Maximum Food Intake Research Articles

Harmfulness and biological characters of a leaf beetle Gastrolina depressa (Coleoptera: Chrysomelidae) to its host plant Pterocarya stenoptera (Fagales: Juglandaceae)

Gastrolina depressa (Coleoptera: Chrysomelidae) has been found to damage many walnut plants in China. It prefers to feed on the annual leaves of an important economic plant, Pterocarya stenoptera (Fagales: Juglandaceae), and causes extensive cosmetic destruction, even plant death. Nevertheless, its biological characteristics are mostly unknown. In this study, we investigate the harmful and biological characteristics of G. depressa with different developmental stages. The results showed that G. depressa had four developmental stages: egg, larva (1st -3rd instar), pupa, and adult, the life history lasted nine days, with obvious overlapping generations. The food intake of the larvae increased with the increase of the instar, and the maximum food intake of the 3rd instar larvae was 448.19 mm2. The abdomen of the females was enlarged before oviposition, and the average number of eggs laid was 47.63 ± 13.53. Bioassay showed that there was no difference in the search time for the young (2.03, 1.25, 1.15, and 0.91 min) and old leaves (1.68, 1.15, 0.90, and 1.93 min) of P. stenoptera between 1st -3rd instar larvae and adults; the feeding preference of 1st -3rd instar larvae and adults for young leaves was higher than that to old leaves (23.33%, 26.67%, 33.33%, and 21.67%, respectively). The successful selection rates of 1st -3rd instar larvae and adults to young leaves (81.67%, 80%, 85.00%, and 70.00%, respectively) was higher than to old leaves (8.35%, 11.67%, 3.34%, and 11.67%, respectively).

Toxicological assessment of cadmium exposure through Hyphantria cunea larvae on the predation fitness of Arma chinensis

Heavy metals are defined as an abiotic factor that affects the efficiency of biological pest control. This study constructed a cadmium (Cd)-polluted artificial diets–Hyphantria cunea–Arma chinensis food chain to analyze the effects of Cd exposure on the ability of A. chinensis to control H. cunea. The results revealed that Cd was transferred through the artificial diet to H. cunea larvae and A. chinensis nymphs via a biological amplification effect. After feeding on Cd-accumulated H. cunea larvae, the body weight of A. chinensis nymphs reduced, mortality increased, developmental duration prolonged, and the expression of growth regulatory genes (EX, cycE, and MER) decreased. Cd activated the antioxidant defense system of the nymphs, accompanied by a significant enhancement in the contents of H2O2 and MDA, marked damage to the midgut sub-microstructure, and a remarkable induction in the expression of genes crucial for the mitochondrial pathway/ER stress–apoptosis pathway. Cd significantly diminished the contents of total amino acids, glucose, free fatty acids, and expression of the genes (HK2, PFK, IDH1, and IDH2) essential for the TCA cycle and glycolysis in the nymphs. The preference of the A. chinensis nymphs to Cd-treated H. cunea larvae was evidently reduced. Cd diminished the search-ability, food intake, instantaneous attack rate, and maximum theoretical daily food intake but prolonged the feeding time of the nymphs. Taken together, Cd exposure reduces the ability of A. chinensis nymphs to control H. cunea and provides a new challenge for the efficiency of insect pest control using natural enemies. These findings have important reference value for optimizing pest control strategies in heavy metal polluted areas.

The effects of feeding frequency on jaw loading in two lemur species.

Studies on oral processing are often snapshots of behaviors that examine feeding through individual bouts. In this study, we expand on our previous work comparing bite/chew variables per feeding bout to summed daily biting, chewing, and food intake to interpret loading that could have potential morphological effects. We observed sympatric Lemur catta and Propithecus verreauxi over two field seasons in the dry forest of Bezà Mahafaly Special Reserve in southwestern Madagascar. Bite and chew rates determined from videos filmed during observations were multiplied with time spent feeding on specific foods during focal follows to calculate daily values for each feeding bout. Food mechanical properties (FMPs) were tested on dietary items with a portable tester. We contrasted daily bite/chew numbers and intake with FMPs, species, season, and food shape. Daily bite and chew numbers increased with maximum, but not average, food toughness. Daily intake decreased with average and maximum toughness. Season had a strong effect on daily bites and chews, but not on intake. Food shape influenced intake and total bite and chew numbers. The lemur species did not differ in our models. Maximum food toughness impacted feeding behaviors and intake, which is consistent with higher loads having a greater effect on morphology. In contrast to feeding per bout, cumulative biting and chewing did not differ between species; taking feeding frequency into consideration affects interpretation of jaw loading. Finally, biting, as much as chewing, may generate strains that impact morphology.

A critical exploration of the diets of UK disadvantaged communities to inform food systems transformation: a scoping review of qualitative literature using a social practice theory lens

The UK food system affects social, economic and natural environments and features escalating risk of food insecurity. Yet it should provide access to safe, nutritious, affordable food for all citizens. Disadvantaged UK communities [individuals and families at risk of food and housing insecurity, often culturally diverse] have often been conceptualised in terms of individual behaviour which may lead to findings and conclusions based on the need for individual change. Such communities face public health challenges and are often treated as powerless recipients of dietary and health initiatives or as ‘choiceless’ consumers within food supply chains. As transforming the UK food system has become a national priority, it is important a diverse range of evidence is used to support understanding of the diets of disadvantaged communities to inform food systems transformation research.A scoping review of UK peer reviewed qualitative literature published in MEDLINE, CINAHL Plus with Full Text, EMBASE, PsycINFO and Web of Science between January 2010 and May 2021 in English. Eligibility criteria were applied, a data extraction table summarised data from included studies, and synthesis using social practice theory was undertaken.Forty-five qualitative studies were reviewed, which included the views of 2,434 community members aged between 5 and 83. Studies used different measures to define disadvantage. Synthesis using social practice theory identified themes of food and dietary practices shaped by interactions between ‘material factors’ (e.g. transport, housing and money), ‘meanings’ (e.g. autonomy and independence), and ‘competencies’ (e.g. strategies to maximise food intake). These concepts are analysed and critiqued in the context of the wider literature to inform food systems transformation research.This review suggests to date, qualitative research into diets of UK disadvantaged communities provides diverse findings that mainly conceptualise disadvantage at an individual level. Whilst several studies provide excellent characterisations of individual experience, links to ‘macro’ processes such as supply chains are largely missing. Recommendations are made for future research to embrace transdisciplinary perspectives and utilise new tools (e.g., creative methods and good practice guides), and theories (e.g., assemblage) to better facilitate food systems transformation for disadvantaged communities.

Sex differences in patch-leaving foraging decisions in rats.

The ubiquity, importance, and sophistication of foraging behavior makes it an ideal platform for studying naturalistic decision making in animals. We developed a spatial patch-foraging task for rats, in which subjects chose how long to remain in one foraging patch as the rate of food earnings steadily decreased. The cost of seeking out a new location was varied across sessions. The behavioral task was designed to mimic the structure of natural foraging problems, where distinct spatial locations are associated with different reward statistics, and decisions require navigation and movement through space. Male and female Long-Evans rats generally followed the predictions of theoretical models of foraging, albeit with a consistent tendency to persist with patches for too long compared to behavioral strategies that maximize food intake rate. The tendency to choose overly-long patch residence times was stronger in male rats. We also observed sex differences in locomotion as rats performed the task, but these differences in movement only partially accounted for the differences in patch residence durations observed between male and female rats. Together, these results suggest a nuanced relationship between movement, sex, and foraging decisions.

Determinant Factors of Anemia in Pregnant Women at Kebomas Health Center

Background: The period of pregnancy is when the body really needs maximum food intake, both physically and spiritually. This study aimed to examine the effect of nutritional intake, trust, and iron consumption compliance on anemia in pregnant women at the Kebomas Health Center. Subjects and Method: This was cross-sectional study in the Kebomas Health Center Work Area. A sample of 168 pregnant women was selected by simple random sampling. The dependent variable was anemia. The independent variables were nutritional intake, trust, and iron consumpt-ion compliance. The data were collected by the questionnaire and analyzed by multiple logistic regression. Results: Anemia in pregnant women increased with poor nutritional intake (aOR= 19.52; 95% CI= 14.87 to 38.37; p= 0.001), less trust (aOR= 18.37; 95% CI= 13.34 to 36.09; p= 0.001), and inadherent to iron con¬sumption (aOR= 14.82; 95% CI= 10.28 to 27.34; p <0.001). Conclusion: Anemia in pregnant women increases with poor nutritional intake, less trust, and inadherent to iron con¬sumption. Keywords: nutrition intake, compliance, anemia.

Wild geladas (Theropithecus gelada) in crops\u2014more than in pasture areas\u2014reduce aggression and affiliation

Human–primate interfaces are expanding and, despite recent studies on primates from peri-urban environments, little research exists on the impact of agriculture and/or pasture areas on primate social behavior and health. We assessed how crop/pasture areas potentially alter social behavior and health of wild geladas (Theropithecus gelada) frequenting the unprotected area of Kundi (Ethiopia). We predicted that compared to pasture areas, crop areas (i) would be more challenging for geladas (prediction 1) and (ii) would have a greater impact on both aggressive and affiliative behavior, by reducing grooming time and enhancing competition (prediction 2). During January–May 2019 and December 2019–February 2020, we collected data (via scan, focal animal sampling, and video analyses) on direct human disturbance, external signs of pathologies and social behavior of 140 individuals from 14 one-male units and two all-male units. Animals experienced the highest level of human disturbance in crop areas (in line with prediction 1). Individuals from the groups preferentially frequenting crop areas showed the highest prevalence of external signs of pathologies consistent with chemical and biological contamination (alopecia/abnormally swollen parts). We collected 48 fecal samples. Samples from frequent crop users contained the highest rates of parasitic elements/gram (egg/larva/oocyst/cyst) from Entamoeba histolytica/dispar, a parasite common in human settlements of the Amhara region. In crop areas, subjects spent less time grooming but engaged in lower rates of intense aggression (in partial agreement with prediction 2). We speculate that the reduction in social behavior may be a tactic adopted by geladas to minimize the likelihood of detection and maximize food intake while foraging in crops.

Dominance style predicts differences in food retrieval strategies

In several species, rank predicts access to food, and subordinates may need specific behavioural strategies to get a share of resources. This may be especially important in despotic species, where resources are strongly biased in favour of dominants and subordinates may more strongly rely on specific tactics to maximize food intake. Here, we compared three macaque species with an experimental set-up reproducing feeding competition contest. Following our predictions, more tolerant species mostly retrieved food in the presence of others and were less dependent on specific tactics. Contrarily, subordinates in more despotic species more likely collected food (1) when dominants could not see food or (2) were attacking others, (3) while “dissimulating”, or (4) “storing food”. Our study reveals that dominance styles reliably predict the probability of using specific food retrieval tactics and provides important insights on the social conditions that might have led to the emergence of tactical deception.

Solving post-prandial reduction in performance by adaptive regurgitation in a freshwater fish.

Foraging animals must balance benefits of food acquisition with costs induced by a post-prandial reduction in performance. Eating to satiation can lead to a reduction in locomotor and escape performance, which increases risk should a threat subsequently arises, but limiting feeding behaviour may be maladaptive if food intake is unnecessarily reduced in the prediction of threats that do not arise. The efficacy of the trade-off between continued and interrupted feeding therefore relies on information about the future risk, which is imperfect. Here, we find that black carp (Mylopharyngodon piceus) can balance this trade-off using an a posteriori strategy; by eating to satiation but regurgitating already ingested food when a threat arises. While degrees of satiation (DS) equal to or greater than 60% reduce elements of escape performance (turning angle, angular velocity, distance moved, linear velocity), at 40% DS or lower, performance in these tasks approaches levels comparable to that at 0% satiation. After experiencing a chasing event, we find that fish are able to regurgitate already ingested food, thereby changing the amount of food in their gastrointestinal tract to consistent levels that maintain high escape performance. Remarkably, regurgitation results in degrees of satiation between 40 and 60% DS, regardless of whether they had previously fed to 40, 60 or 100% DS. Using this response, fish are able to maximize food intake, but regurgitate extra food to maintain escape performance when they encounter a threat. This novel strategy may be effective for continual grazers and species with imperfect information about the level of threat in their environment.

PENGARUH KONSUMSI TELUR AYAM RAS REBUSTERHADAP PENINGKATAN KADAR HB PADA IBU HAMIL TRIMESTER III DI PUSKESMAS SIMARMATAKABUPATEN SAMOSIR 2020

The period of pregnancy is a time when the body really needs maximum food intake for both the mother and the fetus.During pregnancy, there will be major changes in the body of a pregnant woman. One of the changes that occurs is the hematology system, with a lack of quality food intake, one of which is a lack of iron so that it can cause anemia in pregnant women. Anemia occurs due to low hemoglobin levels in the body of pregnant women. One of the efforts that can be done is to increase hemoglobin by consuming boiled eggs. The purpose of this research was to determine the effect of consumption of boiled chicken eggs at the Simarmata Health Center, Samosir Regency.Its benefits are to help pregnant women who have anemia so that the hemoglobin in the body of pregnant women increases, so that pregnant women are expected to consume boiled eggs in the third trimester of pregnancy. The population in this study were pregnant women in the area of the Simarmata Health Center, Samosir Regency, with a sample of 20 people. The research method was quasi-experimental (Quasi experiment) with a pre-test-post-test research design with a control group. The results of this study indicate that the average before consumption of boiled eggs is Mean (8.08) with Std. Deviation (0.5716) after consumption of boiled eggs is (9.39) with Std. Deviation0.5716) after Consumption of Boiled Eggs is (9.39) with Std. Deviation (0.5558) with sig <0.05, this indicates that there is an effect of consumption of boiled eggs on changes in hemoglobin levels for pregnant women in trimester III.

Adaptive differentiation of growth, energetics and behaviour between piscivore and insectivore juvenile rainbow trout along the Pace-of-Life continuum.

Adaptive trade-offs are fundamental mechanisms underlying phenotypic diversity, but the presence of generalizable patterns in multivariate adaptation and their mapping onto environmental gradients remain unclear. To understand how life history affects multivariate trait associations, we examined relationships among growth, metabolism, anatomy and behaviour in rainbow trout juveniles from piscivore versus insectivore ecotypes along an experimental gradient of food availability. We hypothesized that (a) selection for larger size in piscivorous adults would select for higher juvenile growth at the cost of lower active metabolism; (b) elevated growth of piscivores would be supported by a greater productivity of their natal stream and more proactive foraging behaviours and (c) general patterns of multivariate trait associations would match the predictions of the Pace-Of-Life Syndrome. Relative to insectivores, piscivorous fry showed a pattern of higher growth (+63%), maximum food intake (+33%), growth efficiency (+41%) and standard metabolic rate (SMR; +47%), but lower active metabolic capacity (maximum metabolic rate [MMR; -17%], aerobic scope [AS; -48%]), suggesting that faster piscivore growth is supported by greater food intake and digestive capacity but is traded-off against lower scope for active metabolism. A similar trade-off appeared among organ systems, with piscivorous fry exhibiting an 83% greater investment in average mass of organs associated with food consumption and processing (i.e. stomach and intestine), but an apparently smaller relative investment in organs involved in cardiovascular or cognitive activities (heart and brain, respectively). Higher invertebrate drift in their natal rearing habitat, quicker behavioural transition to a novel food source and lower anxiety after a frightening event in piscivorous fry suggest that faster growth requires both proactive foraging behaviours and higher prey availability in the environment. Finally, the sampling of replicate insectivore populations confirmed their lower juvenile growth (-73% on average) and reduced environmental productivity of their natal streams (-45% lower drift abundance) relative to the piscivore ecotype. Our results suggest that selection for large adult body size influences selection on high juvenile growth, high basal metabolism and proactive behaviours, and that the intense phenotypic divergence between piscivorous and insectivorous rainbow trout may be constrained by environmental productivity.

Amnion and collagen-based blended hydrogel improves burn healing efficacy on a rat skin wound model in the presence of wound dressing biomembrane.

A burn wound is one of the most frequent and devastating injuries for patients which requires extensive care. Early treatment of burn wounds improves healing significantly. This study was designed to investigate the efficacy of amnion and collagen-based hydrogels on cutaneous burn wound healing in rats with covering membrane. We prepared a novel cell free hydrogel comprising human amnion, rabbit collagen, carboxymethyl cellulose sodium salt, citric acid, methyl paraben, propyl paraben, glycerin and triethanol amine. The wound covering membrane was developed from rabbit collagen and prawn shell chitosan. Beside swelling ratio, water absorption, equilibrium water content, gel fraction and spreadability analysis, in vitro cytotoxicity and biocompatibility tests were performed for the formulated hydrogels. Following the skin irritation study, second-degree burns were created on the dorsal region of the rats and the gels were applied with/without covering membrane to study the wound contraction and re-epithelialization period. The formulated hydrogels were observed non-cytotoxic and compatible with human blood cells. No erythema and edema were found in skin irritation assay confirming the safety and applicability. Hydrogel consisting in a combination of amnion and collagen demonstrated significantly rapid wound healing, driven by complete re-epithelialization (16.75 ± 0.96 days) and closure by wound contraction (72 ± 3.27%, P < 0.0000009) when wound dressing membrane was used, whereas this gel alone healed about 62.5 ± 4.43% (P < 0.00001) and required 18.75 ± 0.50 days to complete re-epithelialization. Additionally, the gel with covering membrane treated group had maximum average body weight, food and water intake. The amnion and collagen-based blended gel offers alternative possibilities to treat skin wounds when covered with film, which could overcome the limitations associated with modern therapeutic products such as high costs, long manufacturing times, complexities, storing, and presence of living biomaterials.

The Delboeuf illusion's bias in food choice of teleost fishes: an interspecific study

An optimal foraging strategy often requires identifying and choosing the larger amount of food in the presence of multiple options, in order to maximize food intake. Food quantity estimation frequently depends on the perceptual ability to segregate food from the surrounding background. In human and nonhuman animals, it has recently been shown that the perception of food size is affected by the size of the background on which food is presented, with a tendency to overestimate food items encircled by a small background. This perceptual bias resembles an illusory effect known as the Delboeuf illusion. We investigated whether this bias occurs in five fish species: zebrafish, Danio rerio, redtail splitfin, Xenotoca eiseni, angelfish, Pterophyllum scalare, Siamese fighting fish, Betta splendens, and three-spot gourami, Trichopodus trichopterus. In control trials, we observed their spontaneous preference for choosing the larger of two amounts of food. In test trials, two same-sized food amounts were presented on a small and a large plate, a pattern that causes the Delboeuf illusion in humans. Similarities in subjects’ choices between the five species were greater than differences, with a significant bias towards selecting the food amount on the large plate. This suggests the existence of a perceptual bias, although one operating in the opposite direction from that of humans, which might interfere with the accurate food size estimation necessary for an optimal foraging strategy.

Changes of Resting Energy Expenditure in Type 2 Diabetes Rats After Roux-en-Y Gastric Bypass.

This study aimed to investigate the changes of resting energy expenditure (REE) induced by Roux-en-Y gastric bypass (RYGB) in diabetic rats. Thirty male Goto-Kakizaki rats were randomly divided into RYGB, sham RYGB (SR), and control groups. Glucose metabolism, energy expenditure, triiodothyronine, and bile acid levels were measured. Body composition in different groups was compared after sacrifice. RYGB induced significant diabetic improvement, with decreased maximum food intake and body weight. There was no significant difference in the REE between the groups before surgery (P = 0.74), while the REE of the RYGB group (1.15 ± 0.17ml/h/g) was higher than that of the SR group (0.99 ± 0.13ml/h/g) and the control group (0.97 ± 0.13ml/h/g, P = 0.031) at the 20th postoperative week. The ratio of white adipose tissue in the RYGB group was lower (P = 0.02), and the ratio of brown adipose tissue was higher than that of the SR group and the control group (P = 0.045). Moreover, a higher bile acid level was detected in the RYGB group (6.4 ± 1.8μmol/L) than in the SR group (4.2 ± 1.7μmol/L) and the control group (4.0 ± 2.0μmol/L, P = 0.025). RYGB induces a higher REE level in diabetic rats. The circulating bile acid level was enhanced after surgery.

Spatial aggregation of fruits explains food selection in a neotropical primate (Alouatta pigra)

The availability and spatial distribution of food resources affect animal behavior and survival. Black howler monkeys (Alouatta pigra) have a foraging strategy to balance their nutrient intake that involves mixing their consumption of leaves and fruits. The spatial aggregation of food items should impact this strategy, but how it does so is largely unknown. We quantified how leaf and fruit intake combined (here termed food set selection) was spatially aggregated in patches and how food aggregation varied across seasons. Using variograms we estimated patch diameter and with Generalized Least Square models determined the effect of food spatial aggregation on food selection. Only fruits were structured in patches in the season of highest availability (dry-season). The patches of food set selection had a diameter between 6.9 and 14 m and were explained by those of mature fruit availability which were between 18 and 19 m in diameter. Our results suggest that the spatial pattern of food selection is influenced by patches of large fruit-bearing trees, not by particular species. Fruit also occur along spatial gradients, but these do not explain food selection, suggesting that howlers maximize food intake in response to local aggregation of fruit that are limiting during certain seasons. We demonstrate how the independent spatial modelling of resources and behavior enables the definition of patches and testing their spatial relationship.

Morphological changes and habitat shifts with growth of endangered floodplain fish: Possible adaptations to fluctuating environments

AbstractAdaptations that maximise food intake are dependent on food and/or habitat types. However, there have been few studies on the ability of floodplain primary freshwater fish to rapidly change their morphology, especially the internal one, to maximise utilisation efficiency of food resources in response to environmental fluctuations during their life history. We investigated morphological changes of an Acheilognathinae species (Acheilognathus longipinnis) that inhabits creeks in Japan to determine whether body shape variation correlated with environmental characteristics, including water depth, current velocity, vegetation cover and food availability. When shifting from floodwater‐level to low‐water‐level season, the current velocity of the study area increased as the water level decreased, causing a significant increase in periphyton and a significant decline in zooplankton and phytoplankton. Concurrently, during the short period when A. longipinnis grow from the juvenile to the premature stage, changes in internal morphology, that is intestinal elongation, and changes in external morphology such as an increase of body depth were observed. In contrast, intestinal length significantly decreased in the adult stage. Our findings suggest that morphological changes between floodwater‐level and low‐water‐level seasons associated with juvenile to premature development are an adaptation to changes in food availability due to environmental fluctuations. Additionally, the shortening of the intestine from the premature to the adult stage may be an adaptive strategy for reproduction.

Life is uncertain, eat dessert first: feeding ecology and prey-predator interactions of the coffee snake Ninia atrata

ABSTRACTPrey-predator interactions are considered one of the primary drivers of the ecology and evolution of several vertebrate taxa, but particularly, it has played a significant role in the evolutionary biology of snakes. However, feeding ecology of semifossorial tropical snakes has been poorly studied. We employed a multivariate approach to explore the effects of sexual dimorphism, prey-predator interaction, and climatic variability due to El Niño–Southern Oscillation (ENSO) on the abundance and feeding ecology of the semifossorial snake Ninia atrata. Climatic variability analysis revealed conspicuous temporal variation in the prey availability at microhabitat, as well as in the snake abundance and food intake. Multivariate approach provided strong support for links between Ninia atrata abundance, microhabitat quality and snails abundance (more than other prey). Conspicuous intersexual dietary divergence was observed supporting the hypothesis of the sex-specific targets for maximum food intake. ENSO phenomenon promoted a notable decline in Ninia atrata abundances and its food intake, which was related to prey availability and abundance, as well as a strong variability on their body condition index (BCI). Finally, given the high sensitivity of Ninia atrata to the environmental variability, it could consider an indicator species of the environmental changes in the Neotropical oil palm agroecosystems.

Scavengers can be choosers: A study on food preference in free-ranging dogs

Domestic dogs have descended from gray wolves through a process of domestication, evolving from a predominantly hunting to a scavenging lifestyle. Though the exact process of domestication is not yet clearly understood, various behavioral adaptations in dogs are considered to have been crucial to the development of the unique bond shared by dogs and humans. Similarly, an enhanced ability to digest carbohydrates has been suggested as a major adaptation that enabled dogs to adapt to life among humans. Free-ranging dogs in India mostly subsist on a carbohydrate-rich diet but a set of choice tests have revealed that they can use a Rule of Thumb to locate meat, thereby maximizing their protein intake. However, it has never been tested whether they use this Rule of Thumb to preferentially feed on meat in the context of scavenging, especially when they have to find food among garbage. They often compete with conspecifics as well as other scavenging species and are also sometimes threatened by humans during scavenging. Under such constraints, preferential feeding might not be a feasible option. We carried out a choice test on 68 free-ranging dogs on urban streets, simulating scavenging from dustbins, to test whether they use the Rule of Thumb in scavenging situations. The dogs were provided with three choices of baskets filled with garbage mixed with either bread pieces (10), chicken pieces (10) or both (5 + 5). The dogs did apply the Rule of Thumb to eat the protein first, but did not discard the carbohydrate. They utilized a Sniff-and-Snatch strategy for maximizing meat uptake from the noisy background of garbage. This is a highly efficient scavenging strategy that can help them to maximize food intake, while allowing them to eat the most preferred food first, and has perhaps been adaptive for their survival in a highly heterogenous human-dominated environment.

Environmental factors influencing road use in a nocturnal insectivorous bird

Many animals avoid roads due to traffic disturbance, but there are also some species that use roads in their everyday life and even obtain resources from them. Understanding the factors that influence the intensity of road use by these species can help understand temporal patterns of road mortality and thereby maximise the cost-effectiveness of mitigation measures. Here, we use road transect counts conducted once a week for 9 consecutive years (2009–2017) to investigate environmental factors influencing road use in the red-necked nightjar (Caprimulgus ruficollis), a nocturnal insectivorous bird that frequents roads to forage and thermoregulate. We found that the intensity of road use by nightjars was affected by ambient temperature, amount of moonlight and wind conditions—all factors known to influence their foraging efficiency and thermoregulatory requirements. Specifically, the highest numbers of nightjars on roads occurred during no-wind conditions and on either dark-cold or bright-warm nights, suggesting that they preferentially use roads for thermoregulation under unfavourable weather conditions or to maximise food intake during periods of increased insect abundance (i.e. warm nights) and improved conditions for visual prey detection (i.e. full moon). Our results illustrate the role of environmental conditions as drivers of rapid changes in the use of roads by animals. Furthermore, this work suggests that analogous studies can be used to inform mitigation measures, so that mitigation efforts to prevent roadkills can be concentrated during periods of expected peaks in animal use of roads.

Balancing contest competition, scramble competition, and social tolerance at feeding sites in wild common marmosets (Callithrix jacchus).

Models of primate sociality focus on the costs and benefits of group living and how factors such as rank, feeding competition, alliance formation, and cooperative behavior shape within-group social relationships. We conducted a series of controlled field experiments designed to investigate how resource distribution (one or three of four reward platforms) and amount of food on a reward platform affected foraging strategies and individual feeding success in four groups of wild common marmosets (Callithrix jacchus) living in the Caatinga of northeastern Brazil. At our field site, common marmoset groups are characterized by a single breeding female who can produce twin litters twice per year, strong social cohesion, and cooperative infant care provided principally by several adult male helpers. We found that except for the dominant breeding female, rank (based on aggression) was not a strong predictor of feeding success. Although the breeding female in each group occupied the highest rank position and obtained the greatest daily feeding success, all other group members, including adults and juveniles experienced relatively equal feeding success across most experimental conditions. This was accomplished using a balance of behavioral strategies related to contest competition, scramble competition (associated with a finder's advantage), and social tolerance (sharing the same feeding platform). Based on these results, the social structure of common marmosets is best described as "single female dominance," with the breeding female maximizing food intake needed to offset the energetic costs associated with reproductive twinning and the ability to produce two litters per year. Cooperative infant caregiving, in which the number of helpers is positively correlated with offspring survivorship, requires a set of behavioral strategies that serve to reduce contest competition and promote prosocial behaviors at feeding sites.