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Southern hemisphere blue (Balaenoptera musculus intermedia) and fin (Balaenoptera physalus) whales are the largest predators in the Southern Ocean, with similarities in morphology and distribution. Yet, understanding of their life history and foraging is limited due to current low abundances and limited ecological data. To address these gaps, historic Antarctic blue (n = 5) and fin (n = 5) whale baleen plates, collected in 1947-1948 and recently rediscovered in the Smithsonian National Museum of Natural History, were analyzed for bulk (δ13C and δ15N) stable isotopes. Regular oscillations in isotopic ratios, interpreted as annual cycles, revealed that baleen plates contain approximately 6 years (14.35 ± 1.20 cm year-1) of life history data in blue whales and 4 years (16.52 ± 1.86 cm year-1) in fin whales. Isotopic results suggest that: (1) while in the Southern Ocean, blue and fin whales likely fed at the same trophic level but demonstrated niche differentiation; (2) fin whales appear to have had more regular annual migrations; and (3) fin whales may have migrated to ecologically distinct sub-Antarctic waters annually while some blue whales may have resided year-round in the Southern Ocean. These results reveal differences in ecological niche and life history strategies between Antarctic blue and fin whales during a time period when their populations were more abundant than today, and before major human-driven climatic changes occurred in the Southern Ocean.

Food habits are traces of a species' natural history that help us to understand how the organisms interact with the environment. Hylaeamys seuanezi is a forest-specialist rodent also recorded in diverse shaded cocoa agroforestry systems. Here we describe and classify its diet, comparing the results acquired from stomach and fecal contents, collected in forest and cocoa agroforest sites. We analyzed 203 samples from 126 individuals: 51 captured in agroforest and 75 in forest. We measured the relative contribution of vegetable and animal matter and the relative frequency of 17 food items. Our results indicate that H. seuanezi consumes a greater proportion of vegetable than animal matter, but should be considered omnivore, given the frequent consumption of arthropods. The richness and composition of items was similar between stomach and fecal samples. The richness of items also did not vary between the environments, but the composition of the items did. Intact seeds were more frequent in samples from forests and unidentified arthropods and Hymenoptera in samples from agroforest. Despite variation among consumed items, the diverse shaded cocoa agroforestry systems provide a diversity of resources, which likely favor the maintenance of H. seuanezi in these plantations and in the study region. [ABSTRACT FROM AUTHOR]

The Bolkar Mountain Viper, Montivipera bulgardaghica (Nilson & Andren, 1985), is a mountain viper found in the eastern Mediterranean region. In this study, we present data on the seasonal variation in diet composition across two different habitats in the Central Taurus Mountains of Anatolia, Türkiye. The Karboğazı population inhabits a subalpine shrubland, while the Göller Yaylası population resides in forested land. The vipers primarily consumed Lacertidae (47%), followed by Orthoptera (27%), Chilopoda (18%), and Scincidae (8%) in number. In spring, the diet of the Karboğazı population was mainly composed of Lacertidae but shifts toward Orthoptera during summer and autumn. In contrast, the Göller Yaylası population fed on Lacertidae throughout the entire active season. Overall, the Karboğazı population primarily consumed invertebrates, whereas the Göller Yaylası population predominantly fed on lizards. Both populations exhibited partial niche overlap. There was no significant difference in diet composition between sexes, but prey type and quantity varied with the season. Prey diversity increased in summer and decreased in autumn and spring, corresponding with the prey availability in the environment. [ABSTRACT FROM AUTHOR]

This study uses telemetry and stomach content analysis to describe the ringed seals' dive pattern and prey selection within Kangia (Ilulissat Icefjord), Greenland, where the ringed seals are known to be exceptionally large and genetically distinct. Data from twenty-four ringed seals (Pusa hispida) tagged in Kangia, with satellite relay data loggers from 2012 to 2020, were used to describe the dive patterns. The transmitters were active between 28 and 270 days and showed that subadults most frequently dove to around 150 m. Adult males frequently dove to this depth, but they also had a second frequently visited depth at around 400 m, some adults significantly deeper. Adult males generally dove deeper than females and adult seals showed deeper dives during the winter, a feature that was less prominent in subadults. The stomach content from ringed seals (n = 108) harvested in Kangia by subsistence hunters revealed that polar cod (Boreogadus saida), capelin (Mallotus villosus), mysids (Mysis oculata, M. littoralis, M. Polaris) and shrimps (mainly Pandalus borealis) were the dominant prey. Shrimps were observed more often in adults, likely due to the frequently visited dive depth of around 400 m, whereas mysids were more observed in small subadult seals. The stomach content from harp seals (Pagophilus groenlandicus) and Greenland halibut (Reinhardtius hippoglossoides) caught in Kangia also showed a strong niche overlap with the ringed seals. These findings outline the unique ecological adaptations and the importance of Kangia as a critical habitat of ringed seals. [ABSTRACT FROM AUTHOR]

Data on the dietary preferences of species can provide important information that deepens our knowledge of their evolutionary history and contemporary ecology. The combination of low detectability and irregular feeding frequency of snakes has limited the resolution of available diet data for many of these species. A variety of methodologies exist for collecting snake feeding data, however, each of these varies in their strengths and biases. Here, we contrast characterisations of the diet of the brown house snake, Boaedon capensis, based on three common approaches to collecting feeding data: 1) examining gut contents from preserved museum specimens, 2) reviewing published literature, and 3) crowdsourcing feeding records from community science platforms. Gut contents included only mammal and reptile prey, presenting a significantly narrower diet breadth (Levins’ Ba = 0.12) than the community science (Levins’ Ba = 0.66) and literature (Levins’ Ba = 0.49) datasets, which both also included amphibian and avian prey. Interpretation of museum data alone conveys that B. capensis has a relatively specialised, mammal-dominated diet whereas the community science and literature datasets indicate a much wider dietary breadth. Our findings reiterate the importance of utilising multiple methods to assess the dietary composition of snakes to provide a more comprehensive understanding of their feeding ecology. [ABSTRACT FROM AUTHOR]

Achelous spinimanus, a species of swimming crab found along the Western Atlantic from the USA to Brazil, inhabits coastal areas up to 90 m deep across various substrates. While these crabs are known to be omnivorous, the extent of their predatory behaviour remains unclear. This note documents the first record of A. spinimanus actively preying on live fish. In the observed interaction, the fish was still alive and moving its operculum and mouth while being eaten. The observation was made during a night dive at Ilha dos Porcos, Arraial do Cabo, Brazil, where a crab was seen preying on a live Malacoctenus zaluari. The behaviour suggests that A. spinimanus may employ sit‐and‐wait strategy, utilizing its strong chelipeds for capturing prey. Such records are crucial for understanding the trophic dynamics and ecological roles of marine species, emphasizing the importance of both scientific and citizen science contributions to biodiversity knowledge. This finding also underscores the importance of further research on the feeding and behavioural ecology of portunids. [ABSTRACT FROM AUTHOR]

In Lake Erie, yellow perch Perca flavescens support vast commercial and recreational fisheries, yet populations have recently declined. Using N = 5889 yellow perch stomachs collected from 1997 to 2021, we explored trends in the feeding ecology and trophic level of yellow perch with generalized additive models. Models revealed a significant decrease in yellow perch trophic level (−0.15 trophic levels in the last decade), and significant dietary shifts. Yellow perch have shifted away from feeding on piscine prey and round goby Neogobius melanostomus over the 25-year period, and now feed on invertebrates more frequently—including invasive waterfleas (Bythotrephes longimanus and Cercopagis pengoi) and chironomids. Dietary patterns appear to reflect broad ecological changes—invasive waterfleas have proliferated while populations of forage fish and round goby have declined. Furthermore, hypoxia events have increased in duration and severity, which may explain observed increases in chironomid consumption, which are hypoxia tolerant. This study demonstrates trophic adaptability in yellow perch, which have changed feeding behavior and trophic position in response to novel invaders and changing environmental conditions. [ABSTRACT FROM AUTHOR]

As more and more species are in decline, understanding the various aspects underlying their population dynamics is crucial to optimise conservation efforts. Hereto, we studied the diet composition and reproductive performance of Gull-billed Terns forming the last breeding population in Central Europe by analysing population-level data collected between 2011 and 2022 as part of a conservation program. We show that the main prey types vary among breeding stages and across years. When observed foraging for themselves, Gull-billed Terns were mainly found to eat insects, whereas crabs and worms were the main prey items used for courtship feeding and chick provisioning. The proportion of prey of terrestrial origin used for courtship feeding increased over the study period, whereas no such change was observed in prey used for self-feeding or chick provisioning. Clutch and egg size also increased over the study period but were not correlated with the proportion of terrestrial prey used in courtship. Fledging success did not change over time and was not correlated with variation in chick diet. These results confirm that the Gull-billed Terns in this population are generalist feeders and suggest that their breeding success is not currently threatened by a lack of, or changes in, specific prey types. The shift towards more terrestrial prey in part of their diet may, however, indicate changes in the aquatic ecosystem, which should be further assessed, together with other potential risks for these threatened birds, such as inbreeding and pollution. [ABSTRACT FROM AUTHOR]

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Globally, key predators such as lobsters are thought to control urchins. In southeastern Australia, the role of Sagmariasus verreauxi (eastern rock lobster) as a key predator of the native urchin Centrostephanus rodgersii (long-spined urchin) has been questioned while the sympatric Heliocidaris erythrogramma (short-spined urchin) may be eaten more frequently. To test this, we tethered and filmed 100 urchins (50 C. rodgersii and 50 H. erythrogramma) outside of a lobster den over 25 nights to identify predators and quantify predation rates, time to feeding onset and handling time. Sagmariasus verreauxi exhibited very low predation rates (4%), despite being filmed walking past urchins repeatedly whereas Heterodontus galeatus (crested horn shark) was the main predator (45%). Predation rates by all predators (lobsters and sharks) were influenced primarily by tethering night but not urchin size or species. Predation increased throughout the study and while H. erythrogramma and C. rodgersii were eaten at similar rates, there was a trend for lobsters to eat H. erythrogramma and sharks to eat C. rodgersii. Feeding onset had no significant predictors though large C. rodgersii took longer to handle during feeding for both predators. Importantly, sharks readily consumed 25 C. rodgersii up to 121 mm Test Diameter (TD) while lobsters only ate one C. rodgersii (58 mm TD). These findings, although from only one test location, provide important insights into the species eating urchins and highlight the potential significance of overlooked predators such as H. galeatus. [ABSTRACT FROM AUTHOR]

The nature of symbiotic relationships between organisms can be difficult to assess and may range from commensalism, to mutualism, and parasitism. Trophic linkage and feeding ecology are essential to disentangle symbiont-host relationships/interactions. Amphipods of the genus Dactylopleustes are known as urchin symbionts. Though their ecology remains largely unknown, Dactylopleustes was recently reported to aggregate on diseased hosts, suggesting that Dactylopleustes feeds on diseased urchins' tissues and uses urchins as both a habitat and prey. We investigated by DNA metabarcoding analyses, the feeding ecology of Dactylopleustes yoshimurai in relation to growth and disease status of the host (Strongylocentrotus intermedius). Contrary to our hypothesis, sequence reads from the gut contents were dominated by planktonic copepods regardless of body size or host disease status. These results suggest that they mainly feed on copepod fecal pellets deposited on sediments, and do not have a strong trophic linkage with their host. Large individuals on diseased urchins feed more on urchins than those on healthy urchins. However, their main prey still remains copepods, implying that host disease has a limited effect on the feeding behavior. In conclusion, our study indicates that this species is mainly commensal, but also may parasitize its host depending on the situation. [ABSTRACT FROM AUTHOR]

Although extinct sloths exhibited a wide range of dietary habits, modes of locomotion, and occupied various niches across the Americas, modern sloths are considered quite similar in their habits. The dietary habits of living sloths can be directly observed in the wild, and understanding the mechanical behavior of their jaws during chewing through finite element analysis (FEA) provides a valuable validation tool for comparative analysis with their extinct counterparts. In this study, we used FEA to simulate the mechanical behavior of sloth mandibles under lateral mastication loads, using it as a proxy for oral processing. Our research focused on the six extant sloth species to better understand their diets and validate the use of FEA for studying their extinct relatives. We found that all living sloths have the predominancy of low‐stress areas in their mandibles but with significant differences. Choloepus didactylus had larger high‐stress areas, which could be linked to a reduced need for processing tougher foods as an opportunistic generalist. Bradypus variegatus and Choloepus hoffmanni are shown to be similar, displaying large low‐stress areas, indicating greater oral processing capacity in a seasonal and more competitive environment. Bradypus torquatus, Bradypus pygmaeus, and Bradypus tridactylus exhibited intermediary processing patterns, which can be linked to a stable food supply in more stable environments and a reduced requirement for extensive oral processing capacity. This study sheds light on extant sloths' dietary adaptations and has implications for understanding the ecological roles and evolutionary history of their extinct counterparts. [ABSTRACT FROM AUTHOR]

Golden cuttlefish play a significant role in the food web of the East and Yellow Seas and are a valuable fishery resource in Chinese coastal waters. Samples of golden cuttlefish were obtained from the northern East China Sea between September 2021 and March 2022, and stable isotope methods were utilized in this study to examine the variations in the forage ecology of golden cuttlefish. Our findings reveal dynamic shifts in carbon and nitrogen stable isotopes (δ13C and δ15N), highlighting intricate foraging strategies tailored to growth and environmental changes. A notable trend emerges: an initial growth-linked rise in δ13C and δ15N enrichment, followed by seasonal fluctuations mirroring seasonal food availability. The ontogenetic niche evolution displays striking habitat shifts and trophic level escalation in small mantle length stages, transitioning to niche overlap and subtle trophic shifts later on. Sex-specific differences emerge, with females occupying higher trophic levels than males in most samples. This comprehensive study underscores the complexity and adaptability of golden cuttlefish feeding ecology, inviting further inquiry into their intricate relationships within the marine ecosystem. [ABSTRACT FROM AUTHOR]

The Wadden Sea is an important habitat for a large number of fish species, supporting functions such as reproduction, breeding and feeding. The hooknose (Agonus cataphractus, Linnaeus, 1758) is a resident demersal fish species of the Wadden Sea, but due to its non-commercial importance it is rarely studied. In the present study, the feeding strategy and prey selection of the hooknose related to the benthic in- and epifauna in the field were investigated in six different habitat types (circalittoral sand, circalittoral mud, circalittoral mixed sediments, circalittoral coarse and gravel sediments, sublittoral sandbanks and reefs) in coastal waters of the German Wadden sea between 2020 and 2021. The stomach contents of A. cataphractus were dominated in most of the habitat types by very mobile epibenthic prey species, mainly the brown shrimp (Crangon crangon, Linnaeus, 1758), amphipods (Ampelisca spp., Microprotopus maculatus, Norman 1867) and cumaceans (Diastylis bradyi, Norman 1879, Pseudocuma longicorne, Bate 1858), similar to the benthic communities in the field. Infauna species such as the tube-building polychaete Lanice conchilega (Pallas 1766) were rarely consumed and potentially avoided due to their ability to withdraw below the feeding depths. Our results further showed habitat-specific differences in the hooknose diet, especially in reefs, where skeleton shrimps (caprellids) dominated the diet. The habitat type also influences the condition of A. cataphractus being highest in reefs but lowest on sandbanks. Our results highlight the importance of knowledge functional relationships between smaller-sized Wadden Sea fish species and its typical habitats, which in turn is essential for applicable management measures of the whole Wadden Sea area. [ABSTRACT FROM AUTHOR]

Digestion is driven by digestive enzymes and digestive enzyme gene copy number can provide insights on the genomic underpinnings of dietary specialization. The Adaptive Modulation Hypothesis (AMH) proposes that digestive enzyme activity, which increases with increased gene copy number, should correlate with substrate quantity in the diet. To test the AMH and reveal some of the genetics of herbivory vs carnivory, we sequenced, assembled, and annotated the genome of Anoplarchus purpurescens, a carnivorous prickleback fish in the family Stichaeidae, and compared the gene copy number for key digestive enzymes to that of Cebidichthys violaceus, a herbivorous fish from the same family. A highly contiguous genome assembly of high quality (N50 = 10.6 Mb) was produced for A. purpurescens, using combined long-read and short-read technology, with an estimated 33,842 protein-coding genes. The digestive enzymes that we examined include pancreatic α-amylase, carboxyl ester lipase, alanyl aminopeptidase, trypsin, and chymotrypsin. Anoplarchus purpurescens had fewer copies of pancreatic α-amylase (carbohydrate digestion) than C. violaceus (1 vs. 3 copies). Moreover, A. purpurescens had one fewer copy of carboxyl ester lipase (plant lipid digestion) than C. violaceus (4 vs. 5). We observed an expansion in copy number for several protein digestion genes in A. purpurescens compared to C. violaceus, including trypsin (5 vs. 3) and total aminopeptidases (6 vs. 5). Collectively, these genomic differences coincide with measured digestive enzyme activities (phenotypes) in the two species and they support the AMH. Moreover, this genomic resource is now available to better understand fish biology and dietary specialization.

Abstract Chaohusaurus is an early ichthyosauriform represented by three species known from the Early Triassic of Chaohu, Anhui Province, China, with a fourth species—Chaohusaurus zhangjiawanensis—known from the Nanzhang-Yuan’an region of Hubei Province. In contrast to the Chaohusaurus species from Chaohu, Chaohusaurus zhangjiawanensis remains poorly known, hindering our understanding of early ichthyosauriform evolution. Here, we report a new specimen of Chaohusaurus zhangjiawanensis, which provides new information on its dentition. The new specimen confirms that Chaohusaurus zhangjiawanensis had heterodont dentition consisting of pointed anterior teeth and robust, rounded posterior teeth, indicating a generalist diet. The posterior teeth of Chaohusaurus zhangjiawanensis are more robust (broader and larger) than the posterior dentition of Chaohusaurus chaoxianensis and Chaohusaurus brevifemoralis from Chaohu. This suggests differences in hard-shelled prey preference between species of Chaohusaurus from Chaohu and Nanzhang-Yuan’an, with Chaohusaurus zhangjiawanensis likely capable of feeding on harder and larger prey than Chaohusaurus brevifemoralis and Chaohusaurus chaoxianensis. In turn, this probably reflects differences in durophagous prey availability between the shallow-marine palaeoecosystem of Nanzhang-Yuan’an and the deeper, slope-basin palaeoecosystem of Chaohu. The posterior dentition and forefin of Chaohusaurus zhangjiawanensis are strikingly similar to those of Chaohusaurus geishanensis, the rarest species of Chaohusaurus from the Chaohu fauna. The scarcity of Chaohusaurus geishanensis in the Chaohu fauna, and its morphological similarity to Chaohusaurus zhangjiawanensis, possibly indicate that Chaohusaurus geishanensis was closely related with Chaohusaurus zhangjiawanensis and that it was also a shallow-marine species that was not a typical component of the Chaohu fauna. It probably occasionally wandered out into the deeper waters of Chaohu from a nearby coastal environment.

We compared Snowy Owl feeding ecology from 15 breeding season studies throughout Nearctic and Palearctic circumpolar regions. We used raw data and information theory to assess the owls’ feeding niche. Combined studies yielded 59,923 prey items, of which 59,585 were used for calculations. Overall, mean food niche breadth (FNB) was narrow: H′ = 1.95; R = 1.60, D = 0.526. In 10 of 15 studies, lemmings were > 71.8% of the owls’ diet. In four studies, Lemmus was > 90% of the diet, and in three studies Dicrostonyx was >90% of the diet. In three other studies, Lemmus represented 71.8%, 73.8%, and 84.0% of the diet. In one study, Lemmus and Dicrostonyx were about equal: 49.1% and 47.5%. In the four remaining studies, Microtus and Clethrionomys voles were important. In contrast, of 5888 winter prey items from seven North American studies, the mean FNB (H′ = 4.61) was twice that of 15 breeding season scores, FNB (H’ = 1.95). The Snowy Owl is primarily an obligate lemming predator for breeding. Changes to population ecology and distribution of lemmings due to climate change will have direct affects and effects on the Snowy Owls’ reproductive output. The conservation of Snowy Owls is the conservation of lemmings.

Orthetrum sabina is one of the most common dragonflies found in Nepal, but its feeding behavior has not often been reported from there. An example of this species preying on Neurothemis tullia is reported from Maidi Lake, Nepal. This observation was made during a field survey of Odonata using direct observation along transects around the lake. It adds to our knowledge of the species' feeding behavior, elaborating the previous findings and providing scope for further ecological studies on Odonata. [ABSTRACT FROM AUTHOR]

Chaohusaurus is an early ichthyosauriform represented by three species known from the Early Triassic of Chaohu, Anhui Province, China, with a fourth species—Chaohusaurus zhangjiawanensis—known from the Nanzhang-Yuan'an region of Hubei Province. In contrast to the Chaohusaurus species from Chaohu, Chaohusaurus zhangjiawanensis remains poorly known, hindering our understanding of early ichthyosauriform evolution. Here, we report a new specimen of Chaohusaurus zhangjiawanensis, which provides new information on its dentition. The new specimen confirms that Chaohusaurus zhangjiawanensis had heterodont dentition consisting of pointed anterior teeth and robust, rounded posterior teeth, indicating a generalist diet. The posterior teeth of Chaohusaurus zhangjiawanensis are more robust (broader and larger) than the posterior dentition of Chaohusaurus chaoxianensis and Chaohusaurus brevifemoralis from Chaohu. This suggests differences in hard-shelled prey preference between species of Chaohusaurus from Chaohu and Nanzhang-Yuan'an, with Chaohusaurus zhangjiawanensis likely capable of feeding on harder and larger prey than Chaohusaurus brevifemoralis and Chaohusaurus chaoxianensis. In turn, this probably reflects differences in durophagous prey availability between the shallow-marine palaeoecosystem of Nanzhang-Yuan'an and the deeper, slope-basin palaeoecosystem of Chaohu. The posterior dentition and forefin of Chaohusaurus zhangjiawanensis are strikingly similar to those of Chaohusaurus geishanensis, the rarest species of Chaohusaurus from the Chaohu fauna. The scarcity of Chaohusaurus geishanensis in the Chaohu fauna, and its morphological similarity to Chaohusaurus zhangjiawanensis, possibly indicate that Chaohusaurus geishanensis was closely related with Chaohusaurus zhangjiawanensis and that it was also a shallow-marine species that was not a typical component of the Chaohu fauna. It probably occasionally wandered out into the deeper waters of Chaohu from a nearby coastal environment. [ABSTRACT FROM AUTHOR]

Simple Summary: It is common knowledge that Snowy Owls eat lemmings during the nesting season, and it is believed that lemming populations fluctuate dramatically over several years, often termed a cycle. When lemming populations reach high densities, Snowy Owls have a highly successful breeding season, producing numerous young per nest. This successful nesting results in large numbers of young Snowy Owls migrating south during their first winter. This movement, generally called an irruption migration, has been known for over a century, and stirs the admiration of the public. Indeed, each time an irruption migration happens, it is among the most popular wildlife viewing events in North America. Given this predator–prey relationship between Snowy Owls and lemmings, we were interested in quantifying how important lemmings were to Snowy Owls throughout their worldwide breeding range. Of the 15 studies we reviewed, 59,923 prey items were recorded. Lemmings were clearly the most important food source for breeding Snowy Owls, but voles were sometimes also important. Given the near obligate dependency on lemmings for breeding, one wonders how a changing climate will affect lemming populations and distribution, and consequently Snowy Owl breeding. And, will this affect the Snowy Owl breeding population, resulting in fewer young Snowy Owls migrating south during an irruption migration. We compared Snowy Owl feeding ecology from 15 breeding season studies throughout Nearctic and Palearctic circumpolar regions. We used raw data and information theory to assess the owls' feeding niche. Combined studies yielded 59,923 prey items, of which 59,585 were used for calculations. Overall, mean food niche breadth (FNB) was narrow: H′ = 1.95; R = 1.60, D = 0.526. In 10 of 15 studies, lemmings were > 71.8% of the owls' diet. In four studies, Lemmus was > 90% of the diet, and in three studies Dicrostonyx was >90% of the diet. In three other studies, Lemmus represented 71.8%, 73.8%, and 84.0% of the diet. In one study, Lemmus and Dicrostonyx were about equal: 49.1% and 47.5%. In the four remaining studies, Microtus and Clethrionomys voles were important. In contrast, of 5888 winter prey items from seven North American studies, the mean FNB (H′ = 4.61) was twice that of 15 breeding season scores, FNB (H' = 1.95). The Snowy Owl is primarily an obligate lemming predator for breeding. Changes to population ecology and distribution of lemmings due to climate change will have direct affects and effects on the Snowy Owls' reproductive output. The conservation of Snowy Owls is the conservation of lemmings. [ABSTRACT FROM AUTHOR]

Metabarcoding is emerging as an alternative to morphological methods in noninvasive carnivore diet analysis based on scats. A number of metabarcoding markers have been developed but their comparative performance to recover DNA from scats remains mostly untested. We tested three markers covering a wide taxonomic range of prey items and compared them with the results of a morphological analysis. Morphological and genetic methods performed comparably regarding the identity of detected prey species, but the number of identified species varied strongly between markers. Only one, 12S-V5, amplified successfully in all samples and proved to be robust and reliable when working with the highly degraded DNA obtained from scats. [ABSTRACT FROM AUTHOR]

Species of Plesionika Spence Bate, 1888 holds significant importance in the commercial harvesting of deep-sea shrimps along the southern coasts of India. Despite Plesionika quasigrandis Chace, 1985 being a crucial resource on the southwest coast of India, there is a need for comprehensive information on its food and feeding habits. We investigated the diet of P. quasigrandis in relation to sex, size, and season. The species exhibited a diet primarily consisting of crustaceans, foraminiferans, and detritus. Both males and females showed a noteworthy reliance on detritus, as indicated by an index of preponderance values exceeding 45.8. The species displayed active scavenging behaviour alongside predatory dietary habits. We observed a decrease in feeding intensity from pre-monsoon to post-monsoon in both males and females. Permutational multivariate analysis of variance (PERMANOVA) revealed significant differences in the diets of P. quasigrandis , considering the combined effects of size and sex (P < 0.01). No significant distinctions were noted in the diet composition between males and females in relation to season. [ABSTRACT FROM AUTHOR]

This article discusses the feeding behavior of Atlantic herring in coastal waters, specifically in Greifswald Bay in the Baltic Sea. The researchers found that adult herring caught in the fall had unexpectedly consumed demersal fishes and large invertebrates, rather than the expected zooplankton. This behavior was consistent over multiple years of sampling. In contrast, herring stomachs in the spring were mostly empty. The study highlights the importance of considering the feeding traits of marine fish in population models and the need for more holistic approaches in food web science. [Extracted from the article]

Relationships between species and their habitat are strongly related to their feeding habits making its description essential for understanding the species' biology and plan their conservation. This study describes the diet of giant anteaters (Myrmecophaga tridactyla), a specialist insectivorous mammal, and evaluates potential sex-related intraspecific variation. We analyzed fecal matter from live individuals and from road-kills (N = 29 individuals) collected from October 2018 to April 2020 in the Cerrado savanna of Mato Grosso do Sul, Brazil. Anteater's diet was described by the relative frequency (RF; proportion of the sample mass represented by the prey item) and the frequency of occurrence (FO; proportion of samples in which the item was detected) of each prey item, which was classified to the lowest taxonomic level possible. The diet was composed of 14 morphotypes of termites (Blattodea), 28 morphotypes of ants (Formicidae) and grass seeds (Poacea). They fed primarily on termites (FO = 89.65%; RF = 75.85%) and ants (FO = 100%; RF = 23.08%), with no significant differences between sexes. Termites of the genus Syntermes (RF = 75.55%) represented most of the dietary sample mass, and ants of the genus Pheidole represented the most frequent item found in the samples (FO = 96.55%). M. tridactyla is a myrmecophagous specialist that consumes a great richness of prey species associated with multiple habitats. Hence, the preservation of the natural heterogeneity of the Cerrado landscape and their habitats is essential for the conservation of this vulnerable species. [ABSTRACT FROM AUTHOR]

Marine sunfishes (also known as molids) of the Family Molidae are widely distributed from tropical to temperate waters and are typically recognized as predators of gelatinous plankton almost exclusively. Despite similar morphological features and behaviors, the trophic ecology and potential interactions among species of molids remain largely unknown. We reviewed literature on the diets of each species and conducted diet analyses of three species sampled off the east coast of Taiwan. We examined diet separation among sympatric species—ocean sunfish Mola mola, bumphead sunfish Mola alexandrini, and sharptail sunfish Masturus lanceolatus—through stomach content and stable isotope analyses. A literature review revealed that the Family Molidae exhibits broader diets than previously characterized. Mola mola, M. alexandrini, and M. tecta consume prey from epi/mesopelagic environments, while M. lanceolatus and slender sunfish Ranzania laevis consume prey from both epi/mesopelagic environments and benthic habitats. No gelatinous prey was found in the stomachs of R. laevis. Off Taiwan, M. mola and M. alexandrini had similar and relatively narrow diet breadths, primarily feeding on scyphozoans, suggesting similar trophic niches. In contrast, M. lanceolatus displayed a broader diet, mainly consuming tunicates and augmenting their diet from epi- and mesopelagic, coastal, and benthic habitats. Dietary differences between M. lanceolatus and the other species might be linked to morphological differences such as gape size and eye length. Mola mola and M. alexandrini tend to have larger gapes and eyes and our diet analysis shows that they forage on larger sized prey and at greater depths. [ABSTRACT FROM AUTHOR]

Sardinops melanostictus is mainly distributed in Northwest Pacific Ocean, which is significantly affected by climate change. The carbon and nitrogen stable isotope ratios of the muscles of Japanese sardines from the Northwest Pacific Ocean were measured based on samples taken by the ocean-going fishery resources survey ship "Songhang" in the high seas of the Northwest Pacific Ocean between June and July 2021. The GAM model was then used to examine the effects of both biotic (body length) and abiotic (Latitude, sea surface temperature, offshore distance, chlorophyll-a) factors on the stable nitrogen isotopes; The differences in the trophic niche among sex and body length groups were also analyzed in Japanese sardines in Northwest Pacific Ocean. The results showed that there was no significant difference in muscle δ13C and δ15N between males and females during La Niña years. However, both δ13C and δ15N differed among body length groups. The GAM model's results showed that as body length increases, both δ13C and δ15N exhibited a trend of first decreasing and then increasing; δ13C also exhibits this trend with increasing latitude; δ15N exhibits a negative correlation with both offshore distance and chlorophyll-a. The overlap rate between female and male niche is generally high, with a similar niche width between females and males ranging from 100 to 160 mm. The width of the ecological niche varied across the length groups, and its position changed with growth. However, compared to males, females have substantially broader niches, ranging from 161 to 220 mm. In contrast to usual years, the La Niña year's readings for δ13C and δ15N are all low. The study demonstrates that the feeding ecology of Japanese sardines in Northwest Pacific Ocean varies depending on sex and body length, and that changes in the marine environmental elements under La Niña events affected the feeding ecology of Japanese sardines. [ABSTRACT FROM AUTHOR]

Globally, key predators such as lobsters are thought to control urchins. In south-eastern Australia, the role of Sagmariasus verreauxi (eastern rock lobster) as a key predator of the native urchin Centrostephanus rodgersii (long-spined urchin) has been questioned while the sympatric Heliocidaris erythrogramma (short-spined urchin) may be eaten more frequently. To test this, we tethered and filmed 100 urchins (50 C. rodgersii and 50 H. erythrogramma) outside of a lobster den over 25 nights to identify predators and quantify predation rates, time to feeding onset and handling time. Sagmariasus verreauxi exhibited very low predation rates (4%), despite being filmed walking past urchins repeatedly whereas Heterodontus galeatus (crested horn shark) was the main predator (45%). Predation rates by all predators (lobsters and sharks) were influenced primarily by tethering night but not urchin size or species. Predation increased throughout the study and while H. erythrogramma and C. rodgersii were eaten at similar rates, there was a trend for lobsters to eat H. erythrogramma and sharks to eat C. rodgersii. Feeding onset had no significant predictors though large C. rodgersii took longer to handle during feeding for both predators. Importantly, sharks readily consumed 25 C. rodgersii up to 121 mm Test Diameter (TD) while lobsters only ate one C. rodgersii (58 mm TD). These findings, although from only one test location, provide important insights into the species eating urchins and highlight the potential significance of overlooked predators such as H. galeatus.

In lotic ecosystems, a higher availability of allochthonous food resources is expected during floods and rainfall events, which may yield a higher consumption of these resources by consumers. However, allochthonous input and seasonality in environmental conditions are locally dependent. Thus, dietary responses of freshwater consumers to seasonality should also be locally dependent. Herein, we applied a meta‐analytical approach to identify the spatial and seasonal environmental variables associated with the relative consumption of allochthonous food resources by fishes from tropical lotic ecosystems in different seasons.We gathered 566 observations of the diet of fish populations (i.e., restricted to the same sampling event) from 38 studies conducted in 70 localities across the tropics during flood and drought periods (hereafter, high‐water and low‐water periods, respectively). We retrieved latitude, seasonal channel width, elevation and two proxies for allochthonous input for each locality: terrestrial biomass (without considering seasonality) and the normalised difference vegetation index (NDVI; considering seasonality). Then, we applied meta‐regression models using these environmental variables as predictors and the proportion of allochthonous food resources in each consumer's diet (%Allo) as the response variable.Our models revealed that the diet of fishes from tropical lotic ecosystems is mostly autochthonous‐based, independent of the hydrological period (high‐water or low‐water), and aquatic invertebrates were the most consumed food items. Terrestrial vegetation biomass and elevation predicted increasing allochthony in the diet of tropical fishes for high‐water, but only terrestrial biomass predicted allochthony at low‐water periods. We found no relationship between latitude, channel width or NDVI with allochthony.Our study highlights the importance of considering the hierarchical level of biological organisation and fish trophic guilds for understanding seasonal patterns of relative consumption of allochthonous and autochthonous food resources by fishes. We also argue that variations in seasonality across the tropics are likely to have undermined its influence on allochthony in fish diets. The absence of a non‐relationship between channel width and allochthony provides evidence that the River Continuum Concept is better suited to temperate lotic ecosystems.Our results provide novel insights and the big‐picture of seasonal pattern in the diets of tropical fishes for use in future local empirical studies, improving forecasting of the relationship between the factors underpinning the availability of allochthonous and autochthonous food resources, and the diet of freshwater fishes. [ABSTRACT FROM AUTHOR]

Mammalian carnivores exert direct and indirect effects on communities through top-down control and trophic ecology studies are helpful to understand the ecological processes behind these interactions. However, most diet studies reveal only local patterns. Large-scale biogeographic and anthropogenic drivers can also influence carnivore diet patterns. We investigated how latitude, altitude and human disturbance drive changes in Geoffroy's cat (Leopardus geoffroyi) diets on a large geographical scale. Seventeen articles addressing the diet of Geoffroy's cat were reviewed. We estimated the effects of drivers on three diet descriptor variables: diet composition, mean mammal-prey size and diet specialization. Our results uncover the primary use of prey around 300 g in body weight, such as Ctenomys and Cavia, through most of the geographic gradient. Only latitude and altitude caused replacement of prey species in diet composition. An increase in latitude led to higher diet specialization and larger prey selection, possibly guided by an increase in Lepus spp. consumption. Higher altitudes and an intensification of human disturbances decreased diet specialization and prey-size. Lastly, diet specialization increased with consumption of large prey. This further increases our understanding of Geoffroy's cat broad adaptive capacity throughout South America. [ABSTRACT FROM AUTHOR]

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Identifying novel medicinal resources in chimpanzee diets has historically presented challenges, requiring extensive behavioral data collection and health monitoring, accompanied by expensive pharmacological analyses. When putative therapeutic self‐medicative behaviors are observed, these events are often considered isolated occurrences, with little attention paid to other resources ingested in combination. For chimpanzees, medicinal resource combinations could play an important role in maintaining well‐being by tackling different symptoms of an illness, chemically strengthening efficacy of a treatment, or providing prophylactic compounds that prevent future ailments. We call this concept the self‐medicative resource combination hypothesis. However, a dearth of methodological approaches for holistically investigating primate feeding ecology has limited our ability to identify nonrandom resource combinations and explore potential synergistic relationships between medicinal resource candidates. Here we present two analytical tools that test such a hypothesis and demonstrate these approaches on feeding data from the Sonso chimpanzee community in Budongo Forest, Uganda. Using 4 months of data, we establish that both collocation and APRIORI analyses are effective exploratory tools for identifying binary combinations, and that APRIORI is effective for multi‐item rule associations. We then compare outputs from both methods, finding up to 60% agreement, and propose APRIORI as more effective for studies requiring control over confidence intervals and those investigating nonrandom associations between more than two resources. These analytical tools, which can be extrapolated across the animal kingdom, can provide a cost‐effective and efficient method for targeting resources for further pharmacological investigation, potentially aiding in the discovery of novel medicines. Highlights: New methods needed for holistically evaluating chimpanzee diets.Collocation and APRIORI analyses are effective tools for finding nonrandom resource combinations.Relatively high level of agreement between methods.Effective tool for exploring feeding ecology data sets and discovering novel self‐medicative resources. [ABSTRACT FROM AUTHOR]

Documenting intra-specific diet variations among remote populations, thus across different habitats, is important to address evolutionary (e.g., phenotypic plasticity) and conservation issues (e.g., capacity to adapt to changing prey availability). We compared the diet of different populations of Asp vipers (Vipera aspis aspis ; Linnaeus, 1758) living in contrasted habitats of France and Switzerland. We sampled 1680 individuals in five geographical areas, broadly encompassing the distribution range of the species (West to East and North to South): Group 1 = Western Central France; Group 2 = Central France; Group 3 = West France; Group 4 = South France, and Group 5 = Switzerland. We compared mean total body size (TL) of snakes and their diet. We found strong similarities among the groups with a predominance of micromammals in the diet. In mountainous area (Group 5), however, snakes included a substantial number of reptiles and fed occasionally on amphibians and birds. The diet varied ontogenetically (juveniles often consuming lizards, adults heavily feeding on mammals) and sexually (females tending to feed more extensively on mammals). Overall, our results suggest that Asp vipers maintain a diet largely based on micromammals (mostly voles), at least across their continental distribution range. [ABSTRACT FROM AUTHOR]

The Psychedelic Rock Gecko (Cnemaspis psychedelica), is a species endemic to southernmost Vietnam. It was recently assessed as Endangered in the IUCN Red List and also included in the CITES Appendix I, due to anthropogenic threats such as habitat degradation and over-collection for the pet trade. To protect wild populations and the natural habitat of this species, knowledge of its demography and ecology is essential to implement fitting conservation measures. In this study, we conducted field surveys on Hon Khoai Island, Ca Mau Province, southern Vietnam in both dry and wet seasons, and obtained food contents of 114 individuals of C. psychedelica by water-flushing the stomach without sacrificing them. Consequently, 685 invertebrate items were identified, belonging to 24 different prey types of 20 invertebrate orders, as well as flatworms, snails and plant parts. Araneae, Blattodea, Hymenoptera and Isoptera were identified as the most important prey of C. psychedelica , among which Araneae accounted for the highest percentage, and thus the highest importance index, during the dry season and Hymenoptera during the wet season. There was a large overlap in the trophic niche between the two seasons, and between males and females of C. psychedelica. This study shows that not only suitable habitat but also a particular food spectrum is a requirement for the species and this, in addition, is important to optimize conservation breeding programs. [ABSTRACT FROM AUTHOR]

In Germany, wolves live in a human-dominated landscape. The return of the wolf to Germany more than 20 years ago is a prime example of successful nature conservation; however, it has also led to conflict due to the high degree of landscape fragmentation and the feeding habits of the wolf. Here, the wolf diet composition was studied based on an analysis of 11,225 scats. Wolves in Germany mainly feed on wild ungulates, which comprise more than 94% of their diet. The predominant species are roe deer and wild boar, whereby in most territories roe deer dominate the diet composition. Depending on availability, red deer and fallow deer may also make up a high proportion of the diet. Seasonal and territorial variation in diet composition has been noted even in directly neighboring territories. Wolves preferentially hunt juveniles of the main prey species. With the exception of the mouflon, which has all but disappeared locally, no other ungulate species has vanished from the wolf's diet. This study provides an overview of the varied diet of wolves in Germany since recolonization more than 20 years ago. [ABSTRACT FROM AUTHOR]

Research about feeding ecology of fish is important to understand individual behavior and population development, which is also the basic to analyze trophic structure and function of aquatic ecosystems. Chaetrichthys stigmatias is one of the key species in the Haizhou Bay fisheries ecosystem, which has critical ecological niche within the food web. In this study, we collected samples through bottom trawl surveys during the fall of 2018 in the Haizhou Bay, and analyzed the feeding ecology of C. stigmatias based on both stomach content analysis and stable isotope technology. The results showed that the primary diet groups for C. stigmatias were Ophiuroidea and Shrimp, including Ophiothrix marenzelleri, Ophiopholis mirabilis, Ophiura sarsii, Penaeidae, and Alpheus japonicus. The range of δ13C values of C. stigmatias was from -19.39% to -15.74%, with an average value of (-18.07± 0.87)%, which had no significant correlation with body length. The range of δ15N values was from 8.16%c to 12.86%, with an average value of (10.14± 1.51)%, which was positively correlated with body length. The trophic level of C. stigmatias showed a positive relationship with body length, with an average value of (3.74±0.34) and a range value of 3.32 to 4.20 among different size groups. The contribution rates of different prey groups varied significantly. Based on the structural equation modeling, we found that the feeding intensity of C. stigmatias was primally influenced by body length, sea bottom salinity, sea bottom temperature, and water depth, with a particularly significant positive correlation with body length. The combination of stable isotope technology and stomach content analysis methods could contribute to comprehensive understanding on the feeding ecology of C. stigmatias, providing essential data and foundation for research on trophic structures and resource conservation in the Haizhou Bay ecosystem. [ABSTRACT FROM AUTHOR]

The trophic ecology of fishes in the genus Rhamdia remains poorly reported. Here, we aim to describe the diet composition and infer the trophic levels, niche breadth, and niche overlap between Rhamdia guatemalensis and Rhamdia laticauda in northeast Oaxaca, Mexico. Fishes were sampled using an electrofishing device between 2016 and 2017. We calculated the Quotient index and the diet composition was analyzed using the percentage of the Index of Relative Importance (%IRI) to analyze possible ontogenetic and sexual differences on feeding ecology. We then calculated the trophic niche breadth using the Levins´ standardized index (BA). Trophic levels (TLk) of each species were calculated using the trophic index and trophic niche overlap using Pianka´s index (Ojk). The results indicate that both species are carnivorous and tend to prey on aquatic insects, with R. guatemalensis feeding on nine different orders of animals and R. laticauda displaying a broader diet spectrum, encompassing 19 orders. Our data showed ontogeny and sex differences in the trophic ecology of R. guatemalensis. They were secondary consumers (TLk > 3) and showed a specialized diet (BA < 0.4). We found evidence of trophic niche partitioning between adults (Ojk = 0.40) and females (Ojk = 0.42). Our results highlight the fundamental role of this species in the area as a carnivorous/insectivorous, predatory fishes, secondary consumers, and biological control for Diptera, Ephemeroptera, and Megaloptera. Both species minimize the trophic overlap through food resource partitioning mediated by fish body size. Additionally, adults and females consume different prey, which allows the coexistence of closely related species. Our findings regarding trophic ecology could be crucial for devising conservation and management plans for these particular Rhamdia species. [ABSTRACT FROM AUTHOR]

Copyright of Marine Mammal Science is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The changes in the stable isotope ratios of carbon (δ13C), nitrogen (δ15N), oxygen (δ18O), and mercury (Hg) concentrations in muscle and liver tissues during and after lactation were studied in killer whales stranded along the coast of Hokkaido, in the northern area of Japan (n = 16). Calf muscles displayed δ13C- and δ15N-enriched peaks and a δ18O-depleted peak during lactation. The δ13C- and δ15N-enriched peaks appear to reflect the extensive nursing of 13C- and 15N-enriched milk and the onset of weaning, whereas the δ18O-depleted peak may be attributable to the extensive nursing of 18O-depleted milk and the onset of weaning. The δ13C and δ15N values tended to gradually increase after the weaning, whereas the δ18O values tended to decrease. The δ13C and δ15N levels in calves were similar between liver and muscle samples, whereas those in mature animals were higher in liver than in muscle samples. The isotopic turnover rates of C and N may be similar between the liver and muscle tissues in calves, which are rapidly growing animals. The Hg concentrations in muscle tissues were slightly higher in small calves than in large calves, probably due to the Hg transfer across placenta. The Hg concentrations in liver and muscle samples increased with increasing body length, and those in two liver samples from mature animals exceeded the high-risk threshold for marine mammal health effects (82 μg/wet g). [ABSTRACT FROM AUTHOR]

Polar bears (Ursus maritimus) depend on sea ice to hunt their ice‐associated prey. However, climate‐induced sea ice loss is leading to changes in space‐use strategies of polar bears, with bears in some subpopulations spending more time on land or selecting alternative habitats. One such documented alternative habitat is glacier ice, which provides year‐round access to prey, although the feeding habits of polar bears using glacier ice relative to those following the retreating ice and/or seasonally moving onshore are not known. Here, we use adipose tissue from polar bears (n = 104) from the Baffin Bay subpopulation live‐captured in Northwest Greenland during the springs of 2009–2013 to investigate dietary patterns between space‐use strategies inferred from satellite telemetry data, while considering demographic and interannual variation. Using quantitative fatty acid signature analysis (QFASA) to generate diet estimates, ringed seals (Pusa hispida) and bearded seals (Erignathus barbatus) were estimated as the primary and secondary prey of Baffin Bay polar bears for all sex/age classes and sampling years, apart from a single anomalous year (2009) with a relatively high proportion of beluga (Delphinapterus leucas) and narwhal (Monodon monoceros). While demographic and short‐term temporal variation was minimal, fatty acid signatures and QFASA‐generated diet estimates clearly differed between polar bears using coastal and offshore space‐use strategies. "Offshore" adult females (n = 31), which make long‐distance movements across the Baffin Bay pack ice, had high proportions of C22‐chain length monosaturated fatty acids and diet estimates that included beluga, narwhal, harp (Pagophilus groenlandicus), and hooded seal (Cystophora cristata). "Coastal" adult females (n = 6), which remain resident at glacier fronts in Northwest Greenland year‐round including during the sea ice‐free season, consumed proportionally more ringed seals (+13%) and similar proportions of bearded seal, but essentially no beluga and narwhal or harp and hooded seal. Thus, space‐use strategy is a driver of intrapopulation diet variability. As space‐use strategies change with ongoing loss of sea ice habitat, our results suggest important ramifications for polar bear feeding patterns. [ABSTRACT FROM AUTHOR]

Expanding knowledge on natural history of carnivores allows to understand mechanisms species developed for survival and improve decision-making aiming conservation. Studies on eco-morphological aspects of skunks, such Conepatus amazonicus, are scarce and usually based on small sampling size. We assessed roadkill individuals, camera trap records, and biometric data to describe the feeding ecology, activity period, and morphology of striped hog-nosed skunk in agroecosystems and protected areas in Central Brazil. Invertebrates represented critical items in the diet in agroecosystems, and due to an intermediate niche breadth (0.545), skunks could not be classified as specialists or generalists. Males and females have total niche overlap (0.94), and the diversity of items was not affected by proximity to urban centres. Animals develop their activities during the night, with 93% (n = 71) of records from sunset to sunrise. There were significant sex differences in the body masses (t = − 3.7151; d.f. = 29; P < 0.0001). Males (mean = 2.56 kg) were 30% heavier than females (mean = 1.96 kg), allowing us to infer the existence of sexual dimorphism in C. amazonicus. Foot size and dentition were also larger in males, corroborating the sexual selection hypothesis. Behavioural and morphological adaptations favour predation on insects, prey of low physical resistance, which are also available in agroecosystems. This is the first study to report sexual dimorphism in C. amazonicus. Our results fill a gap in the knowledge of a species that plays a unique role for ecosystem functioning, suggesting that skunks represent the primary medium-sized omnivorous-insectivorous organism occupying the Brazilian Savanna. [ABSTRACT FROM AUTHOR]

Context: Hydrological dynamics are crucial in fish ecology. Aims: To evaluate the effect of the flood pulse on the feeding ecology of Doras higuchii in the reduced-flow section of the Belo Monte dam, Xingu River, Brazil. Methods: Collections were conducted between December 2020 and November 2021. The fish were measured and had their stomachs removed. Muscle tissue was also extracted for stable-isotope analysis. Stomach contents were inspected to assess diet, testing the influence of hydrological periods by using GLM. In addition, we evaluated the effect of the flood pulse on the δ13C and isotopic ratios of individuals Results: In total, 362 specimens of D. higuchii were analysed, highlighting a diet mainly on the basis of sediment (74.9%) and aquatic insects (24.8%), not varying between periods characterising the species as a specialist for having detritivorous habit, as well as the extension of the trophic niche. There was variation in food intensity, with higher average food consumption in the flood period. The isotopic composition (δ13C and δ15N) also did not differ between periods. Finally, δ15N did not vary by length class. Conclusions: This information helps understand the interface between environmental and biological factors in an environment affected by a hydroelectric dam. Implications: Our results may help fill gaps in knowledge about the diet of doradid fishes. Exploring what fish eat is important to understand how changes in the environment can affect their lives. In this study, we looked into the diet of an Amazonian catfish in a river affected by the construction of a dam. We found that the catfish mostly fed on sediment and aquatic insects, and these feeding habits were not strongly influenced by changes in the local water levels. [ABSTRACT FROM AUTHOR]

Abstract The quality of swans' nutrition at spring migration stopovers is important for their successful breeding. It is of great interest to study the differences in nutrition of different swan species when sharing the same habitat. Microscopic analysis of Cygnus olor, C. cygnus, and C. columbianus bewickii feces collected in the eastern part of the Gulf of Finland in February-April 2014–2019 was performed. We measured food preferences of the three swan species using non-metric multidimensional scaling (NMDS). The width and overlap of dietary niches were also calculated. The diet of C. olor consists almost entirely of soft submerged aquatic vegetation, mainly macroalgae. Samples of the other two species except macroalgae contained large amounts of young shoots and roots of rigid semi-submerged and coastal vegetation. The dietary niche of C. cygnus is the most isolated because it is dominated by thick rhizomes of Phragmites australis, which are hardly used by other swan species. The diet of Bewick’s swans was similar in many respects to that of the Mute swan, but Bewick’s swans much more often preferred vegetative parts of submerged and semi-submerged plants, such as Stuckenia pectinata, Potamogeton perfoliatus, Sparganium sp., Nuphar lutea, and others. Notably, the dietary niches of Mute swan and Whooper swan overlapped as much as possible in February March during a period of severe food shortage, in contrast to later periods in spring when food was more abundant and varied. In general, differences in diets are well explained by differences in the morphology of birds. Comparison of tarsometatarsus indices shows that C. olor is the most water-related species. C. olor has the longest neck and its beak has the strongest filter features, whereas beaks of the other two species shows noticeable “goose-like grazing” features. Moreover, C. Cygnus has the most powerful beak. These features are due to the history of species. The formation of C. olor occurred during the Miocene-Pliocene of the Palaearctic in the warm eutrophic marine lagoons of the Paratethys with abundant soft submerged vegetation. The evolution of C. cygnus and C. c. bewickii took place in Pleistocene. At that time, periglacial and thermokarst water bodies on permafrost became widespread in the Palearctic, as well as dystrophic peat lakes with much poorer submerged aquatic vegetation, but well-developed coastal and semi-submerged vegetation.

The link between skull shape and dietary ecology in birds at macroevolutionary scales has recently been called into question by analyses of 3D shape that reveal that cranial anatomy is mainly influenced by other factors such as allometry. It is still unknown whether this form‐function disconnect also exists at smaller evolutionary scales, for example within specialized ecological guilds. Vultures are a diverse guild of 23 extant species in two families (Accipitridae and Cathartidae) that exhibit evolutionary convergence as a result of highly specialized feeding ecology. Vultures are the only known obligate scavengers among vertebrates and are usually grouped together under this single dietary category, but within this specialized diet there are three distinct, species‐specific feeding strategies termed ripper, gulper, and scrapper. We use three‐dimensional geometric morphometrics to quantify the relative contributions of feeding ecology, allometry, and phylogeny on vulture skull shape, along with several non‐vulture raptors of similar size, range and ecology. Families show clear separation in shape, but phylogenetic signal is comparatively weak (Kmult = 0.33). Taking into account the influence of phylogeny, skull shape is not significantly correlated with either skull size or feeding type, but there are examples of strong, significant convergence and parallel shape evolution across feeding groups. Furthermore, skull shape performs strongly in predicting feeding ecology in a phylogenetic discriminant function analysis. These findings highlight the importance of detailed assessment of feeding behavior in studies of ecomorphology, rather than broader dietary categories alone, and reveal that ecology can be readily inferred from form given appropriate information. [ABSTRACT FROM AUTHOR]

Simple Summary: Climate change in the high latitudes may endanger cold-water fish that have adapted to the low water temperatures and long winters. Northern oligotrophic lakes, with their naturally sparse food basis for fish, may be especially vulnerable to climate change. However, many aspects of northern fish food ecology have received little attention. We evaluated the dietary habits, trophic positions, and food web interactions of the European vendace, which is regarded as one of the most vulnerable commercial fishes due to modern environmental changes. Using two analyses, fish stomach content and stable isotopes (carbon and nitrogen), we tracked the flow of nutrients through the food web of an example lake (at the White Sea basin) and determined the vendace's main food sources. In spite of clear seasonal differences in the food preferences of vendace, we determined planktonic copepods to be its key energy (carbon) source. The vendace has also adapted to consume its own embryos during the winter, increasing its trophic position in the lake food web. These findings contribute to a better understanding of the vendace's feeding habits, its ability to adapt to low-trophic supplies, and the effects of environmental change. The seasonal feeding patterns of the cold-adapted fish, Coregonus albula, are poorly studied in high-latitude lakes but could provide insight for predicting the effects of global warming. We examined vendace's diet composition, traced the carbon and nitrogen isotope ratios from producers to consumers in the food web, and estimated vendace's trophic position in a subarctic lake (the White Sea basin). Results showed the vendace to be a typical euryphagous fish, but clear seasonal differences were found in the relative importance of plankton and benthos in the diet. The vendace consumed primarily benthic amphipods in the summer, planktonic cladocerans in the autumn, and copepods in the winter–spring (under ice); larvae of aquatic insects were the second-most important food items throughout the year. Because of the substantial proportion of fish embryos in its diet, the vendace had a trophic position similar to that of a predatory fish (perch). The Bayesian food source-mixing model revealed that the majority of vendace energy derives from planktonic copepods. The dominant Cyclops had the lowest carbon isotope values, suggesting a carbon-depleted diet typical for methanotrophic bacteria, as its probable food source was in a lake under ice. Understanding the feeding patterns of vendace provides information to better predict the potential biotic effects of environmental change on lake ecosystems. [ABSTRACT FROM AUTHOR]

Wireworms, the larval stage of pest click beetle species (Coleoptera: Elateridae), are pests of many crops in North America including root vegetables and cereals. There is cause for concern amongst growers who are facing pressure from wireworms because there are a decreasing number of effective pesticides that can be used for wireworm management. Most research on pest elaterids has focused on the wireworm stage, which is the damage causing life stage. Recently, the focus in elaterid research has shifted to the adult click beetle stage, including identification of semiochemicals and development of effective traps. However, there is still a lot to be discovered about the basic biology of click beetles, including their feeding ecology. In an effort to understand the feeding ecology of click beetles, we investigated the presence of plant DNA in the digestive tracts of Limonius californicus (Mann.), L. canus (LeConte), and L. infuscatus (Mots.) beetles collected in 3 different locations within central Washington. To examine dietary histories of beetles and wireworms, specimens were collected from natural habitats and high-throughput sequencing of the plant genes trnF and ITS was used to identify their dietary history. Results revealed that click beetles do feed on a large variety of plants, which included a large quantity of brassicaceous plants commonly found in areas surrounding wireworm infested plots. The identification of the dietary history of the click beetles allowed us to infer their landscape-scale movements thus providing a means to better understand their behavior. [ABSTRACT FROM AUTHOR]