Variation In Food Availability Research Articles

Sex-specific nest attendance rhythm and foraging habitat use in a colony-breeding waterbird

Abstract In most colony-breeding species, biparental care during both egg incubation and chick-rearing is inevitable for successful reproduction, requiring parents to coordinate their nest attendance and foraging time. The extent to which the rhythm of nest attendance is adjusted to temporal and spatial variation in food availability is poorly understood. Here, we investigate whether the rhythm of nest attendance interacts with the spatial and temporal availability of foraging habitats in Eurasian spoonbills Platalea leucorodia breeding on Schiermonnikoog, a Dutch Wadden Sea barrier island. Spoonbills are tactile foragers that forage during both day and night in habitats of varying salinity. GPS-tracking combined with acceleration-based behavioral classification of 9 female and 13 male adult spoonbills between 2013 and 2019 revealed that, despite nearby foraging opportunities following a tidal rhythm, nest attendance followed a sex-specific diel rhythm. During incubation and chick-rearing, females attended the nest at night and foraged during the day, while males showed the reverse rhythm. Females made more and shorter foraging trips to, almost exclusively, nearby marine habitats, whereas the larger males often made long trips to forage in more distant freshwater habitats. Before and after breeding, females as well as males foraged primarily at night, suggesting that this is the preferred period of foraging for both sexes. Nevertheless, foraging habitat use remained sex-specific, being most likely explained by size-dependent foraging techniques. To conclude, the sex-specific rhythm of nest attendance is not shaped by the spatial and temporal availability of foraging habitats.

Short-term temporal variability in offshore benthic biodiversity across hydrographic regions at a sub-Antarctic archipelago

AbstractCommunity composition is one of the main factors influencing the ecological functioning of any given ecosystem, with a more diverse community providing a larger set of services. Benthic community composition can vary at spatial and temporal scales, with the dynamics of primary production and benthic food availability being key determinants of community structure of a given system. Studies have indicated shifts in benthic community composition at sub-Antarctic Islands over a period of 30 years, linked to variability in food availability driven by climate change. Here, we aim to evaluate possible short-term variability in benthic community composition at the sub-Antarctic archipelago Prince Edward Islands (PEIs), sampling stations across three hydrographically dynamic regions over two consecutive years, 2016–2017. The results indicated significantly higher species richness and abundance in 2017 than in 2016, with some taxa also showing variation among regions around the PEIs. Such effects can be linked to different substratum type or hydrographic regime. This study further contributes to understanding variability and changes in benthic communities in the near future, an essential information to develop efficient management strategies for this vulnerable marine system.

The effects of environmental changes on the endocrine regulation of feeding in fishes.

Fishes are exposed to natural and anthropogenic changes in their environment, which can have major effects on their behaviour and their physiology, including feeding behaviour, food intake and digestive processes. These alterations are owing to the direct action of environmental physico-chemical parameters (i.e. temperature, pH, turbidity) on feeding physiology but can also be a consequence of variations in food availability. Food intake is ultimately regulated by feeding centres of the brain, which receive and process information from endocrine signals from both brain and peripheral tissues such as the gastrointestinal tract. These endocrine signals stimulate or inhibit food intake, and interact with each other to maintain energy homeostasis. Changes in environmental conditions might change feeding habits and rates, thus affecting levels of energy stores, and the expression of endocrine appetite regulators. This review provides an overview of how environmental changes and food availability could affect feeding and these endocrine networks in fishes. This article is part of the theme issue 'Endocrine responses to environmental variation: conceptual approaches and recent developments'.

Size‐dependence of food intake and mortality interact with temperature and seasonality to drive diversity in fish life histories

AbstractUnderstanding how growth and reproduction will adapt to changing environmental conditions is a fundamental question in evolutionary ecology, but predicting the responses of specific taxa is challenging. Analyses of the physiological effects of climate change upon life history evolution rarely consider alternative hypothesized mechanisms, such as size‐dependent foraging and the risk of predation, simultaneously shaping optimal growth patterns. To test for interactions between these mechanisms, we embedded a state‐dependent energetic model in an ecosystem size‐spectrum to ask whether prey availability (foraging) and risk of predation experienced by individual fish can explain observed diversity in life histories of fishes. We found that asymptotic growth emerged from size‐based foraging and reproductive and mortality patterns in the context of ecosystem food web interactions. While more productive ecosystems led to larger body sizes, the effects of temperature on metabolic costs had only small effects on size. To validate our model, we ran it for abiotic scenarios corresponding to the ecological lifestyles of three tuna species, considering environments that included seasonal variation in temperature. We successfully predicted realistic patterns of growth, reproduction, and mortality of all three tuna species. We found that individuals grew larger when environmental conditions varied seasonally, and spawning was restricted to part of the year (corresponding to their migration from temperate to tropical waters). Growing larger was advantageous because foraging and spawning opportunities were seasonally constrained. This mechanism could explain the evolution of gigantism in temperate tunas. Our approach addresses variation in food availability and individual risk as well as metabolic processes and offers a promising approach to understand fish life‐history responses to changing ocean conditions.

Temporal and Spatial Signatures of Scylla paramamosain Transcriptome Reveal Mechanistic Insights into Endogenous Ovarian Maturation under Risk of Starvation.

Variability in food availability leads to condition-dependent investments in reproduction. This study is aimed at understanding the metabolic response and regulatory mechanism of female Scylla paramamosain in response to starvation in a temporal- and tissue-specific manner. The mud crabs were starved for 7 (control), 14, 28, and 40 days for histological and biochemical analysis in the hepatopancreas, ovary, and serum, as well as for RNA sequencing on the hepatopancreas and ovary. We further highlighted candidate gene modules highly linked to physiological traits. Collectively, our observations suggested that starvation triggered endogenous ovarian maturation at the expense of hepatopancreas mass, with both metabolic adjustments to optimize energy and fatty acid supply from hepatopancreas to ovary in the early phase, followed by the activation of autophagy-related pathways in both organs over prolonged starvation. These specific adaptive responses might be considered efficient strategies to stimulate ovarian maturation of Scylla paramamosain under fasting stress, which improves the nutritional value of female mud crabs and other economically important crustaceans.

Body Image Determinants for Teenagers Aged 12-16 Years

<div><table cellspacing="0" cellpadding="0" align="left"><tbody><tr><td align="left" valign="top"><p><em>The problem that arises in teenagers today is body image or body image, where body image is a very important and important thing for teenagers because the appearance of the shape and size of a teenager's body can increase self-confidence if they have a positive body image or are satisfied, but on the contrary, teenagers who have Negative or dissatisfied body image will have a negative impact on self-confidence and teenagers health such as bulimia, anorexia, malnutrition and obesity. Teenagers who have a body shape that is not ideal (thin or obese) are more likely to feel negative perceptions, this will have an impact on the mental health and development of teenagers.</em> <em>The aim of this study is to analyze the determinants (nutritional status, food availability, and sleep duration) of body image of teenagers aged 12-16 years. The method used in this study was cross-sectional with a sample of 57 teenagerss aged 12-16 years taken by random sampling and data obtained using a questionnaire and then analyzed using the chi-square test to see the relationship between the independent variable (nutritional status, food availability, and sleep duration) and the dependent variable (body image). The nutritional status variable (0.004) describes a relationship with body image, food availability (1,000) illustrates that there is no relationship with teenagers body image, while sleep duration(1,000) illustrates that there is no relationship with teenagers body image. </em><em>It is necessary to suggest a promotional or educational effort for teenagers to increase nutritional knowledge so that it can improve nutritional status in teenagers and will be able to increase positive perceptions of body image in teenagers.</em><em></em></p><p> </p></td></tr></tbody></table></div><strong><em>Keyword: Body Image, Food Availability, Nutritional Status, Sleep Duration, Teenagers</em></strong>

Varied Macro- and Micronutrient Fertilization Rates Impact Root Growth and Distribution and Fruit Yield of Huanglongbing-affected Valencia Orange Trees

Candidatus Liberibacter asiaticus (CLas), which causes huanglongbing (HLB) in citrus trees, has a great impact on tree root health, fruit development, and juice quality. HLB-affected trees have a fibrous root density loss of ∼30% to 80%, resulting in the limited capacity of citrus trees to uptake nutrients. Therefore, this study was conducted for 3 years to 1) assess the temporal changes in root density as a result of varied fertilization, 2) determine dynamics of HLB with regard to root growth and distribution as a result of varied fertilization for Valencia orange trees, and 3) evaluate the impact of varied fertilization rate and method of fertilization on fruit yield for HLB-affected trees. Macronutrients and micronutrients were applied at varying fertilization rates (0×, 1×, 2×, and 4×, of University of Florida guidelines). Root scans were done using minirhizotrons at 0 to 19.1 cm, 19.1 to 40.7 cm, 38.2 to 59.8 cm, and 57.3 to 78.9 cm soil depths. Results obtained from the study showed that root growth and distribution were greater in 0 to 19.1 cm than 19.1 to 40.7 cm to 57.3 to 78.9 cm soil depths. Thus, root growth decreased (P < 0.0004) with increasing soil depth due to variation in nutrient availability for tree uptake. Increased nutrient availability at occurrence of physiological processes in citrus trees also influenced root growth and distribution, resulting in root growth flushes in the months of Nov to early Feb and Jul to early Aug. Fruit yield was significantly different between treatments in 2 of the 4 years of the study (P = 0.001 and P = 0.003), and largely ascribed to soil fertilization of micronutrients compared with foliar. Therefore, at higher fertilization rates, particularly via soil application, nutrient availability was increased, thus promoting root growth and distribution and fruit yield in HLB-affected orange trees.

Prenatal caloric restriction adjusts the energy homeostasis and behavior in response to acute and chronic variations in food availability in adulthood.

Fetal metabolic programming produced by unfavorable prenatal nutritional conditions leads to the development of a disorder called "thrifty phenotype", which is associated with pathologies such as diabetes and obesity in adulthood. However, from an ecophysiological approach, few studies have addressed the development of thrifty phenotypes in terms of energy. This might represent an adaptive advantage against caloric deficiency conditions extending into adulthood. The objective of this study is to investigate the potential adaptive value of the thrifty phenotype expression through prenatal programming in a rodent model experiencing varying dietary conditions in different temporal contexts. To fill this gap, adult males of Mus musculus (BALB/C) from two maternal pregnancy groups were analyzed: control (ad libitum feeding) and caloric restriction from day 10 of gestation (70% restriction). Adult offspring of these groups were split further for two experiments: acute food deprivation and chronic caloric restriction at 60%. The acute food deprivation was performed for 24, 48 or 72h while the caloric restriction regime was sustained for 20days. For each experiment, morphological variables, such as body and organ mass, and gene expression related to lipid and carbohydrate metabolism from the liver and brain, were evaluated. In chronic caloric restriction, behavioral tests (open-field test and home-cage behavior) were performed. Our results indicate that under acute deprivation, the liver mass and triglyceride content remained unchanged in individuals subjected to prenatal restriction, in contrast to the reduction experienced by the control group. The latter is associated with the expression of the key genes involved in energy homeostasis (Pepck, Pparα/Pparγ), indicating a differential use of nutritional resources. In addition, thrifty animals, subjected to chronic caloric restriction, showed a severe reduction in locomotor and gluconeogenic activity, which is consistent with the regulatory role of Sirt1 and its downstream targetsMaoandPepck. Our results reveal that prenatal caloric restriction translates into a sparing metabolism in response to acute and chronic lack of food in adulthood.

Interactive roles of temperature and food availability in predicting habitat suitability for marine invertebrates

Natural variability in habitat characteristics, including their interactions, can affect marine invertebrate development. Controlled laboratory experiments seek to assess responses to such variability. For marine invertebrates, responses to temperature are typically assessed but a continuous gradient of all temperatures that a species may encounter is not frequently used. For planktonic larvae of marine invertebrates, biotic factors such as food availability receive less attention due to difficulty in simulating planktonic biotic interactions in a controlled laboratory setting. Here, a laboratory experiment was used to quantify larval development (growth, pelagic larval duration and survival) of the Atlantic surfclam, Spisula solidissima, in response to a continuous range of temperatures and food (phytoplankton) concentrations, allowing quantification of thermal and food availability niches. A second experiment was conducted to quantify the thermal and food availability niches for recruit (post-settlement) surfclams. These experiments were uniquely designed to inform future climate change-based forecasting and habitat suitability modeling. Larval growth and survival increased with increased food availability, while pelagic larval duration decreased with increased food availability. Larval survival decreased with increased temperature, growth peaked near 22 °C and pelagic larval duration was lowest near 22 °C. For recruits, survival and growth increased with both temperature and food availability, but growth decreased at temperatures >22 °C. Broadly, results suggest potential food limitation for continental shelf bivalve larvae and demonstrate that natural variation in food availability may affect thermal tolerances. Results also suggest that throughout the range of the surfclam, high food and moderate temperature areas such as New York Bight and Georges Bank are ideal for larvae and early recruits, whereas low food and high temperature areas, including continental shelf waters in the southern Middle Atlantic Bight, are suboptimal for early life stages of surfclams. This framework may be used for habitat suitability modeling, from an energetic perspective, for other marine invertebrate taxa.

TFEB and TFE3 control glucose homeostasis by regulating insulin gene expression.

To fulfill their function, pancreatic beta cells require precise nutrient-sensing mechanisms that control insulin production. Transcription factor EB (TFEB) and its homolog TFE3 have emerged as crucial regulators of the adaptive response of cell metabolism to environmental cues. Here, we show that TFEB and TFE3 regulate beta-cell function and insulin gene expression in response to variations in nutrient availability. We found that nutrient deprivation in beta cells promoted TFEB/TFE3 activation, which resulted in suppression of insulin gene expression. TFEB overexpression was sufficient to inhibit insulin transcription, whereas beta cells depleted of both TFEB and TFE3 failed to suppress insulin gene expression in response to amino acid deprivation. Interestingly, ChIP-seq analysis showed binding of TFEB to super-enhancer regions that regulate insulin transcription. Conditional, beta-cell-specific, Tfeb-overexpressing, and Tfeb/Tfe3 double-KO mice showed severe alteration of insulin transcription, secretion, and glucose tolerance, indicating that TFEB and TFE3 are important physiological mediators of pancreatic function. Our findings reveal a nutrient-controlled transcriptional mechanism that regulates insulin production, thus playing a key role in glucose homeostasis at both cellular and organismal levels.

Slow growing bacteria survive bacteriophage in isolation

The interactions between bacteria and bacteriophage have important roles in the global ecosystem; in turn changes in environmental parameters affect the interactions between bacteria and phage. However, there is a lack of knowledge on whether clonal bacterial populations harbour different phenotypes that respond to phage in distinct ways and whether the abundance of such phenotypes within bacterial populations is affected by variations in environmental parameters. Here we study the impact of variations in nutrient availability, bacterial growth rate and phage abundance on the interactions between the phage T4 and individual Escherichia coli cells confined in spatial refuges. Surprisingly, we found that fast growing bacteria survive together with all of their clonal kin cells, whereas slow growing bacteria survive in isolation. We also discovered that the number of bacteria that survive in isolation decreases at increasing phage doses possibly due to lysis inhibition in the presence of secondary adsorptions. We further show that these changes in the phenotypic composition of the E. coli population have important consequences on the bacterial and phage population dynamics and should therefore be considered when investigating bacteria-phage interactions in ecological, health or food production settings in structured environments.

Insularity determines nestling sex ratio variation in Egyptian vulture populations.

Variation in offspring sex ratio, particularly in birds, has been frequently studied over the last century, although seldom using long-term monitoring data. In raptors, the cost of raising males and females is not equal, and several variables have been found to have significant effects on sex ratio, including food availability, parental age, and hatching order. Sex ratio differences between island populations and their mainland counterparts have been poorly documented, despite broad scientific literature on the island syndrome reporting substantial differences in population demography and ecology. Here, we assessed individual and environmental factors potentially affecting the secondary sex ratio of the long-lived Egyptian vulture Neophron percnopterus. We used data collected from Spanish mainland and island populations over a ca. 30-year period (1995-2021) to assess the effects of insularity, parental age, breeding phenology, brood size, hatching order, type of breeding unit (pairs vs. trios), and spatial and temporal variability on offspring sex ratio. No sex bias was found at the population level, but two opposite trends were observed between mainland and island populations consistent with the island syndrome. Offspring sex ratio was nonsignificantly female-biased in mainland Spain (0.47, n = 1112) but significantly male-biased in the Canary Islands (0.55, n = 499), where a male-biased mortality among immatures could be compensating for offspring biases and maintaining a paired adult sex ratio. Temporal and spatial variation in food availability might also have some influence on sex ratio, although the difficulties in quantifying them preclude us from determining the magnitude of such influence. This study shows that insularity influences the offspring sex ratio of the Egyptian vulture through several processes that can affect island and mainland populations differentially. Our research contributes to improving our understanding of sex allocation theory by investigating whether sex ratio deviations from parity are possible as a response to changing environments comprised by multiple and complexly interrelated factors.

Specialist shorebird respond to prey and habitat availability through trophic plasticity

Spatiotemporal variations in food availability represent a challenge to the persistence of specialist species. The American oystercatcher (Haematopus palliatus) is a shorebird regarded as a bivalve specialist, although foraging habitats and prey species may vary along its distribution. Here, we studied American oystercatcher breeding in sites with variable landscapes to test the effect of temporal and spatial variations in food availability and dietary aspects. Between 2017 and 2021, we sampled oystercatchers (n = 100) and macroinvertebrates at the mesolitoral zone in five foraging areas in southern Brazil, three composed by sand and rock substrates (mixed), and two by sandy beach only. We obtained biological samples from oystercatchers and macroinvertebrates for carbon (δ13C) and nitrogen (δ15N) stable isotope analysis. In addition, we carried out systematic sampling of macroinvertebrates in sandy beaches at foraging areas to assess prey availability. Main findings showed the oystercatcher diet to be influenced both by the heterogeneity of foraging habitats and temporal fluctuations in availability of food resources. Bivalves contributed ∼60% to the diet of oystercatchers, but differences in the preferred bivalve species were detected among areas. In sites with mixed substrates, oystercatchers had a wider isotopic niche, suggesting habitat heterogeneity induced a more varied diet. Finally, we also observed interannual variation in the diet that may be associated with variation in macroinvertebrate availability on sandy beaches, especially for non-bivalve prey. Therefore, both temporal variations in food availability and foraging habitat heterogeneity seem to shape the foraging ecology of oystercatchers in the coastal zone, evidencing trophic plasticity in this specialist shorebird.

Food monotony compromises photoperiod induced responses in migratory redheaded bunting

Food is one of the key environmental factors affecting an organism’s behavior and physiology on daily and seasonal basis. Over the years, studies regarding human food habits and its subsequent impact on their behavior and physiology have been explored a lot but studies on same line are missing with reference to different animal taxa. Thus, in the present study, we investigated the impact of varied food availability over a monotonous food schedule on birds. We were interested in knowing how this treatment affects the birds’ behavior and physiology? The experiment was performed on migratory passerine finch; redheaded bunting ( Emberiza bruniceps), wherein two groups of bird ( N = 10 each) were taken. Group I (Kakuni group; KG) birds were fed only with seeds of Setaria italica (Kakuni) whereas group II (Mixed Diet group; MG) was provided with seeds of kakuni along with sesame seeds ( Sesamum indicum) and egg white, all three separately in different bowls. Results reveal that behaviorally, MG birds were more active with higher gross food intake when compared with KG. MG birds also had significant gain in body mass and testicular volume during the course of experiment, although, the accumulation of fat remained unchanged between the two groups. Thus, the study clearly demonstrates the motivation to eat and stay active besides being reproductively proficient in presence of varied food availability.

Consumer identity but not food availability affects carabid diet in cereal crops

Understanding trophic interactions in agroecosystems is crucial for harnessing ecosystem services such as pest control, thus enabling a reduction in pesticide use. Carabid beetles (Coleoptera: Carabidae) have the potential to regulate not only insect pests but also weed seeds and slugs. The aim of this study was to investigate the food choice of different carabid species in the experimental setting of a cereal field with varying seed and slug prey availability during the season. In addition to varying food availability, the effects of species identity and season on carabid food choice should also be closely examined. Therefore, the gut contents of 1,120 beetles of eight carabid species were screened for the DNA of plants, aphids, springtails, earthworms and slugs via diagnostic multiplex PCR and a nested metabarcoding approach for plant species identification. Plant DNA was detected far more often (72%) than the various animal prey types (less than 12.5% each). Within the plant detections, 80 weed species were identified in the metabarcoding, with Galinsoga parviflora/quadriradiata (Galinsoga spp.—quickweeds) as the most frequently detected species. Carabid food choice was driven by their species identity and seasonality, while no effect of increased availability of seeds and slugs on their food choice was detected. While weed seeds seem to be an important food source for carabids, their availability does not directly affect the carabid diet. The importance of consumer identity and seasonality highlight the need for a diverse carabid species community for resilient pest control services.

Within-year changes in households’ access to food in a unimodal climate rural area of Benin Republic

Food insecurity is a concern in Benin not only because of seasonal variations in food availability but also the limited access to food experienced by some households. This study analysed the effect of seasonality on household access to food in a rural area of Benin characterised by a unimodal climate. One hundred and seventy volunteer households were recruited in the study area and monitored during the increased, intermediate and decreased (or lean) food availability periods (FAPs) from September 2018 to July 2019. Socio-demographic data were collected during individual interviews with household heads and used to describe the sample. Data on households’ access to food were collected on a bimonthly basis using a food consumption score (FCS) questionnaire. Food consumption scores were used to divide the households into three food consumption groups (FCGs): poor (FCS ≤ 21), borderline (21.5 ≤ FCS ≤ 35) and acceptable (FCS > 35). Generalized estimate equation (GEE) was used to compare FCGs among the repeated measures. The principal occupation of household heads was agriculture (72.9%) and the mean household size was 6.8±3.6 persons. The FCS ranged from 59.7±15.5 to 69.4±15.9. The lowest FCS was recorded in September (intermediate FAP) whereas the highest was obtained in May (lean FAP). All the households (100%) had acceptable food consumption during the increased FAP (November to January). The proportion of households with acceptable food consumption was 91% in September and decreased from 99% in March to 90% in July, that is, during the lean FAP. On the other hand, the proportion of households with borderline and poor food consumption was 9% in September and increased from 1% in March to 10% in July. The proportions of FCGs obtained in November, January, March and May significantly differed from that of July (p<0.05) whereas there was no significant difference between September and July. Households had frequent (5 to 7 days/week) and regular (all months) intakes of starchy staples, vegetables, meats and fish. In contrast, the frequency of pulses and fruits consumption varied between months. In conclusion, the lean FAP (May to July) and the following intermediate FAP (September) are characterised by a deterioration in households’ access to food. The variation of pulses and fruits consumption throughout the year is the result of food insecurity and constitutes a major risk factor for micronutrient malnutrition for household members. Keys words: Households, access to food, food consumption score, longitudinal studies, unimodal climate, Benin Republic

Targeting first trimester trophoblast cell metabolism modulates its susceptibility to Zika virus infection.

In the last 15 years Zika virus (ZIKV) caused several outbreaks of increasing scale in Micronesia, South Pacific islands, and more recently in the Caribbean and South America. The severity of the clinical presentation in neonates from pregnant women infected with ZIKV during the last outbreak supports the relevance of unraveling the mechanism of infection and viral persistence in the placenta with local viral isolates. Here, we investigated the relevance of trophoblast metabolic rewiring for viral multiplication and the role of the vasoactive intestinal peptide (VIP) as an endogenous factor associated with placental restriction to ZIKV infection at early pregnancy. Our in vitro model demonstrated that ZIKV triggers metabolic rewiring in first trimester cytotrophoblast-derived cells by increasing glucose utilization as fuel to sustain its replication, decreasing long-chain polyunsaturated fatty acid uptake, and promoting lipid droplets accumulation to favor its multiplication. Of note, variations in nutrient availability modulated viral spread in trophoblast cultures. The presence of VIP during trophoblast infection impaired ZIKV infective particle production and viral replication, restoring cell migration and metabolism. Moreover, the blockade of endogenous VIP signaling increased viral particle production and the viral entry receptor AXL expression. These results highlight the potential role of VIP as an endogenous antiviral factor related to trophoblast cell permissiveness to ZIKV infection at early pregnancy.

Bird community structure and habitat association in Owabi Wildlife Sanctuary, Ashanti Region (Ghana)

Context Globally, an estimated 1.3% of the bird species have gone extinct over the past millennia, largely owing to habitat loss. Aims This study investigated bird–habitat associations and assemblages in the Owabi Ramsar wetland. Methods The study was conducted over 5 months (May–September 2019) in four habitat types (agricultural land, built-up, forest reserve, and open-water area). Data were collected in 84 plots across four habitats (i.e. built-up area = 25, forest reserve = 25, agricultural land = 25 and open-water area = 9 plots), using a point-count technique. The Gambin model, non-metric multidimensional scaling, Chao-1, and Hill numbers models were used to evaluate differences in bird diversity and composition among the habitat types. Key results In all, 1260 individual birds, belonging to 81 species, were encountered. Many of the species occurred in the forest habitat (n = 46, 56.8%. Species from the agricultural land (n = 37) and built-up (n = 30) were mainly habitat generalists that used these two habitats as their shared feeding station. Bird–habitat specialisation grouping equally showed the forest specialists to be the highest (n = 23, 38.4%), whereas the open water had the least number of habitat specialisation associations (e.g. white-faced whistling duck, n = 20, 24.7%). Five species were widely distributed in all four habitats (e.g. bronze-mannikins and white-throated bee-eaters), indicating their broad habitat preferences and ability to adapt to varied conditions. The forest reserve tended to be the most diverse, which was likely mediated by factors such as nesting microhabitats, varied food availability, and human-led activities. Conclusions This study highlighted bird dietary structure and associated habitat type and bird-habitat specialisation in four different land-use types at Owabi Ramsar wetland. Implications Given the increasing level of disturbance, there is the likelihood that the population of forest-dependent and open water-dependent birds will be lost or will have to change or modify their behaviour to be similar to that of open-tolerant or open-country birds if managers of the Owabi Wildlife Sanctuary fail to implement the recommended management interventions highlighted.

Timing and magnitude of net methylmercury effects on waterbird reproductive output are dependent on food availability

Mercury (Hg) is a globally distributed pollutant. Its sub-lethal effects on reproduction of birds have been used as indicators of contamination and of potential demographic effects. However, studies typically used single endpoints that might not be representative of entire reproductive cycle. To estimate timing and net cumulative effects of Hg exposure under field conditions, we used observational data over 11 years from >1200 nests of great egrets breeding under temporally and spatially varying food availability and Hg exposures in the Florida Everglades. We collected measures of fish biomass and availability (>100 locations annually) and used four avian reproductive endpoints that represented the entire breeding cycle. We calculated net reproductive loss by adding estimated Hg effects on failures prior to egg laying, clutch size, hatching success and nestling survival in response to food availability and Hg exposure. To validate and assess results of the observational egret study, we ran the same analyses with data of captive breeding white ibises experimentally exposed to Hg with ad libitum food over 3 years. We found large (>50 %) reductions in great egret offspring with high Hg exposure (18 μg/g dw THg nestling feather, ~0.7 μg/g ww whole egg THg) and high food availability, and even larger reductions (up to 100 %) with high Hg exposure and low food. Timing and the relative contribution of different endpoints to overall reproductive failure varied with food availability. Failures prior to egg laying were relevant at all food availabilities and proportionally most important during high food availability (~70 % of total losses). Under high food, post-hatching failures increased moderately with increasing exposure (~10 % of total losses), and under low food, hatching failures became dominant (~50 % of total losses). Patterns of failure of captive white ibis fed ad libitum resembled those of great egrets under high food availability but differed in total magnitude. We suggest that, a) net reproductive effects of Hg in free-ranging animals are probably much higher than generally reported in studies using single endpoints, b) Hg effect sizes vary considerably among different endpoints and c) food availability is a strong driver of timing and net effects of Hg exposure.

Relative abundance, habitat selection, and diet of the coyote in northern México

The coyote (Canis latrans) is a widespread predator with a high degree of adaptation to different ecosystems. The objective of this study was to estimate the relative abundance index, habitat selection, and diet of C. latrans through scent stations, in two types of vegetation located in northwestern Chihuahua. From April 2018 to March 2019, ten fixed scent stations (SS) were placed in pine-oak forest and other ten in semi-open grassland, with a linear separation of 500 meters between each station to achieve a five km transect in each vegetation during 12 samplings (two sampling night per month) for totaling 420 SS after discarding inactive SS. The relative abundance index of coyote showed that both types of vegetation, pine-oak forest (0.30) and semi-open grassland (0.23) were used in a similar way. The habitat selection test (Chi2) showed that coyote abundance and type of vegetation were independent (χ2 = 2.96, P > 0.05), not showing statistically significant differences in annual relative abundance index of coyotes between the two vegetation types. The food items detected in thirty-four scats collected belonged to mammals (55.9 %), fruits (35.3 %) and arthropods (8.8 %). Rodents and lagomorphs were the main source of food. Throughout the sampling period, the pine-oak forest showed the greatest relative abundance index of C. latrans. This may be because the forest provides them with shelter from climatic situations and a greater variety of seeds, fruits and insects. In this study the two seasons with the highest relative abundance were spring and autumn in both ecosystems, coinciding with an increase in rainfall, resulting in an abundance of potential prey (rodents and lagomorphs), and other food items like fruits. Regarding annual diet the most consumed prey were mammals. We found differences in diet between seasons, that can be explained by the variation in food availability among seasons.