Journal articles on the topic 'Predator management'
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Sandin, Stuart A., Beverly J. French, and Brian J. Zgliczynski. "Emerging insights on effects of sharks and other top predators on coral reefs." Emerging Topics in Life Sciences 6, no. 1 (March 8, 2022): 57–65. http://dx.doi.org/10.1042/etls20210238.
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Predation is ubiquitous on coral reefs. Among the most charismatic group of reef predators are the top predatory fishes, including sharks and large-bodied bony fishes. Despite the threat presented by top predators, data describing their realized effects on reef community structure and functioning are challenging to produce. Many innovative studies have capitalized on natural experimental conditions to explore predator effects on reefs. Gradients in predator density have been created by spatial patterning of fisheries management. Evidence of prey release has been observed across some reefs, namely that potential prey increase in density when predator density is reduced. While such studies search for evidence of prey release among broad groups or guilds of potential prey, a subset of studies have sought evidence of release at finer population levels. We find that some groups of fishes are particularly vulnerable to the effects of predators and more able to capitalize demographically when predator density is reduced. For example, territorial damselfish appear to realize reliable population expansion with the reduction in predator density, likely because their aggressive, defensive behavior makes them distinctly vulnerable to predation. Relatedly, individual fishes that suffer from debilitating conditions, such as heavy parasite loads, appear to realize relatively stronger levels of prey release with reduced predator density. Studying the effects of predators on coral reefs remains a timely pursuit, and we argue that efforts to focus on the specifics of vulnerability to predation among potential prey and other context-specific dimensions of mortality hold promise to expand our knowledge.
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Engeman, Richard M., R. Erik Martin, Henry T. Smith, John Woolard, Carrie K. Crady, Stephanie A. Shwiff, Bernice Constantin, Margo Stahl, and John Griner. "Dramatic reduction in predation on marine turtle nests through improved predator monitoring and management." Oryx 39, no. 3 (July 2005): 318–26. http://dx.doi.org/10.1017/s0030605305000876.
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We describe improvements to monitoring/indexing methodology for predators of marine turtle nests on the east coast of Florida, and the resulting marine turtle conservation implications from integrating the methodology into predator management. A strip transect from dune line to the shore improved an already successful design for monitoring raccoons, and was also sensitive for armadillos. The data were integrated into predator management operations to effectively and efficiently remove the species responsible for turtle nest predation. Tracking plot data also served to validate predator patterns of behavior relative to turtle nesting and improve prospects for preventive predator management strategies. Perhaps the most important finding is that predation at a beach historically suffering nearly complete losses (95%) of marine turtle nests had nest predation reduced to nominal levels (9.4%). For 2002 this predation level represents an estimated 69,000 additional hatchling turtles produced over historical predation rates, and 16,700 additional hatchlings over the previous lowest predation rate.
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Casula, Paolo, and Mauro Nannini. "Evaluating the Structure of Enemy Biodiversity Effects on Prey Informs Pest Management." ISRN Ecology 2013 (October 20, 2013): 1–15. http://dx.doi.org/10.1155/2013/619393.
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Evaluating the structure of enemy biodiversity effects on prey in agroecosystems can provide insights into biological pest control functioning. With this aim, theoretical models that describe biological mechanisms underlying prey suppression can be developed and confronted with experimental data by means of model selection. Here, we confront multiplicative risk models to evaluate the structure of multiple predator effects on the whitefly Trialeurodes vaporariorum provided in tomatoes by two spiders (Oxyopes lineatus and Pityohyphantes phrygianus) and two mirids (Nesidiocoris tenuis and Macrolophus melanotoma). Biologically meaningful parameters retained in the best models showed that several predator traits differently affected pest control: species-specific per capita predation rates, prey use extent, different type of interactions between predators, and the response of predator species to prey density and environmental temperature. Even from a limited perspective of single-pest control and short term experiment, this study suggests that assembly of the four predator species results in predator complementarity across prey life stages and density, interactions of prey and predators with environmental conditions, and interactions between predators that do not result in whitefly control disruption. Such information about enemy biodiversity and whitefly control functioning can drive hypotheses about sustainable pest management options in local agroecosystems.
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Bannister, H., R. Brandle, and K. Moseby. "Antipredator behaviour of a native marsupial is relaxed when mammalian predators are excluded." Wildlife Research 45, no. 8 (2018): 726. http://dx.doi.org/10.1071/wr18060.
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Context Predator-controlled environments can lead to prey species losing costly antipredator behaviours as they exploit their low-risk environment, creating a ‘predator-naïve’ population. If individuals lacking suitable antipredator behaviours are used as source populations for reintroductions to environments where predators are present, their behaviour could result in high post-release predation. In contrast, animals sourced from environments with predators (‘predator-exposed’) may show effective antipredator behaviours and thus higher survival post-release. Aims The aim was to compare the antipredator behaviour of brushtail possums (Trichosurus vulpecula) at predator-exposed and predator-naïve source populations, and then compare post-release survival after their reintroduction to a low predator environment. Methods Data were collected from possums at two sites, one with and one without mammalian predators. The behavioural responses of possums to a spotlighter, their willingness to use supplementary feeders at ‘safe’ and ‘risky’ heights, whether they avoided predator odour at traps and their general willingness to enter traps were recorded. Key results Predator-naïve possums showed weaker antipredator responses, were often found at ground level, engaged with novel objects, did not avoid predator scents and utilised different habitats regardless of associated predation risk. In contrast, predator-exposed possums had higher antipredator responses, chose connected trees, were rarely found at ground level and were generally difficult to capture. Post-translocation survival was high for both source populations. Predator-naïve-sourced female possums began to avoid predator urine (feral cat; Felis catus) 12 months after translocation. Conclusions Our research demonstrates that environmental predation risk can predict prey naïvety in brushtail possums. Some aspects of prey naïvety behaviour appear to be able to change in response to altered predation risk. Implications With many threatened species now existing only in feral predator-free areas, these results have implications for future reintroductions into unbounded areas where feral predators are present, and for the management of fenced reserves. The addition of a small number of predators to fenced reserves may aid in retaining antipredator behaviours in fenced prey populations.
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Engeman, Richard, R. Erik Martin, John Woolard, Margo Stahl, Charles Pelizza, Anthony Duffiney, and Bernice Constantin. "An ideal combination for marine turtle conservation: exceptional nesting season, with low nest predation resulting from effective low-cost predator management." Oryx 46, no. 2 (November 1, 2011): 229–35. http://dx.doi.org/10.1017/s0030605311000020.
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AbstractWe examined impacts from effective predator management on nesting success of marine turtles in an exceptional nesting year at Hobe Sound National Wildlife Refuge, Florida, USA, a beach with a high density of nesting marine turtles that has a history of severe nest predation. Historically up to 95% of nests were predated, primarily by raccoons Procyon lotor and, more recently, armadillos Dasypus novemcinctus. Predator control was identified as the most important conservation tool for marine turtle reproduction. Predator management by refuge staff as ancillary duties typically only held predation levels to c. 50%. However, when experts in predator control were employed predation was substantially reduced. An extraordinary opportunity to evaluate the biological and economic benefits of this management approach occurred in 2008, a year with exceptionally heavy nesting. Loggerhead turtle Caretta caretta nesting resurged, green Chelonia mydas and leatherback Dermochelys coriacea turtles nested in record numbers, producing twice or more than their median number of nests, and the first Kemp’s ridley Lepidochelys kempii nest was observed. Overall predation was 14.7%, resulting in an estimated > 128,000 additional hatchlings emerging compared to estimates had no predator management been in place and historical predation rates occurred, and > 56,000 hatchlings more than expected had predator management been conducted as ancillary duties rather than by experts. The USD 12,000 investment for expert predator management equated to only USD 0.09 spent for each additional hatchling produced compared to the scenario of no predator control and only USD 0.21 compared to the scenario of predator control as ancillary duties.
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Radford, James Q., John C. Z. Woinarski, Sarah Legge, Marcus Baseler, Joss Bentley, Andrew A. Burbidge, Michael Bode, et al. "Degrees of population-level susceptibility of Australian terrestrial non-volant mammal species to predation by the introduced red fox (Vulpes vulpes) and feral cat (Felis catus)." Wildlife Research 45, no. 7 (2018): 645. http://dx.doi.org/10.1071/wr18008.
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Context Over the last 230 years, the Australian terrestrial mammal fauna has suffered a very high rate of decline and extinction relative to other continents. Predation by the introduced red fox (Vulpes vulpes) and feral cat (Felis catus) is implicated in many of these extinctions, and in the ongoing decline of many extant species. Aims To assess the degree to which Australian terrestrial non-volant mammal species are susceptible at the population level to predation by the red fox and feral cat, and to allocate each species to a category of predator susceptibility. Methods We collated the available evidence and complemented this with expert opinion to categorise each Australian terrestrial non-volant mammal species (extinct and extant) into one of four classes of population-level susceptibility to introduced predators (i.e. ‘extreme’, ‘high’, ‘low’ or ‘not susceptible’). We then compared predator susceptibility with conservation status, body size and extent of arboreality; and assessed changes in the occurrence of species in different predator-susceptibility categories between 1788 and 2017. Key results Of 246 Australian terrestrial non-volant mammal species (including extinct species), we conclude that 37 species are (or were) extremely predator-susceptible; 52 species are highly predator-susceptible; 112 species are of low susceptibility; and 42 species are not susceptible to predators. Confidence in assigning species to predator-susceptibility categories was strongest for extant threatened mammal species and for extremely predator-susceptible species. Extinct and threatened mammal species are more likely to be predator-susceptible than Least Concern species; arboreal species are less predator-susceptible than ground-dwelling species; and medium-sized species (35 g–3.5kg) are more predator-susceptible than smaller or larger species. Conclusions The effective control of foxes and cats over large areas is likely to assist the population-level recovery of ~63 species – the number of extant species with extreme or high predator susceptibility – which represents ~29% of the extant Australian terrestrial non-volant mammal fauna. Implications Categorisation of predator susceptibility is an important tool for conservation management, because the persistence of species with extreme susceptibility will require intensive management (e.g. predator-proof exclosures or predator-free islands), whereas species of lower predator susceptibility can be managed through effective landscape-level suppression of introduced predators.
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Tsehaye, Iyob, Michael L. Jones, James R. Bence, Travis O. Brenden, Charles P. Madenjian, and David M. Warner. "A multispecies statistical age-structured model to assess predator–prey balance: application to an intensively managed Lake Michigan pelagic fish community." Canadian Journal of Fisheries and Aquatic Sciences 71, no. 4 (April 2014): 627–44. http://dx.doi.org/10.1139/cjfas-2013-0313.
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Using a Bayesian modeling approach, we developed a multispecies statistical age-structured model to assess trade-offs between predatory demands and prey productivities, with the aim to inform management of top predators. Focusing on the Lake Michigan fish community, we assessed these trade-offs in terms of predation mortalities and productivities of alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) and functional responses of salmonines. Our predation mortality estimates suggested that salmonine consumption has been a major driver of prey dynamics, with sharp declines in alewife abundance in the 1960s–1980s and the 2000s coinciding with increased predation rates. Our functional response analysis indicated that feedback mechanisms are unlikely to help maintain a predator–prey balance, with Chinook salmon (Oncorhynchus tshawytscha) and lake trout (Salvelinus namaycush) consumption declining only at the lowest prey densities, while the other salmonines consumed prey at a maximum rate across all observed prey densities. This study demonstrates that a multispecies modeling approach combining stock assessment methods with explicit consideration of predator–prey interactions can provide a basis for tactical decision-making from a broader ecosystem perspective.
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Hradsky, Bronwyn A. "Conserving Australia’s threatened native mammals in predator-invaded, fire-prone landscapes." Wildlife Research 47, no. 1 (2020): 1. http://dx.doi.org/10.1071/wr19027.
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Abstract Inappropriate fire regimes and predation by introduced species each pose a major threat to Australia’s native mammals. They also potentially interact, an issue that is likely to be contributing to the ongoing collapse of native mammal communities across Australia. In the present review, I first describe the mechanisms through which fire could create predation pinch points, exacerbating the impacts of predators, including red foxes, Vulpes vulpes, and feral cats, Felis catus, on their native mammalian prey. These mechanisms include a localised increase in predator activity (a numerically mediated pathway) and higher predator hunting success after fire (a functionally moderated pathway), which could both increase native mammal mortality and limit population recovery in fire-affected landscapes. Evidence for such interactions is growing, although largely based on unreplicated experiments. Improving native mammal resilience to fire in predator-invaded landscapes requires addressing two key questions: how can the impacts of introduced predators on native mammals in fire-affected areas be reduced; and, does a reduction in predation by introduced species result in higher native mammal survival and population recovery after fire? I then examine potential management options for reducing predator impacts post-fire. The most feasible are landscape-scale predator control and the manipulation of fire regimes to create patchy fire scars. However, robust field experiments with adequate statistical power are required to assess the effectiveness of these approaches and preclude null (e.g. compensatory mortality) or adverse (e.g. mesopredator or competitor release) outcomes. Ongoing predator management and prescribed burning programs provide an opportunity to learn through replicated natural experiments as well as experimental manipulations. Standardised reporting protocols and cross-jurisdiction monitoring programs would help achieve necessary spatial and environmental replication, while multi-trophic, spatially explicit simulation models could help synthesise findings from disparate study designs, predict management outcomes and generate new hypotheses. Such approaches will be key to improving management of the complex mechanisms that drive threatened native mammal populations in Australia’s predator-invaded, fire-prone landscapes.
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Fey, Karen, Peter B. Banks, Hannu Ylönen, and Erkki Korpimäki. "Behavioural responses of voles to simulated risk of predation by a native and an alien mustelid: an odour manipulation experiment." Wildlife Research 37, no. 4 (2010): 273. http://dx.doi.org/10.1071/wr08031.
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Context. Potential mammalian prey commonly use the odours of their co-evolved predators to manage their risks of predation. But when the risk comes from an unknown source of predation, odours might not be perceived as dangerous, and anti-predator responses may fail, except possibly if the alien predator is of the same archetype as a native predator. Aims. In the present study we examined anti-predator behavioural responses of voles from the outer archipelagos of the Baltic Sea, south-western Finland, where they have had no resident mammalian predators in recent history. Methods. We investigated responses of field voles (Microtus agrestis) to odours of native least weasels (Mustela nivalis) and a recently invading alien predator, the American mink (Mustela vison), in laboratory. We also studied the short-term responses of free-ranging field voles and bank voles (Myodes glareolus) to simulated predation risk by alien mink on small islands in the outer archipelago of the Baltic Sea. Key results. In the laboratory, voles avoided odour cues of native weasel but not of alien mink. It is possible that the response to mink is a context dependent learned response which could not be induced in the laboratory, whereas the response to weasel is innate. In the field, however, voles reduced activity during their normal peak-activity times at night as a response to simulated alien-mink predation risk. No other shifts in space use or activity in safer microhabitats or denser vegetation were apparent. Conclusions. Voles appeared to recognise alien minks as predators from their odours in the wild. However, reduction in activity is likely to be only a short-term immediate response to mink presence, which is augmented by longer-term strategies of habitat shift. Because alien mink still strongly suppresses vole dynamics despite these anti-predator responses, we suggest that behavioural naiveté may be the primary factor in the impact of an alien predator on native prey. Implications. Prey naiveté has long been considered as the root cause of the devastating impacts of alien predators, whereby native prey simply fail to recognise and respond to the novel predation risk. Our results reveal a more complex form of naiveté whereby native prey appeared to recognise alien predators as a threat but their response is ultimately inadequate. Thus, recognition alone is unlikely to afford protection for native prey from alien-predator impacts. Thus, management strategies that, for example, train prey in recognition of novel threats must induce effective responses if they are expected to succeed.
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PRASAD, K. DURGA, and SOURAV KUMAR SASMAL. "DYNAMICS OF ANTI-PREDATOR BEHAVIOR AND EFFECT OF FEAR ON PREY–PREDATOR MODEL." Journal of Biological Systems 30, no. 04 (December 2022): 887–912. http://dx.doi.org/10.1142/s0218339022500322.
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Predator–prey interactions are the ubiquitous and natural phenomenon in an ecological system. Predators reduce the prey population’s density by direct killing, which is an essential part of any ecological system. Based on the experimental works, for overcoming predation pressure, prey uses a variety of mechanisms. With Holling type-II functional response, we examined a prey–predator system incorporating anti-predator behavior and the cost of fear into prey. Prey anti-predator activity is a counterattacking strategy in which adult prey targets adolescent predators in order to counteract the potential predation pressure. Fear of predation may disrupt the physiological state of prey species and lead to long loss of prey species. In this study, we investigated this aspect to use a dynamical modeling approach. This research finds a plethora of fascinating phenomena. The studied system exhibits a wide range of dynamics and bifurcations, including saddle-node, Hopf, homoclinic, and a Bogdanov–Takens bifurcation in co-dimension two are among the dynamics and bifurcations observed in the analyzed system. We performed some numerical simulations to investigate the effects of anti-predator behavior and fear on prey and found both affect the prey–predator dynamics significantly. Our numerical examples clearly show that as prey carrying capacity increases, so does the prey’s ability to perceive the risk of predation.
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Malinovskyi, Oleksandr, Lukáš Veselý, Carlos Yanes-Roca, and Tomáš Policar. "The effect of water temperature, prey availability and presence of conspecifics on prey consumption of pikeperch (Sander lucioperca)." Czech Journal of Animal Science 67, No. 11 (November 30, 2022): 465–73. http://dx.doi.org/10.17221/162/2022-cjas.
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In this study, the effect of water temperature, predator’s sex, prey density, and the presence of conspecifics on prey consumption of pikeperch (Sander lucioperca) was experimentally tested. In Experiment 1, predators of both sexes [males: total length (TL) = 473 ± 22 mm and body weight (BW) = 1 070 ± 100 g and females: TL = 464 ± 12 mm and BW = 1 060 ± 100 g] were kept in separate tanks and exposed to different densities of prey (Pseudorasbora parva; 3, 6, 12, 24 and 48 prey fishes per tank) under fixed water temperatures of 4.5 °C, 8.5 °C, and 12.5 °C. After 63 days of this experiment, it was found that pikeperch predation was significantly affected by increasing water temperature. The effect of prey density was significant at all tested temperatures. Pikeperch females tended to have the higher prey consumption than males, although that trend was statistically insignificant. Results suggest that increased feeding demands at temperatures above 4.5 °C can lead to predator starvation in conditions of low prey availability. Due to the higher prey consumption, pikeperch females could be more vulnerable to low prey availability during their culture. In Experiment 2, pikeperch were kept at different densities of 1, 2, 4, and 8 individuals per tank supplied with a prey rate of 50 individuals per predator, ensuring ad libitum feeding rate. The average daily prey consumption was significantly higher in the tanks with multiple predators, accounting for 17.6 ± 3.57 prey fishes/day compared to 11.6 ± 2.33 prey fishes/day in the tank with a single predator. These results indicate that pikeperch predation activity and prey consumption can be significantly affected by the water temperature, prey availability, and the presence of conspecifics. The findings contribute to understanding the predatory function, natural feeding request of pikeperch and its potential importance for broodstock culture and broodstock final maturation for a successful spawning season. Also, this information can be used for better management of pikeperch pond aquaculture or bio-melioration process in open water bodies and ecosystems.
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Rohr, Jason R., David J. Civitello, Patrick W. Crumrine, Neal T. Halstead, Andrew D. Miller, Anna M. Schotthoefer, Carl Stenoien, Lucinda B. Johnson, and Val R. Beasley. "Predator diversity, intraguild predation, and indirect effects drive parasite transmission." Proceedings of the National Academy of Sciences 112, no. 10 (February 23, 2015): 3008–13. http://dx.doi.org/10.1073/pnas.1415971112.
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Humans are altering biodiversity globally and infectious diseases are on the rise; thus, there is interest in understanding how changes to biodiversity affect disease. Here, we explore how predator diversity shapes parasite transmission. In a mesocosm experiment that manipulated predator (larval dragonflies and damselflies) density and diversity, non-intraguild (non-IG) predators that only consume free-living cercariae (parasitic trematodes) reduced metacercarial infections in tadpoles, whereas intraguild (IG) predators that consume both parasites and tadpole hosts did not. This likely occurred because IG predators reduced tadpole densities and anticercarial behaviors, increasing per capita exposure rates of the surviving tadpoles (i.e., via density- and trait-mediated effects) despite the consumption of parasites. A mathematical model demonstrated that non-IG predators reduce macroparasite infections, but IG predation weakens this “dilution effect” and can even amplify parasite burdens. Consistent with the experiment and model, a wetland survey revealed that the diversity of IG predators was unrelated to metacercarial burdens in amphibians, but the diversity of non-IG predators was negatively correlated with infections. These results are strikingly similar to generalities that have emerged from the predator diversity–pest biocontrol literature, suggesting that there may be general mechanisms for pest control and that biocontrol research might inform disease management and vice versa. In summary, we identified a general trait of predators—where they fall on an IG predation continuum—that predicts their ability to reduce infections and possibly pests in general. Consequently, managing assemblages of predators represents an underused tool for the management of human and wildlife diseases and pest populations.
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Berry, Lainie. "Predation rates of artificial nests in the edge and interior of a southern Victorian forest." Wildlife Research 29, no. 4 (2002): 341. http://dx.doi.org/10.1071/wr01022.
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Predation rates of nests at human-induced habitat edges may be greater than in forest interior due to differences in predator assemblages and predator activity. I compared the predation rates on 192 artificial nests containing plasticine eggs placed in forest edge and interior sites at Bunyip State Park, Victoria. The nest-predation rates at the forest edge sites were significantly greater (mean = 52–58%) than that at the forest interior sites (mean = 30–39%). The relative rates of predation by birds compared with mammals were significantly greater at forest edge sites (mean = 78–94%) than at forest interior sites (mean = 36–67%). Higher rates of nest predation at forest edges appeared to be due to greater densities of avian predators such as the grey shrike-thrush (Colluricincla harmonica), and/or lower abundances of small mammals. However, biases towards certain predator types may mask real, or create false, patterns in predation rates of artificial nests. A better understanding of how predators respond to artificial nests compared with natural nests is required. Until then, results of predation studies that use artificial nests should be interpreted with caution.
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Russell, James C., and Margaret C. Stanley. "An overview of introduced predator management in inhabited landscapes." Pacific Conservation Biology 24, no. 4 (2018): 371. http://dx.doi.org/10.1071/pc18013.
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Predators play a critical role in ecosystems; however, when overly abundant, they can disrupt natural processes and cause extinctions of species. In particular, oceanic islands have endured many impacts of introduced mammalian predators. Whereas knowledge and management of introduced mammalian predators on islands is well advanced in natural landscapes, in inhabited landscapes, spanning rural and urban environments, comparatively less is known. We summarise key issues from the natural and social sciences in the management of introduced mammalian predators in inhabited landscapes of Aotearoa–New Zealand. We describe the shift in focus over the past few decades from management of introduced mammalian herbivores to predators in rural environments, and the growth in management of introduced mammalian predators in urban environments, both seeking to emulate conservation gains made in forested landscapes. We discuss the circumstances around companion animal management at the interface of the natural and social sciences. We summarise surveys of attitudes towards introduced mammalian predators, the role of biodiversity co-management between Māori and Pakeha, and the importance of also considering non-biodiversity benefits from introduced predator management. We describe the rise of community predator control and large landscape projects aspiring for a ‘Predator Free New Zealand’, and how such an aspiration must be concurrent with habitat restoration. We make recommendations for further research on the basic population biology of predators in inhabited landscapes, and more long-term studies. Such studies should be integrated with examination of the motivations for predator management, as well as the biodiversity and social outcomes of such management. We conclude by remarking that introduced predator management is only one component of a robust national strategy for conservation of native biodiversity in New Zealand.
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Padyšáková, Eliška, Martin Šálek, Lukáš Poledník, František Sedláček, and Tomáš Albrecht. "Predation on simulated duck nests in relation to nest density and landscape structure." Wildlife Research 37, no. 7 (2010): 597. http://dx.doi.org/10.1071/wr10043.
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Context Density-dependent predation has been recently discussed as a contributing cause of duck nest failure. Aims We tested whether nest density increases the nest predation rate (density-dependent predation) in patches of littoral vegetation surrounding fishponds in two contrasting landscape types, the first dominated by forest and the other dominated by agricultural fields. Methods In total, 576 simulated ground nests were deployed in 48 littoral patches in South Bohemia, Czech Republic, in two replicates (June and July), for two consecutive years (2005 and 2006). Nests were deployed either solitarily (low-density plots) or in groups of five nests (high-density plots). Key results Despite differences in local predator communities, we found no evidence of different survival rates of solitary nests and nests placed in high-density patches in either habitat. Mammalian predators were the most common nest predators, followed by birds. The composition of nest predator community depended on landscape type, with mammals predominating in forest landscape and birds in agricultural areas. Our data thus do not support the theory of density-dependent predation of duck nests in littoral patches, regardless of predominant nest predator type. Conclusions Based on our results, we conclude that nest predator responses to different habitats are complex, taxon specific, and context dependent. Implications Conservation efforts for waterfowl may need to be customised according to the nest-predator species primarily responsible for local nest mortality and the nature of the landscape mosaic.
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Tetzlaff, Sasha J., Alondra Estrada, Brett A. DeGregorio, and Jinelle H. Sperry. "Identification of Factors Affecting Predation Risk for Juvenile Turtles Using 3D Printed Models." Animals 10, no. 2 (February 11, 2020): 275. http://dx.doi.org/10.3390/ani10020275.
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Although it is widely accepted that juvenile turtles experience high levels of predation, such events are rarely observed, providing limited evidence regarding predator identities and how juvenile habitat selection and availability of sensory cues to predators affects predation risk. We placed three-dimensional printed models resembling juvenile box turtles (Terrapene carolina) across habitats commonly utilized by the species at three sites within their geographical range and monitored models with motion-triggered cameras. To explore how the presence or absence of visual and olfactory cues affected predator interactions with models, we employed a factorial design where models were either exposed or concealed and either did or did not have juvenile box turtle scent applied on them. Predators interacted with 18% of models during field trials. Nearly all interactions were by mesopredators (57%) and rodents (37%). Mesopredators were more likely to attack models than rodents; most (76%) attacks occurred by raccoons (Procyon lotor). Interactions by mesopredators were more likely to occur in wetlands than edges, and greater in edges than grasslands. Mesopredators were less likely to interact with models as surrounding vegetation height increased. Rodents were more likely to interact with models that were closer to woody structure and interacted with exposed models more than concealed ones, but model exposure had no effect on interactions by mesopredators. Scent treatment appeared to have no influence on interactions by either predator group. Our results suggest raccoons can pose high predation risk for juvenile turtles (although rodents could also be important predators) and habitat features at multiple spatial scales affect predator-specific predation risk. Factors affecting predation risk for juveniles are important to consider in management actions such as habitat alteration, translocation, or predator control.
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Drever, Mark C., Andreas Wins-Purdy, Thomas D. Nudds, and Robert G. Clark. "Decline of Duck Nest Success Revisited: Relationships With Predators and Wetlands in Dynamic Prairie Environments." Auk 121, no. 2 (April 1, 2004): 497–508. http://dx.doi.org/10.1093/auk/121.2.497.
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Abstract Covariation among factors that may affect nest success of dabbling ducks in the Prairie Pothole Region of North America (e.g. productivity of upland and wetland habitat related to climate variation, and duck and predator densities) often confounds efforts to interpret the effect of any individual factor. A comparison of nest success of dabbling ducks at sites with and without predator management provided an opportunity to separate the effect of predation pressure from other factors because predator management has occurred over a range of climatic conditions. We updated an existing study on temporal trends of nest success for prairie ducks in the Prairie Pothole Region of North America by compiling recent estimates of nest success for five species of dabbling ducks (Mallard [Anas platyhrynchos], Northern Pintail [A. acuta], Northern Shoveler [A. clypeata], Blue-winged Teal [A. discors], and Gadwall [A. strepera]). In addition, we compared trends of nest success at unmanaged sites and sites where nest predators were excluded or removed. We used pond density calculated from annual surveys for breeding waterfowl as an index of upland and wetland productivity and a correlate of predator and duck density. At unmanaged sites, the best approximating local regression model suggested that, rather than having undergone a monotonic decline, average nest success has fluctuated through time, although those changes do not appear to be associated with changes in pond density. At sites where predators were excluded, nest success did not vary with time but varied positively with pond density in the previous year, although that effect was tempered by high pond density in the year of observation. At sites where predators were removed but could emigrate back into study plots, nest success varied widely over time and we found no evidence of an effect of pond density. We show that nest success of dabbling ducks is higher under predator management than at sites without predator management, and that this relationship varies with climatic conditions, possibly related to complex interactions within and among duck species, their predators, and their prey.
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Kulatska, Nataliia, Pamela J. Woods, Bjarki Þór Elvarsson, and Valerio Bartolino. "Size-selective competition between cod and pelagic fisheries for prey." ICES Journal of Marine Science 78, no. 5 (June 1, 2021): 1872–86. http://dx.doi.org/10.1093/icesjms/fsab094.
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Abstract Predators often predate on a limited size range of prey, which may or may not overlap with size ranges of same prey targeted by fisheries. When they do overlap, the effect of competition over that prey is immediate, as the predator removes prey, which are at the same time suitable for the fishery. However, if the predator consumes the same prey species as the fishery, but targets smaller prey sizes, this predation on smaller sizes may result in a potential loss of future, rather than current, fishing opportunities. Comparative analyses of predator size preference and fisheries selectivity are scarce, despite their relevance in the context of integrated management of fish populations. We evaluated how size-selective cod predation influences the dynamics of sprat and herring in the Baltic Sea, as well as the competition with pelagic fisheries through immediate and delayed effects. We found a large overlap (30–60%) between prey lengths targeted by cod and fisheries, which was largest in the 1970s–1980s, when cod had higher abundance and was larger in size. Cod generally consumes herring and sprat, which are smaller than those caught by the fisheries, causing both immediate and delayed effects on prey biomass available for the fisheries.
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Hedgespeth, Melanie Lea, Tomasz Karasek, Johan Ahlgren, Olof Berglund, and Christer Brönmark. "Behaviour of freshwater snails (Radix balthica) exposed to the pharmaceutical sertraline under simulated predation risk." Ecotoxicology 27, no. 2 (January 18, 2018): 144–53. http://dx.doi.org/10.1007/s10646-017-1880-6.
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AbstractDue to their potential for affecting the modulation of behaviour, effects of selective serotonin reuptake inhibitors (SSRIs) in the environment are particularly interesting regarding interspecies interactions and non-consumptive effects (NCEs) induced by predator cues in prey organisms. We evaluated the effects of sertraline (0.4, 40 ng/L, 40 µg/L) over 8 days on activity and habitat choice in the freshwater snail Radix balthica, on snails’ boldness in response to mechanical stimulation (simulating predator attack), and their activity/habitat choice in response to chemical cues from predatory fish. We hypothesised that sertraline exposure would detrimentally impact NCEs elicited by predator cues, increasing predation risk. Although there were no effects of sertraline on NCEs, there were observed effects of chemical cue from predatory fish on snail behaviour independent of sertraline exposure. Snails reduced their activity in which the percentage of active snails decreased by almost 50% after exposure to fish cue. Additionally, snails changed their habitat use by moving away from open (exposed) areas. The general lack of effects of sertraline on snails’ activity and other behaviours in this study is interesting considering that other SSRIs have been shown to induce changes in gastropod behaviour. This raises questions on the modes of action of various SSRIs in gastropods, as well as the potential for a trophic “mismatch” of effects between fish predators and snail prey in aquatic systems.
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Krey, K. L., W. R. Cooper, and J. M. Renkema. "Revealing the Diet of Generalist Insect Predators in Strawberry Fields: Not Only Pests, But Other Predators Beware." Environmental Entomology 49, no. 6 (November 2, 2020): 1300–1306. http://dx.doi.org/10.1093/ee/nvaa125.
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Abstract Generalist invertebrate predators contribute to pest management in agriculture, providing an important ecosystem service, particularly in organically managed fields. DNA-based methods to study food webs and feeding interactions in unrestricted field conditions have transformed dietary analysis of generalist predators. In this study, we used MiSeq next-generation sequencing (NGS) technology and universal arthropod primers to investigate the diet of several generalist insect predators collected in commercial organic Florida strawberry fields from November 2017 to March 2018. Of 12 predator insect taxa, Geocoris spp. (Say) (Hemiptera: Geocoridae) was the most abundant early in the growing season (November) and was collected consistently until the end of the season (early March). DNA sequences from 105 predator samples were matched to 44 arthropod families, and of these, 17 were categorized as pest families, 10 as nonpest or nonpredator families, and 17 as predator families. Drosophilidae was the most detected pest family, and Dolichopodidae was the most detected predator family. Prey diversity differed among the predators. Chrysoperla spp. (Neuroptera: Chrysopidae) consumed more prey earlier in the season than did other predators, whereas the other predators consumed a greater diversity of other predators regardless of month. Our results showed a high amount of intraguild predation, but also that predators are contributing to pest suppression in organic strawberries and providing an important biological control service in Florida organic strawberries.
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Bergerud, Arthur T. "The need for the management of wolves — an open letter." Rangifer 27, no. 4 (April 1, 2007): 39. http://dx.doi.org/10.7557/2.27.4.319.
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The Southern Mountain and Boreal Woodland Caribou are facing extinction from increased predation, predominantly wolves (Canis lupus) and coyotes (Canis latrans). These predators are increasing as moose (Alces alces) and deer (Odocoileus spp). expand their range north with climate change. Mitigation endeavors will not be sufficient; there are too many predators. The critical habitat for caribou is the low predation risk habitat they select at calving: It is not old growth forests and climax lichens. The southern boundary of caribou in North America is not based on the presence of lichens but on reduced mammalian diversity. Caribou are just as adaptable as other cervids in their use of broadleaf seed plant as forage. Without predator management these woodland caribou will go extinct in our life time.
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Pedersen, Åshild Ø., Lasse Asmyhr, Hans Christian Pedersen, and Nina E. Eide. "Nest-predator prevalence along a mountain birch - alpine tundra ecotone." Wildlife Research 38, no. 6 (2011): 525. http://dx.doi.org/10.1071/wr11031.
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Context Nest predation is a major factor influencing life history and population dynamics of ground-nesting birds. The transitions between the northern boreal mountain birch forests and the low-alpine tundra are important habitats for the willow ptarmigan, Lagopus lagopus (Linnaeus, 1758). During the past decades, these landscapes have been extensively developed with cabin resorts in southern Norway, which has led to an increased number of roads and foot paths in relatively undisturbed habitats. Aims The aim of the present study was to investigate relative nest-predation rates in elevation gradients (ecotones) spanning from northern boreal mountain birch forests to low-alpine tundra in three locations with contrasting willow ptarmigan densities. Methods We conducted an artificial nest study by using baited track boards (n = 108). Track boards were placed along transects (200 m) in the following three habitat types: birch forest, edge habitat and low-alpine tundra. Predator prevalence was analysed in relation to study-design variables (location, habitat, study period) and the load of human infrastructure (i.e. distance to foot paths and roads), using generalised linear mixed-effect models assuming binomial distribution for the response variable. Key results Prevalence of avian predators was consistently high (range 38.2–85.3%), in contrast to much lower prevalence of mammalian predators (range 2.8–22.9%). Raven (Corvus corax) was the dominant nest predator, followed by hooded crow (C. cornix) and pine marten (Martes martes). Location, as contrasted by differences in willow ptarmigan density, was not significantly related to total relative predation rates. Species-specific predator prevalence was habitat specific and related to human infrastructure, but with opposite relative predation patterns between pine marten and raven. Hooded crow predation was similar across the ecotone and not related to human infrastructure. Conclusions Predator prevalence was habitat specific and affected by human infrastructure (distance to human foot paths). Our study confirmed that human activity might alter the predation rates by generalist species in these low-alpine environments. Implications We recommend that attractive willow ptarmigan habitat should be avoided when planning human infrastructure in alpine ecosystems. To reduce predation pressure in this ecosystem, it appears that generalist predators should be considered for management actions. Further research is needed to explain the underlying mechanism driving expansion of generalist species into alpine habitats. Such knowledge is also important in developing alternative management actions with focus other than predator control.
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Thompson, Kevin A., Selina S. Heppell, and Grant G. Thompson. "The effects of temperature and predator densities on the consumption of walleye pollock (Gadus chalcogrammus) by three groundfish in the Gulf of Alaska." Canadian Journal of Fisheries and Aquatic Sciences 71, no. 8 (August 2014): 1123–33. http://dx.doi.org/10.1139/cjfas-2013-0260.
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Many multispecies models have assumed that prey density determines per-capita predator consumption rates, following a functional response relationship. However, empirical evidence suggests that a predator’s diet can also be influenced by a variety of environmental factors, including interactions with other predators. We used diet and abundance data from National Marine Fisheries Service (NMFS) bottom trawl surveys for three groundfish predators (Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus stenolepis), and sablefish (Anoplopoma fimbria)) in the Gulf of Alaska (GOA) to determine whether temperature or other species influence the consumption of walleye pollock (Gadus chalcogrammus). Using an information-theoretic approach, we tested for relationships between walleye pollock observed in predator stomachs and predator length, bottom temperature, prey availability (walleye pollock catch per unit effort (CPUE) scaled by observed prey lengths), and CPUE of the three predators and arrowtooth flounder (Atheresthes stomias). Predator length was positively related to walleye pollock presence and proportion of total diet mass in all predators. Increased temperatures negatively affected consumption of walleye pollock by Pacific halibut, but not the other predators. We found evidence for a number of interpredator effects of co-occurring predators, both positive (facultative) and negative (competitive). Surprisingly, observed prey density was not statistically significant with respect to consumption for these predators, suggesting that trawls sample the environment far differently than walleye pollock predators or species interactions are more complex than those used in previous multispecies models. These factors should be considered for future models contributing to ecosystem-based management.
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Brown, Kristy, Jacquomo Monk, Joel Williams, Andrew Carroll, David Harasti, and Neville Barrett. "Depth and benthic habitat influence shallow and mesophotic predatory fishes on a remote, high-latitude coral reef." PLOS ONE 17, no. 3 (March 24, 2022): e0265067. http://dx.doi.org/10.1371/journal.pone.0265067.
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Predatory fishes on coral reefs continue to decline globally despite playing key roles in ecosystem functioning. Remote atolls and platform reefs provide potential refugia for predator populations, but quantitative information on their spatial distribution is required to establish accurate baselines for ongoing monitoring and conservation management. Current knowledge of predatory fish populations has been derived from targeted shallow diver-based surveys (<15 m). However, the spatial distribution and extent of predatory fishes on outer mesophotic shelf environments has remained under described. Middleton Reef is a remote, high-latitude, oceanic platform reef that is located within a no-take area in the Lord Howe Marine Park off eastern Australia. Here we used baited remote underwater stereo video to sample predatory fishes across lagoon and outer shelf habitats from depths 0–100 m, extending knowledge on use of mesophotic depths and habitats. Many predatory fish demonstrated clear depth and habitat associations over this depth range. Carcharhinid sharks and Carangid fishes were the most abundant predators sampled on Middleton Reef, with five predatory fishes accounting for over 90% of the predator fish biomass. Notably, Galapagos shark (Carcharhinus galapagensis) and the protected black rockcod (Epinephelus daemelii) dominated the predator fish assemblage. A higher richness of predator fish species was sampled on reef areas north and south of the lagoon. The more exposed southern aspect of the reef supported a different suite of predator fish across mesophotic habitats relative to the assemblage recorded in the north and lagoonal habitats, a pattern potentially driven by differences in hard coral cover. Biomass of predatory fishes in the more sheltered north habitats was twice that of other areas, predominantly driven by high abundances of Galapagos shark. This work adds to the growing body of literature highlighting the conservation value of isolated oceanic reefs and the need to ensure that lagoon, shallow and mesophotic habitats in these systems are adequately protected, as they support vulnerable ecologically and economically important predator fish assemblages.
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Astarloa, Amaia, Maite Louzao, Guillermo Boyra, Udane Martinez, Anna Rubio, Xabier Irigoien, Francis K. C. Hui, and Guillem Chust. "Identifying main interactions in marine predator–prey networks of the Bay of Biscay." ICES Journal of Marine Science 76, no. 7 (July 30, 2019): 2247–59. http://dx.doi.org/10.1093/icesjms/fsz140.
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AbstractIdentifying the role that environmental factors and biotic interactions play in species distribution can be essential to better understand and predict how ecosystems will respond to changing environmental conditions. This study aimed at disentangling the assemblage of the pelagic predator–prey community by identifying interspecific associations and their main drivers. For this purpose, we applied the joint species distribution modelling approach, JSDM, to the co-occurrence patterns of both prey and top predator communities obtained from JUVENA surveys during 2013–2016 in the Bay of Biscay. Results showed that the co-occurrence patterns of top predators and prey were driven by a combination of environmental and biotic factors, which highlighted the importance of considering both components to fully understand the community structure. In addition, results also revealed that many biotic interactions, such as schooling in prey (e.g. anchovy–sardine), local enhancement/facilitation in predators (e.g. Cory’s shearwater–fin whale), and predation between predator–prey species (e.g. northern gannet–horse mackerel), were led by positive associations, although predator avoidance behaviour was also suggested between negatively associated species (e.g. striped dolphin–blue whiting). The identification of interspecific associations can therefore provide insights on the functioning of predators–prey network and help advance towards an ecosystem-based management.
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Olson, AM, A. Frid, JBQ dos Santos, and F. Juanes. "Trophic position scales positively with body size within but not among four species of rocky reef predators." Marine Ecology Progress Series 640 (April 23, 2020): 189–200. http://dx.doi.org/10.3354/meps13275.
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Intra- and interspecifically, larger-bodied predators generally occupy higher trophic positions (TPs). With widespread declines in large predators, there is a need to understand their size-based trophic roles to predict ecosystem-level responses. In British Columbia, Canada, we examined size-based trophic interactions between predatory fishes—3 rockfish species (genus Sebastes) and lingcod Ophiodon elongatus—and their prey, converting predator δ15N signatures to TP and analyzing stomach contents. Intraspecifically, TP scaled positively with predator length and gape width, but the rates of change varied by species. Interspecifically, TP did not scale positively with the observed mean sizes or known maximum sizes of species. Lingcod TP was lower than that of yelloweye and quillback rockfishes, which were 51 and 37%, respectively, smaller than lingcod. Yellowtail rockfish had the smallest average size, yet their mean TP did not differ significantly from that of lingcod. Neither species differences in some morphometric traits known to influence body size-TP relationships nor phylogenetic history explained these results. Most prey consumed were <20% of the predator’s size, which might partially explain the lack of a size-based trophic hierarchy among species. Currently, large size classes of rockfishes are being lost due to fisheries and perhaps climate-driven changes. Our findings on intraspecific size-TP relationships indicate that fishery removals of large individuals may diminish trophic structures. Interspecific comparisons of TP suggest that, along with size, species remain an important factor in understanding trophic dynamics. In addition, smaller-bodied predator species may have significant ecological roles to be considered in ecosystem-based fisheries management.
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Garrison, Lance P., Jason S. Link, D. Patrick Kilduff, Matthew D. Cieri, Brandon Muffley, Douglas S. Vaughan, Alexei Sharov, Behzad Mahmoudi, and Robert J. Latour. "An expansion of the MSVPA approach for quantifying predator–prey interactions in exploited fish communities." ICES Journal of Marine Science 67, no. 5 (February 26, 2010): 856–70. http://dx.doi.org/10.1093/icesjms/fsq005.
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Abstract Garrison, L. P., Link, J. S., Kilduff, D. P., Cieri, M. D., Muffley, B., Vaughan, D. S., Sharov, A., Mahmoudi, B., and Latour, R. J. 2010. An expansion of the MSVPA approach for quantifying predator–prey interactions in exploited fish communities. – ICES Journal of Marine Science, 67: 856–870. Ecosystem-based fisheries management requires tools to place fish-stock dynamics in the broader context of fishery, predator, and competitive removals. Multispecies virtual population analysis (MSVPA) is an approach to quantifying predator–prey interactions and estimating the rates of predation mortality for exploited fish populations. Here, an extended MSVPA (MSVPA-X) is presented as an alternative to existing MSVPA approaches. Notably, MSVPA-X uses index-tuned VPA methods, applies a more flexible feeding model, and includes an alternative functional feeding response. The MSVPA-X model is applied to a western Atlantic fish community, focusing on Atlantic menhaden and its major fish predators, and a sensitivity analysis of major model parameters is presented. The sensitivity analysis highlights the need for adequate diet sampling. The MSVPA-X represents an improvement over previous approaches by increasing the flexibility to model seasonal and interannual dynamics in the strength of predator–prey interactions. Model results demonstrate that, for menhaden in particular, and forage fish in general, quantifying predation mortality is an important part of effective assessments of forage fish, their predators, and the fisheries of both.
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Ekanayake, Kasun B., Desley A. Whisson, Laura X. L. Tan, and Michael A. Weston. "Intense predation of non-colonial, ground-nesting bird eggs by corvid and mammalian predators." Wildlife Research 42, no. 6 (2015): 518. http://dx.doi.org/10.1071/wr15080.
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Context Loss of eggs to predators is a major cause of reproductive failure among birds. It is especially pronounced among ground-nesting birds because their eggs are accessible to a wide range of predators. Few studies document the main causes of clutch fate of ground-nesting birds. Aims The main objective of the present study was to identify the major egg predator of red-capped plovers (Charadrius ruficapillus). We also investigated the effectiveness of the following two primary strategies available to the plovers to avoid egg predation: (1) the placement of clutches under vegetative cover and (2) avoiding predators by nesting outside the peak season of predator occurrence. Methods Remote-sensing cameras were deployed on plover nests to identify egg predators and nests were monitored over four breeding seasons to document reproductive success and fate. An experiment using false clutches with model eggs investigated the influence of nest cover on the risk of egg predation throughout the year. Line-transect surveys were conducted to estimate the abundance of egg predators in and around the wetlands. Key results The little raven (Corvus mellori) was the major egg predator identified in 78.6% of red-capped plover clutches and in 92.4% of false clutches that were camera-monitored. The hatching success of plover eggs was not influenced by nest cover (P = 0.36), but model egg survival in false clutches improved significantly with the presence of nest cover (P = 0.02). The abundance of little ravens increased during the plover breeding season and was highly negatively correlated with false clutch survival (rpearson = –0.768, P = 0.005). Conclusions Little ravens were the major predator of red-capped plover eggs and their abundance increased significantly during the plover breeding season. Any influence of nest cover on hatching success of eggs may have been masked by the extremely high rate of egg loss associated with the increased little raven abundance during the plover breeding season. Implications The high rate of egg predation is likely to have negative consequences on the local red-capped plover population, suggesting management is warranted. Little raven populations have expanded and, thus, their impact as egg predators needs to be investigated especially on threatened species.
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Temming, Axel, and Marc Hufnagl. "Decreasing predation levels and increasing landings challenge the paradigm of non-management of North Sea brown shrimp (Crangon crangon)." ICES Journal of Marine Science 72, no. 3 (November 26, 2014): 804–23. http://dx.doi.org/10.1093/icesjms/fsu194.
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Abstract The North Sea brown shrimp fishery is currently regulated neither with quotas nor with effort management. The current paradigm of non-management was based on an analysis of the total predation by cod and whiting in relation to commercial catches for the period 1970–1995 and the estimated total dominance of natural mortality. However, since this period, the North Sea ecosystem has undergone pronounced changes with overfishing and climate change causing a substantial decline in predator stocks, namely cod and whiting. In addition, both predators have shifted their range of distribution causing a reduced overlap with brown shrimp. Here, we extend the previous assessment of brown shrimp predation for the years 1996–2011 using updated stock assessment and predator distribution data. For the first time, predation estimates are used together with commercial landings to partition independent estimates of total mortality into fishing and predation mortality. We demonstrate that the decline of key predators of brown shrimp in combination with a shift in the distributional range of the predators has caused a new situation, in which the fishery has become the main mortality source of adult brown shrimp (>50 mm). Average landings since 2000 have been ∼40% higher than in the 1980s and 1990s, indicating that humans have at least partly taken over the share previously taken by juvenile whiting and cod. We discuss that this situation is likely to continue, because three marine mammal species have built up a combined population of over 80 000 individuals, which hunt for potential brown shrimp predators mainly in the distribution area of brown shrimp. The application of two yield-per-recruit models of different complexity indicates potential growth overfishing of brown shrimp and reopens the discussion of management.
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Bodey, Thomas W., Robbie A. McDonald, and Stuart Bearhop. "Mesopredators constrain a top predator: competitive release of ravens after culling crows." Biology Letters 5, no. 5 (July 2009): 617–20. http://dx.doi.org/10.1098/rsbl.2009.0373.
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Although predator control programmes rarely consider complex competitive interactions among predators, it is becoming clear that removal of larger ‘superior’ competitors often releases the ‘inferior’ ones and can precipitate trophic cascades. In contrast, our study indicates that culling hooded crows Corvus cornix appears to release a larger competitor, the common raven Corvus corax . Ravens ranged more widely, and the predation of artificial nests was significantly faster (although total predation was similar), after the removal of crows. Our study provides evidence of a novel reversal of competitive release where a larger species was freed from constraints imposed on its distribution and behaviour by a smaller species, and emphasizes the importance of considering community and ecosystem effects of predator manipulations when undertaken for conservation or game management.
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Putra, Ichsan Luqmana Indra, Novia Saphira Prakusya, and Defi Yuliasari. "Insect predator of spodoptera frugiperda J. E. Smith in Sleman and Gunungkidul regency, Indonesia." International Research Journal of Insect Sciences 8, no. 1 (February 3, 2023): 15–21. http://dx.doi.org/10.18488/irjis.v8i1.3278.
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This research was conducted to identify and found the abundance of predatory insect species of S. frugiperda in Sleman and Gunungkidul Regencies, Yogyakarta Province, Indonesia. This research was conducted in June 2021 - March 2022 on corn plantations in Sleman and Gunungkidul Regencies. Determination of the sampling location was determined by stratified random sampling. Corn land used in sampling was determined by purposive. Insect predator caught by using sweeping net and hand picking. The results showed that there are 3 orders, 8 families, and 16 species of insect predators. 3 orders of the insect predators that found in the Sleman and Gunungkidul Regencies were Coleoptera, Hymenoptera, and Hemiptera. Insect predator families that found in Sleman dan Guungkidul Regencies were Coccinellidae, Carabidae, Staphylinidae, Formicidae, Vespidae, Pentatomidae and Reduviidae. Insect predators species that was most commonly found was Menochilus sexmaculatus with 467 individuals and the least was Sycanus sp. with 1 individual. The conclusion of this study is that there were 16 species of predators from S. frugiperda in Sleman and Gunungkidul Regencies. Practical implications of this research were the insect predators that found in Sleman and Gunungkidul Regencies can be used to maintain the population of Spodoptera frugiperda in two regencies.
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Reddy, Chidanand S., Reuven Yosef, Gianpiero Calvi, and Lorenzo Fornasari. "Inter-specific competition influences apex predator–prey populations." Wildlife Research 46, no. 7 (2019): 628. http://dx.doi.org/10.1071/wr19011.
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Abstract ContextTiger (Panthera tigris), leopard (Panthera pardus) and dhole (Cuon alpinus) represent a typical multi-predator system of species of conservation concern. Several studies have addressed this system, with heterogeneous results, and there’s a lack of information on population dynamics of multi-species assemblages. We studied a time series (1998–2009) of abundance indices for three predators and five prey species in Bor Wildlife Sanctuary (BWS), Maharashtra, India, before it was declared as Bor Tiger Reserve (BTR) in 2009. AimsTo analyse the complex relationships within a predator–prey system in a dynamic fashion, to analyse data collected in a stable and undisturbed area and to form a comparison basis for future studies within the sanctuary after its declaration as a Tiger Reserve. MethodsA 24-h effort was made annually to census the BWS. Predators were counted at waterholes from arboreal hideouts. The prey populations were censused along 353-km line-transects. For each species, we analysed the yearly growth rate, testing the effect of inter-species abundance. Key resultsTiger growth rate did not depend on any particular prey, whereas mesopredators seemed to depend on medium-sized prey. A die-out of dholes in 2001 was followed by an increase in tiger populations (from 4 to 11), which, in turn, negatively affected leopard numbers (from 6 to 2).We found no direct evidence of top-down effect, but the density dependence for three of five prey species could be linked to predation pressure. We found some evidence of interspecific competition among prey species, especially among ungulates, potentially being mediated by predation pressure. ConclusionsThe relationships among species in a predator–prey system are very complex and often could be explained only by more-than-two-species interactions. The disappearance of one predator, not necessarily the top predator, could bring multiple effects, for which it could be difficult to detect causal relationships. ImplicationsAll subsequent changes in human activities in the sanctuary, as a consequence of its designation as the BTR in 2009, should be evaluated with respect to the results of the present study. The conservation of large predators should rely on the maintenance of a rich and abundant prey base, in which different-sized prey could lessen interactive-competition among the predators.
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Golsteyn, Laura, Hana Mertens, Joachim Audenaert, Ruth Verhoeven, Bruno Gobin, and Patrick De Clercq. "Intraguild Interactions between the Mealybug Predators Cryptolaemus montrouzieri and Chrysoperla carnea." Insects 12, no. 7 (July 19, 2021): 655. http://dx.doi.org/10.3390/insects12070655.
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The ladybird Cryptolaemus montrouzieri and the green lacewing Chrysoperla carnea have shown potential for use in augmentative biological control of mealybug pests in greenhouse crops. In the context of combining these predators within an integrated pest management system, the risk of negative intraguild interactions between both predators was evaluated in a laboratory setting. Different life stages of either predator were confronted in petri dish arenas containing a Ficus benjamina leaf, and after 24 h the incidence and direction of intraguild predation (IGP) was recorded for each combination. The effect of adding Planococcus citri nymphs or Ephestia kuehniella eggs as extraguild prey on the level of IGP was also studied. IGP was frequently observed between the two predator species and was asymmetrical in favour of C. carnea in most cases. The presence of extraguild prey reduced the number of IGP events between the predators to a similar extent. The relevance of the observed intraguild interactions for the combined use of these predators in protected cultivation is discussed.
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Essington, Timothy E., Marissa L. Baskett, James N. Sanchirico, and Carl Walters. "A novel model of predator–prey interactions reveals the sensitivity of forage fish: piscivore fishery trade-offs to ecological conditions." ICES Journal of Marine Science 72, no. 5 (December 27, 2014): 1349–58. http://dx.doi.org/10.1093/icesjms/fsu242.
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Abstract Ecosystem-based fisheries management seeks to consider trade-offs among management objectives for interacting species, such as those that arise through predator–prey linkages. In particular, fisheries-targeting forage fish (small and abundant pelagic fish) might have a detrimental effect on fisheries-targeting predators that consume them. However, complexities in ecological interactions might dampen, negate, or even reverse this trade-off, because small pelagic fish can be important predators on egg stages of piscivorous fish. Further, the strength of this trade-off might depend on the extent to which piscivorous fish targeted by fisheries regulate forage species productivity. Here, we developed a novel delay-differential bioeconomic model of predator–prey and fishing dynamics to quantify how much egg predation or weak top-town control affects the strength of trade-off between forage and piscivore fisheries, and to measure how ecological interactions dictate policies that maximize steady-state profits. We parameterized the model based on ecological and economic data from the North Sea Atlantic cod (Gadus morhua) and Atlantic herring (Clupea harengus). The optimal policy was very sensitive to the ecological interactions (either egg predation or weak top-down control of forage by predators) at relatively low forage prices but was less sensitive at high forage fish prices. However, the optimal equilibrium harvest rates on forage and piscivores were not substantially different from what might be derived through analyses that did not consider species interactions. Applying the optimal multispecies policy would produce substantial losses (>25%) in profits in the piscivore fishery, and the extent of loss was sensitive to ecological scenarios. While our equilibrium analysis is informative, a dynamic analysis under similar ecological scenarios is necessary to reveal the full economic and ecological benefits of applying ecosystem-based fishery management policies to predator–prey fishery systems.
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Vanstreels, Ralph ET, Nola J. Parsons, Cuan McGeorge, Renata Hurtado, Katrin Ludynia, Lauren Waller, Monique Ruthenberg, Arne Purves, Lorien Pichegru, and Pierre A. Pistorius. "Identification of land predators of African Penguins Spheniscus demersus through post-mortem examination." Ostrich - Journal of African Ornithology 90, no. 4 (December 13, 2019): 359–72. http://dx.doi.org/10.2989/00306525.2019.1697971.
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The African Penguin Spheniscus demersus is an endangered seabird endemic to southern Africa, and killing sprees by terrestrial predators have been one of the main threats for its mainland colonies. The methods employed to manage predators may differ depending on the species involved, therefore the implementation of strategies to limit the impacts of predation relies on the correct identification of the culprit predator. We report and quantify the lesions seen in African Penguins killed by four species of terrestrial predators: Caracal Caracal caracal (52 kills), Leopard Panthera pardus (27 kills), Domestic Dog Canis lupus familiaris (10 kills), and Cape Grey Mongoose Galerella pulverulenta (4 kills). We discuss patterns of necropsy findings that can be used to identify the predator species involved. Traditional forensic methods are useful tools to direct species-specific management actions for the conservation of the African Penguin and other seabirds so that effective mitigating measures can be deployed quickly to prevent further losses. It should be borne in mind, however, that the age, size and previous hunting experience of the predator are likely to influence the pattern of lesions that will be observed, and not all carcasses will have hallmark lesions or recognisable bite marks.
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Lei, Juan, and David T. Booth. "Who are the important predators of sea turtle nests at Wreck Rock beach?" PeerJ 5 (June 30, 2017): e3515. http://dx.doi.org/10.7717/peerj.3515.
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Excessive sea turtle nest predation is a problem for conservation management of sea turtle populations. This study assessed predation on nests of the endangered loggerhead sea turtle (Caretta caretta) at Wreck Rock beach adjacent to Deepwater National Park in Southeast Queensland, Australia after a control program for feral foxes was instigated. The presence of predators on the nesting dune was evaluated by tracking plots (2 × 1 m) every 100 m along the dune front. There were 21 (2014–2015) and 41 (2015–2016) plots established along the dune, and these were monitored for predator tracks daily over three consecutive months in both nesting seasons. Predator activities at nests were also recorded by the presence of tracks on top of nests until hatchlings emerged. In addition, camera traps were set to record the predator activity around selected nests. The tracks of the fox (Vulpes vulpes) and goanna (Varanus spp) were found on tracking plots. Tracking plots, nest tracks and camera traps indicated goanna abundance varied strongly between years. Goannas were widely distributed along the beach and had a Passive Activity Index (PAI) (0.31 in 2014–2015 and 0.16 in 2015–2016) approximately seven times higher than that of foxes (PAI 0.04 in 2014–2015 and 0.02 in 2015–2016). Five hundred and twenty goanna nest visitation events were recorded by tracks but no fox tracks were found at turtle nests. Camera trap data indicated that yellow-spotted goannas (Varanus panoptes) appeared at loggerhead turtle nests more frequently than lace monitors (V. varius) did, and further that lace monitors only predated nests previously opened by yellow-spotted goannas. No foxes were recorded at nests with camera traps. This study suggests that large male yellow-spotted goannas are the major predator of sea turtle nests at the Wreck Rock beach nesting aggregation and that goanna activity varies between years.
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Khan, Muhammad Zafar, Babar Khan, Muhammad Saeed Awan, and Farida Begum. "Livestock depredation by large predators and its implications for conservation and livelihoods in the Karakoram Mountains of Pakistan." Oryx 52, no. 3 (February 15, 2017): 519–25. http://dx.doi.org/10.1017/s0030605316001095.
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AbstractLivestock depredation has particular significance in pastoral societies across the Himalayas. The dynamics of depredation by the snow leopard Panthera uncia and wolf Canis lupus were investigated by means of household surveys in the Hushey Valley, in the Karakoram Mountains of Pakistan. During 2008–2012 90% of the households in the valley lost livestock to snow leopards and wolves, accounting for 0.8 animals per household per year. The cost of depredation per household was equivalent to PKR 9,853 (USD 101), or 10% of the mean annual cash income. The majority (41%) of predation incidents occurred in summer pastures, predominantly at night in open spaces. Of the total number of predation incidents, 60% were attributed to snow leopards and 37% to wolves; in 3% of cases the predator was unknown. As an immediate response to predation the majority of the local people (64%, n = 99) opted to report the case to their Village Conservation Committee for compensation and only 1% preferred to kill the predator; 32% did not respond to predation incidents. The perceived causes of predation were poor guarding (77%), reduction in wild prey (13%), and livestock being the favourite food of predators (10%). The most preferred strategies for predator management, according to the respondents, were enhanced guarding of livestock (72%), followed by increasing the availability of wild prey (18%), and lethal control (10%). Livestock depredation causing economic loss may lead to retaliatory killing of threatened predators. For carnivore conservation and livestock security in this area we recommend improved livestock guarding through collective hiring of skilled shepherds and the use of guard dogs.
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Ullah, Muhammad Irfan, Nimra Altaf, Muhammad Afzal, Muhammad Arshad, Naunain Mehmood, Muhammad Riaz, Sana Majeed, Sajjad Ali, and Asad Abdullah. "Effects of Entomopathogenic Fungi on the Biology of Spodoptera litura (Lepidoptera: Noctuidae) and its Reduviid Predator, Rhynocoris marginatus (Heteroptera: Reduviidae)." International Journal of Insect Science 11 (January 2019): 117954331986711. http://dx.doi.org/10.1177/1179543319867116.
Full textAbstract:
Entomopathogenic fungi (EPFs), Isaria fumosorosea and Beauveria bassiana, are efficient biological agents in the management of multiple arthropod pests. In this study, the effects of both EPF species on various life stages of Spodoptera litura (F.) (Lepidoptera: Noctuidae) and its natural enemy Rhynocoris marginatus (Fab.) (Hemiptera: Reduviidae) were determined under laboratory conditions. I. fumosorosea significantly ( P < .05) reduced the growth rate of the third and fourth instar larvae of S. litura. For relative consumption rate (RCR), the maximum impact was recorded for I. fumosorosea, which reduced the RCR of the larvae. The larvae of S. litura treated with I. fumosorosea showed significantly lower efficiency of conversion of ingested food (ECI) and the larval mortality rate (58.0%) was also higher compared with B. bassiana (33.3%). Similarly, I. fumosorosea had a significant effect on the pupal formation of S. litura; however, no significant effect was found on adult emergence percentage. To determine the effect of EPF-infected prey on the adult predator, their handling time, predatory rate, consumption rate, and the survival rate were recorded. No significant effect of EPF species on the predation rate was found. Furthermore, no significant difference was found in the survival rate of predators fed on either EPF-infected prey or healthy larvae. The interaction of these EPFs with a reduviid predator suggested that both EPF species, especially I. fumosorosea, could be used together with the predator to boost the biological control of S. litura in commercial crops.
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Boutin, S. "Testing predator - prey theory by studying fluctuating populations of small mammals." Wildlife Research 22, no. 1 (1995): 89. http://dx.doi.org/10.1071/wr9950089.
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Fluctuating populations of small mammals provide an excellent opportunity to study the functional and numerical responses of predators because of the wide range in prey density that occurs. I reinterpret data from six studies that have examined the role of predation in the population dynamics of voles in California, southern Sweden and western Finland, of snowshoe hares in northern Canada, and of house mice and rabbits in Australia. Most studies have measured functional responses by relying on changes in diet as reflected by scat or stomach contents. These methods are probably biased toward showing predator satiation. Contrary to previous conclusions I find that there is little evidence for non-linear (Type 111) functional-response curves or predator satiation at high prey densities. Recent studies indicate that the functional and numerical responses of predators can be rapid and strong enough to initiate cyclic declines, dampen fluctuations, or even cause stable numbers. The exception to this appears to be the irruptions of mice and rabbits in Australia. I propose a general explanation for the role of predation whereby the effect of predation is largely dependent on the entire prey community. When potentially cyclic prey are a small component of the overall prey biomass, generalist predators are able to prevent fluctuations by strong functional or numerical responses. As the prey community becomes dominated by a few species that fluctuate, limit cycles predominate. Limit cycles turn into irruptive population dynamics when seasonal prey reproduction is eliminated because of extended periods of vegetation growth (vegetation flushes following drought). In the future we must test assumptions underlying the way we study predation by telemetric monitoring of prey mortality and by experimentally manipulating predation.
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da S Costa, Michel Iskin, and Lucas Dos Anjos. "The interplay between fishery yield and top predator culling in a multispecies fishery context." Mathematical Medicine and Biology: A Journal of the IMA 37, no. 3 (January 11, 2020): 351–63. http://dx.doi.org/10.1093/imammb/dqz017.
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Abstract In food webs, fishery can play the role of top predator, competing thus with other top predators for valuable food resources. In this view, it has been claimed in fisheries management that culling of top predators can be a means to improve fishery yield. To investigate this hypothesis, we use theoretical population models to assess in a multispecies context how fishery yield from target species harvest responds to top predator cull. Defying crisp summary, the four analysed food web models show that this response may be either positive or negative or both, indicating that in terms of multispecies fishery management the harvest yield may not accrue as a consequence of predator removal. In addition, this multitude of behaviours points also to the fact that the response of fishery yield to top predator cull may be difficult to assess.
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Priyadarshana, Tharaka Sudesh. "Do predatory adult odonates estimate their adult prey odonates’ body size and dispersal ability to proceed with a successful attack?" Journal of Threatened Taxa 13, no. 7 (June 26, 2021): 18949–52. http://dx.doi.org/10.11609/jott.7198.13.7.18949-18952.
Full textAbstract:
Predator-prey encounters are one of the most challenging behaviors that animals engage in and play a key role in structuring trophic linkages within food webs. Empirical studies suggest that predators (except pathogens, parasites, and parasitoids) tend to be larger in body size and have better dispersal ability than their prey items; however, when predators prey upon members of the same taxonomic group, it is unclear whether such relationships exist between predators and their prey items since both groups may have similar body sizes and dispersal abilities. Adult odonates can be used to test this as they prey upon other odonates within the same suborder, family, genus or species, although such records are uncommon. Using a dataset collected from Sri Lanka and India from 2012 to 2020, this study identified three types of predation behaviors between two suborders of Odonata, i.e., (i) Anisoptera (dragonflies) prey upon Anisoptera, (ii) Anisoptera prey upon Zygoptera (damselflies), and (iii) Zygoptera prey upon Zygoptera. There was no evidence of Anisoptera predation by Zygoptera. Study results showed strong evidence that there is a significant difference in body size (i.e., body length) and dispersal ability (i.e., hind-wing length) between adult predatory odonates and adult prey odonates for all three types of predations. This may indicate that predatory odonates estimate other odonate prey precisely to proceed with a successful attack.
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Fraser, Fiona J., and Peter J. Whitehead. "Predation of artificial ground nests in Australian tropical savannas: inverse edge effects." Wildlife Research 32, no. 4 (2005): 313. http://dx.doi.org/10.1071/wr04021.
Full textAbstract:
Depredation of artificial ground nests was examined in tropical savanna in northern Australia to assess potential predation pressures on nests of the partridge pigeon (Geophaps smithii), a declining tropical granivore. Predation rates were examined at two sites, Kakadu National Park (which supported a relatively high density of partridge pigeons) and Berry Springs (which had greater habitat fragmentation and comparatively low partridge pigeon density). The effects of distance from road, understorey structure, topography and nest-microsite concealment on nest predation rates were examined. Artificial-nest predation rates were greater at 150 m from roads than <1 m from the roadside. Predation rates did not vary with understorey structure, topography, or level of nest concealment. There was marked variation between sites, with predation levels at Kakadu more than double those recorded for Berry Springs. Discerning predator identity, or even the size of a predator, from marks left in clay eggs proved difficult and was possible for ~35% of predation events. Of these, 42% of predation events involved predators of a size we considered too small to take a natural partridge pigeon nest. We suggest that extrapolation from artificial to natural ground-nest predation rates be undertaken with caution for landscapes such as Australia’s tropical savanna, which supports a high diversity and abundance of small potential predators of artificial nests. There was no evidence of predation by birds, and the methodology proved inadequate for identifying predation by feral cats (Felis catus).
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O'Neill, Adam J., Kylie M. Cairns, Gisela Kaplan, and Ernest Healy. "Managing dingoes on Fraser Island: culling, conflict, and an alternative." Pacific Conservation Biology 23, no. 1 (2017): 4. http://dx.doi.org/10.1071/pc16026.
Full textAbstract:
Globally, the role of large predators is increasingly understood as essential for the restoration and maintenance of ecosystems. Consequently, predator conservation represents a paradigm shift in ecological thinking, yet the management of predators sets conflicting goals because of ongoing conflict with humans. This is exemplified on Fraser Island where dingoes come into conflict with tourists, and dingoes perceived to be dangerous are regularly culled. It is argued here that this new conservation paradigm premised on protecting predators in conjunction with conventional wildlife management can result in predator populations being held in a perpetual state of social disorder, exacerbating rather than alleviating conflict. We consider the intensity and frequency of lethal control and how this may impact upon predator social structures, healthy ecological function, stable breeding patterns and stable territoriality. The direct effects of management-induced psychological stress for the survivors of episodic culls are discussed, as well as the indirect flow-on effects of social dysfunction. A final consideration is the cyclical nature of lethal control, whereby conflict with humans results in culling which, in turn, gives rise to further social disruption and conflict. In part, our assessment is derived from official data collected in the course of the management of dingoes on Fraser Island. On this basis, and on the basis of the international literature available, we offer new insights, which may inform predator management more broadly.
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Manton, Michael, and Per Angelstam. "Macroecology of North European Wet Grassland Landscapes: Habitat Quality, Waders, Avian Predators and Nest Predation." Sustainability 13, no. 15 (July 21, 2021): 8138. http://dx.doi.org/10.3390/su13158138.
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Wet grassland degradation is a global issue that involves both altered land cover patterns and ecological processes, which affect the distribution and abundance of species. The sharp decline in European wader bird (Charadrii) populations is a good example. The aim of this study is to test the hypothesis that the anthropogenic developmental stage of wet grassland habitats and landscapes drives avian nest predator abundance, and thus the predation pressure on nests, which is a major cause of wader bird declines. Using a macroecological approach we selected six wet grassland landscapes representing a gradient in both grassland habitat development and breeding wader population status in four European countries (Belarus, Iceland, Lithuania and Sweden). We (1) mapped wader and avian predator assemblages in multiple wet grassland patches in each landscape, (2) used artificial nests to estimate the relative rate of egg predation, and (3) analyzed relationships between nest predation pressure, corvid nest predators versus raptors, nest loss and the stage of wet grassland habitat and landscape development. We found (1) inverse relationships between the abundance of corvids and waders, as well as between wet grassland developmental stage and waders, and (2) a positive correlation between the probability of nest loss and the density of corvid birds. In conclusion, we found a clear macroecological pattern linking habitat quality, wader populations, nest predators and nest predation. These linkages stress the importance of including nest predation as a factor limiting wader bird populations, and that corvid control or management may be useful management tools.
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JYOTHIS, DEVASIA, and NERAVATHU RAMANI. "Evaluation of prey stage preference of the phytoseiid predator, Neoseiulus longispinosus (Evans) to the spider mite pest, Tetranychus macfarlanei Baker and Pritchard (Acari: Tetranychidae)." Zoosymposia 22 (November 30, 2022): 114. http://dx.doi.org/10.11646/zoosymposia.22.1.69.
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Tetranychus macfarlanei Baker and Pritchard is considered as a major spider mite pest infesting various agricultural crops across the globe. It is a highly polyphagous species, inducing heavy yield loss annually, thereby affecting the agriculture sector drastically. As an eco-friendly pest management strategy, biological control using phytoseiid predators is gaining significant attention all over the world during the past few decades. Evaluation of predatory potential and prey stage preference provides valuable information on the efficacy of the predatory species in controlling the pest population. Considering this, a comparative evaluation of the feeding preference of a phytoseiid predator, Neoseiulus longispinosus (Evans), was made on different life stages of T. macfarlanei under laboratory conditions of 30±20C and 70±5% RH. The experimental arena used for the feeding experiments consisted of mulberry leaf discs (2 cm2) uniformly arranged over 2% semi-solidified agarose medium placed inside a glass Petri dish. The results revealed that the feeding preference of the adult predator towards the prey stages after 24 hours of experiment followed a decreasing sequence of egg (68%)> nymph (13.3%)> larva (6.6%). The predator nymph also followed a similar order of preference with respective consumption rates of 22%, 6.6% and 6.6% on the egg, larva and nymph of the prey mite, indicating that both the nymphs and the adult females of the predator displayed a significant preference to feed on the eggs of T. macfarlanei. Both predatory life stages showed no preference to the adult females of T. macfarlanei. Statistical analysis using ANOVA revealed a significant variation (p < 0.05) in the feeding preference of the predatory life stages towards the varied prey stages. Thus, the results of the study clearly showed the bio-control potential of N. longispinosus against T. macfarlanei.
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Zabierek, Kristina, and Kristen Epp. "Antipredator response of Eurycea nana to a nocturnal and a diurnal predator: avoidance is not affected by circadian cycles of predators." Amphibia-Reptilia 37, no. 4 (2016): 397–403. http://dx.doi.org/10.1163/15685381-00003070.
Full textAbstract:
Both predators and prey exhibit cyclic shifts in activity throughout the day, which should cause the threat posed by predators to change in a recurrent pattern. If the threat posed by a predator is dependent on their circadian foraging cycle, prey may respond more or less intensely to predators at different times of day, thereby maximizing the effectiveness and efficiency of avoidance behaviors. We examined whether predator-naïveEurycea nana, a federally threatened neotenic salamander, exhibits a different antipredator response to chemical cues of a diurnal predator, the green sunfish (Lepomis cyanellus), and a nocturnal predator, the red swamp crayfish (Procambarus clarkii). We predicted thatE. nanawould show more intense antipredator responses (reduced activity) to a diurnal predator during the day and to a nocturnal predator at night. We found that, although there was significant antipredator behavior ofE. nanatoward sunfish, there was no detectable response to crayfish and no effect of time of day on responses to either predator, suggesting that eitherE. nanadoes not innately exhibit circadian patterns in avoidance of these species or that those patterns were undetectable in this study. Future studies should examine whether experience with predators may cause these salamanders to be more sensitive to the diel variation in threat, as has been found with some other amphibians and fish. Due to the threatened nature of this species, understanding the factors that influence antipredator behavior are crucial for management.
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Hernández, Mᵃ Carmen, Denise M. Jara-Stapfer, Ana Muñoz, Cristian Bonacic, Isabel Barja, and André V. Rubio. "Behavioral Responses of Wild Rodents to Owl Calls in an Austral Temperate Forest." Animals 11, no. 2 (February 7, 2021): 428. http://dx.doi.org/10.3390/ani11020428.
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Ecologically based rodent management strategies are arising as a sustainable approach to rodent control, allowing us to preserve biodiversity while safeguarding human economic activities. Despite predator signals being known to generally repel rodents, few field-based studies have compared the behavioral effects of several predators on different prey species, especially in Neotropical ecosystems. Here, we used camera traps to study the behavior of rodent species native to the Chilean temperate forest (Abrothrix spp., long-tailed pygmy rice rat Oligoryzomys longicaudatus) and an introduced rodent (black rat Rattus rattus). Using playbacks of raptor calls, we experimentally exposed rodents to three predation risk treatments: austral pygmy owl calls (Glaucidium nana), rufous-legged owl calls (Strix rufipes) and a control treatment (absence of owl calls). We evaluated the effects of the treatments on the time allocated to three behaviors: feeding time, locomotor activity and vigilance. Moonlight and vegetation cover were also considered in the analyses, as they can modify perceived predation risk. Results showed that predator calls and environmental factors modified prey behavior depending not only on the predator species, but also on the rodent species. Consequently, owl playbacks could be regarded as a promising rodent control tool, knowing that future studies would be critical to deeply understand differences between species in order to select the most effective predator cues.
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Franco, José Carlos, Manuela Branco, Sofia Conde, André Garcia, Maria Rosário Fernandes, José Lima Santos, Tainan Messina, et al. "Ecological Infrastructures May Enhance Lepidopterans Predation in Irrigated Mediterranean Farmland, Depending on Their Typology and the Predator Guild." Sustainability 14, no. 7 (March 25, 2022): 3874. http://dx.doi.org/10.3390/su14073874.
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Ecological infrastructures (EIs) are considered relevant components in agricultural landscapes to support biodiversity and ecosystem services. We used the predatory attacks on lepidopteran dummies as a proxy to assess predation rates in the agricultural matrix and different EIs types according to their location and vegetation structure. We aimed at comparing the effect of different types of EI on the predation intensity in two intensively irrigated agricultural areas located in the Sorraia and Tagus river valleys in central Portugal. We hypothesized that: (1) the predation rate would be higher near EIs compared with the agricultural matrix, (2) the positive effect of EIs on predation rate would differ with their typologies, and (3) the EIs’ proximity and proportion in the surrounding landscape would have a positive effect on the predation rate in agricultural fields. The EI typologies influenced differently the predator groups and the overall predation rate. Major differences were observed for bird predation, being higher in woody EIs. A positive correlation between predation rate and EIs area of the surrounding landscape, as well as a negative correlation with the distance to the nearest riparian and woody EIs, was observed for birds. The observed dissimilarities in the predators’ response may be related to habitat differences and its functional connectivity. The overall monthly low predation rates are possibly related to the intensive agricultural system and the small area occupied by EIs.
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van Bommel, Linda, and Chris N. Johnson. "Good dog! Using livestock guardian dogs to protect livestock from predators in Australia's extensive grazing systems." Wildlife Research 39, no. 3 (2012): 220. http://dx.doi.org/10.1071/wr11135.
Full textAbstract:
Context Wild predators are a serious threat to livestock in Australia. Livestock guardian dogs (LGDs) may be able to reduce or eliminate predation, but their effectiveness in Australian grazing systems has not been systematically evaluated. In particular, little is known about the effectiveness of LGDs in situations where they range freely over large areas in company with large numbers of livestock. Aims We aimed to evaluate the effectiveness of LGDs as currently used in Australia and determine the factors influencing effectiveness, in particular in relation to scale of management. We also documented how LGDs are managed in Australia, evaluated their cost effectiveness, and identified factors that influence the number of dogs required in different property situations. Methods We conducted a telephone survey of 150 livestock producers with LGDs in Australia, including all livestock types and property situations, in all States. Ten producers were visited, of which one is detailed as a case study. Key results Effectiveness was apparently high: 65.7% of respondents reported that predation ceased after obtaining LGDs, and a further 30.2% reported a decrease of predation. When the number of stock per dog exceeds 100, LGDs might not be able to eliminate all predation. Dogs are often kept free-ranging on large properties where wild dogs are the main predator, but are usually restricted in their movements on smaller properties or with smaller predators. The cost of obtaining a LGD is returned within 1–3 years after the dog starts working. The number of dogs required for a property mainly depends on the number of livestock needing protection, and the main type of predator in the area. Conclusions Provided a sufficient number of LGDs are used, they can be as effective in protecting livestock from predators in Australia when ranging freely on large properties with large numbers of livestock as they are in small-scale farming systems. Implications LGDs can provide a cost-effective alternative to conventional predator control methods in Australia’s extensive grazing enterprises, potentially reducing or eliminating the need for other forms of control. LGDs could play a major role in securing the viability of livestock businesses and reconciling people–predator conflict in Australia.
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Nunny, Laetitia. "Animal Welfare in Predator Control: Lessons from Land and Sea. How the Management of Terrestrial and Marine Mammals Impacts Wild Animal Welfare in Human–Wildlife Conflict Scenarios in Europe." Animals 10, no. 2 (January 29, 2020): 218. http://dx.doi.org/10.3390/ani10020218.
Full textAbstract:
The control of predators, on land and in the sea, is a complex topic. Both marine and terrestrial mammal predators come into conflict with humans in Europe in many ways and yet their situations are rarely compared. Areas of conflict include the predation of livestock and farmed fish, and the perceived competition for wild prey (for example wolves competing with hunters for deer and seals competing with fishermen for salmon). A lethal method (shooting) and non-lethal methods of conflict reduction (including enclosures, guarding, and aversion) used for terrestrial large carnivores (e.g., bear, wolf, wolverine, lynx) and marine mammals (seals) are discussed. Control measures tend to be species- and habitat-specific, although shooting is a widely used method. Potential impacts on predator welfare are described and welfare assessments which have been developed for other wildlife control scenarios, e.g., control of introduced species, are considered for their potential use in assessing predator control. Such assessments should be applied before control methods are chosen so that decisions prioritizing animal welfare can be made. Further work needs to be carried out to achieve appropriate and widely-accepted animal welfare assessment approaches and these should be included in predator management planning. Future research should include further sharing of approaches and information between terrestrial and marine specialists to help ensure that animal welfare is prioritized.