Seasonal Food Availability Research Articles

Diet and Foraging Behavior ofAmeivula ocellifera(Squamata: Teiidae) in the Brazilian Semiarid Caatinga

This study investigated the influence of seasonality on diet and foraging behavior of the whiptail lizard Ameivula (Cnemidophorus) ocellifera in the Caatinga of northeastern Brazil. Diet composition was identified through stomach analysis of lizards collected monthly by active search during 2009 (rainy and dry seasons) and half of 2010 (rainy season). Foraging behavior was investigated during one rainy and one dry month of 2012, allowing us to determine the percent of time spent moving (PTM), number of movements per minute (MPM), and number of successful attacks on prey by lizards during foraging activity. Analysis of stomach contents showed significant seasonal differences in diet: insect larvae, Coleoptera, and Orthoptera predominated during the two rainy seasons (2009 and 2010); insect larvae, Hemiptera, Araneae, and Orthoptera predominated in the dry season. Prey movement index was lower during rainy seasons, mainly because of more insect larvae consumed during those periods. Population niche breadth was broader in the dry season, but individual niches did not differ significantly between seasons. When foraging, the average PTM was 61.1 ± 15.1%; MPM was 2.03 ± 0.30; and prey items captured/min was 0.14 ± 0.14. PTM for A. ocellifera was similar to values found for North American whiptails (Aspidoscelis), but MPM was relatively higher. Seasonal differences were observed in PTM, which were significantly higher in the rainy season. This difference may represent a behavioral adjustment in response to differences in seasonal food availability.

Influence of Seasonal Food Availability on the Dynamics of Seabird Feeding Flocks at a Coastal Upwelling Area.

The formation of multi-species feeding flocks (MSFFs) through visual recruitment is considered an important strategy for obtaining food in seabirds and its functionality has been ascribed to enhanced foraging efficiency. Its use has been demonstrated in much of the world's oceans and includes numerous species. However, there is scant information on the temporal stability of the composition and abundance of MSFFs as well as the effect of seasonal food availability on their dynamics. Between July 2006 and September 2014, we conducted monthly at-sea seabird counts at Valparaiso Bay (32°56′ to 33°01′S, 71°36′ to 71°46′W) within the area of influence of the Humboldt Current in central Chile. This area is characterized by a marked seasonality in primary and secondary production associated with upwelling, mainly during austral spring-summer. Based on studies that provide evidence that flocking is most frequent when food is both scarce and patchy, we hypothesized that seabird MSFF attributes (i.e. frequency of occurrence, abundance and composition) will be modified according to the seasonal availability of food. Using generalized linear models (GLMs), our results show that the contrasting seasonality in food availability of the study area (using chlorophyll-a concentration as a proxy) had no significant influence on MSFF attributes, sparsely explaining their variations (P>0.05). Rather than seasonal food availability, the observed pattern for MSFF attributes at Valparaiso Bay suggests a substantial influence of reproductive and migratory (boreal and austral migrants) habits of birds that modulates MSFF dynamics consistently throughout the whole year in this highly variable and patchy environment. We highlight the importance of visual recruitment as a mechanism by which migratory and resident birds interact. This would allow them to reduce resource unpredictability, which in turn has a major impact on structuring seabird’s MSFF dynamics.

Can benthic community structure be used to predict the process of bioturbation in real ecosystems?

Disentangling the roles of environmental change and natural environmental variability on biologically mediated ecosystem processes is paramount to predict future marine ecosystem functioning. Bioturbation, the biogenic mixing of sediments, has a regulating role in marine biogeochemical processes. However, our understanding of bioturbation as a community level process and of its environmental drivers is still limited by loose use of terminology, and a lack of consensus about what bioturbation is. To help resolve these challenges, this empirical study investigated the links between four different attributes of bioturbation (bioturbation depth, activity and distance, and biodiffusive transport); the ability of an index of bioturbation (BPc) to predict each of them; and their relation to seasonality, in a shallow coastal system – the Western Channel Observatory, UK. Bioturbation distance depended on changes in benthic community structure, while the other three attributes were more directly influenced by seasonality in food availability. In parallel, BPc successfully predicted bioturbation distance but not the other attributes of bioturbation. This study therefore highlights that community bioturbation results from this combination of processes responding to environmental variability at different time-scales. However, community level measurements of bioturbation across environmental variability are still scarce, and BPc is calculated using commonly available data on benthic community structure and the functional classification of invertebrates. Therefore, BPc could be used to support the growth of landscape scale bioturbation research, but future uses of the index need to consider which bioturbation attributes the index actually predicts. As BPc predicts bioturbation distance, estimated here using a random-walk model applicable to community settings, studies using either of the metrics should be directly comparable and contribute to a more integrated future for bioturbation research.

Do Sardinella aurita spawning seasons match local retention patterns in the Senegalese–Mauritanian upwelling region?

AbstractSardinella aurita is the most abundant small pelagic fish in the Senegalese–Mauritanian region. The success of its reproduction crucially depends on the local circulation as this determines whether larvae reach coastal nursery areas favorable to their survival or are dispersed into the open ocean. As a first step towards evaluating sardinella vulnerability to climate‐driven hydrodynamical changes, this study aims at underpinning how transport pathways drive optimal spatial and seasonal patterns for sardinella reproduction. We have used two estimates of the Senegalese–Mauritanian coastal seasonal circulation simulated by two hydrodynamical model configurations that differ in their forcing and topography. Nursery areas are determined by evaluating coastal retention with a Lagrangian individual‐based model that accounts for processes such as diel vertical migration and mortality as a result of lethal temperature exposure. Our results suggest that the shelf zones located at the Arguin Bank (19.5°N–21°N) and south of Senegal (12°N–14.75°N) are highly retentive. We find maximum retention rates in July–August and November–December over the Arguin Bank; from February–July and November–December over the southern Senegalese shelf; and lower retention rates over the central region (14.75°N–19.5°N) that are locally maximum in June–July when the upwelling weakens. These retention areas and their seasonality are in agreement with previously reported spawning patterns, suggesting that the Sardinella aurita spawning strategy may result from a trade‐off between retention patterns associated with the seasonal circulation and food availability. Exposure to lethal temperatures, although not well studied, could be a further limiting factor for spawning. The Lagrangian analysis reveals important connectivity between sub‐regions within and south of the system and hence underlines the importance for joint management of the Sardinella aurita stock.

Seasonal home range and habitat use of a critically endangered marsupial (Bettongia penicillata ogilbyi) inside and outside a predator-proof sanctuary

An understanding of the factors that influence the distribution of the woylie (Bettongia penicillata ogilbyi) at local and regional scales has been identified as a key knowledge gap, because such knowledge may assist in the recovery of this endangered species. We aimed to investigate the seasonal home-range size and habitat use of woylies to update current knowledge of the species in the context of a substantial decline. Specifically, we examined the home range and habitat use of woylies reintroduced into a sanctuary free from invasive predators and compared these data to those from an external reference site. Eight woylies inside the sanctuary and seven outside were radio-tracked in autumn 2011. The average home-range size was 65.4 (±8.2, s.e.) ha. There was little evidence to suggest any difference in home-range size between woylies inside and outside the sanctuary. Woylies were more likely to be found in the slope and low-lying valley habitats, which have greater water-holding capacity and sandier soils. These relatively large seasonal home ranges, compared with previously published estimates for the species, may be accounted for by low population density, lower seasonal food availability and clustered food distribution. Monitoring the home-range size of woylies within the sanctuary may assist in identifying the carrying capacity of the sanctuary, which has implications for how this population is managed.

Levels and temporal trends of persistent organic pollutants (POPs) in arctic foxes (Vulpes lagopus) from Svalbard in relation to dietary habits and food availability

Temporal trends of persistent organic pollutants (POPs) in arctic foxes (Vulpes lagopus) from Svalbard, Norway, were investigated in relation to feeding habits and seasonal food availability. Arctic foxes from Svalbard forage in both marine and terrestrial ecosystems and the availability of their food items are impacted by climatic variability. Concentrations of polychlorinated biphenyls (PCBs), organochlorinated pesticides (OCPs) and brominated flame retardants (polybrominated diphenyl ethers [PBDEs] and hexabromocyclododecane [HBCDD]) were analyzed in the liver of 141 arctic foxes collected between 1997 and 2013. Stable carbon isotope values (δ13C) were used as a proxy for feeding on marine versus terrestrial prey. The annual number of recovered reindeer carcasses and sea ice cover were used as proxies for climate influenced food availability (reindeers, seals). Linear models revealed that concentrations of PCBs, chlordanes, p,p′-DDE, mirex and PBDEs decreased 4–11% per year, while no trends were observed for hexachlorobenzene (HCB) or β-hexachlorocyclohexane (β-HCH). Positive relationships between POP concentrations and δ13C indicate that concentrations of all compounds increase with increasing marine dietary input. Increasing reindeer mortality was related to lower HCB concentrations in the foxes based on the linear models. This suggests that concentrations of HCB in arctic foxes may be influenced by high mortality levels of Svalbard reindeer. Further, β-HCH concentrations showed a positive association with sea ice cover. These results in addition to the strong effect of δ13C on all POP concentrations suggest that climate-related changes in arctic fox diet are likely to influence contaminant concentrations in arctic foxes from Svalbard.

Birth seasonality and pattern in black-and-white snub-nosed monkeys (Rhinopithecus bieti) at Mt. Lasha, Yunnan.

Seasonal variation in environmental factors is vital to the regulation of seasonal reproduction in primates. Consequently, long-term systematic data is necessary to clarify the birth seasonality and pattern of primates in highly seasonal environments. This study indicated that black-and-white snub-nosed monkeys (Rhinopithecus bieti) at Mt. Lasha exhibited strict birth seasonality with a pulse model. Infants were born with a certain degree of synchronization. Birth distribution showed three birth peaks, and the birth pattern showed a "V" style in even-numbered years and a gradual increase in odd-numbered years. The beginning date, end date and median birth date were earlier in even-numbered years than those in odd-numbered years. The higher latitude of their habitats, earlier birth date, shorter birth period, fewer birth peaks and stronger birth synchrony might be adaptations for strongly seasonal variation in climate and food resources. After the summer solstice when daylight length began to gradually shorten, R. bieti at Mt. Lasha started to breed during the period with the highest environmental temperature and food availability, which implied that photoperiod may be the proximate factor triggering the onset of estrus and mating. It appears that R. bieti coincided conception and mid-lactation with the peak in staple foods, and weaning with the peak in high quality of foods. Thus, food availability was the ultimate factor regulating reproductive seasonality, and photoperiod was the proximate factor fine-turning the coordination between seasonal breeding and food availability.

Seasonal variation of child under nutrition in Malawi: is seasonal food availability an important factor? Findings from a national level cross-sectional study.

BackgroundChild under nutrition is an underlying factor in millions of under-five child deaths and poor cognitive development worldwide. Whilst many studies have examined the levels and factors associated with child under nutrition in different settings, very little has been written on the variation of child under nutrition across seasons. This study explored seasonal food availability and child morbidity as influences of child nutritional status in Malawi.MethodsThe study used the 2004 Malawi Integrated Household Survey data. Graphical analysis of the variation of child under nutrition, child morbidity and food availability across the 12 months of the year was undertaken to display seasonal patterns over the year. Multivariate analysis was used to explore the importance of season after controlling for well-established factors that are known to influence a child’s nutritional status.ResultsA surprising finding is that children were less likely to be stunted and less likely to be underweight in the lean cropping season (September to February) compared to the post-harvest season (March to August). The odds ratio for stunting were 0.80 (0.72, 0.90) and the odds ratio for underweight were 0.77 (0.66, 0.90). The season when child under nutrition levels were high coincided with the period of high child morbidity in line with previous studies. Children that were ill in the two weeks prior to survey were more likely to be underweight compared to children that were not ill 1.18 (1.01, 1.38).ConclusionIn Malawi child nutritional status varies across seasons and follows a seasonal pattern of childhood illness but not that of household food availability.

Torpor during Reproduction in Mammals and Birds: Dealing with an Energetic Conundrum

Torpor and reproduction in mammals and birds are widely viewed as mutually exclusive processes because of opposing energetic and hormonal demands. However, the reported number of heterothermic species that express torpor during reproduction is ever increasing, to some extent because of recent work on free-ranging animals. We summarize current knowledge about those heterothermic mammals that do not express torpor during reproduction and, in contrast, examine those heterothermic birds and mammals that do use torpor during reproduction. Incompatibility between torpor and reproduction occurs mainly in high-latitude sciurid and cricetid rodents, which live in strongly seasonal, but predictably productive habitats in summer. In contrast, torpor during incubation, brooding, pregnancy, or lactation occurs in nightjars, hummingbirds, echidnas, several marsupials, tenrecs, hedgehogs, bats, carnivores, mouse lemurs, and dormice. Animals that enter torpor during reproduction often are found in unpredictable habitats, in which seasonal availability of food can be cut short by changes in weather, or are species that reproduce fully or partially during winter. Moreover, animals that use torpor during the reproductive period have relatively low reproductive costs, are largely insectivorous, carnivorous, or nectarivorous, and thus rely on food that can be unpredictable or strongly seasonal. These species with relatively unpredictable food supplies must gain an advantage by using torpor during reproduction because the main cost is an extension of the reproductive period; the benefit is increased survival of parent and offspring, and thus fitness.

Mass gained during breeding positively correlates with adult survival because both reflect life history adaptation to seasonal food availability

Both mass (as a measure of body reserves) during breeding and adult survival should reflect variation in food availability. Those species that are adapted to less seasonally variable foraging niches and so where competition dominates during breeding, will tend to have a higher mass increase via an interrupted foraging response, because their foraging demands increase and so become more unpredictable. They will then produce few offspring per breeding attempt, but trade this off with higher adult survival. In contrast, those species that occupy a more seasonal niche will not gain mass because foraging remains predictable, as resources become superabundant during breeding. They can also produce more offspring per breeding attempt, but with a trade-off with reduced adult survival. We tested whether the then predicted positive correlation between levels of mass gained during seasonal breeding and adult survival was present across 40 species of tropical bird measured over a 10-year period in a West African savannah. We showed that species with a greater seasonal mass increase had higher adult survival, controlling for annual mass variation (i.e. annual variation in absolute food availability) and variation in the timing of peak mass (i.e. annual predictability of food availability), clutch size, body size, migratory status and phylogeny. Our results support the hypothesis that the degree of seasonal mass variation in birds is probably an indication of life history adaptation: across tropical bird species it may therefore be possible to use mass gain during breeding as an index of adult survival.

Influence of food availability on the diet and activity budget of two western lowland gorilla (Gorilla gorilla gorilla) groups of differing size in the Dzanga-Ndoki National Park, Central African Republic

Variation in food availability, body size and group size are known to influence primate diet and activity budgets. Here we report how seasonal food availability shapes the diet and activity patterns of two habituated western lowland gorilla (WLG) groups of differing size. WLGs are ripe fruit opportunists, showing dietary flexibility when preferred foods are scarce. However, as fruit can be rare/ patchily distributed, as intra-group feeding competition increases with group size, access to individual patches may be limited. We thus predicted that frugivory decreases with increased group size and influences diet and activity budgets accordingly (increased diet breadth and time feeding since relying on alternative/lower quality food). First, we compared food availability between home-ranges by monitoring leafing/fruiting patterns of major gorilla food trees. Second, we compared the groups’ activity budgets and diet composition/diversity, testing for differences between high (HF) and low fruit seasons (LF). We measured gorilla activity over six months by continuous focal sampling of 16 target animals rotated daily from both groups (N=9 and N=15). Our results confirm that WLG diet consisted mainly of fruits (36%, then: stems 24%; leaves 21%; insects 14%; other food types 3%, and bark 2%) and spend most of their time feeding (39%, then: resting 33%; traveling 19%; social 5%, and other activities 4%). However, contrary to our predictions, we found no group differences within or between seasons: irrespective of group size both spent significantly less time feeding, but more time traveling and socializing, and consumed significantly more fruits, less leaves and bark during the HF compared to the LF. Our results show that WLG activity budgets and diet appear to vary more in response to ripe fruit availability than group size. We suggest that WLGs may cope with increased group size costs through other mechanisms such as group spread, rather than lowering diet quality or further changing activity patterns. Such flexibility may better allow WLG groups to track ripe fruits when available but, unlike sympatric chimpanzees, switch to more herbivorous diets when necessary, adjusting activity budgets accordingly ; WLGs thus may be considered more resilient faced with environmental change such as forest degradation.

Effects of climate change on European ducks: what do we know and what do we need to know?

The consequences of climate change for bird populations have received much attention in recent decades, especially amongst cavity‐nesting songbirds, yet little has been written on ducks (Anatidae) despite these being major elements of wetland diversity and important quarry species. This paper reviews the major known consequences of climate change for birds in general, and relates these to the limited information available specifically for ducks. Climate change can influence migration distance and phenology, potentially affecting patterns of mortality, as well as distribution and reproductive success in ducks. Studies addressing effects of climate change are, however, restricted to very few duck species, including mallardAnas platyrhynchosand common eiderSomateria mollissima. Shifts in winter duck distributions have been observed, whereas the mismatch hypothesis (mistiming between the periods of peak energy requirements for young and the peak of seasonal food availability) has received limited support with regard to ducks. We propose a range of monitoring initiatives, including population surveys, breeding success monitoring schemes and individual duck marking, which should later be integrated through population modelling and adaptive management to fill these gaps.

Considering Seasonal Variations in Food Availability and Caring Capacity when Planning Complementary Feeding Interventions in Developing Countries

During early childhood, adequate nutrition is critical for preventing and reducing chronic undernutrition and micronutrient deficiencies. Seasonal food availability, access to diverse food and maternal workload are among the known constraints to successful infant and young child feeding practices. In rural areas in developing countries, many populations experience seasonal food shortages, which often coincide with an increase in food prices and a peak period for agricultural labour. Seasonal pressure on women’s time can negatively impact cooking and caring practices and intra-family food distribution. These factors combine to affect the nutritional status of especially children and women. This paper shows how seasonal food availability data are collected and utilized in designing complementary feeding interventions. Examples are drawn from FAO food and nutrition security projects in Afghanistan, Cambodia, Laos and Zambia which began with formative research using Trials of Improved Practices. Methods include use of seasonal food availability calendars and development of season-specific dishes and recipes. How seasonal variations in food availability and caring capacity feature in the educational materials developed by these projects is also reported. Finally, we provide practical ideas for incorporating coping strategies for dealing with seasonal effects when planning such interventions.

The link between feeding ecology and lead poisoning in white‐tailed eagles

AbstractLead poisoning affects numerous threatened raptors and is a major cause of death in white‐tailed eagles (Haliaeetus albicilla). A major reason for intoxication is assumed to be lead fragments ingested while feeding on game animals killed by lead‐based projectiles. However, empirical evidence on the relevance of carrion in raptor diets remains scarce. We therefore investigated the link between raptor feeding ecology and lead poisoning, with white‐tailed eagles as a model species for scavenging birds. We collected data on seasonal diet composition and food availability of 7 territorial white‐tailed eagle pairs in northeastern Germany. We also analyzed stomach contents (SCs) of 126 eagles found dead from 1996 to 2008 throughout Germany. Multiple regression models revealed that fish were the primary prey for eagles, and waterfowl and carcasses of game mammals comprised a large portion of alternative diet components. Eagles used individual foraging tactics, adjusted to local food supply, to maximize profitability. They showed a type II functional response to fish availability. When fish availability sharply declined, eagles switched to waterfowl and carrion. The consumption of game mammal carrion increased over autumn and winter and was positively correlated with a concomitant seasonal increase in the incidence of lead poisoning in eagles throughout Germany. The stomachs of lead‐poisoned eagles predominantly contained game ungulate remains. These results indicate that carcasses of game mammals were the major sources of lead fragments. The link between raptor feeding ecology and lead poisoning is the specific functional response of raptors to changing food availability or poor habitat quality, leading to scavenging on lead‐contaminated carrion. This shows that carrion constitutes a considerable threat to white‐tailed eagles and other birds with similar feeding habits as long as it contains lead bullet fragments. Conservation management of scavenging birds would be substantially improved if carrion was free of lead bullet fragments. One method to achieve this is the widespread introduction of lead‐free ammunition. © 2012 The Wildlife Society.

Seasonal Space Use and Habitat Selection of Adult Raccoons (Procyon lotor) in a Louisiana Bottomland Hardwood Forest

Raccoon ecology is poorly understood in bottomland hardwood systems, despite the fact that bottomland forests are considered high-quality raccoon habitat. We radio-marked 41 raccoons during 2008–2009 and estimated seasonal space use and habitat selection in a bottomland hardwood forest located within the Atchafalaya floodway system in Louisiana. Space use varied seasonally, with home ranges and core areas largest during the breeding season. Forest openings were important when configuring seasonal home ranges, whereas habitat selection within home ranges varied seasonally. The composition of habitats within core use areas was similar to that of home ranges. We concluded that home range size was influenced by reproductive behaviors and seasonal food availability, whereas habitat selection was most influenced by spatio-temporal changes in seasonal food abundance. Raccoons used all available habitat types and landscape heterogeneity is likely important to raccoons when establishing home ranges in bottomland hardwood forest systems.

Reproductive timing and investment in relation to spring warming and advancing agricultural schedules

Advances in mowing schedules have led to early and rapid declines in the seasonal food availability for, and survival rates of, chicks of grassland-breeding waders. Concurrently, increased levels of soil fertilization may have improved food abundance for adults. These developments are assumed to have resulted in an advancement of laying during 1930–1976 in several meadowbird species, including Black-tailed Godwits. Despite an apparent selective advantage of early breeding, after 1976 Godwits stopped advancing their laying dates. We have analyzed the timing of breeding and reproductive investment in Dutch Black-tailed Godwits relative to recent changes in agricultural practices and climate during 1976–2007. Early and late spring temperatures and precipitation in March were used as indicators for the timing of fertilizer application and mowing, and also as qualitative measures of relative food availability for adults and chicks. When precipitation was higher in March, Black-tailed Godwits laid earlier. Following warmer winters, the earliest females laid larger eggs, which hatched heavier chicks with a higher survival probability. We suggest that the positive effect of an increasing March precipitation on invertebrate abundance may be constrained by the current policy of rigid control of the water table. This policy prevents Godwits from further advancing laying dates, which would increase their chick’s survival prospects under increasingly early mowing schedules. Policy-makers should, next to delaying mowing schedules, also consider reduced draining in early spring as a tool to help stop the population decline of the Black-tailed Godwit.

Seasonality of group size, feeding, and breeding in wild red‐shanked douc langurs (Lao PDR)

In Asian colobines, small one-male groups (OMG) seem to predominate alongside all-male groups (AMG), while larger multimale groups (MMG) are rare, but are reported for Hanuman langurs and red-shanked douc langurs. Recently, however, it has been speculated that the genus Pygathrix could have multilevel societies based on (1) a theoretical extension of the multilevel societies found in Rhinopithecus to all odd-nosed colobines and (2) first data for black-shanked douc langurs. This assumes bands composed of small OMG with a skewed adult sex ratio. Band size may vary with seasonal food availability resulting in smaller bands when feeding competition is increased. To investigate the social organization of red-shanked douc langurs and potential seasonal influences, we observed 2 unhabituated groups at Hin Namno National Protected Area, Lao PDR from March 2007 to August 2008 for 803 hr. We recorded births and performed group counts and scan sampling of feeding behavior. Most births (79% of N = 15) occurred from June-September, indicating a 4-month peak conception season from November to February. Group size averaged 24.5 individuals (range 17-45) with 2.45 adult males (range 1-4). Although the smaller group remained at a stable size (about 18 individuals), the larger group reduced from about 45 to 25 individuals during the 7-months long lean season, when less than 50% of the feeding time was spent on fruits. This suggests feeding competition as a potential cause of seasonal variation in group size. With 1.9 females per male the skew in adult sex ratio was much lower compared with Rhinopithecus, indicating MMG rather than multilevel societies. However, data on the spacing and interaction patterns between recognized individuals need to be collected and analyzed before the social organization can be determined. Detailed ecological data are furthermore required to investigate the basis for the seasonal changes in group size found.

Grouping Patterns and Selection of Forage by the Scimitar-Horned Oryx (Oryx dammah) in the Llano Uplift Region of Texas

Abstract Studies quantifying the grouping and forage-selection patterns of scimitar-horned oryx (Oryx dammah) in Texas or in their native range, where they are probably extinct, are scarce. This oryx is less dimorphic in size than most ruminants; dimorphism in size is associated with intersexual differences in grouping patterns and diet. We hypothesized that males and females associate in mixed-sex groups and do not exhibit intersexual differences in selection of forage. Our study was conducted at Mason Mountain Wildlife Management Area, Mason County, Texas, during June 2006–April 2007. Grouping patterns were measured from systematic surveys conducted from vehicles at dawn and in the afternoon in 6 different months. We collected fecal samples from individuals of known sex and assessed diet using fragments of plants in fecal samples. We measured seasonal availability of food in areas where fecal samples were collected. We encountered mixed-sex groups more often than same-sex groups and we detected no diffe...

Contemporary nutritional transition: determinants of diet and its impact on body composition.

The world has experienced a marked shift in the global BMI distribution towards reduced undernutrition and increased obesity. The collision between human biology, shaped over the millennia and modern technology, globalization, government policies and food industry practices have worked to create far-reaching energy imbalance across the globe. A prime example is the clash between our drinking habits and our biology. The shift from water and breast milk as the only beverages available, to a vast array of caloric beverages was very rapid, shaped both by our tastes and aggressive marketing of the beverage industry. Our biology, shaped over millennia by daily consumption of water and seasonal availability of food, was not ready to compensate for the liquid energies. Other dietary changes were similarly significant, particularly the shift towards increased frequency of eating and larger portions. The roles of the food and beverage production, distribution and marketing sectors in not only shaping our diet but also accelerating these changes must be understood. Apart from the role of beverages, there is much less consensus about the role of various components of our diet in energy imbalance. Understanding the determinants of change in the key components of our diet through an array of research provides insights into some of the options we face in attempting to attain a great balance between energy intake and expenditures while creating an overall healthier dietary pattern. A few countries are systematically addressing the causes of poor dietary and physical activity patterns and high energy imbalance.

Seed dispersal of the Brazil nut tree (Bertholletia excelsa) by scatter-hoarding rodents in a central Amazonian forest

Abstract:We know surprisingly little about the fate of seeds of the Brazil nut tree (Bertholletia excelsa) under natural conditions. Here we investigate seed removal, predation and caching of Brazil nuts by scatter-hoarding rodents in the wet and dry seasons, based on an experimental approach using 900 thread-marked seeds. We tracked the fate of seeds handled by these animals to examine how seasonal food availability may influence caching rates, dispersal distances and cache longevity. Most seeds exposed to dispersal trials were removed by scatter-hoarders during the first week in both seasons and seeds were generally buried intact in single-seeded caches within 10 m of seed stations. Seeds were removed significantly faster and buried at greater distances during the dry season. The proportion of seeds buried intact was considerably higher in the wet season (74.4%) than in the dry season (38.2%). Most (99.4%) of the 881 primary caches monitored were recovered, but these had a significantly shorter lifetime in the dry season. Our results show that rodents are highly skilled at retrieving buried Brazil nuts and that caching behaviour appears to be affected by seasonal resource abundance. Reduced seed availability due to intensive harvest could potentially create a dry-season scenario where most seeds succumb to pre-dispersal predation, thereby adversely affecting the natural regeneration of Brazil nut trees.