Individual Predators Research Articles

Wild zebra finches choose neighbours for synchronized breeding

Organisms should aim to time their reproduction to match the optimal ecological conditions and thus maximize their fitness. However, social cues have been identified as determinants of reproductive decisions and might also be involved in coordinating the timing of reproduction. Breeding synchronously with other individuals can bring several advantages, including a reduced individual predation risk and an increased opportunity for social foraging. The behavioural mechanisms underlying reproductive synchrony are versatile and not well understood, particularly in species inhabiting unpredictable environments. In contrast to highly seasonal environments, more variable and unpredictable environments can support periods of extended breeding with lower levels of synchronous breeding overall, but opportunities for individuals to breed synchronously at a finer temporal and spatial scale. Zebra finches, Taeniopygia guttata, are a highly social species, naturally inhabiting the ecologically unpredictable arid zone of Australia. In the wild, reproduction at a broad population level is not highly synchronized and, at any time during a period of breeding activity, reproductive attempts can be found at different stages. However, previous work has suggested that at a finer spatial scale neighbours tend to breed at approximately the same time. Using nestboxes, we tested whether wild zebra finches preferentially seek to settle and initiate a breeding attempt adjacent to conspecifics at an early stage of breeding (nest building), as opposed to others at later stages of breeding and with which the opportunity to breed synchronously was reduced or absent. Pairs were more likely to initiate egg laying in nestboxes close to conspecifics at an early stage of breeding, suggesting that they do try to maximize the level of synchronicity with neighbours. Our results indicate the importance of social effects on both the phenology and spatial distribution of breeding.

Biomagnification of PBDEs and alternative brominated flame retardants in a predatory fish: Using fatty acid signature as a primer

Information on biomagnification of alternative brominated flame retardants (ABFRs) is limited and results are inconclusive, due in part to uncertainty in the understanding of predator/prey relationships. In the present study, a predatory fish, Channa argus, and several forage fish species were obtained from an ABFR contaminated site. The predator/prey relationships were identified based on fatty acid (FA) signatures in the predator and prey. Biomagnification factors (BMFs) for several ABFRs including decabromodiphenyl ethane (DBDPE), 1,2‑bis(2,4,6‑tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB), pentabromotoluene (PBT), and pentabromoethylbenzene (PBEB) were estimated based on the identified predator/prey relationships. The results showed that crucian carp was the main prey of C. argus, contributing to 71%–100% to its total diet. The mean BMFs for DBDPE, BTBPE, and HBB were 0.06, 0.40, and 0.91, respectively, indicating trophic dilution of these ABFRs. However, biomagnification of PBT and PBEB, with BMFs of 2.09 and 2.13, respectively, was observed. The BMFs for PBT, PBEB and HBB were comparable to or even higher than those for some polybrominated diphenyl ether (PBDE) congeners estimated in the same individual predator, indicating that these emerging pollutants may pose significant environmental risks. The BMFs for ABFRs and PBDEs were significantly and negatively correlated to the log KOWs of these chemicals, suggesting that the biomagnification of these chemicals was depressed due to their superhydrophobic nature.

Functional response of the mirid predators Dicyphus bolivari and Dicyphus errans and their efficacy as biological control agents of Tuta absoluta on tomato

Dicyphus bolivari Lindberg and Dicyphus errans (Wolff) (Hemiptera: Miridae) are naturally widespread in many crops with low-pesticide pressure, where they prey upon several arthropods, including the tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). However, their efficacy as biological control agents (BCAs) of this pest needs further investigations. Therefore, in this study the predatory efficacy of D. bolivari and of D. errans on T. absoluta was evaluated on tomato in laboratory and greenhouse trials. Their functional response to different numbers of T. absoluta eggs (up to 350) offered to single females or 5th-instar nymphs for 24 h was assessed in laboratory. Females and nymphs of both predators showed a high voracity and a type II functional response, with an estimated maximum predation rate per day of 189 and 194 eggs for D. bolivari females and nymphs, respectively, and 197 and 179 eggs for D. errans females and nymphs, respectively. The predators showed similar predation rates of T. absoluta eggs on plants in cage trials. However, our greenhouse trial showed that the commonly used Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae), which has a lower individual predation capacity than D. bolivari and D. errans, was more effective in controlling T. absoluta than D. errans and D. bolivari because of its stronger numerical response to densities of T. absoluta and supplemental food than the other two predator species. This shows that long-term greenhouse trials, which include functional and numerical responses to pest densities, are essential to evaluate the efficacy of an omnivorous predator.

Energetically relevant predator-prey body mass ratios and their relationship with predator body size.

Food web structure and dynamics depend on relationships between body sizes of predators and their prey. Species‐based and community‐wide estimates of preferred and realized predator–prey mass ratios (PPMR) are required inputs to size‐based size spectrum models of marine communities, food webs, and ecosystems. Here, we clarify differences between PPMR definitions in different size spectrum models, in particular differences between PPMR measurements weighting prey abundance in individual predators by biomass (r bio) and numbers (r num). We argue that the former weighting generates PPMR as usually conceptualized in equilibrium (static) size spectrum models while the latter usually applies to dynamic models. We use diet information from 170,689 individuals of 34 species of fish in Alaskan marine ecosystems to calculate both PPMR metrics. Using hierarchical models, we examine how explained variance in these metrics changed with predator body size, predator taxonomic resolution, and spatial resolution. In the hierarchical analysis, variance in both metrics emerged primarily at the species level and substantially less variance was associated with other (higher) taxonomic levels or with spatial resolution. This suggests that changes in species composition are the main drivers of community‐wide mean PPMR. At all levels of analysis, relationships between weighted mean r bio or weighted mean r num and predator mass tended to be dome‐shaped. Weighted mean r num values, for species and community‐wide, were approximately an order of magnitude higher than weighted mean r bio, reflecting the consistent numeric dominance of small prey in predator diets. As well as increasing understanding of the drivers of variation in PPMR and providing estimates of PPMR in the north Pacific Ocean, our results demonstrate that that r bio or r num, as well as their corresponding weighted means for any defined group of predators, are not directly substitutable. When developing equilibrium size‐based models based on bulk energy flux or comparing PPMR estimates derived from the relationship between body mass and trophic level with those based on diet analysis, weighted mean r bio is a more appropriate measure of PPMR. When calibrating preference PPMR in dynamic size spectrum models then weighted mean r num will be a more appropriate measure of PPMR.

Feeding ecological knowledge: the underutilised power of faecal DNA approaches for carnivore diet analysis

Abstract Accurate analyses of the diets of predators are key to understand trophic interactions and defining conservation strategies. Diets are commonly assessed through analysis of non‐invasively collected scats, and the use of faecal DNA (fDNA) analysis can reduce the species misidentifications that could lead to biased ecological inference. We review the scientific literature since publication of the first paper on amplifying fDNA, in order to assess trends in the use of genetic non‐invasive sampling (gNIS) for predator species identification in scat‐based diet studies of North American and European terrestrial mammalian carnivores (Carnivora). We quantify error rates in morphology‐based predator species identification. We then provide an overview of how applying gNIS would improve research on trophic interactions and other areas of carnivore ecology. We found that carnivore species identity was verified by using gNIS in only 8% of 400 studies of carnivore diets based on scats. The median percentage of false positives (i.e. samples wrongly identified as belonging to the target species) in morphology‐based studies was 18%, and was consistent regardless of species’ body size. We did not find an increasing trend in the use of gNIS over time, despite the existing technical capability to identify almost all carnivore species. New directions for fDNA studies include employing high‐throughput sequencing (HTS) and DNA metabarcoding to identify the predator species, the individual predator, the entire assemblage of consumed items, and the microbiome of the predator and pathogens. We conclude that HTS protocols and metagenomic approaches hold great promise for elevating gNIS as a fundamental cornerstone for future research in ecology and conservation biology of mammals.

Understanding ontogenetic and temporal variability of Eastern Baltic cod diet using a multispecies model and stomach data

Size of predator and prey determines, to a large extent, predator-prey interactions in aquatic systems. Understanding the relationship between predator and prey size in the individual predator’s food selection process is a cornerstone of ecological modelling. Stomach content data are used to inform such models, as they provide prey species specific information about the predator diet in the wild. These data are strongly relevant as direct observations of species trophic interactions, but they have limitations, and are costly. Our objective was to develop and test a model which is able to predict changes in the Baltic cod diet by reconstructing the dynamics of cod and its prey, herring and sprat, populations, their length distributions, and parametrizing trophic interactions between them. We analysed time-series of cod stomach data and built an age-length structured multispecies model using Gadget. Both observed and predicted diets of smaller (juvenile) cod consisted mainly of benthos, while larger cod fed mostly on fishes (herring and sprat). Our model could predict the main patterns in species and length composition of cod diet. We also identified important knowledge gaps, especially on benthos dynamics and processes affecting prey availability and predator preference.

Predator size-structure and species identity determine cascading effects in a coastal ecosystem.

Cascading consequences of predator extinctions are well documented, but impacts of perturbations to predator size‐structure and how these vary across species remain unclear. Body size is hypothesized to be a key trait governing individual predators' impact on ecosystems. Therefore, shifts in predator size‐structure should trigger ecosystem ramifications which are consistent across functionally similar species. Using a US salt marsh as a model system, we tested this hypothesis by manipulating size class (small, medium, and large) and size diversity (combination of all three size classes) within two closely related and functionally similar predatory crab species over 4 months. Across treatments, predators suppressed densities of a dominant grazer and an ecosystem engineer, enhanced plant biomass, and altered sediment properties (redox potential and saturation). Over the metabolically equivalent experimental predator treatments, small size class predators had stronger average impacts on response variables, and size class interacted with predator species identity to drive engineer suppression. Within both predator species, size diversity increased cannibalism and slightly weakened the average impact. These results show that predator impacts in a salt marsh ecosystem are determined by both size class and size diversity; they also highlight that size class can have species‐dependent and response‐dependent effects, underlining the challenge of generalizing trait effects.

Correction to ‘Lionfish predators use flared fin displays to initiate cooperative hunting’

You have accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Lönnstedt Oona M., Ferrari Maud C. O. and Chivers Douglas P. 2018Correction to ‘Lionfish predators use flared fin displays to initiate cooperative hunting’Biol. Lett.142018071620180716http://doi.org/10.1098/rsbl.2018.0716SectionSupplemental MaterialYou have accessCorrectionsCorrection to ‘Lionfish predators use flared fin displays to initiate cooperative hunting’ Oona M. Lönnstedt Oona M. Lönnstedt Google Scholar Find this author on PubMed Search for more papers by this author , Maud C. O. Ferrari Maud C. O. Ferrari http://orcid.org/0000-0002-3127-9804 Google Scholar Find this author on PubMed Search for more papers by this author and Douglas P. Chivers Douglas P. Chivers http://orcid.org/0000-0002-9497-4329 Google Scholar Find this author on PubMed Search for more papers by this author Oona M. Lönnstedt Oona M. Lönnstedt Google Scholar Find this author on PubMed Search for more papers by this author , Maud C. O. Ferrari Maud C. O. Ferrari http://orcid.org/0000-0002-3127-9804 Google Scholar Find this author on PubMed Search for more papers by this author and Douglas P. Chivers Douglas P. Chivers http://orcid.org/0000-0002-9497-4329 Google Scholar Find this author on PubMed Search for more papers by this author Published:14 November 2018https://doi.org/10.1098/rsbl.2018.0716This article corrects the followingResearch ArticleLionfish predators use flared fin displays to initiate cooperative huntinghttps://doi.org/10.1098/rsbl.2014.0281 Oona M. Lönnstedt, Maud C. O. Ferrari and Douglas P. Chivers volume 10issue 6Biology Letters01 June 2014Biol. Lett.10, 20140281. (Published online 25 June 2014). (doi:10.1098/rsbl.2014.0281)In response to the query of a reader concerning the number of lionfish (Dendrochirus zebra) used in the two experiments described by Lönnstedt et al. 2014, the Editor of Biology Letters requested clarification of the statement: ‘To maintain statistical independence each individual predator was used for only one trial’. In e-mail correspondence from Dr Lönnstedt to Biology Letters in March 2018, she explained that the statement applied only to Experiment 2 and that the fish for Experiment 2 were re-used from Experiment 1. Specifically, Dr Lönnstedt stated… ‘In Experiment 1, the compartment D. zebra fish from the first treatment (D. zebra) were reused as focal lionfish in the empty compartment treatment (they had thus not seen the experimental arena before and care was ensured they were allowed 24 h to rest). In the P. antennata treatment, 1 P. antennata had to be reused as the compartment fish (this fish was used first on the 9th Dec and then for a second time on the 13 December 2012). In Experiment 2 collected fish were used again. Here, care was taken to ensure that no fish was paired with one they had encountered in experiment 1 (no lionfish was used more than once in Experiment 2)’. In line with current Royal Society open data policy (introduced after the study had been published), the reader also requested copies of the primary data generated by the experiments missing from the original article. In March 2018, Dr Lönnstedt provided Biology Letters with: (1) a data file giving details of each trial conducted and (2) a pdf file of a collage of 50 lionfish photographs providing evidence of the number of lionfish caught during the study. These files are now uploaded as additional supplementary materials.This correction, as well as the additions to the supplementary files, was completed by co-authors Prof. Ferrari and Prof. Chivers without input from Dr Lönnstedt, who was not available for comment at the time the correction was written. Previous Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsRelated articlesLionfish predators use flared fin displays to initiate cooperative hunting01 June 2014Biology Letters This IssueNovember 2018Volume 14Issue 11 Article InformationDOI:https://doi.org/10.1098/rsbl.2018.0716PubMed:30429247Published by:Royal SocietyOnline ISSN:1744-957XHistory: Published online14/11/2018Published in print30/11/2018 License:© 2018 The Author(s)Published by the Royal Society. All rights reserved. Citations and impact Large datasets are available through Biology Letters' partnership with Dryad

Sex, size, and prey caloric value affect diet specialization and consumption of an invasive prey by a native predator.

Escaping the control of natural enemies is thought to heavily influence the establishment success and impact of non-native species. Here, we examined how the profitability of alternative prey in combination with the presence of a competitor and predator aggressive behavior explain individual differences in diet specialization and the consumption of the invasive green porcelain crab Petrolisthes armatus by the native mud crab predator Panopeus herbstii. Results from bomb calorimetry estimates show that invasive P. armatus has high caloric value relative to alternative native prey. Laboratory assays indicated that specialization and consumption of invasive P. armatus was mostly exhibited by large, female P. herbstii, but the presence of a competitor and predator aggressiveness did not influence diet and the consumption of P. armatus. Thus, intrinsic factors (e.g., sex and body size) seem to explain consumption of P. armatus and dietary specialization in P. herbstii, more generally. Although there are still many predator individuals that do not consume P. armatus, the proportion of individuals that have begun to specialize on P. armatus suggests that for some, it has become more profitable relative to alternative native prey. Given the high caloric value of P. armatus, we suggest that it is likely that differences in the cost of its consumption, including attack, capture, and handling times relative to alternative prey, determine its net profitability to individual predators.

Using habitat models to identify marine important bird and biodiversity areas for Chinstrap Penguins Pygoscelis antarcticus in the South Orkney Islands

Tracking individual marine predators can provide vital information to aid the identification of important activity (foraging, commuting, rafting, resting, etc.) hotspots and therefore also to delineate priority sites for conservation. However, in certain locations (e.g. Antarctica) many marine mammal or seabird colonies remain untracked due to logistical constraints, and the colonies that are studied may not be the most important in terms of conservation priorities. Using data for one of the most abundant seabirds in the Antarctic as a case study (the Chinstrap Penguin Pygoscelis antarcticus), we tested the use of correlative habitat models (used to predict distribution around untracked colonies) to overcome this limitation, and to enable the identification of important areas at-sea for colonies where tracking data are not available. First, marine Important Bird and Biodiversity Areas (IBA) were identified using a standardised, published approach using empirical data from birds tracked from colonies located in the South Orkney Islands. Subsequently, novel approaches using predicted distributions of Chinstrap Penguins derived from correlative habitat models were applied to identify important marine areas, and the results compared with the IBAs. Data were collected from four colonies over 4 years and during different stages of the breeding season. Results showed a high degree of overlap between the areas identified as important by observed data (IBAs) and by predicted distributions, revealing that habitat preference models can be used to identify marine IBAs for these penguins. We provide a new method for designating a network of marine IBAs for penguins in Antarctic waters, based on outputs from correlative habitat models when tracking data are not available. This can contribute to an evidence-based and precautionary approach to aid the management framework for Antarctic fisheries and for the protection of birds.

Predator (Carcinus maenas) nonconsumptive limitation of prey (Nucella lapillus) feeding depends on prey density and predator cue type

Predators often have nonconsumptive effects (NCEs) on prey. For example, upon detection of predator cues, prey can reduce feeding activities to hamper being detected by predators. Previous research showed that waterborne chemical cues from green crabs (Carcinus maenas, predator) limit the dogwhelk (Nucella lapillus, prey) consumption of barnacles regardless of dogwhelk density, even though individual predation risk for dogwhelks decreases with conspecific density. Such NCEs might disappear with dogwhelk density if dogwhelks feed on mussels, as mussel stands constitute better antipredator refuges than barnacle stands. Through a laboratory experiment, we effectively found that crab chemical cues limit the per-capita consumption of mussels by dogwhelks at low dogwhelk density but not at high density. The combination of tactile and chemical cues from crabs, however, limited the dogwhelk consumption of mussels at both dogwhelk densities. The occurrence of such NCEs at both dogwhelk densities could have resulted from tactile cues indicating a stronger predation risk than chemical cues alone. Overall, the present study reinforces the notions that prey evaluate conspecific density when assessing predation risk and that predator cue type affects their perception of risk.

Shoal sex composition and predation risk influence sub-adult threespine stickleback shoaling decisions

Group living reduces individual predation risk most effectively when group members are behaviorally and phenotypically similar. Group preferences are influenced by the individual, the members of the shoal, and the environmental conditions. While shoaling behavior has been studied extensively in the threespine stickleback (Gasterosteus aculeatus), it is unclear whether the sex of shoal mates influences the shoal preference of non-reproductive males and females and how this changes under increasing predation risk. Although non-reproductively active sticklebacks are sexually monochromatic in appearance, sex-related differences may result in sexual segregation when shoaling. Here we show that male and female sub-adult threespine sticklebacks had contrasting preferences for shoal mate sex, and that this preference was dependent on the level of predation risk during standardized experimental choice tests. In detail, test fish shoal with the opposite sex within low predation risk trials and with same-sex shoals within high predation risk trials. This difference might be linked to activity patterns; test males were more active than females. Our results demonstrate that differences between the sexes in a species with a sexually monochromatic non-reproductive stage can result in sex-related shoaling preferences. Most studies examining sexual segregation focus on sexually dimorphic species, but these results highlight the potentially widespread occurrence of sexual segregation beyond the sexually dimorphic reproductive stage.

Shoal size as a key determinant of vulnerability to capture under a simulated fishery scenario.

Group living is widespread among animals and has a range of positive effects on individual foraging and predator avoidance. For fishes, capture by humans constitutes a major source of mortality, and the ecological effects of group living could carry‐over to harvest scenarios if fish are more likely to interact with fishing gears when in social groups. Furthermore, individual metabolic rate can affect both foraging requirements and social behaviors, and could, therefore, have an additional influence on which fish are most vulnerable to capture by fishing. Here, we studied whether social environment (i.e., social group size) and metabolic rate exert independent or interactive effects on the vulnerability of wild zebrafish (Danio rerio) to capture by a baited passive trap gear. Using video analysis, we observed the tendency for individual fish to enter a deployed trap when in different shoal sizes. Fish in larger groups were more vulnerable to capture than fish tested individually or at smaller group sizes. Specifically, focal fish in larger groups entered traps sooner, spent more total time within the trap, and were more likely to re‐enter the trap after an escape. Contrary to expectations, there was evidence that fish with a higher SMR took longer to enter traps, possibly due to a reduced tendency to follow groupmates or attraction to conspecifics already within the trap. Overall, however, social influences appeared to largely overwhelm any link between vulnerability and metabolic rate. The results suggest that group behavior, which in a natural predation setting is beneficial for avoiding predators, could be maladaptive under a trap harvest scenario and be an important mediator of which traits are under harvest associated selection.

Fish Predation on Juvenile Penaeid Shrimp: Examining Relative Predator Impact and Size-Selective Predation

Predation is likely the primary source of mortality for juvenile penaeid shrimp and, therefore, a key factor driving their population dynamics. We sampled juvenile penaeids and their potential predators in a salt marsh from July to August 2012 to examine the impact of these predators and possible size-selective predation on the shrimp population. We quantified predator impact using the frequency of occurrence (FO) index and a relative predation index (RPI) that accounts for predator abundance and the number of shrimp consumed per individual predator. Size selectivity was assessed by comparing the size distribution of shrimp in the study area to the size distribution of shrimp removed from predator stomachs. Two penaeid species, white shrimp Litopenaeus setiferus and brown shrimp Farfantepenaeus aztecus, were collected, and most (86%) were juvenile white shrimp ≤ 12 mm carapace length. Spotted seatrout Cynoscion nebulosus, which consumed relatively large shrimp, was the most important predator based on the FO index. Bay whiff Citharichthys spilopterus, which ate the smallest shrimp, was the most important predator based on the RPI. The size distribution of shrimp removed from predator stomachs differed from those collected in the study area; the smallest shrimp were disproportionally more abundant in predator stomachs. Using the RPI, we identified some potentially important predators (e.g., bay whiff) that may impact shrimp populations by consuming the smallest shrimp in estuarine nurseries. Our approach could be useful for examining predator impacts on other populations of juvenile penaeids and more generally for any prey consumed by fish predators.

River food webs: an integrative approach to bottom-up flow webs, top-down impact webs, and trophic position.

The majority of food web studies are based on connectivity, top-down impacts, bottom-up flows, or trophic position (TP), and ecologists have argued for decades which is best. Rarely have any two been considered simultaneously. The present study uses a procedure that integrates the last three approaches based on taxon-specific secondary production and gut analyses. Ingestion flows are quantified to create a flow web and the same data are used to quantify TP for all taxa. An individual predator's impacts also are estimated using the ratio of its ingestion (I) of each prey to prey production (P) to create an I/P web. This procedure was applied to 41 invertebrate taxa inhabiting submerged woody habitat in a southeastern U.S. river. A complex flow web starting with five basal food resources had 462 flows >1mg·m-2 ·yr-1 , providing far more information than a connectivity web. Total flows from basal resources to primary consumers/omnivores were dominated by allochthonous amorphous detritus and ranged from 1 to >50,000mg·m-2 ·yr-1 . Most predator-prey flows were much lower (<50mg·m-2 ·yr-1 ), but some were >1,000 mg·m-2 ·yr-1 . The I/P web showed that 83% of individual predator impacts were weak (<10%), whereas total predator impacts were often strong (e.g., 35% of prey sustained an impact >90%). Quantitative estimates of TP ranged from 2 to 3.7, contrasting sharply with seven integer-based trophic levels based on longest feeding chain. Traditional omnivores (TP=2.4-2.9) played an important role by consuming more prey and exerting higher impacts on primary consumers than strict predators (TP ≥ 3). This study illustrates how simultaneous quantification of flow pathways, predator impacts, and TP together provide an integrated characterization of natural food webs.

Complexity of the prey spectrum of Agaronia propatula (Caenogastropoda: Olividae), a dominant predator in sandy beach ecosystems of Pacific Central America.

Olivid gastropods of the genus Agaronia are dominant predators within invertebrate communities on sandy beaches throughout Pacific Central America. At Playa Grande, on the Pacific Coast of Costa Rica, we observed 327 natural predation events by Agaronia propatula. For each predation event, we documented prey taxa and body size of both predator and prey. The relationship between predator and prey size differed for each of the four main prey taxa: bivalves, crustaceans, heterospecific gastropods, and conspecific gastropods (representing cannibalism). For bivalve prey, there was increased variance in prey size with increasing predator size. Crustaceans were likely subdued only if injured or otherwise incapacitated. Heterospecific gastropods (mostly Olivella semistriata) constituted half of all prey items, but were only captured by small and intermediately sized A. propatula. Large O. semistriata appeared capable of avoiding predation by A. propatula. Cannibalism was more prevalent among large A. propatula than previously estimated. Our findings suggested ontogenetic niche shifts in A. propatula and a significant role of cannibalism in its population dynamics. Also indicated were size-dependent defensive behavior in some prey taxa and a dynamic, fine-scale zonation of the beach. The unexpected complexity of the trophic relations of A. propatula was only revealed though analysis of individual predation events. This highlights the need for detailed investigations into the trophic ecology of marine invertebrates to understand the factors driving ecosystem structuring in sandy beaches.

Personality variation in two predator species does not impact prey species survival or plant damage in staged mesocosms

Mounting evidence suggests that consistent individual differences in behavior, better known as animal personality, can shape aspects of population and community ecology. Yet, the potential for animal personality to affect more complex and non-linear food webs, like those seen in nature, remains understudied. Here, we explore the degree to which the aggregate behaviors of two predator species simultaneously interact to alter prey survival rates and the presence and magnitude of trophic cascades. We set up mesocosms in an old-field habitat containing four different insect prey species and either two Phidippus clarus (Salticidae), two Platycryptus undatus (Salticidae), or one of each predator. Prior to initiating each mesocosm, we assayed the activity level and boldness of each individual predator and included these metrics in our models predicting prey survival and plant damage. We then compared the number of surviving prey and plant damage under each of these conditions and tested for associations between each of these response variables and predator behavior. We found no significant effect of predator community composition or predators’ behavior on prey survival or plant damage. These results suggest that the effects of predator personality on prey survival may be subtle or absent in complex species interaction modules. Although much research suggests that animal personality can influence broader scale ecological phenomena, the ability of animal personality to alter complex species interaction modules remains unresolved. We tested whether pairs of predators of different personality types differentially impacted prey survival rates and plant damage in a tritrophic system, and whether these effects varied based on predator community composition. We recovered no evidence that predator personality types influenced prey survival or plant damage regardless of the predator composition considered. These results suggest that the effects of personality may be absent or undetectable in more complex, realistic ecological settings. The majority of laboratory-based personality studies published to date evaluate only dyadic species interactions in simplified environments. Our findings therefore raise concerns that such studies are prone to overestimate the effects of animal personality.

Variability and stability in predation landscapes: A cross‐ecosystem comparison on the potential for predator control in temperate marine ecosystems

AbstractPredation can play an important role in population, community and ecosystem processes. When predator guilds are diverse, fluctuations in individual predator populations may have small influences on the guild at large, suggesting that predator diversity stabilizes the amount of predation prey experience. The strength of this phenomenon depends on how synchronously populations within predator assemblages vary and whether all predators are equally important consumers. We utilized a database of biomasses of fish species across ten temperate marine ecosystems paired with diet composition and feeding rate information from mass‐balance food web models to develop a predation index that weights the importance of predators on a prey based on predator feeding habits. Using the index, we asked how diverse sources of predation in these ecosystems are and how much diversity stabilizes variability in predation. Predator assemblages displayed a wide range of diversity; in one‐third of assemblages, a single predator group accounted for over half of all predation. Abundances of predator populations within assemblages generally varied independently of one another (neither synchronously nor asynchronously), implying an intermediate stabilization on predation intensity by predator diversity. Accounting for interaction strength (versus mere presence) is critical for interpreting the predator landscape; doing so led to a wider range in predator assemblage diversity and less synchronous assemblages. This work challenges conventional notions that marine food webs are diverse and therefore less susceptible to predator control. Future work should consider the temporal variability of the predator assemblages and account for differences in mortality induced by each predator population.

Habitat use by honey badgers and the influence of predators in iSimangaliso Wetland Park, South Africa

Land-use, the extent of cover, and intra-guild competition with larger predators all influence habitat use by mesocarnivores. Understanding this is especially important for little-known mesocarnivore species. We investigated the occurrence of the relatively understudied honey badger (Mellivora capensis) in iSimangaliso Wetland Park (St. Lucia, South Africa), a Protected Area that covers approximately 700 km2 with forestry plantations (agroforestry) on its Western Shores and restored natural vegetation on its Eastern Shores and Western Shores. We used single-season camera-trap data from a grid of 118 trap stations surveying continuously for 24 days, and estimated the probability of occupancy and detection of honey badgers, and modelled the influence of surrounding land-use, habitat characteristics and presence of other predators on each estimate. Mean estimated probability of occupancy of honey badgers was 0.38 ± 0.08 and probability of detection was 0.12 ± 0.03, with a naïve occupancy estimate of 0.25. Distance to water and higher number of trees in adjacent plantations influenced honey badger occupancy positively. Presence of leopard (Panthera pardus pardus) had a negative effect on detection probability of honey badger while presence of spotted hyena (Crocuta crocuta) positively influenced honey badger detection, indicating that the presence of individual predator species influenced honey badger habitat use in varying ways. We found a higher occurrence of honey badgers in Eucalyptus plantations than in natural habitat types. This suggests that human-modified landscapes may not always be detrimental to adaptable, or more habitat-generalised species that are able to exploit new habitat opportunities.

Personality and the retention of neophobic predator avoidance in wild caught Trinidadian guppies

Abstract Neophobic predator avoidance allows prey to reduce the risk of predation but is costly in terms of reduced foraging or courtship opportunities if the novel cues do not represent an actual threat. Consequently, neophobic responses to novel cues should wane with repeated exposures in the absence of an actual threat. We tested the prediction that individual personality traits shape the retention of neophobic predator avoidance in wild-caught guppies. Using extinction trials, we demonstrate that personality (measured as latency to escape or approach a novel object) did not influence the initial response of wild-caught Trinidadian guppies to a novel odour; bolder and shyer guppies both exhibited similarly strong avoidance responses. However, after several exposures, shyer guppies maintain an avoidance response, and bolder guppies no longer respond. Our results highlight the complex nature of the antipredator algorithm of prey, whereby past experience, acute risk, and individual tactics shape neophobic predator avoidance patterns.