Unpredictable Food Research Articles

Effects of COVID-19 on Food Supply: A Systematic Review

Abstract: The COVID-19 outbreak has had a significant influence on several critical industries, including agriculture, education, and the economy. This essay investigates these processes, with a focus on agriculture, where the repercussions have been particularly harsh for poor groups dealing with unpredictable food supplies and food safety. Along with a critical examination of the shift to digital education systems, the report highlights the major obstacles that lie ahead for regions lacking adequate digital infrastructure and digital literacy. There have been notable disruptions in the economy as well. Manufacturing, the financial markets, and tourism have all seen major downturns. The study emphasizes the crucial part that following safety measures and boosting immunization campaigns play in mitigating these negative consequences while supporting economic recovery. Also, new technical solutions have emerged throughout this time. The application of drone technology to contactless food delivery is a notable illustration of how creativity can overcome the challenges posed by the pandemic. Finally, the report recommends the development of specific and rigorous methods to strengthen recovery efforts in these critical areas.

Effects of sublethal methylmercury and food stress on songbird energetic performance: metabolic rates, molt and feather quality.

Organisms regularly adjust their physiology and energy balance in response to predictable seasonal environmental changes. Stressors and contaminants have the potential to disrupt these critical seasonal transitions. No studies have investigated how simultaneous exposure to the ubiquitous toxin methylmercury (MeHg) and food stress affects birds' physiological performance across seasons. We quantified several aspects of energetic performance in song sparrows, Melospiza melodia, exposed or not to unpredictable food stress and MeHg in a 2×2 experimental design, over 3 months during the breeding season, followed by 3 months post-exposure. Birds exposed to food stress had reduced basal metabolic rate and non-significant higher factorial metabolic scope during the exposure period, and had a greater increase in lean mass throughout most of the experimental period. Birds exposed to MeHg had increased molt duration, and increased mass:length ratio of some of their primary feathers. Birds exposed to the combined food stress and MeHg treatment often had responses similar to the stress-only or MeHg-only exposure groups, suggesting these treatments affected physiological performance through different mechanisms and resulted in compensatory or independent effects. Because the MeHg and stress variables were selected in candidate models with a ΔAICc lower than 2 but the 95% confidence interval of these variables overlapped zero, we found weak support for MeHg effects on all measures except basal metabolic rate, and for food stress effects on maximum metabolic rate, factorial metabolic scope and feather mass:length ratio. This suggests that MeHg and food stress effects on these measures are statistically identified but not simple and/or were too weak to be detected via linear regression. Overall, combined exposure to ecologically relevant MeHg and unpredictable food stress during the breeding season does not appear to induce extra energetic costs for songbirds in the post-exposure period. However, MeHg effects on molt duration could carry over across multiple annual cycle stages.

Adolescent food insecurity in female rodents and susceptibility to diet-induced obesity

Food insecurity is defined as having limited or uncertain access to nutritious foods, and adolescent food insecurity is associated with obesity and disordered eating behaviors in humans. We developed a rodent model of adolescent food insecurity to determine whether adolescent food insecurity per se promotes increased susceptibility to diet-induced obesity and altered eating behaviors during adulthood. Female juvenile Wistar rats were singly housed and assigned to three experimental diets: food-secure with standard chow (CHOW), food-secure with a high-fat/sugar Western diet (WD), and food-insecure with WD (WD-FI). Food-secure rats (CHOW and WD) received meals at fixed feeding times (9:00, 13:00, and 16:00). WD-FI rats received meals at unpredictable intervals of the above-mentioned feeding times but had isocaloric amounts of food to WD. We investigated the impact of adolescent food insecurity on motivation for sucrose (Progressive Ratio), approach-avoidance behavior for palatable high-fat food (Approach-Avoidance task), and susceptibility to weight gain and hyperphagia when given an obesogenic choice diet. Secondary outcomes were the effects of food insecurity during development on anxiety-like behaviors (Open Field and Elevated Plus Maze) and learning and memory function (Novel Location Recognition task). Rodents with adolescent food insecurity showed a greater trend of weight gain and significantly increased fat mass and liver fat accumulation on an obesogenic diet in adulthood, despite no increases in motivation for sucrose or high-fat food. These data suggest that adolescent unpredictable food access increases susceptibility to diet-induced fat gain without impacting food motivation or food intake in female rodents. These findings are among a small group of recent studies modeling food insecurity in rodents and suggest that adolescent food insecurity in females may have long-term implications for metabolic physiology later in life.

Explorative behavior allows the successful finding of ephemeral food resources in the wild

AbstractThe repeatable among-individual variation in behavior (animal personality) is considered to affect fitness. The variation in personality traits is shaped by complex evolutionary mechanisms involving energy allocation and resource acquisition. However, an association between personality and individual performance in energy gain in the natural environment still seems underexplored. The aim of our study was to test a hypothesis that consistent individual variation in behavior affects the energy acquisition of unpredictable food resources. We predicted that more explorative individuals would be finding ephemeral food resources with higher probability than those less explorative. The quasi-experiment with ‘random-walking-feeders’ was performed to assess the use of unpredictable food resources in the natural habitat occupied by free-ranging arboreal rodents — edible dormice Glis glis. A repeated open field test at laboratory conditions was conducted to assess whether male dormice show consistent among-individual variation in behavior. The open field test analysis indicated two main components of dormice behavior: exploration and boldness, from which only the first one was repeatable and thus considered as a component of animal personality. The probability of finding a feeder increased with exploration, independently of dormice age and body size. The results indicate that exploration can be considered an adaptive trait that improves energy acquisition. We suggest that the behavioral among-individual variation within populations persists due to the usage of distinct foraging strategies in the face of fluctuations in food resources availability.

Food insecurity as a cause of adiposity: evolutionary and mechanistic hypotheses.

Food insecurity (FI) is associated with obesity among women in high-income countries. This seemingly paradoxical association can be explained by the insurance hypothesis, which states that humans possess evolved mechanisms that increase fat storage to buffer against energy shortfall when access to food is unpredictable. The evolutionary logic underlying the insurance hypothesis is well established and experiments on animals confirm that exposure to unpredictable food causes weight gain, but the mechanisms involved are less clear. Drawing on data from humans and other vertebrates, we review a suite of behavioural and physiological mechanisms that could increase fat storage under FI. FI causes short-term hyperphagia, but evidence that it is associated with increased total energy intake is lacking. Experiments on animals suggest that unpredictable food causes increases in retained metabolizable energy and reductions in energy expenditure sufficient to fuel weight gain in the absence of increased food intake. Reducing energy expenditure by diverting energy from somatic maintenance into fat stores should improve short-term survival under FI, but the trade-offs potentially include increased disease risk and accelerated ageing. We conclude that exposure to FI plausibly causes increased adiposity, poor health and shorter lifespan. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part II)'.

59-OR: Glycemic Control with Extended Use of Automated Insulin Delivery (AID) in Children Age 2–6 Years with Type 1 Diabetes (T1D)

T1D management in children < age 6 yrs is challenging due to unpredictable food intake and activity. Efficacy of AID with the Tandem t:slim X2 insulin pump with Control-IQ technology (CIQ) in this age group has not been well studied. Data included 95 children with T1D age 2 to < 6 yrs (age 3.9±1.2 yrs, 46% male, 75 % non-Hispanic white, 34% on multiple daily injections) enrolled in a 13-week extended use phase of a randomized trial of closed loop control (CLC) with CIQ. In this phase, the group assigned to CLC for the initial 13 weeks continued on CLC (CLC-CLC) and those initially using standard care (SC) were placed on CLC (SC-CLC). CGM time in range 70-180 mg/dL (TIR) was the primary outcome. The SC-CLC group (n=33) increased TIR using CLC in the extension compared to the SC period (68±9% vs. 56±13%, p<0.001) with no significant change in hypoglycemia (%CGM < 54 mg/dL 0.4±0.3% vs. 0.5±0.6%, p=0.03). TIR increased within the first week of CLC use similar to the first 13 weeks of AID use for the CLC-CLC group (Figure). CLC training was completed virtually for 82% of the SC-CLC group. The CLC-CLC group (n=62) maintained TIR (71±11% vs. 70±10%, p=0.80) with slightly lower rates of hypoglycemia (%CGM < 54 mg/dL 0.5±0.4% vs. 0.6±0.5%, p=0.08). In conclusion, these data show that in young children age 2 to < 6, CLC with Control-IQ technology leads to increased TIR without an increase in time in hypoglycemia. Disclosure R.Wadwa: Consultant; Eli Lilly and Company, Other Relationship; Dexcom, Inc., Eli Lilly and Company, Research Support; Dexcom, Inc., Eli Lilly and Company, Beta Bionics, Inc., Tandem Diabetes Care, Inc. C.Kollman: Research Support; Insulet Corporation, Dexcom, Inc., Tandem Diabetes Care, Inc. R.Beck: Consultant; Eli Lilly and Company, Novo Nordisk, Diasome, Insulet Corporation, Research Support; Tandem Diabetes Care, Inc., Beta Bionics, Inc., Dexcom, Inc., Bigfoot Biomedical, Inc., Medtronic, Ascensia Diabetes Care, Roche Diabetes Care, Eli Lilly and Company, Novo Nordisk. M.D.Breton: Consultant; Dexcom, Inc., Tandem Diabetes Care, Inc., Roche Diabetes Care, Sanofi, Arecor, Research Support; Dexcom, Inc., Tandem Diabetes Care, Inc., Novo Nordisk. Pedap trial study group: n/a. Z.Reed: None. B.A.Buckingham: Advisory Panel; Medtronic, Novo Nordisk, Consultant; Lilly, Research Support; Medtronic, Insulet Corporation, Tandem Diabetes Care, Inc. M.D.Deboer: Research Support; Dexcom, Inc., Tandem Diabetes Care, Inc. L.Ekhlaspour: Consultant; Ypsomed AG, Tandem Diabetes Care, Inc., Other Relationship; NIH - National Institutes of Health, Research Support; MannKind Corporation, Tandem Diabetes Care, Inc., JDRF, Speaker's Bureau; Insulet Corporation. E.C.Cobry: None. M.Schoelwer: Research Support; Tandem Diabetes Care, Inc., Insulet Corporation. C.Berget: Consultant; Insulet Corporation, Dexcom, Inc., Other Relationship; Tandem Diabetes Care, Inc. J.W.Lum: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases (U01DK127551); Tandem Diabetes Care, Inc.; Dexcom, Inc.

Torpor-responsive microRNAs in the heart of the Monito del monte, Dromiciops gliroides.

The marsupial Monito del monte (Dromiciops gliroides) utilizes both daily and seasonal bouts of torpor to preserve energy and prolong survival during periods of cold and unpredictable food availability. Torpor involves changes in cellular metabolism, including specific changes to gene expression that is coordinated in part, by the posttranscriptional gene silencing activity of microRNAs (miRNA). Previously, differential miRNA expression has been identified in D. gliroides liver and skeletal muscle; however, miRNAs in the heart of Monito del monte remained unstudied. In this study, the expression of 82 miRNAs was assessed in the hearts of active and torpid D. gliroides, finding that 14 were significantly differentially expressed during torpor. These 14 miRNAs were then used in bioinformatic analyses to identify Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that were predicted to be most affected by these differentially expressed miRNAs. Overexpressed miRNAs were predicted to primarily regulate glycosaminoglycan biosynthesis, along with various signaling pathways such as Phosphoinositide-3-kinase/protein kinase B and transforming growth factor-β. Similarly, signaling pathways including phosphatidylinositol and Hippo were predicted to be regulated by the underexpression of miRNAs during torpor. Together, these results suggest potential molecular adaptations that protect against irreversible tissue damage and enable continued cardiac and vascular function despite hypothermia and limited organ perfusion during torpor.

Unpredictable fasting transiently alters corticosterone and feeding behavior but not body mass or later HPA axis function in zebra finches (Taeniopygia guttata)

The hypothalamic-pituitary-adrenal (HPA) axis is commonly activated in response to unpredictable conditions, including unstable or inadequate food supply. Extended exposure to unpredictable food resources can alter HPA axis function, with the potential for negative fitness consequences. We addressed the interrelationships of unpredictable food resources, HPA axis activity, and food intake in adult and juvenile zebra finches (Taeniopygia guttata). Finches exposed to prolonged periods of unpredictable food elevate corticosterone (the primary avian glucocorticoid) when food is unavailable; however, whether they experience chronic elevation in baseline corticosterone during periods of unpredictability, even when food is available, is unclear. We subjected adults and juveniles to an extended period of temporally unpredictable food (consisting of a random daily fast) or predictable food supply. We investigated baseline corticosterone under fed conditions and in response to an acute fast (mimicking the daily fasting periods in the unpredictable treatment), and assessed differences in body mass, food intake, and corticosterone responses to restraint. Regardless of sex and age, individuals in both treatment groups elevated corticosterone when fasted, and baseline corticosterone under fed conditions was indistinguishable between groups. Thus, corticosterone levels were not persistently elevated in the unpredictably fed group. Treatment groups did not differ in body mass or corticosterone responses to restraint, but unpredictably fed birds consumed food more rapidly when food was available. Our findings suggest that the unpredictably fed birds experienced repeated, moderate elevations in corticosterone. Such elevations may aid birds in coping with unpredictable food sources, in part by activating compensatory changes in foraging behavior.

Thermoregulatory costs of the innate immune response are modulated by winter food availability in a small passerine.

In winter, a challenge to the immune system could pose a major energetic trade-off for small endotherms, whereby increasing body temperature (Tb ; i.e. eliciting fever) may be beneficial to fight off invading pathogens yet incur a cost for vital energy-saving mechanisms. Having previously shown that the availability and acquisition of energy, through manipulation of food predictability, influences the depth of rest-phase hypothermia in a wild bird in winter, we expected that the nocturnal thermoregulatory component of the acute-phase immune response would also be modulated by food availability. By manipulating winter food availability in the wild for great tits Parus major, we created an area offering a "predictable" and constant supply of food at feeding stations, while an unmanipulated area was subject to naturally "unpredictable" food. Birds were subject to an immune challenge shortly after dusk, and the thermoregulatory response was quantified via continuous recording of nocturnal Tb , using subcutaneous thermo-sensitive transponders. In response to immune challenge, all birds increased Tb above the level maintained prior to immune challenge (i.e. baseline). However, birds experiencing a naturally unpredictable food supply elevated Tb more than birds subject to predictable food resources, during the period of expected peak response and for the duration of the night. Furthermore, "unpredictable-food" females took longer to return to their baseline Tb . Assuming baseline nocturnal Tb reflects an individual's optimum, based on their available energy budget, the metabolic cost of eliciting an acute-phase response for "unpredictable-food" birds was more than double that of "predictable-food" birds. The absence of differences in absolute Tb during the peak response could support the idea of an optimal Tb for immune system activation. Alternatively, "predictable-food" birds could have acquired tolerance to endotoxin as a result of using feeding stations, thus affording them reduced costs associated with a smaller Tb increase. These findings shed new light on the trade-offs associated with food acquisition, thermoregulation and immune function in small-bodied endotherms. This knowledge is of increasing importance, given the predicted elevated pathogen risks associated with changes in climate and anthropogenic activities.

Utility of carbon and nitrogen stable isotopes for inferring wild bee (Hymenoptera: Apoidea) use of adjacent foraging habitats.

Isotope analysis has proven useful for understanding diets of animals that are difficult to track for extended periods. Bees are small yet highly mobile and often forage from multiple habitats. However, current methods of assessing diet are limited in scope. Efficient methods of tracking bee diets that integrate across life stages, distinguish habitat use, and are sensitive to taxonomic differences will inform conservation strategies. We evaluated the utility of stable isotope analysis for estimating contributions of adjacent habitats to bees' diets. We also investigated taxonomic variation in bee and flower isotope composition. We measured natural abundance of carbon and nitrogen stable isotopes in two body regions from three wild bee genera, as well as in 25 species of flowers that likely comprised their diets. Bee ∂13C and ∂15N varied with habitat and taxonomic groups (conflated with month), but did not match spatial or seasonal trends in their food plants. Flower ∂13C was lowest in the forest and in April-June, as expected if driven by water availability. However, bee ∂13C was elevated in the spring, likely from overwintering nutritional stress or unpredictable food availability. Bumble bees (Bombus) were enriched in ∂15N compared to others, possibly reflecting differences in larval feeding. Bee diet mixing models had high variation and should be interpreted with caution. Models estimated similar habitat contributions to diets of spring Andrena and overwintered Bombus queens. Summer Bombus queens and workers were indistinguishable. Sweat bees (Halictus) were estimated to use comparatively more field flowers than others. Overall, taxon more strongly influenced isotope composition than either foraging habitat or month, likely because of associated differences in sociality and timing of annual activity. Future studies seeking to reveal bee diets by isotope analysis may gain better resolution in more isotopically distinct habitats, in conjunction with controlled feeding or isotope labeling experiments.

Chronic experience with unpredictable food availability promotes food reward, overeating, and weight gain in a novel animal model of food insecurity

Ubiquitous, easy access to food is thought to promote obesity in the modern environment. However, people coping with food insecurity have limited, unpredictable food access and are also prone to obesity. Causal factors linking food insecurity and obesity are not understood. In this study we describe an animal model to investigate biopsychological impacts of the chronic unpredictability inherent in food insecurity. Female rats were maintained on a 'secure' schedule of highly predictable 4x/day feedings of uniform size, or an 'insecure' schedule delivering the same total food over time but frequently unpredictable regarding how much, if any, food would arrive at each scheduled feeding. Subgroups of secure and insecure rats were fed ordinary chow or high-fat/high-sugar (HFHS) chow to identify separate and combined effects of insecurity and diet quality. Insecure chow-fed rats, relative to secure chow-fed rats, were hyperactive and consumed more when provided a palatable liquid diet. Insecure HFHS-fed rats additionally had higher progressive ratio breakpoints for sucrose, increased meal size, and subsequently gained more weight during 8 days of ad libitum HFHS access. Insecurity appeared to maintain a heightened attraction to palatable food that habituated in rats with secure HFHS access. In a second experiment, rats fed ordinary chow on the insecure schedule subsequently gained more weight when provided ad libitum chow, showing that prior insecurity per se promoted short-term weight gain in the absence of HFHS food. We propose this to be a potentially useful animal model for mechanistic research on biopsychological impacts of insecurity, demonstrating that chronic food uncertainty is a factor promoting obesity.

Collective foraging: Experimentally increased competition decreases group performance exploiting a permanent resource

Abstract Foraging collectively offers advantages, such as access to social information on food locations, but it may also intensify competition for local resources. Social information may be most advantageous during ecologically challenging conditions, when food sources are scarce or unpredictable, which predicts more collective foraging during such conditions. Alternatively, higher within‐group competition when resources are scarce might destabilize social groups and reduce collective foraging. To evaluate these effects, we experimentally decreased the number and predictability of food sources (feeders with ad libitum seeds) available to wild‐caught common waxbills Estrilda astrild living in a large open‐air mesocosm. Compared to control periods, in the treatment with few food sources competitive aggressiveness at feeders increased, the social network became more fragmented, with on average weaker associations between individuals, and foraging groups became smaller. Foraging groups also spent less time per visit to the feeding area, individuals spent less time at the feeders per group visit and had to make more visits to the feeding area per day, all of which indicate less efficient exploitation of the food sources. These effects were also observed when the number of feeders changed unpredictably across days. Even though the collective behaviour of waxbills appeared to exacerbate, rather than mitigate, the ecological challenges of reduced or unpredictable food sources, we suggest that, in nature, this increased aggressiveness and fragmentation of the social network may function adaptively as an early trigger to explore alternative foraging locations before local food sources are severely depleted. Read the free Plain Language Summary for this article on the Journal blog.

Fenced community gardens effectively mitigate the negative impacts of white-tailed deer on household food security

White-tailed deer (Odocoileus virginianus) are large herbivores that thrive in urban and peri-urban landscapes. Their voracious appetite and ubiquity have made deer a significant threat to growing food in home and community gardens; features that often make important contributions towards household food security. Focusing on food availability, stability, utilization, and access, I outline how white-tailed deer threaten household food security. Deer threaten availability of food by widely consuming plants grown for human consumption. Deer threaten stability of household food security by causing spatially and temporally unpredictable food losses. Deer threaten utilization of food, through acting as sources of food-borne pathogens (i.e. Escherichia coli O157:S7). Deer threaten access to food by necessitating relatively high-cost economic interventions to protect plants from browsing. Although numerous products are commercially available to deter deer via behavioural modification induced by olfaction and sound – evidence of efficacy is mixed. Physical barriers can be highly effective for reducing deer browsing, but often come with a high economic cost. Users of community gardens benefit from fencing by receiving shared protection against deer herbivory at a significantly lower per capita cost. Among many other benefits, fenced community gardens are useful in mitigating the threats of white-tailed deer to household food security.

New insight into spatial ecology of Griffon Vulture (Gypsfulvus) on the Balkans provides opportunity for focusing conservation actions for a threatened social scavenger.

The knowledge in the behaviour and movement of endangered species is of key importance for the precise targeting and assessing the efficiency of nature conservation actions, especially considering vultures, which explore vast areas to locate ephemeral and unpredictable food resources. Therefore, a total of 51 Griffon Vultures (Gypsfulvus) from both the re-introduced population and the autochthonous Balkan Peninsula (Balkans) colonies have been tagged with GPS/GSM transmitters in recent years, in order to study their seasonal and spatial distribution. The current study presents the analysis of the high-resolution GPS location data, acquired between January 2016 and March 2021. A total of 1,138,383 locations (an average number of 23,716 ± 18,886 positions per bird, ranged between 2,515 and 76,431 of total fixes per bird; n=48) were used to estimate the home range size and identify the traditional foraging areas and roosting sites of the birds during the wintering, migration/roaming and summering periods. Our results reveal that Griffon Vultures movement activity and home range size varied considerably throughout the annual cycle, especially between their wintering and summering grounds, while exhibiting significant overlapping amongst the tracked individuals. Specifically, immature Griffon Vultures travel long distances across all Balkan Peninsula countries, but always gather with conspecifics, showing strong fidelity to active breeding/roosting sites. The total home range 95% area of the Griffon Vulture population on the Balkans was estimated at 39,986.4 km² and the 50% core area at 1,545.42 km² (n = 48). All tracked birds were found to either visit or frequently use (> 95% of the time) the same seven vulture key zones on the Balkan Peninsula – one in Serbia, one shared between North Macedonia and Bulgaria, one shared between Bulgaria and Greece, two entirely lying in Bulgaria, one in western Greece and one shared between Kvarner Archipelago islands in Croatia and the Julian Alps - Italy, Austria and Slovenia. Several smaller sub-zones were also defined within these general ones. The seven key zones form a coherent network and are used as stepping stones for Griffon Vultures during their migration movements and roaming, but also wintering and summering. The observed concentration tendency of Griffon Vultures on the Balkans and the predictability of their temporal and spatial presence should be used to precisely target, address and substantially increase the efficiency of the conservation measures in this marginal and, thus, still vulnerable meta-population.

Predictability of food supply modulates nocturnal hypothermia in a small passerine : Food supply and nocturnal hypothermia

The combination of short days and long cold winter nights, in temperate regions, presents a major challenge for small diurnal birds. Small birds regularly employ heterothermy and enter rest-phase hypothermia during winter nights to conserve energy. However, we know little about how environmental conditions, such as food availability, shape these strategies. We experimentally manipulated food availability in winter to free-living great tits Parus major. A 'predictable' and constant food supply was provided to birds in one area of a forest, while birds in another area did not have access to a reliable supplementary food source. We found that predictability of food affected the extent of nocturnal hypothermia, but the response differed between the sexes. Whereas male nocturnal body temperature was similar regardless of food availability, females exposed to a naturally 'unpredictable' food supply entered deeper hypothermia at night, compared with females that had access to predictable food and compared with males in both treatment groups. We suggest that this response is likely a consequence of dominance, and subdominant females subject to unpredictable food resources cannot maintain sufficient energy intake, resulting in a higher demand for energy conservation at night. (Less)

Stopover ecology of fall migrating landbirds at an inland stopover site in northeastern Pennsylvania dominated by nonnative vegetation

Landbirds are especially vulnerable during migration as they move through novel habitats and encounter enhanced predation risk, unpredictable food resources, enhanced competition, and inclement weather. Further, numerous studies suggest exotic vegetation species have the potential to alter habitat quality, in turn affecting the fitness of migratory birds. The purpose of this study was to evaluate fitness correlates associated with fall migrant use of shrubland habitat dominated by nonnative honeysuckle (Lonicera spp.) in northeastern Pennsylvania. Additionally, we looked for differences in stopover ecology between demographic cohorts (age, and in the case of Common Yellowthroat [Geothlypis trichas], both age and sex). We used estimates of mass change as our primary fitness indicator, assuming that evidence of positive mass change reflects fat deposition and hence indicates quality habitat. Our results suggest that of 7 species, 1 gained mass, 5 neither gained nor lost mass, and 1 lost mass. Further, while we found little evidence of age or sex differences in migratory timing, we did find evidence that older birds gained mass at a higher rate than younger in 2 species and that, while male Common Yellowthroats maintained mass while using our site, females lost mass. We conclude that our exotic-dominated shrubland habitat does not provide high-quality stopover habitat for most species.

Size variation does not act as insurance in bumble bees; instead, workers add weight in an unpredictable environment

Complex systems (e.g. eusocial insect colonies) exhibit emergent behaviours as a result of the interactions of their components. These components often vary in several traits. Such variation may improve system performance by increasing its efficiency or its robustness to environmental change. These two outcomes, efficiency and robustness, are often thought to be in opposition. Therefore, variation may be beneficial only under certain environmental conditions. Here we aim to understand why variation evolved in a particular system, bumble bee (Bombus impatiens) colonies. Workers in these colonies vary in body size, which affects the tasks they perform as well as their starvation resistance, suggesting potential impacts on efficiency and robustness, respectively. We examine how this variation affects colony performance under different environmental conditions and how colonies respond physiologically to these conditions. We maintained colonies of equal biomass but with either variable or less variable worker body sizes using targeted worker removal. We found that colonies with variable body sizes did not produce more brood (i.e. did not show evidence of increased performance) under predictable or unpredictable food environments. However, workers that developed under the unpredictable environment were smaller relative to their weight at eclosion. This effect was due in part to an increase in stored lipids, particularly in smaller workers. These physiological changes may explain why mortality rates did not differ between the predictable and unpredictable environment. Therefore, our finding that size variation did not affect colony performance suggests that size variation may be a neutral trait, present because selection is not acting against it. Our results also suggest that workers respond physiologically to differences in environmental conditions, which is important to consider when testing system robustness.

Rivaroxaban for the treatment of venous thromboembolism in pediatric patients

ABSTRACT Introduction Anticoagulant therapy is in use for both prevention and treatment of venous and arterial thromboembolic disorders. Delivering safe and effective anticoagulation in the pediatric population is challenging, since the available standard therapy with parenteral UFH and LMWH is troublesome for most pediatric patients, and VKAs require frequent INR monitoring due to the unpredictable pharmacokinetics and numerous food and drug interactions. Rivaroxaban, a direct FXa inhibitor, offers the convenience of oral administration and predictable pharmacokinetics across a wide range of patients. Its safety and efficacy have been previously established in various adult indications. Areas covered This review outlines pharmacologic and clinical aspects regarding rivaroxaban treatment in adults and children, and provides a broad appraisal of the The EINSTEIN-Jr program which evaluated the safety and efficacy of body-weight adjusted pediatric rivaroxaban regimens for the treatment of VTE in children. A review of the literature using the keywords rivaroxaban and pediatric venous thromboembolism was conducted within the National Center for Biotechnology (NCBI) and EMBASE databases. Expert opinion Rivaroxaban represents an appealing therapeutic alternative for VTE in children. Further research should explore additional indications for rivaroxaban in the pediatric population beyond that of VTE.

Glucose Concentrations in Closely Related Titmice (Baeolophus) Species Linked to Regional Habitat Differences Across an Avian Hybrid Zone

Aims:We used physiological data, in conjunction with habitat information, to elucidate the interactions between two hybridizing songbirds within a hybrid zone.Background:Hybrid zones are ideal regions to examine a variety of ecological, behavior, and evolutionary processes. In addition to genetics, behavior, and morphology, physiological differences may impact hybrid fitness, genetic introgression, and even the stability of a hybrid zone.Objective:To assess physiological differences in hybridizing species, we investigated selected venous blood analytes in two species of songbirds hybridizing along the Balcones Escarpment in central Texas.Methods:Using a portable blood analyzer, we assayed blood samples from Black-crested Titmouse (Baeolophus atricristatus) and Tufted Titmouse (B. bicolor) individuals along a longitudinal transect that included the contact zone. Ecologically, this transect varies from higher elevation semi-arid regions on the Balcones Escarpment (and west across the Edwards Plateau) to lower elevation mesic forests east of the escarpment.Results:As expected, several blood analytes differed with age, sex, and sedative administration; however, we observed relatively increased blood glucose concentrations in Black-crested Titmice, which occupy the semi-arid habitats of west Texas. Furthermore, glucose concentrations were further elevated following rainfall events. Blood glucose concentrations often increase during stressful conditions and or related to changes in diet.Conclusion:We suspect that Black-crested Titmice have relatively increased blood glucose concentrations as a product of living in a semi-arid environment that causes chronic stress from unpredictable food and water resources. The link between rainfall and glucose may be a result of the increased and greater diversity of food availability after rainfall. Although further research is needed, we suspect that habitat differences and associated lack of physiological adaptations may be a limiting factor in westward range expansion in the more aggressive Tufted Titmice.

Using GPS and accelerometry data to study the diet of a top avian scavenger

ABSTRACT Capsule The Eurasian Griffon Vulture Gyps fulvus is an obligate scavenger relying on spatially and temporally unpredictable food resources. We demonstrate how high-frequency telemetry data can be efficiently used to identify vultures’ feeding locations in the wild and study their diet. Aims To study the Griffon Vulture diet composition, seasonal variations, and bathing frequency in an area with high natural food availability. Methods We used a remote-sensing technique based on GPS and accelerometry data to identify the feeding locations, and ground-truthing to identify the carcass species and investigate the causes of mortality. Results We identified 13 taxa in the diet of Griffon Vultures. Cattle comprised 48.5% of the diet, followed by sheep (24.3%), while wild animals were 13.1%. We observed seasonal variation in the proportion of small stock and game species in the diet. Predation was reported as the main cause of mortality (60.2%) for prey species, while natural causes accounted for 37.6%. Vultures were mainly feeding in areas south of their breeding colonies in Bulgaria and Greece. Natural springs and fountains were regularly used by the Griffon Vultures for bathing and drinking, especially in the summer. Conclusions Free-ranging livestock creates favourable feeding conditions for vultures, especially in areas with rugged terrain and a high density of predators. An increase in the number of wild ungulates can potentially buffer the fluctuations in livestock numbers and be beneficial for vultures, especially in the autumn and winter months. Lead ammunition must be substituted with non-toxic alternatives to reduce the exposure of vultures and other scavengers to lead poisoning.