Prey Population Dynamics Research Articles

Diet of St. Lawrence Estuary Beluga (<i>Delphinapterus leucas</i>) in a changing ecosystem

Ecosystems and community structure fluctuate over time as a result of natural and anthropogenic factors that may affect prey availability and population dynamics. Most of what we know about St. Lawrence Estuary (SLE) Beluga (Delphinapterus leucas) diet comes from stomach contents collected 80 years ago mainly from a hunting site that Beluga no longer use. How reflective these data are of Beluga diet at other sites and at the current time is unknown. In the context of the recent population decline, general information of prey species alone may help identify useful conservation actions for potentially important prey or habitats. Here, we examined the diet of SLE Beluga using digestive tracts collected from carcasses recovered over the past 30 years, in the context of historical diet data and recent changes in the St. Lawrence ecosystem. We showed they have a varied diet composed of fish and invertebrates generally <30 cm in length, and that adult males and females differ in their summer diet in a way that is consistent with the sex segregation observed in this population. Our results also indicate that polychaete worms, squid, and cod are still among the most prevalent prey, and that species such as redfish (Sebastes spp.) might be important prey items. This study shows that Beluga diet has changed since the 1930s, and that prey from digestive tracts identified to species are valuable for making comparisons to the past, and for improving applications of molecular analyses, such as stable isotopes and fatty acids.

Dynamics of Predator-Prey Community with Age Structures and Its Changing Due To Harvesting

The paper studies dynamic modes of discrete-time model of structured predator-prey community like “arctic fox – rodent” and changing its dynamic modes due to interspecific interaction. We paid special attention to the analysis of situations in which changes in the dynamic modes are possible. In particularly, 3-cycle emerging in prey population can result in predator extinction. Moreover, this solution corresponding to an incomplete community simultaneously coexists with the solution describing dynamics of complete community, which can be both stable and unstable. The anthropogenic impact on the community dynamics is studied, that is realized as harvest of some part of predator or prey population. It is shown that prey harvesting leads to expansion of parameter space domain with non-trivial stable numbers of community populations. In this case, the prey harvest has little effect on the predator dynamics; changes are mainly associated with multistability areas. In particular, the multistability domain narrows, in which changing initial conditions leads to different dynamic regimes, such as the transition to a stable state or periodic oscillations. As a result, community dynamics becomes more predictable. It is shown that the dynamics of prey population is sensitive to its harvesting. Even a small harvest rate results in disappearance of population size fluctuations: the stable state captures the entire phase space in multistability areas. In the case of the predator population harvest, stability domain of the nontrivial fixed point expands along the parameter of the predator birth rate. Accordingly, a case where predator determines the prey population dynamics is possible only at high values of predator reproductive potential. It is shown that in the case of predator harvest, a change in the community dynamic mode is possible because of a shifting dynamic regime in the prey population initiating the same nature fluctuations in the predator population. The dynamic regimes emerging in the community models with and without harvesting were compared.

Dynamics of Predator-Prey Community with Age Structures and Its Changing Due To Harvesting

The paper studies dynamic modes of discrete-time model of structured predator-prey community like “arctic fox – rodent” and changing its dynamic modes due to interspecific interaction. We paid special attention to the analysis of situations in which changes in the dynamic modes are possible. In particularly, 3-cycle emerging in prey population can result in predator extinction. Moreover, this solution corresponding to an incomplete community simultaneously coexists with the solution describing dynamics of complete community, which can be both stable and unstable. The anthropogenic impact on the community dynamics is studied, that is realized as harvest of some part of predator or prey population. It is shown that prey harvesting leads to expansion of parameter space domain with non-trivial stable numbers of community populations. In this case, the prey harvest has little effect on the predator dynamics; changes are mainly associated with multistability areas. In particular, the multistability domain narrows, in which changing initial conditions leads to different dynamic regimes, such as the transition to a stable state or periodic oscillations. As a result, community dynamics becomes more predictable. It is shown that the dynamics of prey population is sensitive to its harvesting. Even a small harvest rate results in disappearance of population size fluctuations: the stable state captures the entire phase space in multistability areas. In the case of the predator population harvest, stability domain of the nontrivial fixed point expands along the parameter of the predator birth rate. Accordingly, a case where predator determines the prey population dynamics is possible only at high values of predator reproductive potential. It is shown that in the case of predator harvest, a change in the community dynamic mode is possible because of a shifting dynamic regime in the prey population initiating the same nature fluctuations in the predator population. The dynamic regimes emerging in the community models with and without harvesting were compared.

Hair cortisol as a reliable indicator of stress physiology in the snowshoe hare: Influence of body region, sex, season, and predator–prey population dynamics

Hair cortisol concentration is increasingly used as a convenient, non-invasive, and integrative measure of physiology and health in natural populations of mammals. However, the use of this index is potentially confounded by individual variation in body region-specific differences in cortisol deposition rates. Here we examine correlations in cortisol concentrations in hair collected from the ear, shoulder, and thigh of wild snowshoe hares, Lepus americanus, as well as the influence of sex on cortisol measurements. We further evaluated this technique’s ability to capture seasonal and cyclical patterns of snowshoe hare glucocorticoid secretion from 2013 to 2015 in the southwestern Yukon (Canada). We found positive correlations (R2 = 0.20–0.32) in all pairwise comparisons among body regions, and differences among individuals accounted for the greatest proportion of variance (47.3%) in measurements. From 2013 to 2015 the hares’ primary predator – Canada lynx – approximately doubled in population abundance. We found a significant increase in hare hair cortisol concentrations across this time period. Cortisol indices were higher in summer than winter pelage, reflecting predicted physiological responses to seasonal variation in food availability and individual risk. Variation in hair cortisol concentrations was more similar to long-term (weeks-months) integrative indices of adrenal capacity than point samples of fecal glucocorticoid metabolite concentrations. Overall, we find that hair cortisol analysis is a simple and useful tool for estimations of population-level stress physiology in wild mammals, and sampling of core body regions with consistent moulting patterns produced the most robust results in this species.

The Impact of Microplastic Particles on Population Dynamics of Predator and Prey: Implication of the Lotka-Volterra Model

Microplastic particles are widely distributed in a variety of ecosystems and can be transferred to predators along a food chain after being ingested by prey. However, how microplastic particles affect prey and predator populations is not fully understood. In this study, using the Lotka-Volterra model, we theoretically investigated predator-prey population dynamics in terms of toxicological response intensity (strength to population growth rate) to microplastic particles, and examined the negative effects on prey feeding ability and predator performance due to microplastic particles. Results of numerical simulations indicate the critical properties of the predator-prey system in response to microplastic particles: (i) predators are more vulnerable than prey under exposure to microplastic particles; (ii) the effect of microplastic particles on prey and predator population growths can be negligible when toxicological response intensities of prey and predator are small; (iii) this system is prey dependent for predator functional response, whose stability highly relies on the density of prey; (iv) the reduced feeding capacity of prey and predator induced by microplastic particles does not significantly affect the population dynamics of the predator-prey system. Moreover, our analysis suggests that dynamic Lotka-Volterra models can play a vital role in predicting ecological impacts of microplastic particles on predator-prey population dynamics.

Complex plankton dynamics induced by adaptation and defense

In this paper, we investigate a model for phytoplankton–zooplankton interaction and incorporated the adaptation (dormancy of the predators such as resting eggs) and defense. The dormant stage is the better equipment to withstand unpleasant environmental conditions than active ones. The ability to defense from predator attack is an important trait shaping prey population dynamics. We study how (i) adaptations allow an organism to be successful in a particular harsh environment, (ii) toxin spread surrounding the water surface provide a defense? Analytically, we study the local stability condition of the model system. To understand the effect of adaptation and defense on plankton dynamics, we have plotted the bifurcation diagram, time series and spatiotemporal pattern. Our numerical investigation reveals that the adaptation can suppress the fluctuation in population density and system shows a transient complex spatiotemporal pattern which is either a mixture of spatially periodic steady states or traveling/standing waves by increasing the time and space.

Vertebrate prey composition analysis of the Pallas’s cat (Otocolobus manul) in the Gongga Mountain Nature Reserve, based on fecal DNA

Abstract Diet analysis is essential to fully understanding the biology of a species and its function within the ecosystem, and is also key in identifying food web interactions and the population dynamics of predators and prey. There is currently little information on the diet of small to mid-sized carnivores due to their elusive behavior. We used a DNA-based method to analyze the vertebrate prey of the Pallas’s cat (Otocolobus manul) in the Gongga Mountain Nature Reserve of southwestern China, a global biodiversity hotspot region. We confirmed 14 scat samples containing the Pallas’s cat DNA from 100 small carnivore scats collected at altitudes between 3200 and 4900 m, and then performed polymerase chain reaction (PCR) amplifications using primers targeting the vertebrate mitochondrial 12S rRNA gene with a blocking oligonucleotide specific to the predator sequence. We identified a total of 18 prey taxa, including nine mammals, eight birds and one fish. Our results show that pikas (in 79% of the scats) and birds (in 50% of the scats) are the predominant prey consumed by the Pallas’s cat in our investigation area. The most important finding in our study is that Cypriniformes species were found in the Pallas’s cat’s diet, exhibiting dietary diversification consistent with the accessible fauna of the surrounding environment. In order to increase the detectability of both typical and rare vertebrate prey items, we constructed a blocking primer to inhibit the amplification of the Pallas’s cat DNA.

Age and sex differences in numerical responses, dietary shifts, and total responses of a generalist predator to population dynamics of main prey

Fluctuations in the abundance of main prey species might shape animal communities, by inducing numerical responses and dietary shifts in predators. Whether numerical responses and dietary shifts differ among individuals of different age and sex has so far gained little attention. These differences could affect how much predators consume main and alternative prey, thus causing variation in predation pressure on main and alternative prey species. We studied the effect of fluctuating main prey abundance (voles) in autumn on the age and sex composition of a food-hoarding population of Eurasian pygmy owls Glaucidium passerinum (327 individuals), and on the species composition of their food stores in western Finland during 2003–2017 (629 food stores). Numbers of yearlings (< 1-year old) of both sexes and adult (+ 1-year old) females increased with increasing vole abundance. During low vole abundance, adult owls stored more small birds and less small mammals than yearlings. Females stored more small mammals than males and showed a tendency to store less birds. The amount of consumed birds (the most important alternative prey), and in particular of crested, willow, great, and blue tits, increased with low vole densities. Our results show that numerical, functional, and total responses of pygmy owls, and probably also other vertebrate predators, to the availability of the main prey in winter are shaped by the age and sex composition of the predator population, which both show large spatio-temporal variation in boreal forests.

Distribution and diet of feral cats (Felis catus) in the Wet Tropics of north-eastern Australia, with a focus on the upland rainforest

Abstract ContextFeral cats have been identified as a key threat to Australia’s biodiversity, particularly in arid areas and tropical woodlands. Their presence, abundance and potential impacts in rainforest have received less attention. AimsTo investigate the distribution and diet of feral cats (Felis catus) in upland rainforest of the Wet Tropics. MethodsWe collated available occurrence records from the Wet Tropics, and data from upland camera-trapping surveys over an 8-year period, to assess geographic and elevational distribution of feral cats in the bioregion. We also assessed the diet of feral cats from scats collected at upland sites. Key resultsFeral cats are widespread through the Wet Tropics bioregion, from the lowlands to the peaks of the highest mountains (&amp;gt;1600m), and in all vegetation types. Abundance appears to vary greatly across the region. Cats were readily detected during camera-trap surveys in some upland rainforest areas (particularly in the southern Atherton Tablelands and Bellenden Ker Range), but were never recorded in some areas (Thornton Peak, the upland rainforest of Windsor Tableland and Danbulla National Park) despite numerous repeated camera-trap surveys over the past 8 years at some of these sites. Scat analysis suggested that small mammals comprise ~70% of the diet of feral cats at an upland rainforest site. Multivariate analysis could not detect a difference in mammal community at sites where cats were detected or not. ConclusionsFeral cats are widespread in the Wet Tropics and appear to be common in some upland areas. However, their presence and abundance are variable across the region, and the drivers of this variability are not resolved. Small mammals appear to be the primary prey in the rainforest, although the impacts of cats on the endemic and threatened fauna of the Wet Tropics is unknown. ImplicationsGiven their documented impact in some ecosystems, research is required to examine the potential impact of cats on Wet Tropics fauna, particularly the many upland endemic vertebrates. Studies are needed on (1) habitat and prey selection, (2) population dynamics, and (3) landscape source–sink dynamics of feral cats in the Wet Tropics.

Prey–Predator Dynamics with Two Predator Types and Michaelis–Menten Predator Harvesting

We consider the population dynamics of prey under the effect of the two types of predators. One of the predator types is harvested, modelled with a term with a Michaelis–Menten type functional form. Besides local stability analysis, we are interested that how harvesting could directly affect the dynamics of the ecosystem, such as existence and dynamics of coexistence equilibria and periodic solutions. Theoretical and numerical methods are used to study the role played by several bifurcations in the mathematical models.

Lotka Volterra Model Simulation for Rice-field Rat and Tyto Alba Owls in Sumpiuh District, Banyumas Regency, Central Java

Rice-field rat (Rattus argentiventer) is a rodent that has a high level of productivity. These animals attack rice plants from the vegetative to the generative phase. This research aimed to analyze and to predict the accuracy of the use of owls with mathematical equations model in Kebokura and Lebeng villages, Sumpiuh district. Lotka - Volterra and Competitive Lotka-Volterra models were used to predict the population dynamics of Owl (predator) and rice-field rats (prey), then Runge - Kutta numerical method was applied to analyze the population dynamics of predator and prey at a certain time. The results of the analyses using the Lotka – Volterra, Competitive Lotka - Volterra equations and simulation data, each graph data showed that the rats’ population was able to be maximally suppressed. Based on the analysis result, started with 24 owls and 1,689 rats, the rats’ population could be suppressed to 104 using Lotka – Volterra, and to 176 using the Competitive Lotka – Volterra model. Then in the first and second simulation, started with 50 and 100 owls and 1,689 rats, analysis using Lotka – Volterra and Competitive Lotka – Volterra showed that the rat population could be suppressed to as much as 126, 188 and 145, 189, respectively. Based on the analysis, it could be concluded that use of Serak Jawa owl strategy was able to reduce and stabilize the rat populations. Furthermore, the higher population of owls can prevent the population explosion of rats and can suppress the rat population to a lower number.

Mayflies avoid sweets: fish skin mucus amino sugars stimulate predator avoidance behaviour of Baetis larvae

Nonconsumptive effects of predators can have knock-on effects on prey fitness, life history and population dynamics. However, the origin of cues stimulating predator avoidance behaviour and the mechanisms underlying prey responses need further investigation. Previous studies revealed that nonconsumptive effects of predatory fish on Baetis mayfly larvae are mediated by water-borne chemical cues released from fish mucus. However, there are conflicting results regarding the nature of these cues and the specific role of the activity of fish mucus-dwelling bacteria in stimulating predator avoidance by prey. To address those conflicting results, we investigated whether bacteria dwelling in fish mucus and/or chemical components present in fish mucus are responsible for the predator avoidance response by Baetis mayflies to salmonids. Results of five bioassays conducted in microcosms revealed that to stimulate Baetis predator avoidance behaviour: (1) bacteria do not need to be present in salmonid mucus; (2) the saccharide fraction of the fish mucus glycosaminoglycan component, but neither the protein fraction nor the whole molecule, functions as a kairomone; (3) specific active components of the saccharide fraction are primarily amino sugars in the form of hexosamines; and (4) there is a minimum dose of mucus and specifically of hexosamine needed. Our study provides the first experimental evidence that mayfly larvae recognize fish predators via the amino sugars naturally present in fish skin mucus. These sugars are released into the water by microbially mediated breakdown of glycosaminoglycans. Further research on the responses of different invertebrate prey species to similar predator cues are needed to understand the evolutionary history of this kairomone recognition behaviour.

Optimal harvesting of prey-predator fishery modeling in a two patch environment and harvesting in unprotected area

This article deals with the dynamics of prey and predator populations in a two patch environment, a protected area and an unprotected area for fishing. The prey disperses between the two patches and migrates easily. There are two predators, one is in the protected area and another is in the unprotected area. The predators cannot migrate. Both prey and predator in unprotected area are harvested with constant efforts. The dynamical behavior of the populations is stated as a system of differential equations. The existence of a positive equilibrium point and its stability are investigated. We discuss the local stability of the positive equilibrium point. The stable equilibrium point is then associated with optimal harvesting problems. Based on the analysis, we found that there exist a stable positive equilibrium point when there is no harvesting. For model with constant efforts for both prey and predator, we found that over fishing will maximize the profit but the predator in the unprotected area will be extinct. With the help of Pontryagin’s maximum principle in maximizing the present value of revenues, we found the extremal of the efforts that maximize the present value of revenues. This means that both prey and predator in the protected area as well as the prey and predator in the unprotected area are possibly coexist although the prey and the predator in the unprotected area are harvested with constant efforts. Some numerical simulations area given to confirm the result of analysis.

Fear alone reduces energy processing by resident ‘keystone’ prey threatened by an invader; a non-consumptive effect of ‘killer shrimp’ invasion of freshwater ecosystems is revealed

Non-consumptive effects (NCEs) of predators – so called ‘fear’ responses – encompass costly antipredator behaviours, such as reduced feeding efficiency. NCEs can influence prey population dynamics and community structure, if prey are ‘keystone’ species such as Gammarus spp. amphipod ‘shrimps’. These freshwater macroinvertebrates have the ecosystem functional role of shredding fallen leaf litter, making it accessible to other taxa. Across Europe, the invasive predatory ‘killer shrimp’ Dikerogammarus villosus is replacing resident Gammarus spp., potentially threatening this vital ecosystem function. While predation (consumptive effects (CEs)) of this invader has been well studied, for the first time we test whether NCEs can be evident in prey only exposed to D. villosus presence and whether this could potentially impact on the prey's functional role. In mesocosms, exposure to constrained D. villosus did not result in mortalities of any of three Gammarus prey species but the leaf shredding efficiencies of all prey were significantly reduced compared to a control treatment. This clear NCE has the potential to propagate through the ecological community via decreased energy processing. This study demonstrates the potential for fear of invasive predator presence alone to impact on ecosystem function.

Predator foraging mode controls the effect of antipredator behavior in a tritrophic model

Antipredator behavior is known to have a strong effect on prey population dynamics. While there have been many studies of antipredator behavior in population dynamic models, none have examined how antipredator behavior interacts with predator foraging mode. To examine this process, we incorporated predator and prey velocities into a simple tritrophic food chain. In this model, antipredator behavior allows prey to respond to predators by slowing their velocity in response to predator density. Prey can slow their velocity to hide from predators, but this in turn reduces their ability to consume resources, creating a trade-off between hiding and foraging. We examined the effects of both fast-moving “mobile” predators and slow-moving “sit-and-wait” predators on equilibrium prey density and amplitude of predator-prey cycles. We found that antipredator behavior was ineffective against mobile predators, but it was very effective against sit-and-wait predators. Antipredator responses to sit-and-wait predators reduced top-down control and allowed prey density to increase with increased carrying capacity. Furthermore, antipredator responses to sit-and-wait predators eliminated population cycles within the community, whereas antipredator behavior had no effect on population cycles within mobile predator communities. Therefore, our model demonstrates predator foraging mode must be taken into account when examining predator-prey cycles. We discuss the potential implications of this model for invasive species and for trophic cascades.

Top–down limits on prey populations may be more severe in larger prey species, despite having fewer predators

Variation in the vulnerability of herbivore prey to predation is linked to body size, yet whether this relationship is size‐nested or size‐partitioned remains debated. If size‐partitioned, predators would be focused on prey within their preferred prey size range. If size‐nested, smaller prey species should become increasingly more vulnerable because increasingly more predators are capable of catching them. Yet, whether either of these strategies manifests in top–down prey population limitation would depend both on the number of potential predator species as well as the total mortality imposed. Here we use a rare ecosystem scale ‘natural experiment’ comparing prey population dynamics between a period of intense predator persecution and hence low predator densities and a period of active predator protection and population recovery. We use three decades of data on herbivore abundance and distribution to test the role of predation as a mechanism of population limitation among prey species that vary widely in body size. Notably, we test this within one of the few remaining systems where a near‐full suite of megaherbivores occur in high density and are thus able to include a thirtyfold range in herbivore body size gradient. We test whether top–down limitation on prey species of particular body size leads to compositional shifts in the mammalian herbivore community. Our results support both size‐nested and size‐partitioning predation but suggest that the relative top–down limiting impact on prey populations may be more severe for intermediate sized species, despite having fewer predators than small species. In addition we show that the gradual recovery of predator populations shifted the herbivore community assemblage towards large‐bodied species and has led to a community that is strongly dominated by large herbivore biomass.

Chronology of reproductive investment determines predation risk aversion in a felid-ungulate system.

Fear of predators can behaviorally mediate prey population dynamics, particularly when predation risk influences reproductive investment. However, the costs of reproductive investment may mitigate predation risk aversion relative to periods when the link between reproductive output and prey behavior is weaker.We posit that intensity of reproductive investment in ungulates may predict their response to predation risk such that the sexes increase risk exposure during biological seasons that are pivotal to reproductive success, such as the fawn‐rearing and breeding seasons for females and males, respectively.We examined the activity patterns of sympatric white‐tailed deer (Odocoileus virginianus), a sexually segregated polygynous ungulate, and Florida panthers (Puma concolor coryi) in the context of the “risky times – risky places hypothesis” and the reproductive strategy hypothesis. We compared detection rates and diel activity overlap of both species using motion‐triggered camera traps positioned on (n = 120) and off (n = 60) anthropogenic trails across five reproductive seasons.Florida panthers were nocturnal and primarily observed on‐trail providing an experimental framework with risky times and risky places. Contrary to studies in other taxa inversely correlating prey reproductive investment to predation risk, the sexes of deer were more risk prone during sex‐specific seasons associated with intense reproductive investment.Our results suggest spatiotemporally variable predation risk influences sex‐specific behavioral decision‐making in deer such that reproductive success is maximized.

Diversity of Weeds and Population Dynamics of Predators and Prey Present in Wheat-Mustard Ecosystem at Paklihawa, Rupandehi, Nepal

A study was conducted at Institute of Agriculture and Animal Science (IAAS), Paklihawa Rupandehi, agronomy field to study the diversity of weeds and population dynamics of predators and prey in wheat-mustard ecosystem. The study was conducted by quadrate sampling method using the wooden frame by selecting 40 sample spots, and locating its coordinates. Predator, prey, some of the beneficial and harmful insects as well as weed species was recorded in 5 days interval in the study. Relationships between the population of the mustard aphid and wheat aphid, lady bird beetle to maximum and minimum temperature were recorded in order to know the effect of temperature in relation to population density. Number of mustard aphid and its nymph has shown the positive significant relationship with the population of the spider in the wheat mustard ecosystem. Shannon Weiner Index value was calculated and the species richness was found to be 2.63 with the effective number of species value 9. The species evenness value was found to be 0.83 in the studied ecosystem which signifies that the given weed ecosystem is somewhat even. The importance value index (IVI) of the given ecosystem with the value of different weed species was calculated and it was found that the weed Anagalis arvensis was ranked as first with the IVI value of 57.98 following Vicia sativa and Chenopodium album. This signifies that the species Anagalis arvensis has greater control over the wheat mustard ecosystem of Paklihawa, Rupandehi.

Prey-specific impact of cold pre-exposure on kill rate and reproduction.

Temperature influences biological processes of ectotherms including ecological interactions, but interaction strengths may depend on species-specific traits. Furthermore, ectotherms acclimate to prevailing thermal conditions by adjusting physiological parameters, which often implies costs to other fitness-related parameters. Both predators and prey may therefore pay thermal acclimation costs following exposure to suboptimal temperatures. However, these costs may be asymmetrical between predator and prey, and between the predator and different species of concurrent prey. We investigated whether thermal pre-exposure affected subsequent kill rate and predator fitness when foraging on prey that differ in ease of capture, and whether changes were primarily caused by predator or by prey pre-exposure effects. Specifically, we were interested in whether there were interactions between predator pre-exposed temperature and specific prey. Using the mesostigmatid mite Gaeolaelaps aculeifer as a generalist predator and the collembolans Folsomia candida and Protaphorura fimata as prey, we measured the impact of present temperature, predator pre-exposure temperature, prey pre-exposure temperature (all 10 or 20°C), prey species, and all interactions on prey numbers killed, predator eggs produced, and exploitation of killed prey in a full factorial design. Mites killed P.fimata in equal numbers independent of the presence of F.candida, but killed F.candida when P.fimata was absent. Mite kill rate and reproduction were significantly affected by mite pre-exposure temperature and test temperature, but not by prey pre-exposure temperature. Significantly more of the slower prey was killed than of the quicker prey. Importantly, we found significant synergistic negative interaction effects between predator cold pre-exposure and hunting prey of higher agility on predator kill rate and reproduction. Our findings show that the negative effects of cold and cold pre-exposure on kill rate and reproduction may be more severe when predators forage on quick prey. The study implies that predator cold exposure has consequences for specific prey survival following cold due to altered predation pressures, which in nature should influence the specific prey population dynamics and apparent competition outcomes. The findings exemplify how not only current but also preceding conditions affect ecological interactions, and that effect strength depends on the species involved.

Spatial distribution and dietary niche breadth of the leopard Panthera pardus (Carnivora: Felidae) in the northeastern Himalayan region of Pakistan

Knowledge of a predato's diet is important for understanding its ecology and for predicting its influence on the dynamics of prey populations. We investigated the spatial distribution and diet composition of the leopard ( Panthera pardus ) in the northeastern Himalayan region of Pakistan. We used molecular scatology technique to identify scats of common leopard collected from the field. The leopard was recorded at 30 different surveyed sites with an elevational range between 757-1891 m a.s.l. Its diet comprised 17 prey species, including both wild and domestic prey. Frequency of occurrence of wild prey was approximately 35% of the total leopard diet, while domestic prey contributed approximately 59%. The dietary niche breadth of the leopard was found to be broad during the spring but narrow during the winter. Prey species diversity index was high during summer but low during winter. Results of the current study highlight that common leopard is mainly subsisting on domestic animals, which may result in negative human-leopard interactions. We suggest that local communities should be educated to conserve the leopard and its wild prey species.