a within individual trade‐off between the JND of chromatic and achromatic coloration. Finally, we tested for disruptive viability selection on color using predation trials, and for antagonistic directional selection between viability selection and reproductive investment of females. We found that wood frogs present continuous color variation that does not correlate with body size or condition, but that changes with age. Wood frogs present subtle sexual dichromatism, but we found no evidence for a role of color in sex recognition. Instead, we discuss the possibility that sex differences might, at least in part, have a demographic explanation. Predator visual models indicated that wood frogs cannot solely rely on dorsal coloration for camouflage. Moreover, different predators might present selective pressures in different color channels, while individuals’ achromatic and chromatic coloration trade‐off in JND. Therefore, different selective pressures caused by different predators might interact with ontogenetic changes and developmental/physiological trade‐offs to maintain color variation. We found no relationship between color and survival or reproductive investment, suggesting further work is required to fully understand selection on color. Our results highlight the importance of understanding evolutionary trade‐offs and developmental/physiological constraints in combination with one another, and suggest the potential for an interaction between these proximate and ultimate mechanisms in the evolutionary maintenance of variation. These results likely extend beyond color expression in amphibians, and exemplify a more general process for such evolutionary outcomes.

Stability and Bifurcation Analysis in a Nonlinear Harvested Predator–Prey Model with Simplified Holling Type IV Functional Response

In this paper, a type of predator–prey model with simplified Holling type IV functional response is improved by adding the nonlinear Michaelis–Menten type prey harvesting to explore the dynamics of the predator–prey system. Firstly, the conditions for the existence of different equilibria are analyzed, and the stability of possible equilibria is investigated to predict the final state of the system. Secondly, bifurcation behaviors of this system are explored, and it is found that saddle-node and transcritical bifurcations occur on the condition of some parameter values using Sotomayor’s theorem; the first Lyapunov constant is computed to determine the stability of the bifurcated limit cycle of Hopf bifurcation; repelling and attracting Bogdanov–Takens bifurcation of codimension 2 is explored by calculating the universal unfolding near the cusp based on two-parameter bifurcation analysis theorem, and hence there are different parameter values for which the model has a limit cycle, or a homoclinic loop; it is also predicted that the heteroclinic bifurcation may occur as the parameter values vary by analyzing the isoclinic of the improved system. Finally, numerical simulations are done to verify the theoretical analysis.

The Diversity of Pest Generalist Predator in Potato Plants (Solanum tuberosum L.) Treated By Non-Synthetic Chemistry Insecticide on The Medium Plain of Lombok Island

This study aims to determine the diversity, abundance, and dominance of predators in potato plants treated by synthetic non-chemical insecticides on the medium plain of Lombok Island. The research used Randomized Block Design with ten different synthetic non-chemical insecticide treatments such as Metarhizium anisopliae, Beauveria bassiana, and Bacillus thuringiensis, Neem extract, tobacco stem extract, soursop leaf extract, babandotan leaf extract, chemical insecticide treatment, and one treatment without insecticide as a control. The insecticide was applied after 37 days of planting eight times at 7-day intervals. The type and population of predators were observed five days after the treatments. The diversity index (H'), abundance (K), and dominance (D) of the predators are then identified and determined. Data were analyzed by using a Diversity analysis followed by a 5% beda nyata jujur (BNJ). The yield shows six predatory families: Formicidae, Coccinellidae, Mantidae, Lycosidae, Oxyopidae, and Aranedae. H' and K values are generally classified as the low category, and no species dominates in each treatment (D <0.5). The value of H' and K in B. thuringiensis treatment was higher than other treatments. The highest D value was obtained from chemical insecticide treatment. Formicidae is the family with the highest population compared to other families

Conspicuous colours in a polymorphic orb-web spider: evidence of predator avoidance but not prey attraction

Conspicuous colours in animals are usually explained by mate attraction, predator avoidance and prey attraction. Predators may lure prey by mimicking food or other resources. Alternatively, some animals avoid predation by visually signalling unpalatability to predators. The evolution of a signal is affected by receiver processing mechanisms. Therefore, variation in sensory systems may explain the evolution of colour polymorphism of conspicuous species. We aimed to investigate the role of receivers in the evolution and maintenance of colour conspicuousness and polymorphism in Gasteracantha cancriformis (Araneidae). We tested two hypotheses: (1) conspicuous coloration is a prey lure strategy; (2) conspicuous coloration is a warning signal to predators. Furthermore, we identified the taxonomic order of prey captured and the type of predator (avian versus arthropod). To assess the role of prey, we conducted a field experiment in which webs were assigned to one of four treatments: yellow, red or black spider models, or no model. For each treatment, we counted the number of prey trapped on the webs and calculated the damaged area of the webs. To assess the role of predators, we conducted a second field experiment in which we attached yellow, red and black models to trees using nylon thread and observed the number of attack markings on each model. Our results did not corroborate the prey attraction hypothesis. In the predation experiment, black models had more attack markings, indicating that yellow and red models were less preferred. This suggests that spider coloration may play a role in predator avoidance. Colour polymorphism in this species is possibly a multifunctional attribute, where some morphs benefit from aposematism, whereas others may have alternative fitness advantages. Nonadaptive explanations should also be considered in future experiments of the evolution and maintenance of colour polymorphisms.

Habitat Characteristics Nesting Environment of Green Turtle (Chelonia mydas) Pandan Island of West Sumatera

This research was conducted in February until March 2017 at Pandan Island island pandan area tourist Park Pieh Island. The purpose of this study was to investigate the characteristics of the nesting habitat of the hawksbill turtle (Chelonia mydas). The method used in this research is the survey method, with measuring directly on the habitat of hawksbill turtle covering the slope of the beach, texture of sediments, within the nest of tides, the temperature of the nest, fecundity, and the type of vegetation and predators in the nesting habitat. The results showed that the nesting habitat characteristics vary between nest with each other. Nesting beach ramps ranged 2,75-4,60º with medium sand sediment texture to coarse sand. Temperatures nest ranging between 27-31ºC. The dominant vegetation in the area is a nesting plant pandan laut (Pandanus tectorius) whereas the dominant predator was biawak (Varanus salvator).

Dialects in the alarm calls of black- tailed prairie dogs (Cynomys ludovicianus): A case of cultural diffusion?

Prairie dogs (Cynomys spp.) produce an alarm call when a predator appears. Gunnison’s prairie dogs (Cynomys gunnisoni) produce calls that vary in spectral structure according to predator type and specific characteristics unique to the individual predator, such as color and shape. These calls vary depending on geographic location and have been characterized as dialects. Black-tailed prairie dogs (Cynomys ludovicianus) also encode information about terrestrial predators in their alarm calls. However, nothing is known about whether there are dialects in these alarm calls, and if so, why these dialects might have arisen. We studied the alarm calls and habitat characteristics of eight different black-tailed prairie dog colonies within the Southwestern USA: Maxwell National Wildlife Refuge, NM, Vermejo Park Ranch, NM, Kiowa National Grasslands, NM, Rita Blanca National Grasslands, TX, and Comanche National Grasslands, CO. An analysis of time and frequency changes in alarm calls showed that colony sites that were located within 30 km each other did not have significant differences in alarm call structure, but sites that were more distant were significantly different from the other sites, consistent with the existence of dialects as well as with genetic models of isolation by distance. The acoustic structure of the alarm calls was not explained by differences in habitat characteristics at each site. A comparison of Squared Euclidian Distances (D2) of alarm calls versus linear distances between sites showed a significant positive correlation, implying that alarm call dialect differences increase the farther one site is from another. This relationship is consistent with a cultural diffusion model of dialects, and is similar to that observed in human dialects.

On the solutions of the two preys and one predator type model approached by the fixed point theory

The purpose of this paper is to discuss a special type of functional equation that describes the relationship between the predator animals and their two choices of prey with their corresponding probabilities. Our aim is to find the existence and uniqueness results of the proposed functional equation using the Banach fixed point theorem. Finally, we give an illustrative example that supports our main results.

Being hunted high and low: do differences in nocturnal sleeping and diurnal resting sites of howler monkeys (Alouatta nigerrima and Alouatta discolor) reflect safety from attack by different types of predator?

Abstract Predation risk is important in influencing animal behaviour. We investigated how the choice of nocturnal sleeping and diurnal resting sites by two species of primates was influenced by the most likely forms of attack (diurnal raptors and nocturnal felids). We recorded vertical and horizontal patterns of occupancy for 47 sleeping and 31 resting sites, as well as the presence of lianas or vines on trees. We compared the heights of trees used as resting or sleeping sites by the monkeys with those of 200 forest trees that the monkeys did not use. Trees used as nocturnal sleeping sites were taller than those used as diurnal resting sites, and taller than trees that the monkeys did not use. However, while trees used as diurnal resting sites were not significantly taller than non-used trees, diurnal resting sites were located on branches closer to the ground, closer to the main trunk of the tree and in trees with more lianas/vines than nocturnal sleeping sites. The differences in site location can be explained by the type of predator most likely to attack at a particular time: raptors in the day and felids at night.

Exploring individual and population eco-evolutionary feedbacks under the coupled effects of fishing and predation

Intensive fishing that selects for large and old individuals can have pervasive effects on traits directly associated with the fecundity and survival of the target species. The observed reduction in fish body size can result in earlier sexual maturity at a smaller body size, leading to a lower individual reproductive output and population productivity in the long term. In addition, increased predation can induce similar responses in age and size at maturity due to the release of intraspecific competition and the lower population density. Thus, the combined impact of fisheries and predation is more difficult to predict due to their competition for fish, ultimately limiting and directing the prey size selectivity of each competitor. This can lead to various responses of fish on individual and population levels, depending on how the impacts of fisheries and predation affect each other. To explore this topic, we used an individual-based model to investigate the responses of the European hake (Merluccius merluccius) to the coupled pressures of the prevailing fishing regime and predation by bottlenose dolphins (Tursiops truncatus) as a study system. By simulating the growth trajectories of hake with consideration to its pronounced sexual size dimorphism (SSD), we applied Holling’s Type II and III functional responses (FRII and FRIII, respectively) and the Rosenzweig-MacArthur predator model to describe prey–predator dynamics. Our results demonstrate how the intensity, duration, and prey sizes selected by predation and fisheries determine the potential for evolutionary changes in hake life-history traits. Additionally, pronounced SSD in hake as well as the predation type play a pivotal role in hake resilience and recovery following a period of overexploitation. Different types of predation reveal the discrepancy in the intensity of competition between predators and fisheries for fish, as well as predator survival, which is relevant for sustainable fisheries management and effective predator conservation strategies.

Ecological and evolutionary factors of intraspecific variation in inducible defenses: Insights gained from Daphnia experiments.

Phenotypic variation among individuals and species is a fundamental principle of natural selection. In this review, we focus on numerous experiments involving the model species Daphnia (Crustacea) and categorize the factors, especially secondary ones, affecting intraspecific variations in inducible defense. Primary factors, such as predator type and density, determine the degree to which inducible defense expresses and increases or decreases. Secondary factors, on the other hand, act together with primary factors to inducible defense or without primary factors on inducible defense. The secondary factors increase intraspecies variation in inducible defense, and thus, the level of adaptation of organisms varies within species. Future research will explore the potential for new secondary factors, as well as the relative importance between factors needs to be clarified.

Defense of Milkweed Bugs (Heteroptera: Lygaeinae) against Predatory Lacewing Larvae Depends on Structural Differences of Sequestered Cardenolides.

Predators and parasitoids regulate insect populations and select defense mechanisms such as the sequestration of plant toxins. Sequestration is common among herbivorous insects, yet how the structural variation of plant toxins affects defenses against predators remains largely unknown. The palearctic milkweed bug Lygaeus equestris (Heteroptera: Lygaeinae) was recently shown to sequester cardenolides from Adonis vernalis (Ranunculaceae), while its relative Horvathiolus superbus also obtains cardenolides but from Digitalis purpurea (Plantaginaceae). Remarkably, toxin sequestration protects both species against insectivorous birds, but only H. superbus gains protection against predatory lacewing larvae. Here, we used a full factorial design to test whether this difference was mediated by the differences in plant chemistry or by the insect species. We raised both species of milkweed bugs on seeds from both species of host plants and carried out predation assays using the larvae of the lacewing Chrysoperla carnea. In addition, we analyzed the toxins sequestered by the bugs via liquid chromatography (HPLC). We found that both insect species gained protection by sequestering cardenolides from D. purpurea but not from A. vernalis. Since the total amount of toxins stored was not different between the plant species in H. superbus and even lower in L. equestris from D. purpurea compared to A. vernalis, the effect is most likely mediated by structural differences of the sequestered toxins. Our findings indicate that predator–prey interactions are highly context-specific and that the host plant choice can affect the levels of protection to various predator types based on structural differences within the same class of chemical compounds.

KERAGAMAN JENIS DAN PERILAKU PEMANGSA PREDATOR YANG BERASOSIASI DENGAN HAMA KEPIK PENGISAP BUAH KAKAOHelopeltis spp. PADA TANAMAN KAKAO

Helopeltis spp. is one of the pests that attack cocoa fruit and can lead to decreased quality and quantity of fruit. Efforts to control that can be done is the utilization of natural enemy one of them is a predator. The large predator populations in the cocoa ecosystem will decrease the pest population of Helopeltisspp. the aim of this study was to know the predator species of pests associated with Helopeltisspp pests and predatory behavior. This research was conducted in Ende Sub-district in 6 villages and Laboratory of Agricultural Faculty of Flores University from March to May 2017. The method used was observation in the field by taking predator samples and observed their morphology and testing of predatory behavior. The variables observed were predators and behavioral diversity and predator predation time. The results obtained 3 species of predators namely Oecophyllasmaragdina, Gasteracanthacancriformis, and Leucaugevenusta. The diversity of predator types associated with Helopeltis spp. all of which are low in Randorama village of 0.29; Randotonda village 0.31; village Ndetundora I 0.26; village Ndetundora II 0.16; village Ndetundora III 0.18; and Embutheru village 0.23. Predator behavior of each predator differs from the predation time of Oecophyllasmaragdina 47 min/ tail, Gasteracanthacancriformis 1 hour 51 min/tail and Leucaugevenusta 1 hour 29 min/ head.

Risk assessment in the plateau pika (Ochotona curzoniae): intensity of behavioral response differs with predator species

BackgroundThe ability of a prey species to assess the risk that a predator poses can have important fitness advantages for the prey species. To better understand predator–prey interactions, more species need to be observed to determine how prey behavioral responses differ in intensity when approached by different types of predators. The plateau pika (Ochotona curzoniae) is preyed upon by all predators occurring in its distribution area. Therefore, it is an ideal species to study anti-predator behavior. In this study, we investigated the intensity of anti-predator behavior of pikas in response to visual cues by using four predator species models in Maqu County on the eastern Qinghai-Tibetan Plateau.ResultsThe behavioral response metrics, such as Flight Initiation Distance (FID), the hiding time and the percentage of vigilance were significantly different when exposed to a Tibetan fox, a wolf, a Saker falcon and a large-billed crow, respectively. Pikas showed a stronger response to Saker falcons compared to any of the other predators.ConclusionsOur results showed that pikas alter their behavioral (such as FID, the hiding time and the vigilance) response intensity to optimally balance the benefits when exposed to different taxidermy predator species models. We conclude that pikas are able to assess their actual risk of predation and show a threat-sensitive behavioral response.

On a solution of the probabilistic predator–prey model approached by the fixed point methods

In this paper, we are dealing with a particular type of predator–prey model in which a predator has two choices of preys with probabilities x and $$1-x$$ , respectively. Our aims are to analyze the behavior of predator animals in such situation and to construct a general functional equation for it, which covers all the aspects of such type of relationship. The Banach fixed point theorem is being used to investigate the existence and uniqueness results of the proposed predator–prey model; Hyers–Ulam and Hyers–Ulam–Rassias type stability of the functional equation has also been discussed in it.

Population of Natural Enemies in Three Varieties of Rice Plants in Turikale Subdistrict, Maros District

Rice (Oryza sativa L.) is an annual crop that plays an important role in meeting the food sources of the Indonesian population. In addition, rice plants have a diversity of insects as their natural enemy. This study aims to determine the population of natural enemies of 3 rice varieties, namely Inpari 30, Ciliwung, and Mekongga varieties. The research location is the rice fields in Turikale Subdistrict, Maros District. The method used for the study was the survey location of rice fields with each paddy field size of about 20 x 15 m. The results showed that there were 3 types of predators namely Lycosa, Coccinella, and Orthetrum which were found in each variety with varied total numbers at every 2-week observation interval. The highest population of Lycosa was found in the Inpari 30 (6 wap) variety, the highest Coccinella population also was found in the Inpari 30 (10 wap) variety, while the highest Orthetrum population was found in the Mekongga variety (6 wap). The highest proportion of each variety was Lycosidae 50% in the Inpari 30 variety, Lycosidae 51.35% in the Ciliwung variety, and Lycosidae 44.44% in the Mekongga variety