Seasonal patterns of food storing in the Jay Garrulus glandarius

This study investigated seasonal patterns in food consumption and food storage in six captive Jays Garrulus glandarius. In the first experiment, seasonal changes in food-storing intensity were tested by presenting acorns (oak seeds, Quercus spp.) in spring, summer and autumn. There were no significant differences between the seasons in the amount of food eaten. However, significantly more food was taken and stored in the autumn than in the spring and summer months. In the spring and summer, the acorns were stored between the doorframes, on the ledges of the aviaries and under the bark of branches. In the autumn, Jays also began to hoard underneath the plastic sheeting covering the hard-board flooring by ripping the polythene to create a hidden cache site. The length of time over which the stored food was left before retrieval increased from summer to autumn. Food storing also occurred in spring and summer but was short term. The second experiment tested whether or not there were seasonal changes in food preference by presenting birds with acorns, peanuts and mealworms in the summer and autumn. More peanuts were eaten, taken and stored in the autumn than in the summer, and, as in the first experiment, significantly more acorns were taken and stored in the autumn. In the autumn, only a few mealworms were eaten before the birds stored acorns and peanuts, whereas in the summer, birds tended to eat most of the mealworms before they began to store. As in the first experiment, items tended to be buried in the ground in the autumn and left for longer periods before retrieval. These results are discussed in relation to the demand that each food type places on the Jay's time.     

Storage of stones by Jays Garrulus glandarius

The aims of this study were to test whether or not Jays Garrulus glandarius store stones and, if so, to examine the conditions under which they store stones. By directly observing the behaviour of five captive Jays that were housed individually in flight cages, we found that stones were stored only in the absence of food items or when food items were no longer available to store and that there was a strong preference for storing stones that resembled acorns in both size and appearance (in terms of colour, shape and smoothness of the surface) and were undamaged rather than heavily chipped. These results are discussed in terms of Tinbergen's classic ethological model in which animals respond selectively to certain key features and ignore other features of the stimulus.     

Acorns,insects, and the diet of adult versus nestling Acorn Woodpeckers

ABSTRACT The diet of Acorn Woodpeckers (Melanerpes formicivorus) in central coastal California consists of a mixture of high‐quality (insects) and low‐quality (stored acorns) food during the spring breeding season. We used stable isotope ratios obtained from blood samples to estimate possible differences in the proportion of these items being fed to nestlings and being consumed by breeding adults, as well as the extent to which the diet of nestlings shifts between insects and acorns during the nestling period. Based on both feeding observations and items recovered from nestlings, older nestlings were fed 28% acorns. Using this value as a baseline for the isotope analyses, the diet of breeding adults was estimated to consist of 90% acorns. Based on repeated samples from the same nestlings over time, the estimated proportion of acorns in their diet increased from 19% in 9‐ to 12‐d‐old nestlings to 42% in 23‐ to 26‐d‐old nestlings. There was a significant correlation between the isotope values of adults and the nestlings they fed, indicating that different groups of Acorn Woodpeckers have significantly different diets. Although important for successful reproduction in this species, stored acorns are not the primary food resource used to feed young. Instead, the availability of stored acorns allows adult Acorn Woodpeckers to provide nestlings with more protein‐rich insects while maintaining themselves on relatively protein‐poor, low‐quality acorns. Differences in the diets of adults and their nestlings are likely widespread among species that feed, at least in part, on low‐quality foods, such as fruit and seeds, during the breeding season.     

Feeding ecology of rooks (Corvus frugilegus) on the Heretaunga Plains,Hawke's Bay,New Zealand

Abstract

The food resources of rooks were measured and related to changes in the birds' feeding behaviour during 1968-1970. In all, 381 birds were individually marked with wing tags and colour-coded leg bands and released; their activities were recorded for set periods. Rooks preferred to eat invertebrates and walnuts, but also took seed of cereals, pulses, and stock feeds. They spent at least 40% of their feeding time (75-80% in spring) eating invertebrates, 30-60% finding or hiding walnuts and sometimes acorns in autumn and winter, and 45% eating seed during hot, dry weather in summer. Up to 6% of feeding time was spent eating newly sown or ripening seed. Throughout winter rooks frequently searched for hidden nuts, which they ate or moved to new positions. The proportion of time they spent feeding and the kind of food taken varied seasonally and, in summer and winter, hourly; there were only slight differences between morning, mid-day, and afternoon periods. Rooks spent 65% of the time feeding in autumn, but only 25-30% in spring. Conversely, they spent longer at nest sites from late autumn, peaking at 60% in spring, then less time at nests as they spent longer searching for food. The size of flocks altered with the food being eaten and therefore with season and time of day. Small flocks were widespread where favoured food was plentiful in autumn, winter, and spring, but flocks were larger where food was unevenly abundant in summer and sometimes in winter. During early autumn each bird usually ate and stored walnuts in a selected area of 1-2 km3, returning there later in the season to recover stored nuts. The areas formed only part of the total range used by the study population, and were usually shared with other birds. Tests in aviaries showed that rooks preferred earthworms and walnuts to acorns, maize, and wheat (in that order), and field tests confirmed that rooks preferred walnuts to maize. The numbers of each food item required to sustain a rook for a daylight hour were estimated. Summer is the most difficult season for rooks to find food.     

Recaching Decisions of Florida Scrub‐Jays are Sensitive to Ecological Conditions

Food caching animals depend on their caches at times of low food availability. Because stored food is susceptible to being stolen or degraded, many species employ cache protection strategies such as ceasing caching in the presence of others or avoiding storing perishable items for long periods. Several species frequently recover their caches and recache, which may reduce pilferage or degradation of cached items. We studied the food handling decisions of Florida scrub‐jays (Aphelocoma coerulescens) after cache recovery to determine the roles that social and ecological environments play in post‐recovery decisions. Instead of reducing recaching in the presence of others, recovering jays flew away from the recovery site, allowing them to eat or recache a recovered item regardless of the social context. Microhabitat type and soil moisture of the recovery sites had a significant influence on whether recoveries were eaten or recached; most items that were recached had been recovered from bare sand sites or sites with low soil moisture. Taken together, our results suggest that food store management of Florida scrub‐jays are unaffected by the social context, but are strongly affected by the habitat conditions that influence the quality of caches.     

The Proximate Basis of the Oak Dispersal Syndrome: Detection of Seed Dormancy by Rodents

Previously we have shown how a range of physical and chemicalcharacteristics of acorns influences the behavioral decisionsof food-hoarding rodents which in turn affects the dispersal,establishment and spatial arrangement of oaks. One such behaviorinvolves the selective caching of acorns of red oaks (subgenus:Erythrobalanus) over those of white oaks (Quercus) because ofreduced perishability that results from delayed germinationof acorns in the red oak group. In this study, we sought toidentify the specific proximate cues (visual and olfactory)that eastern gray squirrels (Sciurus carolinensis) use whenmaking these decisions. In two series of field experiments,we presented individual, free-ranging animals with pairs ofexperimentally altered acorns (that differed with respect toa single chemical or visual characteristic) and recorded theirfeeding and caching responses. Squirrels cached artificial acornswith pericarps (shells) of red oak acorns and ate those withshells of white oak regardless of the internal chemical compositionof either type of acorn. Only when the shells of artificialacorns were first soaked in acetone (to remove potential chemicalodors) did animals eat artificial acorns made with the shellsof red oak acorns. Squirrels also ate one-year old red oak acornsthat had broken dormancy, even when they exhibited no signsof germination. We argue that a chemical cue in the shell ofacorns is important in the detection of seed dormancy and thedecision to cache acorns, and that such a cue might ultimatelycontribute to the differential dispersal of red and white oaksby rodents.     

Structures associated with feeding in three broad-mouthed, benthic fish groups

Synopsis The flatheads, toadfishes, and goosefishes discussed here hold certain features in common. All are bottom-living forms with depressed head areas and broad gapes, and all eat large food items: fishes and/or crabs. All have developed structural specializations in association with this diet. The three groups are at most distantly related, and their feeding specializations are different and have evolved from different bases. In flatheads the combination of large food items and depressed head regions seems to have led to the separation of the two halves of the pelvic girdle, a feature in which they differ from their scorpaenoid relatives. Toadfish peculiarities associated with feeding are various but most notable in those that pass crabs they eat through the gape and into the mouth. Goosefish feeding is centered around the use of a lure to attract prey to within striking distance. The three fish groups are discussed separately, but their feeding structures are compared to one another in the final section of the paper.     

Dung Beetles Eat Acorns to Increase Their Ovarian Development and Thermal Tolerance

Animals eat different foods in proportions that yield a more favorable balance of nutrients. Despite known examples of these behaviors across different taxa, their ecological and physiological benefits remain unclear. We identified a surprising dietary shift that confers ecophysiological advantages in a dung beetle species. Thorectes lusitanicus, a Mediterranean ecosystem species adapted to eat semi-dry and dry dung (dung-fiber consumers) is also actively attracted to oak acorns, consuming and burying them. Acorn consumption appears to confer potential advantages over beetles that do not eat acorns: acorn-fed beetles showed important improvements in the fat body mass, hemolymph composition, and ovary development. During the reproductive period (October-December) beetles incorporating acorns into their diets should have greatly improved resistance to low-temperature conditions and improved ovarian development. In addition to enhancing the understanding of the relevance of dietary plasticity to the evolutionary biology of dung beetles, these results open the way to a more general understanding of the ecophysiological implications of differential dietary selection on the ecology and biogeography of these insects.     

围栏条件下社鼠的食物贮藏行为

在北京东灵山地区, 用活捕笼从野外捕获社鼠, 并在野外建造围栏, 以山杏种子和辽东栎坚果为备选食物, 对围栏条件下社鼠的食物贮藏行为进行了研究。数据的统计分析采用SPSS for Windows (version 1010) 进行。结果表明: 1) 社鼠主要表现出食物的集中贮藏方式; 2) 贮藏食物被模拟盗窃使社鼠的食物贮藏活动加强; 3)社鼠倾向于选择山杏种子进行贮藏, 而对辽东栎坚果则取食较多。文中还讨论了食物类型、模拟盗窃等因素对社鼠食物贮藏行为的影响。     

Orangutans' color preference for food items

The effects of the addition of color to a dry primate diet on the feeding behavior of orangutans were studied. Purina Monkey Chow was dipped in food coloring (red, green, blue, orange). Colored and plain chow was offered to the subjects, three adults, and two juveniles. Time to eat or lose interest in feeding, quantity, and color of pieces of chow handled and eaten were recorded for each group. The juveniles' consumption of chow increased when offered colored chow, and adults required less time to consume their food. One juvenile showed a significant preference for red monkey chow.     

The Ultimate Basis of the Caching Preferences of Rodents, and the Oak-Dispersal Syndrome: Tannins, Insects, and Seed Germination

We have shown that eastern gray squirrels and other animalsconsistently prefer to store intact acorns from the red oakgroup rather than those from the white oak group. We hypothesizedthat the ultimate advantage to this behavior comes from thedormancy of red oak acorns. Acorns of the white oak group germinateearly in the autumn; thus, we hypothesize that avoiding germinationis the primary selective advantage to the preference for cachingred oak acorns. Here, we test two alternative hypotheses toexplain the benefits of this caching preference: 1) storingred oak acorns allows the high tannin concentrations in redoak acorns to decline (making them more palatable), and 2) storingred oak acorns minimizes losses to insects, presuming they areless infested with insects. We also test the effect of germinationschedule on squirrel caching preferences directly, by presentingthem with dormant red oak acorns, and red oak acorns about togerminate. We find no evidence that tannin concentrations inred oak acorns decline, although tannin levels did decline inour white oak acorns. We found high losses to insect infestationsin one white oak species, but a second white oak species lostvery little mass to insects. Finally, we found that germinationschedule directly affects squirrel caching preferences: redoak acorns that are near germination are treated like whiteoak acorns. We conclude that the primary advantage to the preferencefor caching red oak acorns is that they are less perishable,due to their dormancy. We discuss the effects of this preferenceon the dispersal of red and white oak acorns, and the subsequenteffects of differential dispersal on the ecology and evolutionof oaks.     

Effect of Acorn Burying Depth on Germination,Seedling Emergence and Development of Quercus aliena var. acuteserrata

Acorns of Quercus aliena var. acuteserrata Maxim. are often predated by small mammals and birds in natural forests. These animals not only eat the acorns during the acorn ripening season, but also cache and hoard most of the remaining acorns on the forest floor in the soil for their future use. These buried acorns form the main seed resource for regeneration. Burying depth is potentially important for germination and for seedling development. The effects of burying depth on germination and seedling development in relation to acorn size were studied in an experiment, in which acorns were planted at 6 cm-, 12 cm- and 18 cm-depth. The experimental results showed that fewer acorns germinated as burying depth increased. From the deeply buried acorns fewer seedlings emerged at later time than from those acorns buried less deeply. They appeared to have more difficulties to emerge above-ground than the seedlings from shallowly buried acorns. The deeply buried acorns and their seedlings also appeared to be more susceptible to rot. Acorn size did not significantly affect germination and emergence of the seedlings. As early emerged seedlings had longer developmental periods in their first growing season, and therefore grew better than the late emerged seedlings, seedlings from the shallowly buried acorns took the advantage.     

昆虫蛀蚀对鼠类介导下的锐齿槲栎种子扩散的影响

森林鼠类的种子贮藏行为对植物的扩散和自然更新有着非常重要的影响。然而,鼠类是否具有鉴别虫蛀种子的能力还存在一定的争议。此外,鼠类的鉴别能力是否受到食物丰富度变化的影响也未见相关报道。采用标签标记法,2011年秋季(9—11月,食物丰富季节)和2012年春季(4—6月,食物匮乏季节)分别在秦岭南坡的佛坪国家级自然保护区内,调查了森林鼠类对完好和虫蛀锐齿槲栎(Quercus aliena)种子的选择差异。结果显示:1)在秋季,尽管2种类型种子的存留动态没有显著差异,但是在后期虫蛀种子的存留时间相对更长;而在春季2种类型种子的存留动态则极为显著,几乎所有的完好种子(99%)在释放后的第3天就被鼠类全部扩散,虫蛀种子的存留时间则相对较长。2)在秋季,鼠类更喜好扩散后取食完好种子;而在春季,鼠类则喜好在原地取食绝大部分的种子,并且优先取食完好种子。3)在秋季,鼠类贮藏了更多的完好种子;而在春季,尽管完好种子在释放后第1天便达到贮藏高峰,然而由于后期的大量被捕食,2种类型种子在贮藏动态上没有显示出显著差异。研究结果表明秦岭地区森林鼠类可以准确区分完好与虫蛀种子,但是食物丰富度会影响鼠类对种子的选择策略。在食物丰富的秋季,鼠类更多地选择贮藏完好种子;而在食物相对匮乏的春季,鼠类更倾向于同时取食2种类型种子。森林鼠类通过对2种类型种子的鉴别和选择,影响不同种子的命运,从而可能对种子的扩散和自然更新产生重要影响。     

Enhancement of the response of rock crabs, Cancer irroratus, to prey odors following feeding experience

The rock crab, Cancer irroratus Say, uses chemically mediated learning in the search for food. Rock crabs are opportunistic benthic predators and scavengers. Observations indicate that although they eat a variety of items, they are more sensitive to, and prefer, odors of food items that they have been eating. We found that C. irroratus is more responsive to a familiar food source than to an unfamiliar one and can distinguish between the odors of two different prey after being fed one species for an extended time. Initial preferences for two mytilid bivalves, Mytilus edulis and Geukensia demissa, were determined in a Y-maze. Crabs were then fed only one of the mussel species for 28 days and retested, using sequential and simultaneous presentations, for their responses to familiar and unfamiliar prey odors. Crabs increased their responses to familiar prey odors, but not to unfamiliar odors. In foraging tests, crabs ate M. edulis more often regardless of the species to which they had been familiarized.     

Memory for the location of stored food in marsh tits

Marsh tits store several hundred food items per day, in separate locations within their territory, and recover most items within 24 h. Experiments in the laboratory determined that marsh tits return accurately to the sites of stored sunflower seeds 3 h and 24 h after storage. The proportion of returns exceeded chance encounter and initial preferences for those sites. The lack of interocular transfer in birds for some visual tasks provided a test for the hypothesis that memory is used to relocate stored food. After storing food with one eye covered, marsh tits did not return to storage sites when using only the ‘naive’ eye, but did so when using only the eye uncovered during storage. It seems likely that recovery of stored food by marsh tits and other birds occurs by memory of storage sites, not by chance encounter during foraging.     

锐齿槲栎橡子埋藏深度对发芽、幼苗出土和发育的影响

锐齿槲栎（Quercus aliena var.acuteserrata Maxim.)林内活动的许多型哺乳动物和鸟类不仅采食橡子,而且还常窖贮或在土壤大量的橡 子以便季后利用。这些埋藏的橡子构成了发育有效更新苗的主要种子来源。橡子被埋藏的深度和橡子的大小对幼苗的发育有潜在的影响。把橡子埋藏在6、12和18cm3个土层深度的实验结果显示：随着埋藏深度的增加,橡子的发芽率和发芽橡子的幼苗出土率都有明显下降,由深埋橡胶子发育的幼苗出土比较困难,所需时间较长,也更易腐烂,橡子的大小对发芽和幼苗出土没有明显的影响,早出土幼苗在第一个生长季内由于有较长的生长发育期,季末发育得较好,所以,由浅埋橡子发育的幼苗在更新成功方面有优势。     

How plants manipulate the scatter-hoarding behaviour of seed-dispersing animals

Some plants that are dispersed by scatter-hoarding animals appear to have evolved the ability to manipulate the behaviour of those animals to increase the likelihood that seeds and nuts will be stored and that a portion of those items will not be recovered. Plants have achieved this in at least four ways. First, by producing large, nutritious seeds and nuts that are attractive to animals and that stimulate hoarding behaviour. Second, by imposing handling costs that cause animals to hoard rather than to eat items immediately. These handling costs can take one of two forms: physical barriers (e.g. hard seed coats) that take time to remove and secondary chemicals (e.g. tannins) that impose metabolic costs. Third, by masting, where a population of plants synchronizes reproductive effort, producing large nut crops at intervals of several years. Mast crops not only satiate seed predators, but also increase the amount of seed dispersal because scatter-hoarding animals are not easily satiated during caching (causing animals to store more food than they can consume) but are satiated during cache recovery. And fourth, by producing seeds that do not emit strong odours so that buried seeds are less likely to be discovered. These, and perhaps other, traits have increased the relative success of plant species with seeds dispersed by scatter-hoarding animals.     

同种竞争压力对小泡巨鼠贮藏油茶种子行为的作用分析

2002年11～12月,在四川省都江堰地区的亚热带常绿阔叶林内利用人工修建的半自然状态围栏进行实验,研究了小泡巨鼠在有同种竞争存在条件下对油茶种子的埋藏行为。结果表明,小泡巨鼠在有竞争存在条件下,显增加了埋藏油茶种子的量。这一结果支持了“竞争的存在刺激鼠类埋藏”的假说。同时,研究结果表明,小泡巨鼠在有竞争存在条件下,显增加了对埋藏种子的搬运距离,每个贮藏点埋藏种子的数量也有所增加,同时埋藏的生境更多地偏向于遮蔽较好的微生境(草丛底层、灌丛下层)中。这些行为策略有可能有利于种子被埋藏植物的种群扩散。在讨论中,我们还通过比较鸟类和兽类在感觉器官上的差别,分析它们在有竞争存在条件下所采取的不同贮食策略。     

Diet and feeding behaviour of samango monkeys (Cercopithecus mitis labiatus) in Ngoye Forest, South Africa

The samango monkey occurs at the southern limit of the range of Cercopithecus mitis. Greater climatic seasonality at this latitude results in more predictable fruiting patterns. In addition, there are no diurnal sympatric primate frugivores. Under these conditions, the diet and feeding strategies of samango monkeys would be expected to differ notably from those of central or east African C. mitis subspecies. Contrary to these expectations, the preliminary observations reported here indicate that diets of samango and blue monkeys differ only superficially in the proportions of items eaten. Similarities in feeding behaviour are especially marked during the dry season period when fruit is not abundant. Both samango and blue monkeys tend to be less selective in their choice of food species and to eat available food species regardless of their energy content; a shift toward less nutritious items such as leaves is also noted. Feeding behaviour during the summer wet season is characterized by the selection of fruits with high-energy values. A high proportion of visits by the monkeys to areas of greater food availability suggests a concentration of feeding effort in food patches and the selection of higher energy food species within patches.     

岩松鼠和松鸦对辽东栎坚果的捕食和传播

脊椎动物对栎属(Ｑｕｅｒｃｕｓ)坚果的捕食和传播是栎属通过实生苗更新的关键因子,栎属中一些物种坚果的分布格局以及动物对坚果的捕食作用已有较多研究[1～6]。一般情况下,栎属的坚果成熟落地后立即开始发芽,落在地表的坚果里的种子胚根长出后,由于地表枯落物的阻碍作用...