Dietary Items Research Articles

Antihypertensive and Vasorelaxant Effects of Citrus aurantifolia Linn. Fruit: Proposed Mechanisms.

Background Citrus aurantifolia Linn. fruit, a natural dietary item, has long been used traditionally to treat hypertension in Pakistan. The current research work aims to explore the effect on blood pressure and its mechanisms. Methods The aqueous methanol extract of plant fruit was used to evaluate hypotensive/antihypertensive, vasorelaxation, and safety profiles. Moreover, the in vitro inhibitory effect of AMECA on phosphodiesterase was also evaluated. Results In hypotensive studies, extracts of Citrus aurantifolia fruit exhibited a concentration-dependent reduction in SBP, DBP, MAP, and heart rate. A similar effect has been observed on anesthetized rats, but the effects exerted by the extract were not altered significantly in the presence of L-NAME, atropine, captopril, and propranolol. Moreover, in coronary arteries, the extract significantly potentiated relaxations induced by cGMP- and cAMP-dependent relaxing agonists. When exposed to PDEs, the extract concentration dependently subdued cGMP-hydrolyzing activity of different PDEs with IC50 values of 40–130 μg/mL. Conclusion It is conceivable that extracts obtained from Citrus aurantifolia fruit produced hypotensive and antihypertensive effects in rats. The extract elicited endothelium-independent vasorelaxation, possibly by acting directly on smooth muscles of the coronary artery and by increasing cGMP and cAMP via nonselective inhibition of vascular PDEs.

Validation of quantitative fatty acid signature analysis for estimating the diet composition of free-ranging killer whales

Accurate diet estimates are necessary to assess trophic interactions and food web dynamics in ecosystems, particularly for apex predators like cetaceans, which can regulate entire food webs. Quantitative fatty acid analysis (QFASA) has been used to estimate the diets of marine predators in the last decade but has yet to be implemented on free-ranging cetaceans, from which typically only biopsy samples containing outer blubber are available, due to a lack of empirically determined calibration coefficients (CCs) that account for fatty acid (FA) metabolism. Here, we develop and validate QFASA for killer whales using full blubber from managed-care and free-ranging individuals. First, we compute full, inner, and outer blubber CCs from the FA signatures across the blubber layers of managed-care killer whales and their long-term diet items. We then run cross-validating simulations on the managed-care individuals to evaluate the accuracy of diet estimates by comparing full-depth and depth-specific estimates to true diets. Finally, we apply these approaches to subsistence-harvested killer whales from Greenland to test the utility of the method for free-ranging killer whales, particularly for the outer blubber. Accurate diet estimates for the managed-care killer whales were only achieved using killer whale-specific and blubber-layer-specific CCs. Modeled diets for the Greenlandic killer whales largely consisted of seals (75.9 ± 4.7%) and/or fish (20.4 ± 2.4%), mainly mackerel, which was consistent with stomach content data and limited literature on this population. Given the remote habitats and below surface feeding of most cetaceans, this newly developed cetacean-specific QFASA method, which can be applied to outer-layer biopsies, offers promise to provide a significant new understanding of diet dynamics of free-ranging odontocetes and perhaps other cetacean species throughout the world’s oceans.

Migraine Prevalence and Analysis of Dietary Habits in Relation to Headache in the Female Population: A Single-Center Study From Jeddah, Saudi Arabia

IntroductionLifestyle-related factors including dietary intake can significantly increase the chances of developing migraine. Some components of food items are thought to induce the release of vasoactive substances leading to the dilation of blood vessels, which in turn results in migraine episodes. This research aimed to assess the prevalence of migraine and examine the relation of the headache to the dietary patterns of female students and employees of King Saud bin Abdulaziz University for Health Sciences (KSAU-HS) - Jeddah experiencing migraine attacks as well as to assess the relationship between the migraine attacks and the available dietary items served at the food outlets within the campus.MethodsTwo questionnaires were developed for this study. The first questionnaire was a short survey asking about the characteristics of headaches. This survey aimed to estimate the prevalence of migraine among female students and employees in KSAU-HS. Of the participants who filled the first questionnaire, those who met the International Classification of Headache Disorders (ICDH-III) criteria for migraine were given a second questionnaire to further understand the characteristics of their migraine headaches and to assess lifestyle and diet-related aggravating factors.ResultsThe final sample size for the calculated prevalence was 410; 352 were students and 58 were faculty members. It has been found that 165 (40.24%) participants of the KSAU-HS female population met the criteria for migraine. Two (2.2%) reported an association between chocolate consumption and headaches and seven (7.8%) reported a significant association between caffeine and headaches. No specific association was perceived by the respondents between migraine attacks and the following food items: citrus fruits, pickles, cheese, and dairy products.ConclusionOur study revealed that the widespread trends for excessive consumption of coffee and caffeinated beverages at food outlets within the educational institution are occult triggers for headache attacks in a significant portion of students with migraine. The recent shift in dietary habits in our community for excessive consumption of coffee and other tyramine-rich food items has negative consequences on productivity and the economy. Our results can be conceivably extrapolated to reflect the effect of dietary habits on other streams of society, including companies, firms, schools, and workplaces that are driven by the new dietary trends.

Genus-specific and Habitat-dependent Plant Ingestion in West African Sabre-toothed Frogs (Anura, Odontobatrachidae: Odontobatrachus)

Although frogs are predominately opportunistic carnivores, numerous studies report large amounts of plant material in anuran stomachs, citing accidental ingestion as the likely cause. Herein, we present evidence suggesting deliberate plant uptake in the Sabre-toothed Frog (Odontobatrachus ziama) and propose that this trait is specific to the entire family Odontobatrachidae. We performed stomach-flushing on 814 frogs, resulting in 665 dietary samples comprising all 5 Odontobatrachus species and two similar-sized, syntopic frogs, Astylosternus occidentalis and Conraua alleni. We collected dietary samples across the entire range of Odontobatrachus, in both wet and dry season. Additionally, we collected stomach contents of an O. ziama population during a 12-d capture–mark–recapture study in three different river habitats and compared the consumed and available plant material. We found that all Odontobatrachus spp. ingested the pinnate leaf of the riparian tree Parkia bicolor. These leaves were the most abundant food items in the stomachs of three out of the five Odontobatrachus species. Although mean proportional uptake of the leaflets did not differ seasonally, the maximum amount of leaflets was greater during the dry season, coinciding with peak leaflet availability. We found up to 100 single leaflets in stomachs of Odontobatrachus arndti, but syntopic Astylosternus and Conraua had ingested considerably smaller quantities of Parkia leaflets. Lastly, we found a greater prevalence of Parkia leaflets in females, with significant variation in leaflet uptake between stream microhabitats that could not be explained by the availability of the plant material. Consequently, we analyzed the dietary items for co-occurrences of plant material and preyed-upon animals that would support the hypothesis of an accidental uptake. However, we could not find biologically meaningful co-occurrences. Based on the combined results of stomach-flushing, availability of food items, absence of meaningful co-occurrences of plant with animal matter and feeding experiment, we concluded that leaflets were likely swallowed deliberately, but not eaten for energy demands. The reason for the deliberate ingestion of plant material across the genus Odontobatrachus so far remains unresolved. Key words: Astylosternus occidentalis; Conraua alleni; Frog diet; Guinea; Herbivory; Parkia bicolor; Stomach-flushing

To Regulate or Not to Regulate: Assimilation of Dietary Fatty Acids in the Temperate Copepod Temora longicornis

Consumer regulation of lipid composition during assimilation of dietary items is related to their ecology, habitat, and life cycle, and may lead to extra energetic costs associated with the conversion of dietary material into the fatty acids (FAs) necessary to meet metabolic requirements. For example, lipid-rich copepods from temperate and polar latitudes must convert assimilated dietary FAs into wax esters, an efficient type of energy storage which enables them to cope with seasonal food shortages and buoyancy requirements. Lipid-poor copepods, however, tend to not be as constrained by food availability as their lipid-rich counterparts and, thus, should have no need for modifying dietary FAs. Our objective was to test the assumption thatTemora longicornis, a proxy species for lipid-poor copepods, does not regulate its lipid composition. Isotopically-enriched (13C) diatoms were fed to copepods during a 5-day laboratory experiment. Compound-specific stable isotope analysis of algae and copepod samples was performed in order to calculate dietary FA assimilation, turnover, and assimilation efficiency into copepod FAs. Approximately 65% of the total dietary lipid carbon (C) assimilated (913 ± 68 ng C ind-1at the end of the experiment) was recorded as polyunsaturated FAs, with 20 and 15% recorded as saturated and monounsaturated FAs, respectively. As expected,T. longicornisassimilated dietary FAs in an unregulated, non-homeostatic manner, as evidenced by the changes in its FA profile, which became more similar to that of their diet. Copepods assimilated 11% of the total dietary C (or 40% of the dietary lipid C) ingested in the first two days of the experiment. In addition, 34% of their somatic growth (in C) after two days was due to the assimilation of dietary C in FAs. Global warming may lead to increased proportions of smaller copepods in the oceans, and to a lower availability of algae-produced essential FAs. In order for changes in the energy transfer in marine food webs to be better understood, it is important that future investigations assess a broader range of diets as well as lipid-poor zooplankton from oceanographic areas throughout the world’s oceans.

DNA metabarcoding reveals a broad dietary range for Tasmanian devils introduced to a naive ecosystem.

Top carnivores are essential for maintaining ecosystem stability and biodiversity. Yet, carnivores are declining globally and current in situ threat mitigations cannot halt population declines. As such, translocations of carnivores to historic sites or those outside the species’ native range are becoming increasingly common. As carnivores are likely to impact herbivore and small predator populations, understanding how carnivores interact within an ecosystem following translocation is necessary to inform potential remedial management and future translocations. Dietary analyses provide a preliminary assessment of the direct influence of translocated carnivores on a recipient ecosystem. We used a metabarcoding approach to quantify the diet of Tasmanian devils introduced to Maria Island, Tasmania, a site outside the species’ native range. We extracted DNA from 96 scats and used a universal primer set targeting the vertebrate 12S rRNA gene to identify diet items. Tasmanian devils on Maria Island had an eclectic diet, with 63 consumed taxa identified. Cat DNA was detected in 14% of scats, providing the first instance of cats appearing as part of Tasmanian devil diets either via predation or scavenging. Short‐tail shearwaters and little penguins were commonly consumed, corresponding with previous surveys showing sharp population declines in these species since the introduction of Tasmanian devils. Our results indicate that the introduction of carnivores to novel ecosystems can be very successful for the focal species, but that commonly consumed species should be closely monitored to identify any vulnerable species in need of remedial management.

Radiocesium accumulation and germline mutations in chronically exposed wild boar from Fukushima, with radiation doses to human consumers of contaminated meat

Genetic effects and radioactive contamination of large mammals, including wild boar (Sus scrofa), have been studied in Japan because of dispersal of radionuclides from the Fukushima Dai-ichi Nuclear Power Plant in 2011. Such studies have generally demonstrated a declining trend in measured radiocesium body burdens in wildlife. Estimating radiation exposure to wildlife is important to understand possible long-term impacts. Here, radiation exposure was evaluated in 307 wild boar inhabiting radioactively contaminated areas (50–8000 kBq m−2) in Fukushima Prefecture from 2016 to 2019, and genetic markers were examined to assess possible germline mutations caused by chronic radiation exposures to several generations of wild boar. Internal Cs activity concentrations in boar remained high in areas near the power plant with the highest concentration of 54 kBq kg−1 measured in 2019. Total dose rates to wild boar ranged from 0.02 to 36 μGy h−1, which was primarily attributed to external radiation exposure, and dose rates to the maximally exposed animals were above the generic no-effects benchmark of 10 μGy h−1. Using the estimated age of each animal, lifetime radiation doses ranged from <0.1 mGy to 700 mGy. Despite chronic exposures, the genetic analyses showed no significant accumulation of mutation events. Because wild boar is an occasional human dietary item in Japan, effective dose to humans from ingesting contaminated wild boar meat was calculated. Hypothetical consumption of contaminated wild boar meat from radioactively contaminated areas in Fukushima, at the per capita pork consumption rate (12.9 kg y−1), would result in an average effective annual dose of 0.9 mSv y−1, which is below the annual ingestion limit of 1 mSv y−1. Additionally, a consumption rate of about 1.4 kg y−1 of the most contaminated meat in this study would not exceed annual ingestion limits.

Temporal Variation and Habitat Management Influence Arthropod Prey for Northern Bobwhites (Colinus virginianus)

Variation in the relative abundance and biomass of arthropods has important potential consequences for insectivores. We studied the influence of temporal variation and habitat management (i.e., burning and strip-disking) on the availability of potential arthropod prey for brooding northern bobwhites (Colinus virginianus) in the mixed-grass prairie of western Oklahoma. Burning changed the composition of the arthropod community by biomass, but disking did not result in any community-level changes. Burning also increased the total abundance and biomass of arthropods collected compared with the control, but disking did not affect total abundance or biomass. Temporal variation exerted a broader influence on arthropods, and total abundance and biomass increased throughout the duration of the sampling period (May-July) at paired burn/control and paired disked/control sites. Ants, which had the highest abundance and biomass of any taxa, appeared to drive these patterns. The response of individual orders to management and temporal variation varied in size and direction, though we observed more and stronger effects of temporal variation than burning or disking. These results support the idea that burning provides benefits to foraging bobwhite broods through increased total availability of arthropod prey, as well as favorable habitat characteristics (i.e., bare ground, structural heterogeneity). Large temporal variation in total arthropod abundance and biomass, as well as that of individual orders, likely also influences the relative importance of individual prey items in the bobwhite diet based on the timing of nest initiation and hatching. A better understanding of how these temporal and management-induced shifts in arthropod availability influence potential nutrient gains and limitations for bobwhites will require data on macronutrient content and digestibility (i.e., exoskeleton) of prey taxa.

Assessing Effects of Impounded Water on Life History, Reproduction, and Diets of a Fluvial Specialist Fish

Species richness and abundances of fluvial specialist fishes often decrease within waters impounded by dams, but mechanisms underlying these decreases are poorly understood. Purpose of this study was to assess the effects of impounded water on fluvial specialist Greenthroat Darter Etheostoma lepidum by quantifying differences in life history (i.e., age structure, life span), reproduction (i.e., gonadosomatic index [GSI], stages of ovarian development), and stomach contents (i.e., diet items and parasites) between a population taken from a lentic environment (Lake Site) and a lotic environment (River Site). Among fishes taken from both sites, Greenthroat Darters lived up to 1.5 y, spawned for 11 mo, and consumed primarily aquatic insects and crustaceans. Differences in reproduction were not detected between populations at the Lake Site and at the River Site. Greenthroat Darters taken from Lake Site consumed fewer diet items, fewer aquatic insects, and greater number of crustaceans than those taken from River Site; however, diet weight, percent stomach fullness, and percent empty stomachs were similar between sites. Greenthroat Darters taken from Lake Site exhibited lower condition factors than those taken from River Site, which corresponded with a greater number of parasites (i.e., Acanthocephala and Nematoda) in individuals taken from Lake Site. Differences quantified herein were not sufficient to cause extirpation of Greenthroat Darters in the impounded waters, given the species has persisted in the impounded water at least since the late 1800s; however, differences in diets and parasites might explain the lower abundance of Greenthroat Darters in Lake Site compared to River Site.

Examining dietary self-talk content and context for discretionary snacking behaviour: a qualitative interview study

ABSTRACT Background: Consuming discretionary snack foods high in calories, salt, sugar or fat in between regular meals can have a negative impact on weight management and health. Despite the intention to refrain from discretionary snacking, individuals often report feeling tempted by snack foods. A cognitive process to resolve food choice related tension may be dietary self-talk which is one’s inner speech around dietary choice. This study aimed to understand the content and context of dietary self-talk before consuming discretionary snack foods. Methods: Qualitative semi-structured interviews based on Think-Aloud methods were conducted remotely. Participants answered open-ended questions and were presented with a list of 37 dietary self-talk items. Interview transcripts were analyzed thematically. Results: Interviews (n = 18, age: 19–54 years, 9 men, 9 women) confirmed the frequent use of dietary self-talk with all 37 content items endorsed. Reported use was highest for the self-talk items: ‘It is a special occasion’; ‘I did physical activity/exercise today’; and ‘I am hungry’. Three new items were developed, eight items were refined. Identified key contextual themes were: ‘reward’, ‘social’, ‘convenience’, ‘automaticity’, and ‘hunger’. Conclusions: This study lists 40 reasons people use to allow themselves to consume discretionary snack foods and identifies contextual factors of dietary-self talk. All participants reported using dietary self-talk, with variation in content, frequency and degree of automaticity. Recognising and changing dietary self-talk may be a promising intervention target for changing discretionary snacking behaviour.

A two-step metagenomics approach for the identification and mitochondrial DNA contig assembly of vertebrate prey from the blood meals of common vampire bats (Desmodus rotundus)

The feeding behaviour of the sanguivorous common vampire bat (Desmodus rotundus) facilitates the transmission of pathogens that can impact both human and animal health. To formulate effective strategies in controlling the spread of diseases, there is a need to obtain information on which animals they feed on. One DNA-based approach, shotgun sequencing, can be used to obtain such information. Even though it is costly, shotgun sequencing can be used to simultaneously retrieve prey and vampire bat mitochondrial DNA for population studies within one round of sequencing. However, due to the challenges of analysing shotgun sequenced metagenomic data such as false negatives/positives and typically low proportion of reads mapped to diet items, shotgun sequencing has not been used for the identification of prey from common vampire bat blood meals. To overcome these challenges and generate longer mitochondrial contigs which could be useful for prey population studies, we shotgun sequenced common vampire bat blood meal samples (n = 8) and utilised a two-step metagenomic approach based on combining existing bioinformatic workflows (alignment and mtDNA contig assembly) to identify prey. After validating our results from detections made through metabarcoding, we accurately identified the common vampire bats’ prey in six out of eight samples without any false positives. We also generated prey mitochondrial contig lengths between 138 bp to 3231 bp (median = 770 bp, Q1 = 262 bp, Q3 = 1766 bp). This opens the potential to conduct phylogenetic and phylogeographic monitoring of elusive prey species in future studies, through the analyses of blood meal metagenomic data.

Vampyrum spectrum (Phyllostomidae) movement and prey revealed by radio-telemetry and DNA metabarcoding.

The spectral bat (Vampyrum spectrum), the largest bat species in the Americas, is considered Near Threatened by the International Union for Conservation of Nature and is listed as a species of special concern or endangered in several countries throughout its range. Although the species is known as carnivorous, data on basic ecology, including habitat selection and primary diet items, are limited owing to its relative rarity and difficulty in capturing the species. Leveraging advances in DNA metabarcoding and using radio-telemetry, we present novel information on the diet and movement of V. spectrum based on locations of a radio-collared individual and fecal samples collected from its communal roost (three individuals) in the Lowland Dry Forest of southern Nicaragua. Using a non-invasive approach, we explored the diet of the species with genetic markers designed to capture a range of arthropods and vertebrate targets from fecal samples. We identified 27 species of vertebrate prey which included birds, rodents, and other bat species. Our evidence suggested that V. spectrum can forage on a variety of species, from those associated with mature forests to forest edge-dwellers. Characteristics of the roost and our telemetry data underscore the importance of large trees for roosting in mature forest patches for the species. These data can inform conservation efforts for preserving both the habitat and the prey items in remnants of mature forest required by Vampyrum spectrum to survive in landscape mosaics.

Dietary ecology of the southern gelada (Theropithecus gelada obscurus) living in an Afroalpine ecosystem of the Borena Sayint National Park, Wollo, Ethiopia

Primates show dietary flexibility as a result of spatial and temporal variation in the food availability which in turn influences the ecology of a species. Southern geladas ( Theropithecus gelada obscurus ) are endemic subspecies of gelada that inhabit in north central Ethiopian Highlands. During the 18 months of the first intensive study period, we examined the feeding ecology of southern geladas and their dietary responses to seasonal variations in an Afroalpine ecosystem, Borena Sayint National Park, an important site for the conservation of biodiversity in the north central Ethiopia. We collected monthly diet data from a band of southern geladas using instantaneous scan sampling method, and monthly temporal changes in green graminoid leaves and/or forb availability data using visual inspection from the randomly selected plots. The overall diet of southern geladas at Keywasha consisted of 54.4% graminoid leaves, 9.4% graminoid underground, 9.0% graminoid seeds, 17.0% forb leaves, 7.4% forb underground and 1.5% invertebrates. The diet of geladas exhibited wide variability across months. Southern geladas spent significantly more time feeding on the graminoid leaves, and significantly less time on the graminoid and forb underground diet items during the wet season than the dry season. Graminoid leaf consumption was significantly positively correlated with monthly increment of green graminoid leaf availability. By contrast, there was a significant increase in the consumption of graminoid underground when monthly green graminoid leaf availability becomes low. The result shows that southern geladas adapt seasonal shifts in their diet consumption as staple foods changed temporally in the Ethiopian Afroalpine ecosystem. Our findings contribute to a better understanding of the dietary flexibility of primates in response to local environment conditions that may shape primate ecology and evolution.

Consumption of Non-Native Bigheaded Carps by Native Blue Catfish in an Impounded Bay of the Upper Mississippi River

Adult bigheaded carps Hypophthalmichthys spp. have never been observed in the diets of native fishes in the Mississippi River Basin. In addition, blue catfish Ictalurus furcatus diet preference and foraging behavior have never been studied in the presence of non-native bigheaded carps in the Mississippi River system. We examined the gut contents of adult blue catfish (567–1020 mm, n = 65), captured from a Mississippi River backwater using trammel nets. All items in diets were separated and enumerated, and all fish-like diet items were genetically identified to confirm species-level ID. Bigheaded carp ages were determined by sectioning hard structures (pectoral spines, post-cleithra, and vertebrae). Adult silver carp Hypophthalmichthys molitrix (age 3–5, mean = 3.9 years, SE = 0.2; n = 21) had the highest frequency of occurrence (70%) and constituted the greatest percentage by number (58%) and weight (60%) in/of blue catfish diets. Gizzard shad Dorosoma cepedianum ranked second by all three measures (34%, 25%, and 26%). Finally, 50% to 100% of probable age-based sizes of silver carp exceeded gape measurements of blue catfish, suggesting scavenging was the dominant means of predation. More intensive sampling efforts are required to determine the system-wide importance of bigheaded carp in blue catfish diets.

DNA metabarcoding reveals broad woodpecker diets in fire-maintained forests

Abstract Ecological disturbance is a key agent shaping the spatial and temporal landscape of food availability. In forests of western North America, disturbance from fire can lead to resource pulses of deadwood-associated arthropods that provide important prey for woodpeckers. Although the foraging strategies among woodpecker species often demonstrate pronounced differences, little is known about the ways in which woodpeckers exploit and partition prey in disturbed areas. In this study, we employed DNA metabarcoding to characterize and compare the arthropod diets of 4 woodpecker species in Washington and California, USA—Black-backed Woodpecker (Picoides arcticus), Hairy Woodpecker (Dryobates villosus), Northern Flicker (Colaptes auratus), and White-headed Woodpecker (Dryobates albolarvatus)—primarily using nestling fecal samples from burned forests 1–13 years postfire. Successful sequencing from 78 samples revealed the presence of over 600 operational taxonomic units (OTUs) spanning 32 arthropod orders. The nestling diets of two species in particular—Northern Flicker and Black-backed Woodpecker—proved to be much broader than previous observational studies suggest. Northern Flicker nestlings demonstrated significantly higher diet diversity compared to other focal species, all of which displayed considerable overlap in diversity. Wood-boring beetles, which colonize dead and dying trees after fire, were particularly important diet items for Black-backed, Hairy, and White-headed woodpeckers. Diet composition differed among species, and diets showed limited differences between newer (≤5 yr) and older (&amp;gt;5 yr) postfire forests. Our results show mixed evidence for dietary resource partitioning, with three of the four focal species exhibiting relatively high diet overlap, perhaps due to the pulsed subsidy of deadwood-associated arthropods in burned forests. Woodpeckers are frequently used as management indicator species for forest health, and our study provides one of the first applications of DNA metabarcoding to build a more complete picture of woodpecker diets.

Food Selection by Spring-Migrating Green-Winged Teal

AbstractThe Mississippi Flyway supports millions of waterfowl during spring migration as individuals replenish vital nutrients en route to breeding locations. Green-winged teal Anas crecca consume natural plant and animal foods in shallow wetlands during autumn and winter, but little information is available to describe food use and selection during spring migration. We experimentally collected green-winged teal and quantified food use and availability to determine selection in the Illinois River Valley during February–April 2016–2018. We removed, dried, and weighed (±0.1 mg) food items by taxa from the upper digestive tract (proventriculus and esophagus) of birds and core samples for comparison. Additionally, we evaluated retention of common diet items between small (#60; 250 μm) and medium (#35; 500 μm) sieves and the effect of processing sieve size on selection coefficients. Seeds of moist-soil vegetation occurred in all green-winged teal diets, while invertebrates and vegetation material occurred in 67.4% and 25.8% of diets, respectively. Green-winged teal consumed 85.8% (CI95 = 81.2–90.3%) plant material and 14.2% (CI95 = 9.6–18.7%) invertebrates based on aggregate dry biomass. We failed to find support for selection of either plant or animal foods in general, but green-winged teal selected Cyperus spp., Ammannia spp., Leptochloa spp., and Potamogeton spp. and avoided Amaranthus spp., Ipomoea spp., Echinochloa spp., and Oligochaeta individual taxa. We found no support for a difference in selection ratios between sexes, but selection ratios differed among years and wetland connectivity regimes with changes in food availability. Sieve size had minimal impact on rank and selection intensity of most food items, but only small sieves captured Ammannia spp., which was an important diet item. We found no evidence that green-winged teal selected invertebrates in our midlatitude migration study area, as has been speculated for dabbling ducks in general during spring migration (i.e., spring diet-shift hypothesis). We encourage managers to provide shallowly flooded wetlands with desirable plant taxa (e.g., Cyperus spp., Ammannia spp., Leptochloa spp.) for green-winged teal by maintaining actively managed moist-soil wetlands that are made available during spring migration.

Artificial selection for predatory behaviour results in dietary niche differentiation in an omnivorous mammal.

The diet of an individual is a result of the availability of dietary items and the individual's foraging skills and preferences. Behavioural differences may thus influence diet variation, but the evolvability of diet choice through behavioural evolution has not been studied. We used experimental evolution combined with a field enclosure experiment to test whether behavioural selection leads to dietary divergence. We analysed the individual dietary niche via stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) in the hair of an omnivorous mammal, the bank vole, from four lines selected for predatory behaviour and four unselected control lines. Predatory voles had higher hair δ15N values than control voles, supporting our hypothesis that predatory voles would consume a higher trophic level diet (more animal versus plant foods). This difference was significant in the early but not the late summer season. The δ13C values also indicated a seasonal change in the consumed plant matter and a difference in food sources among selection lines in the early summer. These results imply that environmental factors interact with evolved behavioural tendencies to determine dietary niche heterogeneity. Behavioural selection thus has potential to contribute to the evolution of diet choice and ultimately the species' ecological niche breadth.

Characterizing Husbandry Risk Factors Associated with Metastatic Soft Tissue Mineralization in Zoo-Housed Komodo Dragons (Varanus komodoensis) in the United States

Metastatic soft tissue mineralization has emerged as a major cause of death in captive Komodo dragons (Varanus komodoensis). A cross-sectional survey-based study was performed to evaluate husbandry-related risk factors for metastatic mineralization in zoo-housed Komodo dragons in the United States. Nineteen institutions participated, nine of which (47.4%) had a history of metastatic mineralization within their collections. Husbandry at participating institutions varied in temperature gradients, outdoor exposure, artificial lighting, and diet items offered. Differences in husbandry were tested between institutions with and without a history of mineralization by using univariate analyses, and variables resulting in a significance level of ≤0.10 were entered into a multinomial logistic regression model. The only variable demonstrating a significant difference during univariate analyses was the number of Komodo dragons per enclosure (P = 0.036), whereas the only significant predictive variable after modeling was humidity approximation. Zoos that approximated rather than measured humidity were 12.0 times as likely to have a history of mineralization in their Komodo dragons (odds ratio [OR] = 12.0, P = 0.045). These variables likely reflect the under- or overestimation of exhibit humidity levels and the tendency to house males and females together. Based on postmortem findings for 27 Komodo dragon mortalities from these institutions, the presence of mineralization at necropsy was significantly associated with female dragons (OR = 18.2, P = 0.0044) and yolk coelomitis or embolism (OR = 6.76, P = 0.046). Although this study did not identify definitive links between husbandry and the prevalence of mineralization at the institutional level, the survey revealed high variation in husbandry conditions and potential deficiencies in management based on the Association of Zoos and Aquariums and the European Association of Zoos and Aquaria guidelines.

Pesticide residues in juvenile Chinook salmon and prey items of the Sacramento River watershed, California – A comparison of riverine and floodplain habitats

Juvenile Chinook salmon (Oncorhynchus tshawytscha) of the Sacramento River system encounter many anthropogenically-induced stressors while rearing and migrating to the Pacific Ocean. Located in a prominent agricultural region, the watershed serves as a source of notable contaminants including pesticides. Salmon rearing in riverine and floodplain areas are potentially exposed to these compounds via dietary exposure, which can vary based on selected food webs. Previous studies have suggested that juvenile Chinook salmon rearing in riverine and floodplain environments of the Sacramento River watershed are characterized by different dietary preferences, with potential for contrasting pesticide exposure between habitats. To examine the potential for pesticide exposure, juvenile Chinook salmon and known dietary items were collected in the mainstem Sacramento River and an adjacent floodplain, the Yolo Bypass, in 2019 and 2020, and analyzed for 33 pesticides, including degradates and isomers. Organochlorine pesticides including the DDX group (p,p’-DDT, p,p’-DDD and p,p’-DDE) were prevalent in all examined biota. There was a significantly greater number of total pesticide detections across all classes in zooplankton compared to macroinvertebrates, coupled with higher bifenthrin concentrations in zooplankton across regions and years, which may indicate different exposure potential depending on fish dietary preferences. Detection frequencies and concentrations of organochlorines were higher in prey items during flooding than in drought conditions, suggesting resuspension of legacy compounds. Significantly higher concentrations of organochlorines were recorded in floodplain rearing fish compared to the Sacramento River. These findings suggest that within these habitats, juvenile Chinook salmon feeding primarily on zooplankton within the water column may be exposed to a greater range of pesticides than those feeding on benthic macroinvertebrates, and that the benefits of floodplain rearing may come at a cost of increased organochlorine exposure.

Effects of food availability and its seasonal changes on the dietary habits of wild silvery lutungs (Trachypithecus cristatus) in a coastal forest in west Sumatra, Indonesia

Abstract The dietary composition of primates is often affected by the availability of food, as well as seasonal variations within their habitat. This study presents quantitative data on the feeding behavior of wild silvery lutungs (Trachypithecus cristatus) inhabiting a coastal forest in West Sumatra, Indonesia. This research emphasizes the relationship between food availability and the way this changes by season. Feeding strategies of these primates was also examined. Feeding behavior of a group of wild silvery lutungs was observed for 12 months from August 2018 to July 2019, with a total observation time of 482 hours. We recorded 74 items from 37 different plant species that were included in the lutungs’ diet. Nineteen out of 37 plant species comprised &gt; 1% of the lutung’s annual diet. They can therefore be considered the main plant food sources for the lutungs. The lutungs mainly fed on young leaves (68.3%). However, during certain months, both ripe and unripe fruit formed a major part of their diet. Plant part-based analyses showed a negative correlation between the availability of young leaves and ripe fruit feeding. Plant species-based analyses revealed few significant positive relationships between the feeding percentages of the main dietary items (mainly young leaves) and their availability. This implies that young leaves and ripe fruit were both the preferred and the fallback foods. This also indicates that lutung activity, ranging patterns, and activity at the study site are affected mainly by food distribution and availability. Further research is needed to increase the understanding of Asian colobine feeding strategies, feeding patterns, and food resource characteristics.