Acorn Consumption Research Articles

Acorn (Quercus spp.) Consumption in Algeria

Acorns have been a vital food source for many communities worldwide, but there is limited research on their traditional uses and nutritional and medicinal properties. To address this gap, a study was conducted to explore the traditional methods of preparing and consuming acorns in Algeria and their potential benefits for human health. A questionnaire-based survey was conducted with a large sample of individuals from all over Algeria to collect data on their acquaintance with Quercus species, acorn consumption, consumption habits, and therapeutic uses of acorns. Results were subjected to a chi-square test and logistic regression statistical analysis to test the association between acorn consumption and the different sections under study. The survey found that 91% of participants consumed acorns, with sweet Holm and Cork oak being the most commonly consumed species. Acorn consumption was found to be influenced by gender, geographical position, familiarity with Quercus species, and belief that acorns are not exclusively animal food. The most common method of consumption was cooking, with roasting and boiling being the preferred cooking methods, and acorns were consumed seasonally, primarily during autumn. The study shows that acorn consumption in Algeria has the potential for economic benefits and can be a viable alternative to wheat flour. It also reveals the traditional gastronomic knowledge associated with acorn-based products and meals. The survey results highlight the diverse and significant knowledge of oak fruits by the local population and suggest that future research could enhance the practices and knowledge of acorn-based products and promote acorn consumption.

Predation of oak acorns by Baird's tapir in one of the last remnants of mountain cloud forest in Southern Mexico

The consumption of fruits and seeds by mammals can have a strong impact on the regeneration of tropical forests. Our knowledge of this biotic interaction has steadily increased recently but it remains fragmentary. This is largely due to most of the studies focusing on a small proportion of the diverse mammals and plants involved in these interactions and to the fact most commonly used methods provide just partial information about the whole seed dispersal/predation process. The use of camera traps has opened the opportunity to greatly improve our knowledge of the intricacies of frugivory and seed predation by increasing the likelihood to record very secretive animal species and providing detailed accounts of their behavior. Based on camera trap data we report acorn consumption of Quercus benthamii and Q. sapotifolia by the threatened Baird's tapir (Tapirus bairdii). This study was conducted in the largest remnant of Mountain cloud forest in Mexico, located in El Triunfo Biosphere Reserve (ETBR) in the state of Chiapas. Despite the fact that ten mammal species were recorded in the focal trees, only two of them (T. bairdii and Sciurus deppei) were documented exhibiting acorn consumption. We obtained 82 videos showing the consumption of Q. benthamii acorns by tapirs (sampling effort = 133 camera trap days, n = 8 trees) with an average of 6.04 ± 3.56 (± sd) minutes spent on this activity. In comparison, we only obtained one video of a tapir consuming Q. sapotifolia acorns (sampling effort = 264 camera trap days, n = 5 trees) during 35 s. Consumption of these Quercus species by tapir was not previously reported. Moreover, our study is the first (to our knowledge) to show video-recorded evidence of the interaction between tapirs and Quercus trees. Due to tapirs' large body size, the consumption of acorns might be an important source of mortality for some Quercus species (e.g., Q. benthamii).

First documentation of acorn consumption by eastern screech owl (Megascops asio)

We present evidence for the first documentation of consumption of a water oak (Quercus nigra) acorn by an eastern screech owl (Megascops asio). A screech owl diet typically consists of small mammals, small birds, and arthropods. In our study, we had a 1-m x 1-m sand pad under observation from a game camera that was set on a 1-min time-lapse delay. On this sand pad, we placed five water oak acorns. In a series of six images over six minutes, we observed an eastern screech owl land near the sand pad, walk to an acorn, and appear to consume the acorn. Although there could be other plausible explanations and events that transpired between 1-min image intervals, we believe this acorn was consumed by the eastern screech owl. The importance of this addition of food type to the diet of a raptor is largely unexplored and undocumented.

Low Rate of Pre-Dispersal Acorn Predation by Eurasian Jays Garrulus glandarius during Non-Mast Years

Mast-seeding is widely considered to be an adaptation that minimizes seed predation. The superabundance of seeds during mast years greatly exceeds the capacity of seed predators to consume them. These notions were based on research on food specialists such as insects and rodents. However, mast-seeding may have different impact on the behavior of corvids that are food generalists. The Eurasian Jay Garrulus glandarius is a widespread scatter-hoarding corvid that uses acorns as a food reserve for winter. In mast-years, the birds are supposed to be satiated by the greater seed supply and are able to store their surplus, acting as dispersal agents, whereas in poor crop seasons they use most of the crop for current consumption and thus become seed predators. In such a situation, a dispersal agent may become a seed predator, and vice versa. The main task of this study was to determine the levels of pre-dispersal acorn predation by Jays during non-mast years to verify the notion that under such conditions Jays act mostly as seed consumers. During two consecutive non-mast years, tagged acorns were radio-tracked and the acorns' fate (cached or eaten) was assessed. We found extremely low pre-dispersal acorn predation by Jays (0.9%). The possible reason is that temperatures in period of acorns collecting (September–October) are high enough to allow invertebrates to remain active, so the Jays may supplement their diet with insects and also fleshy fruits. Therefore, almost all acorns were cached and scatter-hoarding Jays provided effective seed dispersal, with extremely low consumption of acorns.

Unravelling the influence of annual weather conditions and Mediterranean habitat types on acorn production, availability and predation

Seed production and survival are critical steps in the life cycle of plants, and could become bottlenecks for plant regeneration in case of failure. During regeneration many factors, both abiotic and biotic, intervene and interact with each other. After dispersal, environmental variation affects the success of the plant population, so seedling recruitment can display spatial variability. However, few studies of seed production and availability cover a range of habitat conditions (e.g. mature, transitional and post-fire habitats), which makes it difficult to evaluate the potential of site-production relationships. We study how the heterogeneity of habitat structure and composition affects the phenology, production and availability of acorns, mainly holm oak, in a Mediterranean Natural Park. Our results show that meteorological variables determine the phenology of acorn fall. Habitat types present temporal mismatches in falls since, for example, shrublands required a longer period of time for all seeds to fall. Furthermore, habitats with greater tree density and low understory complexity had higher production but smaller acorns. Lower densities promote higher acorn volume (seedling size) as a consequence of less intraspecific competition and more reserves for germination. The proportion of viable acorns available on the ground also decreased substantially in winter, when the proportion of infested acorns increase because the selective consumption of sound acorns by predators. Acorns from mixed forests and shrublands had less pre-dispersal predation by arthropods and post-dispersal predation by wild boar as a result of oak isolation and understory complexity. Conversely, rodents are more abundant in shrublands, where they find a greater diversity of anti-predator refuges and large nutritious acorns available in autumn and winter. Understanding the reproductive constraints imposed by time and space allows us to infer the consequences of environmental changes on population recruitment and persistence. We thus show that habitats with a high density of oak trees, less plant diversity and understory cover had a greater prevalence of infested acorns, thereby reducing recruitment viability. These habitats also had more available acorns on the ground for seed predators. Therefore, habitat type is an important factor affecting acorn production and should be taken into account in future studies.

Influence of soil chemical composition on U, 226Ra and 210Pb uptake in leaves and fruits of Quercus ilex L.

To determine their transfer factors, activity concentrations of natural radionuclides were measured in the leaves and acorns of holm oak (Quercus ilex L.) trees collected from seven locations with different soil properties and radionuclide activity concentrations. The chemical and mineralogical compositions of the soils were also analysed to investigate the effect these had on radionuclide absorption by the trees. Soil chemistry showed significant effects on radionuclide incorporation into Quercus ilex L. tissues. A significant relationship was established between activity concentrations and soil content of Ca and P with 238U and 226Ra in the leaves and acorns of Quercus ilex L. Differentiated transfer was found for 40K, which showed greater transfer to the leaves than the other radionuclides. The activity concentration of U and 226Ra was higher in the fruits than in the leaves, with the opposite effect being observed for 40K. The risk of U and 226Ra transfer into the food chain through acorn consumption by livestock is predicted to increase in soils poor in Ca and rich in P.

Impacts of wild pigs on acorn availability as a food source for native wildlife

Context Wild pigs (Sus scrofa) are a non-native invasive species that causes millions of dollars in damage each year to agriculture in the United States of America, destroys native plant communities, and competes with native wildlife for seasonally available pulse resources such as acorns. Despite many anecdotal observations and diet studies suggesting wild pigs reduce acorn availability for other wildlife species, no studies have comparatively examined acorn consumption among species in a natural environment (i.e. competition). Aims Our objective was to estimate the consumption of acorns by wild pigs relative to that of other native wildlife species. Methods We established 40 monitoring stations beneath acorn-producing trees in a 3406-ha study area in eastern Alabama with an approximate density of 9 pigs/km2. At each monitoring station, we placed five acorns on a 1-m × 1-m sand pad and positioned a game camera to record acorn fate during 2-week intervals once a month from September to February 2018–2019 and 2019–2020. Cameras were set to capture images once every minute continuously during the survey period. Additionally, we constructed acorn traps from 18.9-L plastic buckets to estimate the timing and relative amounts of acorns that were potentially available for consumption at each monitoring station. Key results From approximately 7.3 million camera images, we observed 15 wildlife species consuming 707 acorns over the 2 years. Aside from animal consumption, acorn fate was categorised as lost due to flooding (n = 153), remaining on the sand pad at time of camera failure (n = 720), or not consumed during the sampling period (n = 536). Key conclusions Top acorn consumers were squirrel (Sciurus spp.), white-tailed deer (Odocoileus virginianus), raccoon (Procyon lotor), and wild pig. In the 2018–2019 sampling period, wild pigs consumption accounted for 23.4% (n = 87) of the total consumed acorns. After wild pig removal efforts were initiated in the summer and autumn of 2019, wild pigs consumed only 7.2% (n = 24) of consumed acorns. Implications Wild pigs consume a significant number of acorns and likely reduce the availability of this pulse resource for other native wildlife species and may potentially influence oak regeneration.

Cattle dung and bioturbation by dung beetles improve oak seedling establishment in Mediterranean silvopastoral ecosystems

This study aims to determine whether the application of cattle manure and associated bioturbation by dung beetles and other invertebrates can increase oak seedling establishment in the high biodiversity Mediterranean silvopastoral systems known as “dehesas”, which are comprised of scattered oaks and a grassland layer and are used for livestock rearing. A two-year study was conducted in a representative dehesa in southern Spain. Firstly, the effect of cattle dung pads on acorn consumption by livestock and wild predators was monitored, along with dung beetle abundance and plot bioturbation. Secondly, the indirect effects of bioturbation on acorn burial, acorn predation by rodents and oak seedling establishment were assessed under the condition of livestock exclusion. The results consistently demonstrate a high positive indirect effect of the presence of cattle manure on the persistence of acorns, as well as on seedling establishment, as a result of reduced predation by rodents and improved microhabitat conditions for the acorns and seedlings. These processes were mediated by bioturbation. Tunneler dung beetles, which move a great amount of soil material, were dominant in our records, which suggest their importance for passive acorn burial, without disregarding the influence of other edaphic invertebrates present. We conclude that the presence of cattle manure significantly improves oak seedling establishment in Mediterranean dehesas through the passive burial of acorns by bioturbation, which acts to protect them from predation by rodents, desiccation and other damage. Passive acorn burial by dung beetles and other invertebrates thus emerges as an important ecosystem service that has been little-studied to date. Appropriate rotational management of livestock could therefore contribute to addressing the bottleneck of oak regeneration in Mediterranean dehesas.

Partial Consumption of Acorns by Some Rodents Leads Their Relationship with Oaks Species Towards Mutualism

Numerous interactions between plants and animals vary in their outcome between predation and mutualism. Depending on the costs and benefits, the relationship is placed at one end of the scale or the other. A thin line separates both interactions. Acorn consumption by rodent species has been considered a predation relationship. Rodents consume acorns, which is a cost to oaks species as they are prevented from colonizing new places. The aim of this study is to show that part of the costs allocated to depredation due to loss of acorns cannot be allocated to costs. Some attacked acorns are partially consumed, but preserve their embryo and are not lost as they can germinate. This behavior, preserving the embryo, is observed in certain species. We will attempt to verify whether the behavior of conserving the embryo shown by some rodent species during partial consumption of acorns is intended to bring their relationship with oaks species closer to mutualism. To do this, we studied and compared the behavior of two acorns-consuming rodent species (<i>Apodemus sylvaticus</i> and <i>Mus spretus</i>) with another species that has never used this type of resources (<i>Microtus arvalis</i>), during acorns consumption. The results show that only two acorn-consuming species preserved the embryo, and not by species that are incorporating acorns into their diet. Species that have consumed acorns since ancient times show embryo-acorns preserving behavior. These species (<i>Apodemus sylvaticus</i> and <i>Mus spretus</i>) start consuming the acorns at the basal part, away from the embryo, at a higher energy expense, but they assume it because the mutualistic relationship they seek provides them with food guarantees in the future. This behavior is the contribution made by mutualistic rodents to maintain their relationship with oaks plants within the term of mutualism. Both species benefit from the relationship. Plants seeds are successfully transported to and germinated in suitable places and rodents obtain nutrients and the possibility of providing their offspring with future resources. The species not using acorns as food (<i>Microtus arvalis</i>) behaves as a predatory. The most convenient way for it to open the acorn is to devour the embryo, thus posing a threat to oak species.

Linking landscape structure and vegetation productivity with nut consumption by the Cantabrian brown bear during hyperphagia

In bears, reproduction is dependent on the body reserves accumulated during hyperphagia. The Cantabrian brown bear mainly feeds on nuts during the hyperphagia period. Understanding how landscape heterogeneity and vegetation productivity in human-dominated landscapes influence the feeding habits of bears may therefore be important for disentangling species-habitat relationships of conservation interest. We determined the spatial patterns of nut consumption by brown bears during the hyperphagia period in relation to landscape structure, characteristics of fruit-producing patches and vegetation productivity. For this purpose, we constructed foraging models based on nut consumption data (obtained by scat analysis), by combining vegetation productivity data, topographical variables and landscape metrics to identify nut foraging patterns during this critical period for bears. The average wooded area of patches where scats were collected and where the nuts that the bears had consumed were produced was larger than that of the corresponding patches where nuts were not produced. For scats collected outside of nut-producing patches, the distance between the scats and the patches was greatest for chestnut-producing patches. Elevation, Gross Primary Production (GPP) and the Aggregation Index (AI) were good predictors of acorn consumption in the models. Good model fits were not obtained for data on chestnut consumption in bears. The findings confirm that brown bears feeding on nuts show a preference for relatively large, highly aggregated patches with a high degree of diversity in the landscape pattern, which may help the bears to remain undetected. The nut prediction model highlights areas of particular importance for brown bears during hyperphagia. The human presence associated with sweet chestnut forest stands or orchards may make bears feel more vulnerable when feeding.

Inter-trophic Interaction of Gut Microbiota in a Tripartite System.

Gut microbiota can be transmitted either environmentally or socially and vertically at intraspecific level; however, whether gut microbiota interact along trophic levels has been largely overlooked. Here, we characterized the gut bacterial communities of weevil larvae of Curculio arakawai that infest acorns of Mongolian oak (Quercus mongolica) as well as acorn-eating mammals, Siberian chipmunk (Tamias sibiricus), to test whether consumption of seed-borne larvae remodels the gut bacterial communities of T. sibiricus. Ingestion of weevil larvae of C. arakawai significantly altered the gut bacterial communities of T. sibiricus. Consequently, T. sibiricus fed larvae of C. arakawai showed higher capability to counter the negative effects of tannins, in terms of body weight maintenance, acorn consumption, N content in feces, urine pH, and blood ALT activity. Our results may first show that seed-borne insects as hidden players have a potential to alter the gut microbiota of seed predators in the tripartite system.

Cold temperature improves tannin tolerance in a granivorous rodent.

The foraging ecology of mammalian herbivores is regulated in part by their ability to detoxify plant secondary metabolites (PSM). Ambient temperature has been shown to alter liver function in rodents and the toxicity of some PSMs, but little is known about the physiological and nutritional consequences of consuming PSMs at different ambient temperatures. Furthermore, the effect of ambient temperature on the response of mammals to the most ubiquitous class of PSM, tannins, is unknown. We measured the effect of temperature and tannin intake on liver function, and the subsequent effect on the tannin tolerance of wild Japanese wood mice, Apodemus speciosus. The experiment involved acclimation to one of two ambient temperatures (10°C or 20°C) followed by acclimation to a diet of acorns (6.2% tannin DW). Liver function was measured both before and after acclimation to acorns by measuring the clearance time of a hypnotic agent. Finally, the mice were fed only acorns in a 5-day feeding experiment to assess their tolerance to tannin in the diet. Acclimation to acorns had a significant effect on liver function, but the direction of this effect was dependent on ambient temperature. Acorn consumption improved the liver function of wood mice at 10°C, but reduced liver function at 20°C, revealing a complex relationship between ambient temperature and tannin intake on liver function. Furthermore, mice with better liver function, indicated by faster clearance of the hypnotic agent, exhibited higher protein digestibility on an acorn-only diet, indicative of higher tannin tolerance. These results suggest that environmental temperature plays a significant role in the tolerance of A.speciosus to tannins, providing new insight into their seasonal feeding behaviour and winter ecology. We contend that cold-induced tannin tolerance may help to explain the population dynamics of mammalian herbivores with seasonal changes in the tannin content of their diet, and inform predictions about the response of these animals to a changing climate.

Case Report - Chronic oak toxicity (Quercus suber) in beef cattle in the south of Portugal

Oak toxicity in cattle results from ingestion of acorns, buds, leaves, sprouts, and saplings from several species of trees in the genus Quercus, all of which contain high concentrations of tannins. Consumption of acorns by ruminants, principally between late summer and early winter, is common in the south of Portugal, where there is a high prevalence of Quercus suber. Oak poisoning can lead to progressive damage to the kidneys and may result in renal failure and death. This study involved 17 beef cows that died of chronic oak poisoning related to ingestion of Quercus suber. The most relevant findings from necropsy examinations were abdominal fluid accumulation, atrophic/fibrotic kidneys, mesenteric and sub-mandibular edema, absence of body fat reserves and muscle atrophy, and weight loss. The most significant histopathologic finding was chronic interstitial nephritis. Elevated blood urea nitrogen, creatinine, and K+ values and reduced albumin values were found in 4 cows examined ante-mortem. Straight-bred Mertolengo cows appeared to be highly resistant to oak toxicity.

Iberian pig adaptation to acorn consumption: II. Net portal appearance of amino acids.

In Iberian pig outdoor production, pigs are fed equilibrated diets until the final fattening period when grazing pigs consume mainly acorns from oak trees. Acorns are rich in energy but poor in crude protein where lysine is the first limiting amino acid (AA). Net portal appearance (NPA) is very useful to ascertain AA available for liver and peripheral tissues. The aim of this study was to determine NPA of AA in Iberian gilts fed with acorns and to ascertain if there was an effect of acorn feeding over time. Two sampling periods were carried out (after one day and after one week of acorn feeding) with six gilts (34 kg average BW) set up with three catheters: in carotid artery and portal vein for blood sampling, and ileal vein for a marker infusion to measure portal plasma flow (PPF). Pigs were fed at 2.5 × ME for maintenance a standard diet in two meals, at 09:00 (0.25) and 15:00 h (the remaining 0.75). The day previous to first sampling, pig diet was replaced by 2.4 kg of acorn. A serial blood collection was done at −5 min, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5 and 6 h after feeding 0.25 of total daily acorn ration. Following identical protocol, one week later the second sampling was done. NPA of sum of essential AA (EAA) was poor. Although increased NPA of histidine (P < 0.001), leucine, phenylalanine and valine (0.05 < P < 0.08) was found after one week of acorn consumption, the sum of EAA did not change. Furthermore, fractional absorption (NPA/AA intake) of EAA, non-essential AA (NEAA) and total AA was 97, 44 and 49% lower, respectively, at the beginning of eating acorn than a week later. Supplementation, with some of the EAA and NEAA to Iberian pigs during the grazing period would be beneficial to overcome the increased portal-drained viscera (PDV) utilization of AA observed in the present study.

The effects of four repellents on bank vole consumption and germination of beech nuts and acorns

Consumption and removal of buried seeds by granivorous rodents is one of the major problems when direct seeding is applied for restoration of oak (Quercus robur) and European beech (Fagus sylvatica) forests. In this laboratory study, the use of four seed treatments to potentially reduce bank vole (Myodes glareolus) consumption of beech nuts and acorns and a control was evaluated using a no-choice feeding set-up. The five seed treatments were: Chili (Capsicum chinense)/coconut fat, citronella (Cymbopogon winterianus)/rapeseed oils, mink (Mustela vision) excrement, sand coating as a physical barrier and a control. Seed germination tests were carried out with all the treatments. A total of 40 bank voles were individually given access to beech nuts or acorns at a rate of one treatment per day during two sessions. Mink excrement and chili/coconut fat treatments greatly reduced the consumption of beech nuts, and also reduced touching of beech nuts and acorns. In contrast, the sand coating treatment increased the consumption of both types of seeds. Germination of both beech nuts and acorns was reduced by the chilli/coconut fat and citronella/rapeseed oils treatments. Our results suggest that mink excrement has a potential as an effective repellent against bank voles when direct seeding is applied. However, further studies to determine the best method of application, as well as the efficiency under field conditions, are needed before definitive recommendations can be given to restoration managers.

Deciphering the effects of disperser assemblages and seed mass on patterns of seed dispersal in a rodent community.

The sizes of both seed dispersers and seeds are traits that are likely to interact to influence seed fate in many synzoochoric plant species. Here, we examined whether members of a granivorous rodent community consisting of species of different body size vary in their effectiveness as seed dispersers, and how this relationship may be altered by seed size. We marked northern red oak (Quercus rubra) acorns with plastic tags and placed them in size-selective rodent exclosures. The exclosures allowed differential access of rodent groups based on different body size: (i) small (e.g. Peromyscus spp.); (ii) small and medium (e.g. Tamias striatus); and (iii) small, medium and large (e.g. Sciurus carolinensis) species of rodents. Acorn removal did not differ among exclosure types, but more seeds were missing when removed by small rodents, probably because of larderhoarding. The treatments did not influence the relative frequency of acorn consumption. However, small rodents cached considerably fewer and partially ate more acorns than the other 2 groups. The mean dispersal distance was the longest for cages with medium openings, intermediate for cages with large openings and the shortest for cages with small openings. Acorn mass positively affected the probability of caching and this relationship was unaffected by exclosure type. In conclusion, granivorous rodents of different body sizes strongly differed in their interactions with acorns, with small rodents acting primarily as acorn predators and medium and large species contributing significantly more to dispersal of red oaks.

The Consumption of Acorns (from Quercus spp.) in the Central West of the Iberian Peninsula in the 20th Century

There is evidence of the consumption of acorns from Quercus species in the Iberian Peninsula from prehistory through the 20th century up until the 1960s. Acorns were used primarily for human consumption, mainly during food shortages. The high abundance and even distribution of Quercus tree species made it possible for acorn consumption to be widespread across the Iberian Peninsula. The favored species was the holm oak (Quercus ilex subsp. ballota), because a large part of its harvest consists of sweet acorns, while in other species the acorns are almost always bitter. People developed a substantial knowledge base underpinning a great variety of uses of acorns, from eating them directly from the tree to preparation with very simple treatments, such as drying, roasting, or boiling. By manipulating levels of bitterness in a number of species, cooks were able to prepare dishes that ranged from salty to sweet. Based on interviews with knowledgeable people and a review of ethnobotanical papers, this article describes the forms of consumption, the processed products, and the other uses of acorns of the species of the genus Quercus in the central west of the Iberian Peninsula. We also suggest why acorns lost their prominence in the late 1960s. At present, the main use of the acorn is as food for Iberian black pigs to obtain quality sausages. In addition, new products such as acorn liquor, caramels, and other items have recently appeared, marketed as distinctive products on a small scale.

A grid-like incised pattern inside a Natufian bedrock mortar, Raqefet Cave, Israel

[Report]Bedrock features are a hallmark of the Natufian (ca. 15,000-11,500 cal BP) in the southern Levant and beyond and they include a large variety of types, from deep variants to shallow ones and from narrow mortars to wide basins. They are usually interpreted as food preparation facilities, associated with Natufian intensification of cereal and acorn consumption. However, inside the shaft of one deep narrow Natufian mortar at the entrance to Raqefet Cave (Mt. Carmel, Israel), we found a set of grid-like incisions accompanied by irregular lines. This pattern is similar in the general impression and the details of execution to incised stone slabs and objects found in other Natufian sites. As in several other Natufian objects, the incised patterns were hardly visible at the time, due to their light appearance and concealed location. The engraving act and symbolic meaning of the contents were likely more important than the display of the results. Furthermore, the Raqefet mortar was incorporated in a structured complex that also included a slab pavement and a boulder mortar. Thus, the complex motif, the specific feature it was carved on (inside a deep mortar), the associated features, and the location at the entrance to a burial cave all suggest an elaborate ceremonial and symbolic system.

The Interplay among Acorn Abundance and Rodent Behavior Drives the Spatial Pattern of Seedling Recruitment in Mature Mediterranean Oak Forests.

The patterns of seedling recruitment in animal-dispersed plants result from the interactions among environmental and behavioral variables. However, we know little on the contribution and combined effect of both kinds of variables. We designed a field study to assess the interplay between environment (vegetation structure, seed abundance, rodent abundance) and behavior (seed dispersal and predation by rodents, and rooting by wild boars), and their contribution to the spatial patterns of seedling recruitment in a Mediterranean mixed-oak forest. In a spatially explicit design, we monitored intensively all environmental and behavioral variables in fixed points at a small spatial scale from autumn to spring, as well as seedling emergence and survival. Our results revealed that the spatial patterns of seedling emergence were strongly related to acorn availability on the ground, but not by a facilitationeffect of vegetation cover. Rodents changed seed shadows generated by mother trees by dispersing most seeds from shrubby to open areas, but the spatial patterns of acorn dispersal/predation had no direct effect on recruitment. By contrast, rodents had a strong impact on recruitment as pilferers of cached seeds. Rooting by wild boars also reduced recruitment by reducing seed abundance, but also by changing rodent’s behavior towards higher consumption of acorns in situ. Hence, seed abundance and the foraging behavior of scatter-hoarding rodents and wild boars are driving the spatial patterns of seedling recruitment in this mature oak forest, rather than vegetation features. The contribution of vegetation to seedling recruitment (e.g. facilitation by shrubs) may be context dependent, having a little role in closed forests, or being overridden by directed seed dispersal from shrubby to open areas. We warn about the need of using broad approaches that consider the combined action of environment and behavior to improve our knowledge on the dynamics of natural regeneration in forests.

Unravelling trophic subsidies of agroecosystems for biodiversity conservation: Food consumption and nutrient recycling by waterbirds in Mediterranean rice fields

Waterbirds can reallocate a considerable amount of nutrients within agricultural fields and between agriculture sites and wetlands. However their effects on biogeochemical cycles have rarely been quantified. We estimated bird numbers, diet (from stable isotope analysis), food supply, and the food consumption on rice fields by overwintering waterbirds in one of the most important areas for rice production in southwestern Europe and a key area for various migrating and resident waterbird species. Herein, we modelled the nutrient (N and P) recycling in rice fields, and their transport to reservoirs. The energy consumption by waterbirds (96,605±18,311 individuals) on rice fields during winter averaged at 89.9±39.0kJ·m−2, with its majority (89.9%) belonging to foraging on rice seeds. Thus, the birds removed about 26% of rice seeds leftover after harvest (estimated in 932.5±504.7 seeds·m−2 in early winter) wherein common cranes and dabbling ducks (four species) were the most important consumers. Waterbirds foraging and roosting in the rice fields recycled more than 24.1 (1.0kg·ha−1) of N and an additional 5.0tons (0.2kg·ha−1) of P in the Extremadura's rice fields during winter. Additionally, we estimated that 2.3tons of N and 550kg of P were removed from rice fields and transported to reservoirs. The seasonal foraging of wildlife should result in a direct benefit for rice farmers by improving nutrient recycling through defecation by waterbirds with respect to artificial fertilisation. Additionally, rice fields located in the cranes' core wintering areas can provide sufficient food supply to induce habitat shift from their traditional wintering habitat in ‘dehesas’ to rice fields, which causes indirect socioeconomic benefit through reduced acorn consumption by cranes. Our modelling approach may thus be especially helpful for management decisions regarding rice agroecosystems in areas which are also important for the conservation of migratory waterbirds.