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Disentangling the determinants of trophic structure is central to ecology. The capacity to capture subjugate and consume a prey (i.e. gape limitation) is a relevant limitation to acquire energy for most organisms, especially those in smaller size ranges. This generates a size hierarchy of trophic positions in which large organisms consume small ones. Body size is tightly correlated to gape limitation and explains a large fraction of variance in the body size‐trophic position relationship. However, a considerable fraction of variance still remains to be explained. Consumer search space dimensionality (2D or 3D) and feeding strategies, temperature and the size structure of primary producers can alter the trophic structure, but tests based on information from natural food webs are scarce. We generated specific predictions about the body size trophic position relationship and evaluated them using information from a subtropical South Atlantic coastal marine ecosystem: benthic realm (2D, rocky shore and sandy beach) and the pelagic realm (3D). We characterized this marine coastal food web based on stable isotopes of carbon and nitrogen from 256 samples from primary producers (macroalgae and phytoplankton) to large predators (sand shark) in summer and winter. Consumer body size encompassed six orders of magnitude in weight from 10−2 to 6 × 104 g. Isotopic signal corresponded to an integration of carbon sources from basal consumers to top predators. The body size‐trophic position relationship showed a linear positive association with different slopes for the benthic and pelagic environments. This implies a smaller predator prey size ratio for pelagic (3D) with respect to benthic consumers (2D) as theoretically expected. No seasonal differences were found in slopes and most of the overall variance in benthic environments was largely explained by feeding strategies of the different taxonomic groups. We provide an integrated evaluation on the role of body size, consumer search space and feeding strategy to understand the determinants of trophic position. Results demonstrate that integrating gape limitation hypothesis, the dimensionality of consumer search space and feeding strategies into a formal robust framework to understand trophic structure is feasible even in complex natural ecosystems. [ABSTRACT FROM AUTHOR]

In the Southern Ocean, myctophids (family Myctophidae) are speciose, dominate the mesopelagic fish biomass, and are important in the diets of many fishes, squids, seabirds, and marine mammals. Consequently, they play a key role in carbon export and energy transfer from primary consumers to top predators. However, they are delicate and rarely found intact in predator stomachs, which makes them difficult to identify to species. Fortunately, their otoliths (sagittae) are mostly distinctive and therefore useful for species identification. Previous studies describing Southern Ocean myctophid otoliths were often limited by small sample sizes or focused on only a few species. To facilitate myctophid identifications in diet studies, we provide scanning electron microscope images of otoliths with brief descriptions for 37 species of Southern Ocean myctophids. The identities of problematic taxa were confirmed with DNA. Most species were found to have distinctive otoliths, which can be used to identify them to the species level. Large Gymnoscopelus piabilis otoliths comprised two types, which may represent different species. In addition, allometric equations are provided for 32 species to enable back calculation of fish size. [ABSTRACT FROM AUTHOR]

Modern-day terrestrial amphibians pale in comparison to their monstrous ancient relatives, the Late Carboniferous and Early Permian trematopid temnospondyls. With a skeleton that clearly indicated a terrestrial mode of life and armed with an impressive set of large, recurved marginal dentition and palatal fangs for holding their prey—this group of terrestrial temnospondyls roamed North America and Central Europe as a top predator. Lack of substantial informative fossil material has previously limited our understanding of trematopid diversity and ontogeny. Fortunately, this has improved in the last few decades with the help of exceptional localities like the Early Permian locality Richards Spur. While multiple species of dissorophid temnospondyl have been described from Richards Spur, only one trematopid species has been confidently recognized -Acheloma dunni. Here, we report on the presence of a new large, relatively mature trematopid skull from this famous locality, found encased within a limestone rich block composed mostly of skeletal remains from several other taxa. With the help of neutron computed tomography (nCT), a non-invasive method of analyzing internal and external morphologies, this specimen has revealed several features consistent with the genus, Acheloma, but distinct from Acheloma cumminsi and Acehloma dunni. The identification of these new features, in addition to the characters it shares with other Acheloma species, not only constitute it as a new species of this genus, but also challenges the notion of having synonymized Acheloma dunni with Acheloma cumminsi. In this study, we also unveil new anatomical characters that are potentially independent of ontogeny and could therefore help clarify some of the phylogenetic relationships of this fascinating group of Paleozoic terrestrial predators. [ABSTRACT FROM AUTHOR]

The expansion of northern Pike Esox lucius outside its native range into the western states of North America is a growing problem due to their negative effects on fish communities. Illegally introduced E. lucius were first detected in Box Canyon Reservoir in northeast Washington in 2004. By 2010, the E. lucius population was estimated at more than 10,000 individuals. Between 2012 and 2019, a gillnet suppression programme was conducted, which reduced the E. lucius catch per unit effort in Box Canyon Reservoir by 97% and their biomass by 98%. Between 2004 and 2019, four standardized surveys were conducted to characterize changes in the Box Canyon Reservoir fish community. Even after E. lucius were effectively suppressed, native species showed no signs of recovery during the study. The relative abundance of all native species decreased 82% in total number and 56% in total biomass between 2004 and 2019. Conversely, the relative abundance of non‐native species increased 26% in total number and 33% in total biomass over the same period. As an apex predator, E. lucius had a significant impact on the fish community in Box Canyon Reservoir over a relatively short period of time (7 years), and appeared to act as a catalyst to increase the rate of replacement of native species with non‐native species, which likely increased the pace of taxonomic homogenization in the reservoir. [ABSTRACT FROM AUTHOR]

Simple Summary: Harbour seals from the Wadden Sea area of Lower Saxony, Germany were investigated for their health status and causes of death for the first time. In newborn seals, weakness and emaciation were the main findings, most likely caused by a separation from the mother. After the weaning period, pulmonary parasitosis and bronchopneumonia were the most frequent pathological findings. These investigations emphasize the importance of a health monitoring programme for this top predator species in the Wadden Sea, as it can provide critical insights into changes in the ecosystem. Monitoring harbour seals, which are sentinel species, will support the implementation of the Trilateral Wadden Sea Agreement and the Marine Framework Directive to protect this important marine environment. Harbour seals (Phoca vitulina) are the most common pinniped species in the Wadden Sea of Schleswig-Holstein, Hamburg and Lower Saxony, Germany. Their numbers have recovered after significant depletion due to viral outbreaks and effects of anthropogenic activities like pollution and habitat disturbance. Within the Wadden Sea National Park of Lower Saxony the harbour seal is protected. As a top predator in the Wadden Sea ecosystem, the harbour seal is a sentinel species for the state of the environment. Between 2015 and 2017, a total of 80 stranded dead harbour seals were collected along the coastline of Lower Saxony and submitted for pathological investigations. Of these, 70 seals were born in the same year (0–7 months, age group 1) and eight in the previous year (8–19 months, age group 2), due to high mortality rates in these age groups. However, two perennial animals were also available for examination during this period, one of which was in good nutritional condition. Many of the seals that had been mercy-killed and found dead were in poor nutritional status. Histopathological, microbiological, parasitological and virological examinations were conducted on 69 individuals (86% (69/80)) in a suitable state of preservation. Respiratory tract parasitosis, cachexia, and bronchopneumonia were the most common causes of death or disease. Overall, there was no evidence of a relapse of a viral disease outbreak. Macrowaste, such as plastic waste or fishery-related debris, were not found in any gastrointestinal tract of the animals examined. There was also no evidence of grey seal predation. Weakness and cachexia were prominent causes of disease and death in harbour seals found within a few weeks after birth, but bronchopneumonia and septicaemia also developed in slightly older animals. Frequently found microbial pathogens in seals from Lower Saxony were similar to those found in other studies on seals from the Wadden Sea region in Schleswig-Holstein, for example streptococci and Escherichia coli/v. haemolytica, Brucella spp. and Erysipelothrix rhusiopathiae, potentially human pathogenic germs. The results of the examinations of dead harbour seals from Lower Saxony show that pathological investigations on a representative number of animals deliver urgently needed information on the health status of the population. The results represent an important contribution to the state of the top predators of the Wadden Sea as part of the obligations within the Trilateral Wadden Sea Agreement, Oslo and Paris Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) and the Marine Framework Directive. The investigations should be continued as a matter of urgency and the stranding network should be expanded. [ABSTRACT FROM AUTHOR]

Conserving mammal community stability in forest ecosystems is an urgent challenge in the face of global biodiversity threats and complex trophic interaction. However, understanding of the stability of mammal communities and targeted functional groups is still limited, hindering adaptive strategy development. We collected 210 120 camera trap photos across 5897 km2 within the Amur tiger (Panthera tigris altaica) range in China's natural forests. We decomposed stability into compensatory effects, statistical-averaging effects and population stability. Using structural equation modelling, we explored the impact of external factors, species diversity and vertical effects on the stability of the community and of four functional groups. As external factors, primary productivity increased the stability of top predators, while precipitation had inconsistent effects. Horizontal diversity (richness and evenness) positively impacted community stability. However, the vertical structure of the community, including trophic-level richness and functional groups' compensatory dynamics, were the largest drivers for maintaining community stability. Horizontal diversity within functional groups and the diversity or biomass of their food resources/consumers both influenced the stability of functional groups. Our results recognize the importance of conserving and even re-establishing vertical trophic structures in forest communities. Acknowledging multiple levels of stability, from functional groups to communities, is an indispensable step for effective conservation strategies. [ABSTRACT FROM AUTHOR]

Environmental change is expected to alter trophic interactions and food web dynamics with consequences for ecosystem structure, function and stability. However, the mechanisms by which environmental change influences top‐down and bottom‐up processes are poorly documented. Here, we examined how environmental change caused by shrub encroachment affects trophic interactions in a dryland. The predator–prey system included an apex canid predator (coyote; Canis latrans), an intermediate canid predator (kit fox; Vulpes macrotis), and two herbivorous lagomorph prey (black‐tailed jackrabbit, Lepus californicus; and desert cottontail, Sylvilagus audubonii) in the Chihuahuan Desert of New Mexico, USA. We evaluated alternative hypotheses for how shrub encroachment could affect habitat use and trophic interactions, including (i) modifying bottom‐up processes by reducing herbaceous forage, (ii) modifying top‐down processes by changing canid space use or the landscape of fear experienced by lagomorph prey and (iii) altering intraguild interactions between the dominant coyote and the intermediate kit fox. We used 7 years of camera trap data collected across grassland‐to‐shrubland gradients under variable precipitation to test our a priori hypotheses within a structural equation modelling framework. Lagomorph prey responded strongly to bottom‐up pulses during years of high summer precipitation, but only at sites with moderate to high shrub cover. This outcome is inconsistent with the hypothesis that bottom‐up effects should be strongest in grasslands because of greater herbaceous food resources. Instead, this interaction likely reflects changes in the landscape of fear because perceived predation risk in lagomorphs is reduced in shrub‐dominated habitats. Shrub encroachment did not directly affect predation pressure on lagomorphs by changing canid site use intensity. However, site use intensity of both canid species was positively associated with jackrabbits, indicating additional bottom‐up effects. Finally, we detected interactions between predators in which coyotes restricted space use of kit foxes, but these intraguild interactions also depended on shrub encroachment. Our findings demonstrate how environmental change can affect trophic interactions beyond traditional top‐down and bottom‐up processes by altering perceived predation risk in prey. These results have implications for understanding spatial patterns of herbivory and the feedbacks that reinforce shrubland states in drylands worldwide. [ABSTRACT FROM AUTHOR]

Apex predators are vulnerable to environmental changes which can cascade through trophic levels of an ecosystem. Investigating prey‐predator relationships is important for directing conservation efforts and understanding how species may respond to ecosystem changes. This case study examined the diet and breeding success of the threatened powerful owl Ninox strenua in central Victoria where the box‐ironbark forests have undergone widespread clearing, fragmentation, and degradation. The powerful owl preys predominantly on arboreal mammals, however, some birds are also consumed. By analysing the contents of regurgitated owl pellets of two owl pairs, we found that birds comprised 29.3% of all prey items and contributed the largest proportion of prey biomass for one pair (34.4%). All mammalian prey species identified in the pellet remains are dependent on tree hollows, which are now a scarce and competitive resource in box‐ironbark forests. Despite consuming a diet lower in mammalian prey than found in other studies, breeding success over five consecutive years was 1.4 chicks fledged per pair per year, which is notably higher than historical observations in the region and similar to powerful owls in other parts of their distribution. Our observations suggest that flexibility in prey selection enables powerful owls to occupy ranges that have undergone significant ecosystem change. [ABSTRACT FROM AUTHOR]

The classical Hastings–Powell model is well known to exhibit chaotic dynamics in a three-species food chain. Chaotic dynamics appear through period-doubling bifurcation of stable coexistence limit cycle around an unstable coexisting equilibrium point. A specific choice of parameter value leads to a situation, where the chaotic attractor disappears through a collision with an unstable limit cycle originated due to subcritical Hopf-bifurcation around the coexistence equilibrium. As a consequence, the top predator goes to extinction. The main objective of this work is to explore the structural sensitivity of this phenomenon by replacing the Holling-type II functional responses with Ivlev functional responses. In this work, we have shown the existence of two Hopf-bifurcation thresholds and numerically verified the existence of an unstable limit cycle. The model with Ivlev functional responses does not indicate any possibility of extinction of the top predator due to any collision of chaotic attractor with the unstable limit cycle for the chosen range of parameter values. Moreover, the model with Ivlev functional responses depicts an interesting scenario of bistable oscillatory coexistence. [ABSTRACT FROM AUTHOR]

Simple Summary: Giant water bugs play an important role as top predators in wetland ecosystems, helping to control freshwater snails and mosquitoes. In this study, we used MaxEnt models to predict how climate change might affect the distribution of two Korean species, Appasus japonicus and Diplonychus esakii. Our findings suggest that A. japonicus may lose habitat and shift northward, while D. esakii is expected to expand its range, potentially causing occupancy turnover between the two species. The range shifts of the two species are primarily driven by different factors—elevation for A. japonicus and annual mean temperature for D. esakii. This research helps us understand how climate change could affect two giant water bugs and supports efforts to manage and conserve wetland ecosystems in South Korea. Giant water bugs (Hemiptera: Belostomatidae) are top predators in wetland ecosystems, serving as biological indicators of the health of lentic ecosystems and as effective biological control agents for freshwater snails and mosquitoes. This study aimed to predict the current and future distribution of two Korean giant water bugs, Appasus japonicus and Diplonychus esakii, under three climate change scenarios, contributing to the sustainable management of wetland ecosystems in South Korea. Using MaxEnt models, we employed seven climatic and three non-climatic variables to investigate the habitat preferences and distribution patterns of the species. The results revealed that A. japonicus is likely to experience a northward range contraction due to climate change, while D. esakii is predicted to expand its distribution northward without losing its current range. These responses may lead to occupancy turnover between the two species, potentially driving reassembly in aquatic organism community. Elevation was the primary factor influencing the distribution of A. japonicus, whereas annual mean temperature was the most informative variable for D. esakii, both factors derived under the current climate conditions. These findings suggest that both species are highly sensitive to climate change, with potential range shifts toward higher latitudes and elevations. This study provides insights into how climate change could impact two giant water bugs, thereby supporting future efforts to manage and conserve wetland ecosystems in this country. [ABSTRACT FROM AUTHOR]

Simple Summary: An endangered giant water bug species, Diplonychus esakii, is one of the top predators in Korean freshwater ecosystems. This study investigates D. esakii populations in South Korea, a species potentially endemic to this region, and identifies 11 haplotypes with a haplotype diversity value of 0.623 out of 318 individuals across 27 sites. Through AMOVA (analysis of molecular variance) and FST analyses, we discovered significant genetic differentiation among populations and limited gene flow, indicating potential vulnerability to environmental changes. Consequently, we emphasize the need for conservation efforts to protect D. esakii. We also highlight the value of the Upo Wetland and Jeju Island populations as important conservation units to conserve the genetic diversity of Korean D. esakii. We also suggest an evaluation of the conservation status of D. esakii compared to the level of genetic diversity known from other endangered insect species. The genetic information in this study will provide valuable data for developing effective conservation strategies. Diplonychus esakii, a water bug from the family Belostomatidae, plays an important role in freshwater ecosystems as one of the top predators. In this study, we investigated the genetic diversity and population structure of D. esakii by analyzing 318 specimens across 27 sites in South Korea. We found that the populations of D. esakii possess 11 haplotypes with a haplotype diversity of 0.623. This represents a relatively low level of genetic diversity compared to other known belostomatids and endangered species. AMOVA and FST analyses revealed significant genetic differentiation among populations, with most populations harboring only 1–2 haplotypes, suggesting restricted gene flow between populations and a low level of genetic diversity. This low genetic diversity and limited gene flow suggest a potential vulnerability to environmental changes and an increased risk of extinction, indicating that D. esakii should be designated as a protected species in South Korea as part of future conservation efforts. Based on the results of this study, Upo Wetland, which maintains relatively high levels of genetic diversity and Jeju Island, which, despite its lower genetic diversity compared to the mainland, does not share haplotypes with other regions, should be considered key conservation units for this species. This study highlights the importance of incorporating genetic information into conservation status assessments under the Red List Categories and Criteria and also emphasizes the need to evaluate this species on the Korean Red List. The data provided here will serve as essential baseline information and valuable resources for the development of effective conservation strategies. [ABSTRACT FROM AUTHOR]

We are already experiencing the rapid pace of environmental perturbation in the Anthropocene, necessitating the development of new tools and techniques for measuring changes in ecosystem dynamics. Sentinel species, from birds to invertebrates, have been used to provide insights into ecosystem function, as leading indicators of risk to human health and as harbingers of future change, with implications for ecosystem structure and function. Here, we offer an update to previous research identifying marine top predators as indicators of ecosystem shifts and examine terrestrial sentinels and the latest research on sentinels of pollution and human health. Using ecosystem sentinels enables rapid response and adaptation to ecosystem variability and environmental change in part because they may be easier to observe and in part because they may serve as leading indicators of ecosystem disruption. While there may not be a given taxon that is best suited as sentinels, we highlight how to select the most effective sentinels, including examples of when sentinel species have been incorporated into management. Choosing a suite of appropriate sentinels both will give insight into ecosystem processes and can help manage changing ecosystems into the future. [ABSTRACT FROM AUTHOR]

Habitat preferences of invasive predators determine where and for which prey species they pose a threat upon. This is crucial information for the conservation of endangered prey species because invasive predators pose additional predation on top of that caused by natural predators. In large parts of Europe, the most common invasive mesopredator is the raccoon dog (Nyctereutes procyonoides). To understand the risk that the raccoon dog poses for wetland-associated species, we collected information about its habitat preferences near these habitats. We used data on 24 GPS-collared raccoon dogs from three landscape types in Finland, to study their spatial and temporal habitat preferences. We first determined their home ranges, within which we then examined habitat use and preferences. Raccoon dogs showed generalist habitat use, which was evident in their wide range of used habitats. However, in spring and summer, during the breeding seasons of waterfowl and amphibians, they preferred wetlands and peatlands. They also preferred shorelines and the edges of forests and agricultural fields. During autumn and winter, raccoon dogs did not prefer wetlands. These findings support the conclusion that the raccoon dog's habitat preferences pose a particular threat to wetland-associated species, such as nesting waterfowl and amphibians. The species' habitat preferences coupled with high numbers of this invasive mesopredator pose additional predation for endangered wetland-associated species on top of that of native predators. [ABSTRACT FROM AUTHOR]

Bioindication, evaluating biological responses to environmental disturbances, is crucial for assessing the ecological status of an ecosystem. While historical bioindication relied on macroscopic organisms, the introduction of environmental DNA (eDNA) techniques allows the application of protists without the necessity of morphological identification. In this study, we propose a novel bioindication methodology utilizing Arcellinida, a group of top predators among protists, as bioindicators of freshwater ecosystems. For that purpose, we first characterized the Arcellinida diversity over 1 year at three different points of Lake Sanabria, an ancient glacier lake known to be subjected to anthropogenic disturbances. We compared this diversity with an undisturbed control site. Second, we characterized the Arcellinida diversity in other ecosystems to generate the ecological background to test the connectivity between them. Results indicate limited connectivity between the different ecosystems and an edge effect between terrestrial and aquatic ecosystems. Disturbed freshwater ecosystems exhibited reduced Arcellinida diversity at both specific and infraspecific levels, providing valuable insight into recent disturbances. Arcellinida‐based bioindication provides a sensitive, accurate and easy‐to‐interpret protocol for monitoring disturbances in freshwater ecosystems. It represents a valuable tool for environmental assessments and conservation strategies. [ABSTRACT FROM AUTHOR]

Apex predators exert suppressive effects on mesocarnivores; however, they also provide important carrion subsidies. Optimal foraging theory predicts that individuals respond to resource competition by using high-value resources, while competition theory predicts that individuals respond by partitioning resources. This study investigated how the return of wolves (Canis lupus Linneas, 1758) to Washington state impacted the diet of a subordinate carnivore—the coyote (Canis latrans Say, 1823). We collected coyote scats from two areas of northern Washington with differing wolf densities and used traditional analysis of undigested remains to infer diet. We tested for differences in the volumes of prey categories, the proportion of ungulate prey that was scavenged, and diet diversity between seasons, study sites, and inside and outside of wolf pack territories. Coyote scats contained more adult ungulate remains inside of wolf pack territories (27%) compared to outside (14%), while seeds and berries were more commonly consumed outside of wolf pack territories (23%) than inside of wolf pack territories (4%). These findings suggest that coyotes are taking advantage of wolf kills to increase ungulate carrion consumption, as predicted by optimal foraging theory, which may substantially affect plant and wildlife communities as wolves continue to recover and coyote diets shift in response. [ABSTRACT FROM AUTHOR]

The landscape theory of food web architecture (LTFWA) describes relationships among body size, trophic position, mobility, and energy channels that serve to couple heterogenous habitats, which in turn promotes long‐term system stability. However, empirical tests of the LTFWA are rare and support differs among terrestrial, freshwater, and marine systems. Further, it is unclear whether the theory applies in highly altered ecosystems dominated by introduced species such as the Laurentian Great Lakes. Here, we provide an empirical test of the LTFWA by relating body size, trophic position, and the coupling of different energy channels using stable isotope data from species throughout the Lake Michigan food web. We found that body size was positively related to trophic position, but for a given trophic position, organisms predominately supported by pelagic energy had smaller body sizes than organisms predominately supported by nearshore benthic energy. We also found a hump‐shaped trophic relationship in the food web where there is a gradual increase in the coupling of pelagic and nearshore energy channels with larger body sizes as well as higher trophic positions. This highlights the important role of body size and connectivity among habitats in structuring food webs. However, important deviations from expectations are suggestive of how species introductions and other anthropogenic impacts can affect food web structure in large lakes. First, native top predators appear to be flexible couplers that may provide food web resilience, whereas introduced top predators may confer less stability when they specialize on a single energy pathway. Second, some smaller bodied prey fish and invertebrates, in addition to mobile predators, coupled energy from pelagic and nearshore energy channels, which suggests that some prey species may also be important integrators of energy pathways in the system. We conclude that patterns predicted by the LTFWA are present in the face of species introductions and other anthropogenic stressors to a degree, but time‐series evaluations are needed to fully understand the mechanisms that promote stability. [ABSTRACT FROM AUTHOR]

Ontogenetic changes in area use, habitat use, and trophic interactions play an important role in the ecology, demography, and ultimately population dynamics of many species. Assumed to be driven by shifting life‐history requirements, trophic niche shifts in white sharks (Carcharodon carcharias) are well documented, but the timing of the spatial niche shift that is hypothesized to occur with the trophic niche shift remains poorly understood. To document how fine‐scale area use varies as sharks age and the timing of the ontogenetic spatial shift of this top predator, we tracked individual white sharks tagged as young‐of‐the‐year or young juveniles over multiple years. Using data from juvenile white sharks detected over multiple years in a nursery habitat with a high‐density receiver array, we found no difference in area use with age. However, using a coast‐wide receiver array including nursery and adult habitat, we found the probability of detecting a juvenile white shark in nursery habitat decreased with age, with a concurrent increasing probability of detection in adult habitat. As the conservation and management of this species relies on understanding nursery habitat use and age‐related movements, data presented here address an important knowledge gap for the understudied juvenile to subadult life stages and the ontogenetic habitat shift of this species. [ABSTRACT FROM AUTHOR]

The results of our preliminary studies indicated that the diets of predatory fishes can be bioindicators of faunistic changes in ecosystems and indirectly of changes taking place in aquatic environments in the Pomeranian Bay. We examined the diet composition of top predators Gadus morhua, Sander lucioperca, Perca fluviatilis, and the mesopredator Neogobius melanostomus. The diet composition of the perch, pikeperch, and round goby in the Pomeranian Bay was analyzed for the first time. Our findings indicated that perch, an euryphagous species, is the best potential bioindicator because it is present in the area studied most of the year and has a low to moderate feeding index (FI). Baltic cod, also an euryphagous species, could be a good bioindicator in the areas where it is abundant and occurs frequently, but not in the Pomeranian Bay, where it is caught mainly in the fall. Round goby, which is present in the area studied and had a low FI, is a stenophagous species that preys mainly on benthic species, while pikeperch had a very high FI and the least number of prey species in its diet. The results of trophic interaction analysis among the predators analyzed and their non-native/invasive prey are also provided. [ABSTRACT FROM AUTHOR]

This article, titled "Shortened Food Chain Length in a Fished vs. Unfished Coral Reef," explores the impact of fishing on the trophic architecture of coral reef ecosystems. The study conducted in two high-diversity coral reef ecosystems found that moderate intensity fishing pressure led to significant reductions in the trophic position of top predators, but not in lower level consumers. There were also no changes in basal resource consumption, indicating a compression in overall food chain length. The article includes photographs illustrating the impact of fishing on coral reefs. [Extracted from the article]

Tiger sharks are apex predators with a circumglobal tropical and warm-temperate distribution, with a general lack of population data for the central Indian Ocean. In Fuvahmulah, Maldives, tiger sharks display frequent use of the harbour area, attracted by discarded fish waste. Here, we document the population structure, residency, and reproductive characteristics of the world's largest known tiger shark aggregation in a geographically-restricted area. Using non-invasive methods, photo identification and laser photogrammetry, we identified 239 individual tiger sharks over a 7-year study period. The aggregation was female-dominated (84.5%), with both large juveniles and adults present. Adult females were resighted over the entire study period displaying strong inter- and intra-annual site fidelity. Modelled residency using maximum likelihood methods suggests they spent 60.7 ± S.E. 7.5 days in Fuvahmulah, with a larger aggregation size, shorter residence periods and longer absence periods compared to juvenile females. Prolonged abdominal distensions of adult females indicate they likely stay near Fuvahmulah during gestation and reproduce biennially. Fuvahmulah seems to provide suitable conditions for gestation given the year-round provision of food and warm waters, exhibited by strong site fidelity and temporal residency. Our results show indications of a thriving population within the confines of protected waters. [ABSTRACT FROM AUTHOR]

In this paper, we study a prey–predator–top predator food chain model with nonlinear harvesting of top predator. We have derived two important thresholds: the top predator extinction threshold and the coexistence threshold. We found that the top predator will die out if the nonlinear harvesting from predator to top predator is larger than the top predator extinction threshold. On the other hand, the prey, predator and top predator coexist if the nonlinear harvesting from predator to top predator is less than the coexistence threshold. While the parameter value of nonlinear harvesting from predator to top predator is between two critical thresholds, the system displays bistability phenomena, implying that the top predator species either die out or exist with the prey and predator species, which largely depend on the initial condition. Thus, a bistable interval exists between two critical thresholds, which is a significant phenomenon for the model. Meanwhile, we performed bifurcation analysis for the model, showing that the system would arise backward/forward bifurcation and saddle-node bifurcation and Hopf bifurcation. Finally, we performed numerical simulations to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

Background: In ecosystems influenced by strong seasonal variation in insolation, the fitness of diverse taxa depends on seasonal movements to track resources along latitudinal or elevational gradients. Deep pelagic ecosystems, where sunlight is extremely limited, represent Earth's largest habitable space and yet ecosystem phenology and effective animal movement strategies in these systems are little understood. Sperm whales (Physeter macrocephalus) provide a valuable acoustic window into this world: the echolocation clicks they produce while foraging in the deep sea are the loudest known biological sounds on Earth and convey detailed information about their behavior. Methods: We analyze seven years of continuous passive acoustic observations from the Central California Current System, using automated methods to identify both presence and demographic information from sperm whale echolocation clicks. By integrating empirical results with individual-level movement simulations, we test hypotheses about the movement strategies underlying sperm whales' long-distance movements in the Northeast Pacific. Results: We detect foraging sperm whales of all demographic groups year-round in the Central California Current System, but also identify significant seasonality in frequency of presence. Among several previously hypothesized movement strategies for this population, empirical acoustic observations most closely match simulated results from a population undertaking a "seasonal resource-tracking migration", in which individuals move to track moderate seasonal-latitudinal variation in resource availability. Discussion: Our findings provide evidence for seasonal movements in this cryptic top predator of the deep sea. We posit that these seasonal movements are likely driven by tracking of deep-sea resources, based on several lines of evidence: (1) seasonal-latitudinal patterns in foraging sperm whale detection across the Northeast Pacific; (2) lack of demographic variation in seasonality of presence; and (3) the match between simulations of seasonal resource-tracking migration and empirical results. We show that sperm whales likely track oceanographic seasonality in a manner similar to many surface ocean predators, but with dampened seasonal-latitudinal movement patterns. These findings shed light on the drivers of sperm whales' long-distance movements and the shrouded phenology of the deep-sea ecosystems in which they forage. [ABSTRACT FROM AUTHOR]

The puma (Puma concolor Linnaeus, 1771) is the top predator with the widest distribution in America. Since the establishment of European settlers on the American continent, puma populations have experienced significant contractions and reductions in their original distribution. In Argentina, the management of the conflict between humans and pumas (direct persecution and habitat modification) focused on reduction or elimination methods, leading to a drastic contraction, even total eradication, of puma populations as seen in Patagonia and the eastern part of the country. Despite the lack of knowledge about puma population demographic trends, there are taxonomic issues that remain controversial and need to be resolved to implement appropriate management and conservation measures. Therefore, the aim of this study was to genetically characterize puma populations in the central-southern region of Argentina using two mitochondrial markers, evaluate their demographic history, compare our results at a macro-regional level, and discuss our findings in a conservation and management context. A total of 203 individuals were used, and a fragment of the control region and another of ND5 were sequenced. The genetic variability obtained was moderate. Substitution rates for each locus and the tMRCA were calculated from calibrated trees. In a concatenated tree, two main phylogenetic clades were identified (posterior probability = 1), although a reciprocal monophyly was not observed, with a divergence time of 228 thousand years and a 95% CI [117-363 thousand years]. When evaluating population structuring, three genetic clusters were found, one characteristic of the Patagonian region and the others in the central part of the country. Calculating the ФST values for pairs resulted in significant structuring between Patagonia and the rest of the populations, suggesting the arid diagonal as a possible barrier to gene flow. When evaluating the demographic history, neutrality tests would support a recent expansion in Patagonia. These findings are crucial in defining two distinct Management Units (MUs) in the southern part of puma distribution and providing valuable information for management and conservation measures for the species. [ABSTRACT FROM AUTHOR]

Rapid coagulation of reptile blood often hinders its use in studies in remote and difficult-to-access areas, necessitating chemical preservation. Therefore, understanding the potential effects of anticoagulants on the isotopic compositions of blood is essential to avoid issues in interpreting the results for ecological studies. In this study we aimed to verify whether the storage time of the blood tissue in anticoagulants can influence its isotopic compositions of the broad-snouted caiman (Caiman latirostris), an ectothermic top predator from eastern South America. Blood samples were obtained from ten adult females of C. latirostris from a commercial breeding facility in 2015. Samples were stored in vials containing ethylenediaminetetraacetic acid (EDTA) and sodium heparin (SH) and centrifuged after 2 and 8 h to separate red blood cells and plasma. No effect of time was found on the δ13C and δ15N of whole blood, plasma, and red blood cells in contact with the two types of anticoagulants, EDTA and SH. The findings have practical implications for researchers in this field, as they suggest that anticoagulants can be used effectively for at least eight hours under refrigeration. [ABSTRACT FROM AUTHOR]

Simple Summary: Understanding the activity patterns of snow leopards is important for the conservation of this species, but the activity patterns of snow leopards in the Qilian Mountain National Park (Qinghai area) are largely unknown. Therefore, we used camera trap data for snow leopards and analyzed activity patterns at different time scales and under different weather conditions. The results demonstrate the patterns of regional snow leopard activity and play an important role in the management and conservation of snow leopards in the region. In recent years, there has been growing concern about the condition of snow leopards. The snow leopard (Panthera uncia), an apex predator of alpine ecosystems, is essential for the structural and functional stability of ecosystems. Monitoring of snow leopards' activity patterns based on camera traps in the Qilian Mountain National Park (Qinghai area) between August 2020 to October 2023 was performed. The results showed that autumn is the peak period of snow leopard activity, especially in September when the frequency of activity is the highest, and there is one peak in the frequency of snow leopard daily activity in the time period of 18:00–22:00, while the highest overlap of the daily activity curves of snow leopards in different months was from spring to autumn (Δ = 0.97), and there were significant differences in diurnal activity rhythm between spring and autumn (p = 0.002). Snow leopards prefer sunny days, and they tend to be active at temperatures of −10–9 °C. Our research aimed to uncover the activity patterns of snow leopards at different scales within the study area and provide data for further studies on snow leopards and other wildlife by researchers. This study can be used to gain a comprehensive understanding of the ecological characteristics of snow leopards and to assess their habitats, and it will also serve as a reference for the local wildlife management authorities in formulating snow leopard conservation measures. [ABSTRACT FROM AUTHOR]

ABSTRACT Fishes use a variety of physical and biological resources that shift ontogenetically, seasonally and spatially. Quantifying what resources such as prey are required for persistence can improve understanding of ecological needs of fishes and riverine macrosystem functioning. Bowfin (Amia ocellicauda) and largemouth bass (Micropterus nigricans) cohabitate in their native range and potentially compete with one another. Yet, there have been no direct comparisons of their diets across spatial gradients to assess whether they partition resources or shift in prey use. We used multiple univariate and multivariate analyses to compare diet composition, diet overlap, feeding strategy, prey importance and diet partitioning between largemouth bass and bowfin across three reaches of the Upper Mississippi River. Largemouth bass ontogenetically shifted their diet from aquatic invertebrates to fishes and a more diverse assemblage of aquatic invertebrates. Bowfin and adult largemouth bass were top predators which consumed mostly crayfish and fish and overlapped in their diets. Despite overlapping diets, predators partitioned resources by consuming different lengths and abundances of prey, and largemouth bass had greater trophic plasticity. Within a predator group, few differences in diets existed spatially, underscoring the relative homogeneity in resource use potentially from similarities in the river's physical structure. Combined, prey use likely differed sufficiently to reduce potential competition between largemouth bass and bowfin, allowing long‐term coexistence in this system. Our results also highlighted the importance of crayfishes to riverine food webs and underscored the use of multiple prey and habitat types that sustain these predators. [ABSTRACT FROM AUTHOR]

ABSTRACT Glaciers host a variety of cold‐adapted taxa, many of which have not yet been described. Interactions among glacier organisms are even less clear. Understanding ecological interactions is crucial to unravelling the functioning of glacier ecosystems, particularly in light of current glacier retreat. Through a review of the existing literature, we aim to provide a first overview of the biodiversity, primary production, trophic networks, and matter flow of a glacier ecosystem. We use the Forni Glacier (Central Italian Alps) – one of the best studied alpine glaciers in the world – as a model system for our literature review and integrate additional original data. We reveal the importance of allochthonous organic matter inputs, of Cyanobacteria and eukaryotic green algae in primary production, and the key role of springtails (Vertagopus glacialis) on the glacier surface in sustaining populations of two apex terrestrial predators: Nebria castanea (Coleoptera: Carabidae) and Pardosa saturatior (Araneae: Lycosidae). The cryophilic tardigrade Cryobiotus klebelsbergi is the apex consumer in cryoconite holes. This short food web highlights the fragility of nodes represented by invertebrates, contrasting with structured microbial communities in all glacier habitats. Although further research is necessary to quantify the ecological interactions of glacier organisms, this review summarises and integrates existing knowledge about the ecological processes on alpine glaciers and supports the importance of glacier‐adapted organisms in providing ecosystem services. [ABSTRACT FROM AUTHOR]

Alarm calls produced by basal prey have a well-known informative value. In multi-predator communities, mesopredators, when faced with top predators, may emit alarm calls that could inform basal prey about their lowered predation risk. To test this unexplored possibility, we conducted one field and one mesocosm experiment in which we simulated alarm and non-alarm calls from little owls (Athene noctua) as mesopredators and measured their effects on grasshoppers as prey of little owls but not of top predators. In the field experiment, we found that grasshopper species were significantly more abundant in patches where we simulated either the presence of scared little owls (alarm treatment) or no owls (control treatment) compared to patches where the presence of non-scared little owls (non-alarm treatment) was simulated. In the mesocosm experiment, locusts (Locusta migratoria) moved significantly more to exposed areas when we simulated the presence of scared little owls (alarm treatment) or of a granivorous bird (control treatment), while they moved to sheltered areas when we simulated the presence of non-scared owls (non-alarm treatment). These results show that prey could cue on predators' calls to assess their predation risk and make decisions, revealing unprecedented potential ecological consequences of alarm calls in invertebrate communities. [ABSTRACT FROM AUTHOR]

Cases of anomalous coloration are regularly reported in Neotropical mammals, including the rodent family Dasyproctidae (agoutis and acouchis) where leucistic and albino individuals have been observed. Here, we document the first case of leucism in the Brown Agouti (Dasyprocta variegata) in Bolivia. During a camera trap survey of the Barba Azul Nature Reserve, we obtained footage of a Brown Agouti with a completely white body. Additional pictures of this individual revealed that it has black eyes, indicating leucism instead of albinism. Previous observations (since 2017) of a white agouti in the area suggest that these anomalously colored individuals can survive in the wild. Rare observations of top predators suggest a relatively low predation pressure in the area. We had only one record of a South-American Puma (Puma concolor) during our camera trap survey. Hence, leucistic individuals of a common prey species might also be indicative of the dwindling population densities of top predators in the region. [ABSTRACT FROM AUTHOR]

Anthropogenic activities may alter felid assemblage structure, facilitating the persistence of tolerant species (commonly mesopredators), excluding ecologically demanding ones (top predators) and, consequently, changing coexistence rules. We aimed to determine how human activities influence intraguild relationships among top predators and their cascading effects on mesopredators, which remain poorly understood despite evidence of top carnivore decline. We used structural equation modeling at a continental scale to investigate how habitat quality and quantity, livestock density, and other human pressures modified the intraguild relations of the 3 species that are at the top of the food chain in the Neotropics: jaguars (Panthera onca), pumas (Puma concolor), and ocelots (Leopardus pardalis). We included presence–absence data derived from systematic studies compiled in Neocarnivores data set for these felid species at 0.0833° resolution. Human disturbance reduced the probability of jaguar occurrence by −0.35 standard deviations. Unexpectedly, the presence of sheep (Ovis aries) or goats (Capra aegagrus hircus) and jaguars was positively related to the presence of pumas, whereas puma presence was negatively related to the presence of ocelots. Extent of forest cover had more of an effect on jaguar (β = 0.23) and ocelot (β = 0.12) occurrences than the extent of protected area, which did not have a significant effect. The lack of effect of human activities on puma presence and the positive effect of small livestock supports the notion that pumas are more adaptable to habitat disturbance than jaguars. Our findings suggest that human disturbance has the potential to reverse the hierarchical competition dominance among large felids, leading to an unbalanced community structure. This shift disadvantages jaguars and elevates the position of pumas in the assemblage hierarchy, resulting in the exclusion of ocelots, despite their relatively lower susceptibility to anthropogenic disturbance. Our results suggest that conservation efforts should extend beyond protected areas to encompass the surrounding landscape, where complexities and potential conflicts are more pronounced. [ABSTRACT FROM AUTHOR]

Background: Tigers, as iconic apex predators and symbols of biodiversity conservation, face numerous threats to their existence. Effective tracking and monitoring are essential for understanding and preserving these majestic creatures and their habitats. The convergence of machine learning and drone technology has emerged as transformative tools in the field of tiger tracking. Drones, or Unmanned Aerial Vehicles (UAVs), have rapidly become invaluable assets in wildlife conservation. Machine learning algorithms, with their capacity to analyze complex datasets, make predictions and automate decision-making processes, offer a novel approach to processing the massive amounts of data generated by drones, including images, sounds and sensor readings. Methods: This paper explores the historical significance of tiger tracking, the pivotal role of drones in conservation and the transformative capabilities of machine learning in wildlife monitoring. In this work, an accurate framework for tiger detection based on YOLOv8 is utilized. Result: By examining the interplay between machine learning, drone technology and tiger conservation, this paper highlights the potential for innovation and the challenges that lie ahead, promising a brighter future for these iconic creatures and their ecosystems. The fine-tuned YOLOv8 model demonstrates exceptional object detection performance, boasting a mAP50 of 0.9820 and a mAP50-95 of 0.6856, coupled with precise classification (precision 0.9646) and robust instance capture (recall 0.9580). [ABSTRACT FROM AUTHOR]

The Mesozoic Marine Revolution restructured the world's ocean biodiversity into the complex marine ecosystems of today. This revolution began during the Triassic but the origin of this complexity is poorly understood due to a lack of detailed ecosystem reconstructions throughout time. We present the first site-specific ecological network for a marine Mesozoic fauna based on the Early Cretaceous Paja Formation biota of Colombia that preserves numerous, large-bodied, predatory marine reptiles. The trophic food-web was quantitatively reconstructed based on inferred trophic interactions of marine producers, consumers, and large apex predators. Compared to well-studied Caribbean reef ecosystem networks, the Paja biota network is missing a great proportion of benthic invertebrates and fishes, despite its rich higher trophic levels. We hypothesize that the ammonites from the Paja biota either mirrored the diversity represented by some fishes today or established a novel trophic unit with no living analogue. Recalibrating the Paja biota network to trophic analogues in the Caribbean, such as sea turtles, estimates that the largest Paja marine reptile hyper-apex predators occupied trophic levels a full tier higher than any extant marine apex predator. The Paja biota network is a starting point to tracing the evolution of marine ecosystems across the Mesozoic Marine Revolution. [ABSTRACT FROM AUTHOR]

Livestock farming has been a practice of great importance for the evolution of civilization, not only influencing social, economic, and cultural aspects at a global level, but also food, the economy, and sustainability, especially in developing countries, where it generates significant pressure on natural resources and biodiversity. In this context, conflict arises between wildlife, mainly top predators, and livestock farmers. Despite the efforts of different communities to implement measures against predation, the conflict continues to increase. In Latin America, the livestock sector is growing at a much higher rate than in the rest of the world, particularly in Chile, where around a third of agricultural production units use livestock as their main source of livelihood. To understand the factors influencing the behavior of goat farmers when adopting measures, we applied a hurdle model with social, spatial, economic, and productive information to assess the decision to adopt measures and the intensity of the adoption of such practices. To perform this, we used data from a survey, administered in 2014 to 476 farmers located in the three provinces of the Coquimbo Region. Our dependent variable was defined by six measures: a protection dog, night confinement of the herd, supervised grazing, anti-carnivore corral, the death or capture of the predator, and repelling the predator. The adoption decision, as well as the intensity of adoption, were influenced by the location, household size, the type of livestock, the income generated by the livestock, health management, and access to technical advice. The decision to adopt measures was influenced by the production system and whether it was self-sustaining, while the intensity of adoption was influenced by herd size and the number of losses due to predation. The results showed the importance of developing and adjusting livestock support initiatives in the study area, including those that could be created, based on differentiated measures according to the profiles of farmers in the territory. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFASs) are contaminants of great concern due to their ubiquitous environmental occurrence in the environment and their potential adverse effects on organisms. There is currently limited information regarding the occurrence of PFASs in Scopoli's Shearwater (Calonectris diomedea). In this study, two feather samples per bird were obtained from 26 adults on Strofades colony (Ionian Sea/Greece) during the early phase of the chick-rearing period (late July 2019). The samples consisted of barbs and barbules of the primary feathers, P1 and P10, reflecting pollution pressures at the time and the place of feather growth, i.e., at the species' breeding and wintering grounds for P1 and P10, respectively. There were 25 PFAS detected in the feathers, with detection rates ranging from 2% (perfluorododecanoic acid—PFDoDA; perfluorohexane sulfonate—PFHxS; 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate—9Cl-PF3ONS; 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)propanoate—Gen-X) to 98% (sodium 1H,1H,2H,2H-perfluorooctane sulfonate; 6:2 FTSA). ∑PFAS ranged from 25.93 ng/g to 426.86 ng/g of feather sample. The highest mean concentration (109.10 ng/g feather) was reported for perfluorononanoic acid (PFNA). No significant differences in PFAS concentrations with high detection rate (>20%) were found according to the sex of the birds. PFAS concentrations with a detection rate > 20% in the P1 vs. P10 feathers of Scopoli's Shearwater adults were not significantly different, reflecting the fact that breeding grounds in the Mediterranean and wintering grounds in the Atlantic seem to be contaminated with similar PFASs levels, even though some compounds showed regional trends. [ABSTRACT FROM AUTHOR]

Populations of marine top predators have been sharply declining during the past decades, and one‐third of chondrichthyans are currently threatened with extinction. Sustainable management measures and conservation plans of large pelagic sharks require knowledge on population genetic differentiation and demographic connectivity. Here, we present the case of the Mediterranean blue shark (Prionace glauca, L. 1758), commonly found as bycatch in longline fisheries and classified by the IUCN as critically endangered. The management of this species suffers from a scarcity of data about population structure and connectivity within the Mediterranean Sea and between this basin and the adjacent Northeast Atlantic. Here, we assessed the genetic diversity and spatial structure of blue shark from different areas of the Mediterranean Sea and the Northeast Atlantic through genome scan analyses. Pairwise genetic differentiation estimates (FST) on 203 specimens genotyped at 14,713 ddRAD‐derived SNPs revealed subtle, yet significant, genetic differences within the Mediterranean sampling locations, and between the Mediterranean Sea and the Northeast Atlantic Ocean. Genetic differentiation suggests some degree of demographic independence between the Western and Eastern Mediterranean blue shark populations. Furthermore, results show limited genetic connectivity between the Mediterranean and the Atlantic basins, supporting the hypothesis of two distinct populations of blue shark separated by the Strait of Gibraltar. Although reproductive interactions may be limited, the faint genetic signal of differentiation suggests a recent common history between these units. Therefore, Mediterranean blue sharks may function akin to a metapopulation relying upon local demographic processes and connectivity dynamics, whereby the limited contemporary gene flow replenishment from the Atlantic may interplay with currently poorly regulated commercial catches and large‐scale ecosystem changes. Altogether, these results emphasise the need for revising management delineations applied to these critically endangered sharks. [ABSTRACT FROM AUTHOR]

In many intact African savannah ecosystems, martial eagles are the top avian predator, while lions are the top terrestrial predator. Here, we report seven records of martial eagle predation or attempted predation of lion cubs in the greater Mara region, Kenya. These events resulted in the death of nine lion cubs, most of which were at least partially consumed, and are the first detailed records of this behaviour to be published. While these observations represent intraguild interactions, we suggest that they reflect neither intraguild predation nor interspecific killing. Rather, the ecology of both species coupled with the details of our records suggest that martial eagles opportunistically kill lion cubs purely to eat them. We hope that by publishing these records we will encourage others to share their observations of raptors predating on large mammalian carnivores, thus improving our understanding of a behaviour that we suspect may be more widespread than the current lack of evidence suggests. [ABSTRACT FROM AUTHOR]

Simple Summary: Sharks, as important members of marine food webs, are often targeted by commercial and sport fishing, and moreover they constitute a significant part of the bycatch along with marine mammals and turtles. Overfishing, especially of top-predator species, disrupts the entire food web through a process called "mesopredator release", where the removal of top predators leads to an increase in mid-level predators, altering the ecosystem balance. Despite their crucial ecological role, there is limited information on sharks' diets. Traditional methods like stomach content analysis and newer, less invasive techniques, such as stable isotope analysis (SIA) of muscle tissue biopsies, provide insights into their feeding habits. A study on the pyjama shark or striped catshark (Poroderma africanum), a species native to South Africa, used SIA to explore its trophic ecology. The study found that as pyjama sharks grow, their diet shifts from more planktonic species as juveniles to more benthic prey. Juvenile sharks have a more varied diet, while adults are more selective. Although the pyjama shark population is increasing, according to the IUCN, there is a lack of structured monitoring programmes and catch data. Understanding the trophic ecology of mesopredators like the pyjama shark is crucial for predicting the impacts of their predation on marine ecosystems. Sharks may occupy both intermediate and upper levels of marine food webs. They are overfished worldwide and constitute one of the largest portions of the bycatch. The removal of top-predator species has negative cascading effects on the entire food web, causing the "mesopredator release" phenomenon, which leads to an increase in mesopredators with consequent changes in the ecosystem's energetic balance. Despite their important ecological role, information on their trophic ecology is limited. This essential information can be obtained through the analysis of stomach contents and, more recently, by using less invasive techniques, such as the stable isotope analysis of muscle tissue, obtained through biopsies. Here, we analysed the trophic ecology of the pyjama shark or striped catshark Poroderma africanum, an endemic species of South Africa, by means of SIA. The results obtained from SIA were analysed using the R SIMMR and SIBER packages to estimate the contribution of potential food sources to the diet and to evaluate the extent of the trophic niches. The SIMMR outputs showed that adults select more benthic prey than juveniles, which consume more planktonic species, with juveniles being more generalist than adults, according to SIBER outputs. As assessed by IUCN, the population of P. africanum is increasing, and given its role as mesopredator, future monitoring efforts could be crucial to elucidating their potential effects in marine food webs. [ABSTRACT FROM AUTHOR]

This article discusses a case of nest predation involving a Japanese Sparrowhawk and a Siberian Weasel in China. The researchers observed the weasel attacking the sparrowhawk and taking all of the nestlings and the remaining unhatched egg. The study highlights the vulnerability of small raptors to nest predation and its potential impact on their reproductive success. The document is a list of literature cited in a research article on various topics related to raptors, including breeding biology, nesting habits, and behavior, with studies conducted in different regions. The topics explored in the cited literature range from nesting failure to population decline and include aspects such as fearfulness, competitive interactions, migration routes, and parental investment theory. [Extracted from the article]

The Eurasian Eagle-Owl (Bubo bubo) shows reversed sexual size dimorphism. We aimed to evaluate morphological size differences between the sexes of the smallest eagle-owl subspecies (B. b. kiautschensis), for which little morphometric information is available, and to develop a discriminant function for sex using a minimum number of morphometric parameters. We compared nine morphological measurements of 41 genetically or anatomically sexed eagle-owls admitted to a Korean wildlife rescue center and used discriminant function analysis of 29 birds (17 female, 12 male) with complete measurement data of nine biometrics. We developed four equations using three measurements (total length, head length, and weight) that had 86–96% accuracy for sexing Korean Eagle-Owls. The subspecies-specific morphometric data and discriminant functions we developed can help fill the current knowledge gap regarding the morphological characteristics of this little-known subspecies, benefiting researchers, wildlife managers, and veterinarians who work with or study this apex predator in the Korean forest ecosystem. [ABSTRACT FROM AUTHOR]

Size‐ and species‐selective harvest inevitably alters the composition of targeted populations and communities. This can potentially harm fish stocks, ecosystem functionality, and related services, as evidenced in numerous commercial fisheries. The high popularity of rod‐and‐reel recreational fishing, practiced by hundreds of millions globally, raises concerns about similar deteriorating effects. Despite its prevalence, the species and size selectivity of recreational fisheries remain largely unquantified due to a lack of combined catch data and fisheries‐independent surveys. This study addresses this gap by using standardised monitoring data and over 60,000 digital angling catch reports from 62 distinct fisheries. The findings demonstrate a pronounced selectivity in recreational fisheries, targeting top predators and large individuals. Catch‐and‐release practices reduced the overall harvest by 60% but did not substantially alter this selectivity. The strong species‐ and size‐specific selectivity mirror patterns observed in other fisheries, emphasising the importance of managing the potential adverse effects of recreational fisheries selective mortality and overfishing. [ABSTRACT FROM AUTHOR]

An association of eighteen coprolites (specimens 01–18) and one isolated coprolite (specimen 209,210) were found in a vertebrate fossil-rich paleosol at the Gratkorn site (south-eastern Austria; late Middle Miocene). The specimens consist mostly of calcium phosphate (apatite) and a matrix formed by microglobules. Coprolites 01–18 show cylindrical and spherical morphologies and are considerably smaller than the tube-shaped specimen 209,210, in which no inclusions were observed. In contrast, coprolites 01–18 contain numerous, highly altered bone fragments (sub-mm-sized long bones and several mm-sized trabecular bone remains) as well as hair imprints, plant detritus and palynomorphs. Based on composition, morphology, size, microstructure, and inclusions, and considering the body fossil record of this site, we assume the hyaenid Protictitherium and the barbourofelid Albanosmilus, as producers of coprolites 01–18 and 209,210, respectively. The preserved bone remains in specimens 01–18 suggest that Protictitherium fed on small vertebrates, but possibly also cracked bones of medium-sized animals. The hair imprints found were either from the hyaenid itself or its prey, while the plant material was probably ingested accidentally. The lack of inclusions in specimen 209,210 is related to the presumably hypercarnivorous diet of Albanosmilus, which was certainly the apex predator in this biome. [ABSTRACT FROM AUTHOR]

Climate change is impacting marine species, leading to shifts in their distribution to higher latitudes and to deeper locations. Parasite communities are dynamic systems influenced by biotic and abiotic factors, making them valuable tools for studying ecological processes of their hosts. This work aims to assess possible changes in parasite structure that occurred in the northern stock of Cynoscion guatucupa in the Argentine Sea, over approximately 25 years, by using parasites as tags in a region characterized as a hotspot of significant warming in recent decades. Parasite assemblages of adult and juvenile fish from two periods caught at two regions of the Argentine Sea were analyzed. Species richness remained relatively constant across samples, although four of the eight compared species from juvenile fish showed significant increases in prevalence, while for adults three species decreased. Differences in parasite assemblages were significant between periods, but not between regions, indicating that the stock structure has apparently remained stable in recent years, even under a warming process that, in turn, seems to have affected its parasite assemblages which however, continue showing homogeneous parasitological attributes throughout the habitats. Most results indicate that changes in parasite burdens are not related to the population density or geographic distribution of C. guatucupa, but to changes in temperature, salinity or in the density of top predators. Parasites seem to have felt the impact of global change before their host, thus, they can be considered early sentinels to monitor the stability and distribution of this important resource. [ABSTRACT FROM AUTHOR]

The white shark (Carcharodon carcharias) is a globally distributed top predator. Due to its ecological importance and historical declining population trends, data contributing to conservation initiatives (e.g. habitat protections and resource management) pertaining to all life stages of this species are essential to facilitate population recovery. Of particular interest, the locations and discrete seasonality of C. carcharias parturition remain uncertain. Understanding C. carcharias parturition in relation to each population is relevant to population recovery since neonate to young-of-the-year (YOY) sharks are more vulnerable to predation and particularly threatened by and susceptible to commercial fishing pressure. Herein, this paper provides a synthesis from published literature across seven well-studied C. carcharias populations to identify common trends associated with parturition location, seasonality, and habitat characteristics. The data reviewed in this study are consistent with previous population-specific hypotheses, that C. carcharias parturition occurs during spring and summer for all populations. Further, this review also indicates that parturition likely occurs in insular shelf waters and water temperatures ranging from15.7 to 23.1 °C. Although discrete parturition sites were not identified, the compiled data are suggestive that C. carcharias parturition may occur over horizontal and vertical spatial scales that exceed the inshore, shallow water environments associated with nursery area habitat to perhaps minimize predation by conspecifics. Due to the vulnerability of C. carcharias, conducting non-lethal technological (e.g., baited remote underwater video systems—BRUVS), morphological (i.e., ontogenetic changes in dorsal fin shape), and reproductive (e.g., blood chemistry and ultrasonography) research that may help identify parturition location and seasonality are thus warranted. [ABSTRACT FROM AUTHOR]

Microplastics have been found in the gastrointestinal (GI) fluid of bottlenose dolphins (Tursiops truncatus), inhabiting Sarasota Bay, FL, suggesting exposure by ingestion, possibly via contaminated fish. To better understand the potential for trophic transfer, muscle and GI tissues from 11 species of dolphin prey fish collected from Sarasota Bay were screened for microplastics (particles < 5 mm diameter). Suspected microplastics were found in 82% of muscle samples (n = 89), and 97% of GI samples (n = 86). Particle abundance and shapes varied by species (p < 0.05) and foraging habit (omnivore vs. carnivore, p < 0.05). Pinfish (Lagodon rhomboides) had the highest particle abundance for both tissue types (muscle: 0.38 particles/g; GI: 15.20 particles/g), which has implications for dolphins as they are a common prey item. Findings from this study support research demonstrating the ubiquity of estuarine plastic contamination and underscore the risks of ingestion exposure for wildlife and potentially seafood consumers. [ABSTRACT FROM AUTHOR]