Patterns Of Food Availability Research Articles

Model of mesopelagic fish predation on eggs and larvae shows benefits of tuna spawning under full moon

AbstractMost mesopelagic fish are small planktivores that migrate up at nightfall to feed in the safety of darkness and descend to depth at dawn to escape visual predators. However, the trophic roles can reverse since mesopelagic fishes also predate eggs and larvae of their predators. We use the Atlantic bluefin tuna as a model species to test the hypothesis that fishes in the open ocean synchronize spawning to moon‐lit nights (when mesopelagic fishes avoid near‐surface waters) to increase offspring fitness. Our analysis over two decades of field observations shows that tuna spawn most intensively the week before full moon. This fits predictions from a mechanistic model where spawning around full moon increases offspring fitness by two orders of magnitude due to low predation from mesopelagic fishes. Circalunar patterns of food availability can also favor fitness of offspring spawned the days before full moon. Our findings suggest that mesopelagic fishes may have an important impact on pelagic fish through predation of early life stages and cause an evolutionary drive to synchronize spawning to the lunar cycle.

The phenology and clutch size of UK Blue Tits does not differ with woodland composition

The deciduous tree‐herbivorous caterpillar‐insectivorous bird food chain is a well‐studied system for investigating the impacts of climate change across trophic levels. To date, across Europe, most attention has focused on the impacts of increasing spring temperature on changes to phenology in Oak‐dominated (Quercus spp.) woodlands. Paridae species and Pied Flycatcher Ficedula hypoleuca are the most studied secondary consumers, all of which demonstrate an advancement in reproductive phenology with increases in spring temperature. Shifts in climate and phenology may also impact on reproductive investment in clutch size, and the effects of climate on phenology and clutch size may vary depending on woodland composition. To date, the effects of among‐habitat variation in phenology and reproductive investment have received little attention. Insectivorous birds inhabiting woodlands that differ in tree composition may differ in the timing of breeding, due to local tree leafing phenology acting as a cue for egg‐laying date and/or clutch size. Moreover, for most insectivorous birds, woodland composition within a territory is likely to be the main determinant of food availability for both adults and chicks. Consequently, if warming springs affect the temporal patterns of food availability differently across different woodland compositions, this may affect the optimal average local phenology for nesting birds. Here, using data from 34 long‐term (mean 15 years) nest monitoring sites across the UK, we investigate the effect of woodland tree composition and temperature on Blue Tit Cyanistes caeruleus first egg date (FED) and clutch size. We supplemented the nest monitoring data by quantifying woodland composition, at a site level, through modified point counts. We predict that birds breeding in woodlands with greater proportions of late‐leafing species, such as Oak and Ash Fraxinus excelsior, will breed later than those breeding in woodlands with greater proportions of early‐leafing species, such as Birch Betula spp. and Beech Fagus sylvatica. We found no evidence for differences in Blue Tit FED or clutch size in relation to the proportion of any of the tree species investigated, after controlling for temperature and latitude (FED: −3.4 and 2.2, clutch size: −0.4 and − 0.2 eggs for one‐unit increase in temperature and latitude, respectively). In recent decades and across all sites, clutch size has decreased as spring temperatures have increased, a strategy which could allow birds flexibly to adjust their breeding phenology such that nestling demand coincides with peak food availability. The lack of an effect of woodland composition on Blue Tit phenology suggests Blue Tits do not fine‐tune their reproductive phenology to the local tree composition. Whether this lack of evidence for phenological divergence is due to an absence of divergent selection on breeding phenology and clutch size or to gene flow is not clear.

Development and validation of the food availability and related eating behaviors questionnaire: A stage 1 registered report.

Historically, eating disorder research has excluded marginalized and underserved populations, such as those with food insecurity (which also impacts higher numbers of Black/African American and Latinx communities). However, burgeoning research suggests an association between food insecurity and the development of eating disorder pathology. Examining patterns of food availability and related eating behaviors may elucidate the association between food insecurity and eating disorder pathology. However, to date, there are no comprehensive measures that accurately capture food availability patterns and related eating behaviors. In Study 1, 40 participants (20 adolescents, 20 adults) will respond to and provide qualitative feedback on the Food Availability and Related Eating Behaviors Questionnaire (FAREB-Q). In study 2, 50 participants (approximately 25 with and without food insecurity) will complete the FAREB-Q at two time-points, and respond to questions about food insecurity, disordered eating, and every day stress to assess the FAREB-Q's reliability and validity. Results will clarify whether the FAREB-Q is a reliable and valid instrument that measures food availability and related eating behavior patterns. The present study aims to develop, pilot, and examine the psychometric properties of the FAREB-Q, a self-report measure examining food availability and related eating behaviors in community populations. The novel FAREB-Q assesses food availability and related eating patterns in the general community. The FAREB-Q will be reviewed by experts in disordered eating, food insecurity, psychometric statisticians and piloted in the general public before being psychometrically evaluated in a larger sample. The FAREB-Q is anticipated to help elucidate the mechanisms linking food availability, food (in)security, disordered eating behaviors, and eating pathology.

Factors affecting age at primiparity in black bears

AbstractEffective wildlife management requires an understanding of the factors affecting population vital rates. Age at primiparity can be an important determinant of population growth rates. Thus, understanding the factors influencing age at primiparity in wild populations is important for their management and conservation. American black bears (Ursus americanus) are widely distributed in North America and show considerable variation in age at primiparity across their range. We tested hypotheses regarding top‐down and bottom‐up drivers of age at primiparity in black bears across the province of Ontario, Canada. We obtained estimates of age at primiparity using cementum patterns in 1,033 bear teeth collected as part of regulated harvest in 2018 and 2019. We compared mean ages at primiparity between 2 distinct forest regions in Ontario using a Wilcoxon test. To quantify the effects of multiple putative drivers of variation in primiparity (e.g., harvest density, food availability, land use, climate), we paired yearly probability of primiparity data with environmental covariates in a mixed effects logistic regression model. Age at primiparity was significantly lower in the more productive forest region, likely reflecting broad‐scale patterns of food availability. Further, there was a significant positive effect of growing degree days (annual sum of daily mean degrees >5°C) on probability of primiparity, likely related to its influence on ecosystem productivity. Harvest density was negatively related to the probability of primiparity, possibly because harvest is positively correlated with bear density at this broad scale, and competition for food resources increases with bear density. Overall, temporal variation in food availability had a positive effect on probability of primiparity in a model fit to data for which we had the highest confidence in age estimates from cementum. Mean age at primiparity was older (5.57 yr) than in other more southernly populations, and most harvested bears (53%) were harvested prior to reproducing. Our analysis suggests that black bear age at primiparity is primarily driven by bottom‐up forces related to climate and vegetation differences that lead to greater food availability in the south. The relatively old age at primiparity and high apparent mortality rate of young animals in this population suggests that harvest can limit recruitment substantially, which needs to be considered when making management decisions.

Spatio-temporal patterns of earthworm abundance suggest time-limited food availability for a subalpine bird species

Changes in food availability may act as a major mechanism by which global change impacts populations of birds, especially in seasonal environments at high elevations or latitudes. Systematic sampling of invertebrates, which constitute the diet of many bird species during the breeding season, is however largely missing in mountain ecosystems and is overall very rare for soil-dwelling species or stages. Here, we repeatedly sampled earthworms (Lumbricidae), the staple prey of the Ring Ouzel Turdus torquatus, over a whole breeding season in a study area in the Swiss Alps. Our main goal was to finely characterise spatio-temporal patterns of food availability for this declining bird species, in relation to elevation, habitat type and snowmelt stage. In 24 sampling plots, we extracted two soil cores every week for 6–10 weeks and hand-sorted soil invertebrates separately for two 5-cm soil layers. We then analysed the abundance of earthworms in those two layers in relation to various environmental parameters. We show that within our study area, edaphic and topographical parameters are poor predictors of the mean abundance of earthworms over the breeding season. Ground vegetation cover and soil moisture, however, are suitable predictors for the number of earthworms within the soil profile at each sampling time, i.e., of their availability for Ring Ouzels. Moreover, we provide evidence for a clear seasonal peak in earthworm availability, which was more pronounced in open grasslands compared to forested areas and happened later in the season where snow lingered. This study, by improving our understanding of the factors driving food availability for a mountain bird species, provides insights into how shifts in land-use and climate might lead to altered predator-prey interactions.

Geographical patterns in food availability from pollinator-dependent crops: Towards a Pollinator Threat Index of food security

The discussion of food availability has expanded beyond staple foods to foods required for healthy diets. These include fruits, tree nuts, pulses, and some vegetables. Traditional metrics such as production, supply, and trade are being contextualized by an understanding of the link to land use, specifically as it relates to biodiversity, climate change, and ecosystem services. Pollinator-dependent crops provide significant proportions of many key nutrients to humans. To examine the dependence of crop production on pollinators, we develop a worst-case scenario of complete pollinator decline and apply it to FAO crop production data for 182 countries. We then use FAO trade and agri-environmental data to develop a Pollinator Threat Index for 121 countries which considers fluctuations in temperature, non-practice of organic agriculture, pesticide use, and beehive trade. Findings illustrate that there is universal vulnerability to crop production for citrus fruits, fruit, pulses, tree nuts, and vegetables. The greatest losses would occur in fruit (northern hemisphere) and tree nuts (southern hemisphere). Many highly populated countries, along with much of the northern hemisphere, experience the greatest threats to their pollinator populations. Results suggest geographical inequities in access to food for healthy diets might be compounded by losses of pollinator-dependent crops.

Simultaneous estimation of seasonal population density, habitat preference and catchability of wild boars based on camera data and harvest records.

Analyses of life history and population dynamics are essential for effective population control of wild mammals. We developed a model for the simultaneous estimation of seasonal changes in three parameters—population density, habitat preference and trap catchability of target animals—based on camera-trapping data and harvest records. The random encounter and staying time model, with no need for individual recognition, is the core component of the model—by combining this model with the catch-effort model, we estimated density at broad spatial scales and catchability by traps. Here, the wild boar population in central Japan was evaluated as a target population. We found that the estimated population density increased after the birth period and then decreased until the next birth period, mainly due to harvesting. Habitat preference changed seasonally, but forests having abandoned fields nearby were generally preferred throughout the season. These patterns can be explained by patterns of food availability and resting or nesting sites. Catchability by traps also changed seasonally, with relatively high values in the winter, which probably reflected changes in the attractiveness of the trap bait due to activity changes in response to food scarcity. Based on these results, we proposed an effective trapping strategy for wild boars, and discussed the applicability of our model to more general conservation and management issues.

O7 Fresh Fruit and Vegetable Availability and Cost in SNAP-participating Retail Stores in Mississippi: Differences by Rurality

Background Access to healthy, affordable food is an environmental factor that can influence food security. Research suggests healthy food availability varies by store type, rurality/urbanicity, Supplemental Nutrition Assistance Program (SNAP) participation, and sociodemographic characteristics. Objective The purpose of this study was to investigate differences in variety and cost of fresh fruits and vegetables in convenience stores, grocery stores, and supermarkets in Mississippi across Rural Urban Continuum Codes (RUCCs). Study Design, Setting, Participants A survey design was used to collect data in 461 convenience stores, grocery stores, and supermarkets. Trained surveyors (Extension county agents, Extension nutrition educators, and research team members) selected an assigned number of SNAP-participating stores by county to represent food availability across Mississippi. Measurable Outcome/Analysis Availability and cost data were collected using an adapted version of the Nutrition Environment Measures Survey-Corner Store (NEMS-CS). Metro areas were defined as those with RUCCs of 1 to 3, while non-metro areas were defined as those with RUCCs of 4 to 9. Independent samples t-tests and Mann-Whitney U tests were used to compare means in metro vs non-metro areas within store types. Results Variety of fresh fruits and fresh vegetables was greater in non-metro vs metro areas in convenience and grocery stores but not supermarkets. Cost of 6 most commonly available fruits and vegetables was similar within store types when comparing metro vs non-metro areas. Conclusion Elucidation of food availability patterns in retailers serving SNAP clients is important for planning outreach efforts. Smaller retailers may be important partners and could be a setting for SNAP-Education social marketing messages encouraging healthy food selection behaviors. Involving agents and educators in data collection and in building shared goals with local food retailers may be a promising strategy for improving purchase and consumption of healthy foods in Mississippi. Funding Mississippi State University Extension.

No effects of asynchrony between hatching and peak food availability on chick growth in Semipalmated Plovers (Charadrius semipalmatus) near Churchill, Manitoba

Birds rely on consistent patterns of food availability on their breeding grounds to successfully complete their breeding cycle. Due to ongoing warming of the sub-Arctic, there is potential for a mismatch between the peak in available invertebrate biomass and the peak in food demand for shorebird chicks. During the summers of 2010 and 2011, we investigated the relationship between temperature and benthic and terrestrial invertebrate biomass, measured using three sampling techniques in Churchill, Manitoba. We also investigated the relationship between timing of breeding of Semipalmated Plovers (Charadrius semipalmatus) and timing of peaks in invertebrate biomass. In 2011, chick growth rates were also measured to examine whether hatching in synchrony with the peak in invertebrate biomass during the brood rearing period affected growth rates. In 2010, emergent and core invertebrate biomass were negatively related to soil degree days, whereas in 2011, core biomass increased with soil degree days and pitfall biomass increased with air temperature. Total invertebrate biomass (summed over trap types) peaked from 25 to 31 days before the median chick hatch date in 2010 and 10 days after the median chick hatch date in 2011. In 2011 we did not detect any effects of asynchrony on the growth of Semipalmated Plover chicks. These results may indicate that food resources in their environment remain adequate throughout the breeding season, despite inter-annual fluctuations in the timing of invertebrate peaks.

Seasonal drought in North America's sagebrush biome structures dynamic mesic resources for sage-grouse.

The North American semi‐arid sagebrush, Artemisia spp., biome exhibits considerable climatic complexity driving dynamic spatiotemporal shifts in primary productivity. Greater and Gunnison sage‐grouse, Centrocercus urophasianus and C. minimus, are adapted to patterns of resource intermittence and rely on stable adult survival supplemented by occasional recruitment pulses when climatic conditions are favorable. Predictions of intensifying water scarcity raise concerns over new demographic bottlenecks impacting sage‐grouse populations in drought‐sensitive landscapes. We estimate biome‐wide mesic resource productivity from 1984 to 2016 using remote sensing to identify patterns of food availability influencing selective pressures on sage‐grouse. We linked productivity to abiotic factors to examine effects of seasonal drought across time, space, and land tenure, with findings partitioned along gradients of ecosystem water balance within Great Basin, Rocky Mountains and Great Plains regions. Precipitation was the driver of mesic resource abundance explaining ≥70% of variance in drought‐limited vegetative productivity. Spatiotemporal shifts in mesic abundance were apparent given biome‐wide climatic trends that reduced precipitation below three‐quarters of normal in 20% of years. Drought sensitivity structured grouse populations wherein landscapes with the greatest uncertainty in mesic abundance and distribution supported the fewest grouse. Privately owned lands encompassed 40% of sage‐grouse range, but contained a disproportional 68% of mesic resources. Regional drought sensitivity identified herein acted as ecological minimums to influence differences in landscape carrying capacity across sage‐grouse range. Our model depictions likely reflect a new normal in water scarcity that could compound impacts of demographic bottlenecks in Great Basin and Great Plains. We conclude that long‐term population maintenance depends on a diversity of drought resistant mesic resources that offset climate driven variability in vegetative productivity. We recommend a holistic public–private lands approach to mesic restoration to offset a deepening risk of water scarcity.

Food availability and livelihood strategies among rural households across Uganda

Despite continuing economic growth, Uganda faces persistent challenges to achieve food security. The effectiveness of policy and development strategies to help rural households achieve food security must improve. We present a novel approach to relate spatial patterns of food security to livelihood strategies, including the contribution of on- and off-farm activities to household food availability. Data from 1927 households from the World Bank Living Standards Measurement Study were used to estimate the calorific contribution of livelihood activities to food availability. Consumption of crops produced on-farm contributed most to food availability for households with limited food availability, yet the majority of these households were not food self-sufficient. Off-farm and market-oriented on-farm activities were more important for households with greater food availability. Overall, off-farm income was important in the north, while market-oriented on-farm activities were important in western and central Uganda. Food availability patterns largely matched patterns of agroecological conditions and market access, with households doing worst in Uganda’s drier and remote northeast. Less food-secure households depended more on short-cycle food crops as compared with better-off households, who focused more on plantation (cash) crops, although this varied among regions. Targeting interventions to improve food security should consider such differences in enterprise choice and include options to improve household market access and off-farm income opportunities.

Food availability and breeding season as predictors of geophagy in Amazonian parrots

Geophagy, the consumption of soil, is common in many species, but the drivers of geophagy are not well understood. The best‐studied example of avian geophagy is the parrots of the western Amazon Basin, but even here, there is debate over what drives the behaviour. There are two possible explanations: (1) extra nutritional demands of reproduction drive an increase in geophagy, which would predict that geophagy should be highest during the breeding season, and (2) consumption of naturally toxic plant foods increases the need for the toxin protection effects of soil, which would predict that geophagy should be highest when food availability is low and animals are forced to consume more toxic foods. We used long‐term data from lowland Amazonia to compare seasonal fluctuations in rainfall, food availability, parrot breeding and parrot geophagy, and conducted novel tests of these hypotheses. Our analyses of annual patterns suggested that seasonal changes in rainfall drive plant fruiting, the resulting food availability patterns drive the timing of parrot breeding, and breeding drives seasonal patterns of geophagy. Surprisingly, chicks of the largest psittacine species fledged as food supplies approach their annual lows, suggesting that future climatic changes that alter peaks in food availability could have unexpected impacts on the reproduction of large psittacines in this system. Our tests found no evidence to support the toxin‐protection hypothesis. Instead, we found that the peak of geophagy occurred during species’ breeding seasons, which strongly supports the supplemental nutrients hypothesis. Our findings join a growing body of biochemical, physiological, behavioural, ecological and biogeographical evidence suggesting that a need for sodium is driving soil consumption in this classic model system of avian geophagy.

Food availability as a major driver in the evolution of life‐history strategies of sibling species

Life‐history theory predicts trade‐offs between reproductive and survival traits such that different strategies or environmental constraints may yield comparable lifetime reproductive success among conspecifics. Food availability is one of the most important environmental factors shaping developmental processes. It notably affects key life‐history components such as reproduction and survival prospect. We investigated whether food resource availability could also operate as an ultimate driver of life‐history strategy variation between species. During 13 years, we marked and recaptured young and adult sibling mouse‐eared bats (Myotis myotis and Myotis blythii) at sympatric colonial sites. We tested whether distinct, species‐specific trophic niches and food availability patterns may drive interspecific differences in key life‐history components such as age at first reproduction and survival. We took advantage of a quasi‐experimental setting in which prey availability for the two species varies between years (pulse vs. nonpulse resource years), modeling mark‐recapture data for demographic comparisons. Prey availability dictated both adult survival and age at first reproduction. The bat species facing a more abundant and predictable food supply early in the season started its reproductive life earlier and showed a lower adult survival probability than the species subjected to more limited and less predictable food supply, while lifetime reproductive success was comparable in both species. The observed life‐history trade‐off indicates that temporal patterns in food availability can drive evolutionary divergence in life‐history strategies among sympatric sibling species.

Chickadees discriminate contingency reversals presented consistently, but not frequently.

Chickadees are high-metabolism, non-migratory birds, and thus an especially interesting model for studying how animals follow patterns of food availability over time. Here, we studied whether black-capped chickadees (Poecile atricapillus) could learn to reverse their behavior and/or to anticipate changes in reinforcement when the reinforcer contingencies for each stimulus were not stably fixed in time. In Experiment 1, we examined the responses of chickadees on an auditory go/no-go task, with constant reversals in reinforcement contingencies every 120 trials across daily testing intervals. Chickadees did not produce above-chance discrimination; however, when trained with a procedure that only reversed after successful discrimination, chickadees were able to discriminate and reverse their behavior successfully. In Experiment 2, we examined the responses of chickadees when reversals were structured to occur at the same time once per day, and chickadees were again able to discriminate and reverse their behavior over time, though they showed no reliable evidence of reversal anticipation. The frequency of reversals throughout the day thus appears to be an important determinant for these animals' performance in reversal procedures.

High spatiotemporal variability in meiofaunal assemblages in Blanes Canyon (NW Mediterranean) subject to anthropogenic and natural disturbances

We investigated the natural and anthropogenic drivers controlling the spatiotemporal distribution of the meiofauna in the submarine Blanes Canyon, and its adjacent western slope (NW Mediterranean margin of the Iberian Peninsula). We analyzed the relationships between the main sedimentary environmental variables (i.e. grain size, Chl-a, Chl-a: phaeopigments, CPE, organic carbon and total nitrogen) and the density and structure of the meiofaunal assemblages along a bathymetric gradient (from 500 to 2000m depth) in spring and autumn of 2012 and 2013.Twenty-one and 16 major taxa were identified for respectively the canyon and slope, where the assemblages were always dominated by nematodes. The gradual decreasing meiofaunal densities with increasing depth at the slope showed little variability among stations and corresponded with a uniform pattern of food availability. The canyon was environmentally much more variable and sediments contained greater amounts of food resources (Chl-a and CPE) throughout, leading not only to increased meiofaunal densities compared to the slope, but also different assemblages in terms of composition and structure. This variability in the canyon is only partly explained by seasonal food inputs. The high densities found at 900m and 1200m depth coincided with significant increases in food availability compared to shallower and deeper stations in the canyon. Our results suggest that the disruption in expected bathymetric decrease in densities at 900–1200m water depth coincided with noticeable changes in the environmental variables typical for disturbance and deposition events (e.g., higher sand content and CPE), evoking the hypothesis of an anthropogenic effect at these depths in the canyon. The increased downward particle fluxes at 900–1200m depth caused by bottom trawling along canyon flanks, as reported in previous studies, support our hypothesis and allude to a substantial anthropogenic factor influencing benthic assemblages at these depths. The possible relationships of the observed patterns and some major natural environmental (e.g., surface productivity or dense shelf water cascading) and anthropogenic (e.g. the lateral advection and downward transport of food-enriched sediments resuspended by the daily canyon-flank trawling activities) drivers are discussed.

What commodities and countries impact inequality in the global food system?

The global distribution of food production is unequal relative to the distribution of human populations. International trade can increase or decrease inequality in food availability, but little is known about how specific countries and commodities contribute to this redistribution. We present a method based on the Gini coefficient for evaluating the contributions of country and commodity specific trade to inequality in the global food system. We applied the method to global food production and trade data for the years 1986–2011 to identify the specific countries and commodities that contribute to increasing and decreasing inequality in global food availability relative to food production. Overall, international trade reduced inequality in food availability by 25%–33% relative to the distribution of food production, depending on the year. Across all years, about 58% of the total trade links acted to reduce inequality with ∼4% of the links providing 95% of the reduction in inequality. Exports from United States of America, Malaysia, Argentina, and Canada are particularly important in decreasing inequality. Specific commodities that reduce inequality when traded include cereals and vegetables. Some trade connections contribute to increasing inequality, but this effect is mostly concentrated within a small number of commodities including fruits, stimulants, and nuts. In terms of specific countries, exports from Slovenia, Oman, Singapore, and Germany act to increase overall inequality. Collectively, our analysis and results represent an opportunity for building an enhanced understanding of global-scale patterns in food availability.

Growth and Life History Patterns of a Small-bodied Stream Fish,Cottus cognatus, in Hydropeaking and Natural Rivers of Northern Ontario

Hydroelectric facilities can dramatically alter the quantity and quality of fish habitat; however it is not well known how these habitat changes affect the growth and life history of fish. We examine the growth and life history of slimy sculpin (Cottus cognatus), a small-bodied sedentary, benthic stream fish, in two regulated and eight unregulated tributaries of Lake Superior, Canada. Among rivers, we found that slimy sculpin grew faster in the regulated Magpie River than in nearby unregulated systems, whereas growth in the Michipicoten River was intermediate. Sculpin were also in better condition in the regulated Magpie and Michipicoten than in nearby natural rivers. Faster growth of sculpin, however, potentially led to their rapid maturity and higher instantaneous mortality in regulated rivers. Within the regulated rivers, there are strong longitudinal gradients in growth, with sculpin at sampling sites near the dams growing more rapidly, maturing earlier and attaining a larger size-at-age than sculpin at sites farther downstream or in natural systems. Differences in sculpin life history traits within rivers closely followed spatial patterns in food availability. We caution future researchers and managers to acknowledge the longitudinal gradients in abiotic and biotic conditions below dams early in experimental designs and monitoring programmes and how this may impact the measures of central tendency and statistical power when comparing rivers. Copyright © 2015 John Wiley & Sons, Ltd.

Differential Effect of Fruit Availability on Avian Frugivore Guilds in a Moist Deciduous Forest of India

Frugivores provide a critical ecosystem service by dispersing seeds and therefore play a major role in the survival and maintenance of trees in tropical forests. Avian frugivores constitute one of the major guilds in tropical forests whose activities are significantly governed by the availability of fruits across space and time. In our current study we examined the effects of the spatial and temporal pattern of food availability on avian frugivores and various avian frugivore functional groups in particular. We found a differential effect of fruit density and number of tree species in fruiting on different functional groups of avian frugivores along both spatial and temporal scales. Total frugivore density was best explained by ‘number of tree species in fruiting’ at both special and temporal scale. The variation in large frugivore density was best explained both by ‘fruit density’ and ‘fruit density’ and ‘number of tree species in fruiting’ together. This pattern was observed at a spatial scale but not along temporal scale. Along temporal scale large frugivore density was best explained only by ‘number of tree species in fruiting’. The medium sized frugivore density was not significantly explained by either ‘fruit density’ or ‘number of tree species in fruiting’. The medium sized frugivores are dependent both on insects and fruits and variation in insect density may determine spatial and temporal variation in medium sized frugivore density. The mixed diet frugivore group with a smaller gape width is limited by the variety of fruit they consume and thus their population was significantly controlled by the number of fleshy fruited tree species in fruiting along spatial scale. We observed breeding synchronization during the time of fruiting peak and we suggest that this could be a strategy for effective seed dispersal. Our study indicated very strong dependability of the large frugivore (dependent only on fruit) population on fruit availability unlike the mixed diet frugivore guild (fruit as secondary diet).

Risk‐sensitive allocation in seasonal dynamics of fat and protein reserves in a long‐lived mammal

Body reserves of numerous taxa follow seasonal rhythms that are a function of temporal patterns in food availability and life-history events; however, tests of the theory underlying the allocation of somatic reserves for long-lived organisms are rare, especially for free-ranging mammals. We evaluated the hypothesis that allocation of somatic reserves to survival (i.e., metabolic processes) and reproduction should be sensitive to current nutritional state relative to seasonal thresholds in those reserves. Our goal was to reveal the linkages between nutrition and life-history traits to understand how long-lived, iteroparous organisms balance the allocation of somatic reserves to reproduction, while retaining reserves as insurance for survival in unpredictable environments. Our evaluation was based on seasonal dynamics in fat (measured as ingesta-free body fat; IFBFat) and protein reserves (measured as ingesta-free, fat-free body mass; IFFFBMass) of 136 female mule deer (Odocoileus hemionus) over 8years. Although mean changes in fat and protein reserves were positive over summer and negative over winter, accretion and catabolism of those reserves was not consistent among individuals. Over winter, both lipid and protein stores available in autumn were catabolized in proportion to their availability above a post-winter threshold (5·8% IFBFat, 33kg IFFFBMass); however, lean body tissue was spared at the expense of lipid reserves. Female deer mostly synthesized lean body tissue over summer and committed post-winter fat reserves to reproduction relative to their availability above an autumn threshold (>8·6% IFBFat), which was lowered by 2·8 percentage points (pp) for each additional young recruited. Mothers reduced their autumn fat threshold to secure current reproductive investment and, thereby, endured a cost of reproduction at the expense of fat accumulation. Allocation of somatic reserves occurred in a risk-sensitive framework; females allocated reserves relative to their availability above seasonal thresholds. In contrast to current notions of summer accretion and winter catabolism of body reserves, some individuals deposited reserves over winter and catabolized reserves over summer, mainly because regulation of individual condition was state-dependent. Consequently, behaviour and life-history strategies may be as much a function of nutritional contributions of the previous season as of the current one.

Circadian integration of sleep-wake and feeding requires NPY receptor-expressing neurons in the mediobasal hypothalamus

Sleep and feeding rhythms are highly coordinated across the circadian cycle, but the brain sites responsible for this coordination are unknown. We examined the role of neuropeptide Y (NPY) receptor-expressing neurons in the mediobasal hypothalamus (MBH) in this process by injecting the targeted toxin, NPY-saporin (NPY-SAP), into the arcuate nucleus (Arc). NPY-SAP-lesioned rats were initially hyperphagic, became obese, exhibited sustained disruption of circadian feeding patterns, and had abnormal circadian distribution of sleep-wake patterns. Total amounts of rapid eye movement sleep (REMS) and non-REMS (NREMS) were not altered by NPY-SAP lesions, but a peak amount of REMS was permanently displaced to the dark period, and circadian variation in NREMS was eliminated. The phase reversal of REMS to the dark period by the lesion suggests that REMS timing is independently linked to the function of MBH NPY receptor-expressing neurons and is not dependent on NREMS pattern, which was altered but not phase reversed by the lesion. Sleep-wake patterns were altered in controls by restricting feeding to the light period, but were not altered in NPY-SAP rats by restricting feeding to either the light or dark period, indicating that disturbed sleep-wake patterns in lesioned rats were not secondary to changes in food intake. Sleep abnormalities persisted even after hyperphagia abated during the static phase of the lesion. Results suggest that the MBH is required for the essential task of integrating sleep-wake and feeding rhythms, a function that allows animals to accommodate changeable patterns of food availability. NPY receptor-expressing neurons are key components of this integrative function.