The autecology of the chub, Squalius cephalus (L.), of the River Lugg and the Afon Llynfi

(1) Seasonal variation in the intensity of feeding activity was demonstrated in two chub populations. Feeding activity was higher in summer and more pronounced in the young age-classes. The intensity of feeding activity was significantly correlated with temperature. (2) The diet of the total chub populations embraced a wide range of food items but vegetable material predominated. Substrate material was frequently encountered which suggested considerable feeding on the river bed. Fish were the most important animal food, by volume, in the River Lugg but Trichoptera larvae were most important in the Afon Llynfi. No remains of salmon parr or trout were found in chub stomachs but grayling were eaten. The most important prey fish, by volume, was the eel but cyprinids, especially minnows, were most important by frequency of occurrence. (3) Seasonal variation in the composition of the diet could be related to availability of food organisms but some selection was shown. Vegetable foods were most important in summer; animal foods, Trichoptera larvae in particular, were important in winter. (4) Analysis of the variation in the composition of the diet with age revealed several trends, notably a decrease in the importance of plant material, aquatic and aerial insects with age and a corresponding increase in the importance of larger prey foods such as fish, frogs and crayfish. (5) The commonly held view that chub are deleterious to salmonid stocks was examined. The absence of direct predation and the small likelihood of direct competition suggests that this view is incorrect.     

Effects of season and body-size on the distribution and diet of the Iberian chub Leuciscus pyrenaicus in a lowland catchment

Seasonal and ontogenetic variations in space and food use by Leuciscus pyrenaicus were analysed in a Portuguese lowland catchment. Large fish occurred mostly in deep permanent-flowing sites whereas small fish occurred mostly in the shallowest intermittent-flowing site. No seasonal or size-related changes in feeding intensity were found, but the diet changed both across seasons and throughout ontogeny. The diet was dominated by aquatic prey over all seasons, but during winter and summer more plant material and terrestrial prey, respectively, were eaten. Throughout ontogeny fish shifted from soft-bodied to hard-shelled prey and decreased animal prey breadth. Mean prey size increased with fish size but the prey size spectrum was more variable for medium-sized fish than for either small or large fish. It is suggested that: (i) large fish avoid shallow drying areas owing to the risk of mortality, either by thermal and respiratory stresses or increased predation by mammals and birds; (ii) seasonal changes in diet are a response to differences in prey availability; and (iii) morphological constraints, prey handling costs and habitat partitioning are responsible for size-related changes in diet.     

黑麂食物组成及其季节变化

2002年12月至2003年11月在浙江省九龙山和古田山自然保护区,分季节采集黑麂 (Muntiacus crinifrons)粪便,采用粪便显微组织学分析方法为主,辅以野外观察,对其食性进行研究。结果表明 :黑麂食物包括29科43种(属)植物。食物中的植物类型包括乔木、灌木、藤本、非禾草类草本和禾草类草本五种类型;灌木是黑麂全年的主要食物,它在食物组成所占的比例为55.4%;三尖杉 (Cephalotaxus fortunei)、光叶菝葜(Smilax glabra)、矩圆叶鼠刺(Itea chinensis var. oblonga)、南五味子(Kadsura longipedunculata)和络石(Trachelospermum jasminoides)为黑麂四季都取食且在食物组成中所占比例较高的植物,分别为 17%、16.5%、9%、8.7%和 4.3%,是黑麂取食的主要食物。方差分析表明 :黑麂的主要食物及其主要种类都存在季节变化。夏秋季节,乔木植物在黑麂食物组成的比例低于冬春季节 ,而藤本植物和草本植物则相反,灌木植物变化较小;黑麂取食的五种主要食物中,其中三尖杉和光叶菝葜季节变化极显著,在冬季,三尖杉和光叶菝葜在食物组成比例中最高,达到 21.7%和 24 .3%;在夏季,它们在食物组成比例中下降到最低点,分别是 11.3%和 11.6%,但相对密度(RD)值仍保持最高序位 ;矩圆叶鼠刺和南五味子变化较平缓 ,基本变化趋势相同:冬春季节比例较高,夏秋季节比例有所下降;络石季节变化不明显;由于黑麂的食物组成中禾草类占的比例很小,说明黑麂更接近嫩食者     

Effects of natural and commercial diets on the fatty acid content of European grayling

Eicosaenoic acid (20:1ω9) and docosaenoic acid (22:1ω11) levels were about 10 and 100 times higher in food pellets fed to cultured grayling than in the insect larvae on which wild grayling fed. Among the PUFA, docosahexaenoic acid (DHA) was very high in the pellets, resulting in an unnaturally elevated, and probably unbalanced, ω3/ω6 ratio of 7–13 in the cultured fish whereas the same ratio varied only from 4 to 6 in the wild fish. Despite very low DHA levels in the native food, wild grayling muscle tissue contained relatively high amounts of DHA. DHA is probably not essential in the diet of grayling.     

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.     

The food of emus

The results of a study of the food of emus, Dromaius novaehollandiae, in inland Western Australia show that they feed on a great variety of fruits, seeds, flowers, insects and green herbage of annual and perennial plants. Shrubs provide most of the food in spring and autumn (September to March), annuals in the autumn and winter (April to August) and insects are taken whenever they occur in abundance, usually in autumn and spring. Although shrubs provide a reliable supply of food in summer, annuals often produce little in the autumn and winter so that emus would have to move extensively to keep in contact with a supply of food. Records from other parts of Australia indicate that the type of food eaten by emus is similar throughout the continent, but the precise species eaten varies from time to time and place to place. Some incidental observations on characteristics of the digestive system of emus are reported. Large quantities of mineral material are carried in the gizzard and individual items may be retained for 3 or 4 months. The acidity of the anterior sections of the gut make bacterial action unlikely. The crude form of copography has been observed. Some food passes through the gut in 3h but other material from the same intake may be retained for at least 48 h. The emu's diet is nutrient-rich, but only a catholic taste and great mobility ensure that it is able to find a continuous supply of food.     

The role of food in the dynamics of populations of the landsnail Cepaea nemoralis

Summary The food of the landsnail Cepaea nemoralis has been studied in natural environments.The diet of Cepaea in nature consists predominantly of senescent or dead plant material. Green material of some species, especially Urtica dioica, is also eaten in large quantities and algae, animal remains, fungi and, possibly, living aphids and thripses are included in the diet.The place where a snail is found during the day usually has a great predictive value for the food it ate during the preceding night. There are, however, exceptions. Species such as Aegopodium podagraria, Calystegia sepium and Phragmites communis are used very often to sit on but are hardly ever eaten. On the other hand species such as Urtica dioica and Ranunculus repens were very much favoured as foodplants but much less favoured as resting places. The distribution of the snails over the various components of the vegetation is not random and neither is the selection of food. The snail distribution does not explain the food selection or vice versa.Quantity of food probably is hardly ever limiting for the distribution and abundance of Cepaea. Some essential components may, however, very well be in short supply and thus be limiting.     

Feeding ecology of kererū (

The diet and food preferences of the kererū (Hemiphaga novaeseelandiae) were studied in Whirinaki Forest Park, central North Island, New Zealand, during February 2000 ? March 2001. The study was carried out in two areas of podocarp?hardwood forest, Oriuwaka (1750?ha) and Otupaka (1830?ha). Fruit dominated in the diet at both sites (65% in Oriuwaka, 87% in Otupaka), but there were seasonal changes. Foliage and flowers were more important in the diet in winter and spring, but the timing of the switch from fruit to foliage differed between the areas. The main fruit eaten also changed seasonally from tawa (Beilschmiedia tawa) in early summer to miro (Prumnopitys ferruginea) in late summer and autumn. Variation in diet partly reflected seasonal phenology of the plants and differences in vegetation between the two areas, but when food-type availability is considered, kererū showed selective preference for some food types at some times. Miro and tawa fruits were highly preferred food types in both areas. This study highlights the likely need of kererū to have access to various vegetation types in order to meet their seasonally changing nutritional requirements in a podocarp?hardwood forest where the availability of food, especially fruits, can differ markedly both in time and space. Thus, large forest blocks that contain a variety of habitat types, or landscapes containing patches of various habitat types, are needed for the long-term conservation of kererū populations.     

Selective Feeding of age-0 Arctic Grayling in Lake-Outlet Streams of the Northwest Territories, Canada

A paucity of information exists on the diet of Arctic grayling, Thymallus arcticus, particularly for young-of-the-year (YOY). We examined the diet of YOY Arctic grayling in relation to food availability, in the Barrenlands region of the Northwest Territories, Canada, where lake-outlet streams serve as nursery habitat for these fish. Given the small size of YOY grayling and the abundance of lake-derived microcrustacea in the drift of these lake-outlet streams, we anticipated that these prey would make up a major component of the YOY's diet. Food selectivity by YOY grayling, however, was strongly sized-biased; although microcrustacea dominated the drift, YOY primarily consumed larger taxa, especially Chironomidae and Simuliidae. Even among these taxa, grayling tended to select the larger individuals. As they grew, YOY grayling took larger numbers of both large and small prey, particularly the larger invertebrates, although prey size range did not change after mid-July. Selection of pupae and avoidance of Ephemeroptera suggest that prey characteristics other than size also contribute to selectivity by YOY grayling. The relatively limited consumption of terrestrial invertebrates and other large prey may reflect the small sizes of fish in this arctic study, as well as differences in prey availability. Despite the abundance of lake-derived prey, instream production of invertebrates should largely determine the productive capacity of Barrenlands streams as fish habitat.     

青木川自然保护区川金丝猴食性的季节性变化

2005 ～2008 年于陕西省青木川自然保护区使用瞬时扫描法观察了川金丝猴的食性。结果表明,川金丝猴冬季和夏季共取食42 种植物,可鉴定植物归属23 科34 属。川金丝猴食物类型包括果实、花、树叶、树皮、树芽。夏季取食21 种植物的果实或树叶;冬季取食25 种植物。树叶是其冬季主要食物,取食频次占总取食频次的73.0% ;夏季取食果实的频次占总取食频次的72.2% ,灯台树果实是其主要食物。啃食树皮行为主要发生在落叶阔叶林、针叶林与落叶阔叶混交林;在常绿和落叶阔叶混交林中,树皮啃食强度则相对较小。与其它地区金丝猴的食性比较,该地区川金丝猴食物谱较宽。蔷薇科和壳斗科植物在川金丝猴食物组成中最多,杨柳科、桦木科、山茱萸科、槭树科和忍冬科植物也取食较多。     

Diet of wild boar Sus scrofa in Western Europe, with particular reference to consumption of agricultural crops

1. The diet of wild boar Sus scrofa in Western Europe is reviewed, paying particular attention to the consumption of agricultural crops and the implications of this from the point of view of crop damage. Data were taken mainly from 11 studies that provide quantitative information about the consumption of different food types, but we also list all the foods reported as being eaten by wild boar in a total of 21 studies. 2. Vegetable foods occurred more frequently in the diet than animal foods, and also constituted the bulk of the food ingested. Overall, there were four major vegetable food categories: mast, roots, green plant matter and agricultural crops. Depending on the study area, wild boar always consumed at least one energy‐rich plant food such as acorns, beechnuts, chestnuts, pine seeds, olives, cereal grains or other crops. The number and types of agricultural crops consumed varied between study areas but crops represent an important component of wild boar diet throughout its Western European range. Among animal foods, insects, earthworms, birds and mammals were eaten most consistently but the diet also included amphibians, reptiles, gastropods and myriapods. 3. Seasonal, interannual and regional differences in the diet, together with its striking overall breadth, indicate that wild boar are opportunistic omnivores whose diet, in any particular instance, is largely determined by the relative availability of different food types. Dependence on energy‐rich plant material as a major component of the diet, coupled with large body size and a propensity to trample crops as well as consume them, means that wild boar cause significant agricultural damage.     

Analysis of the characteristics of fruit eaten by possums,Trichosurus vulpecula,in New Zealand

Abstract

The colours and sizes of the fleshy fruits of native trees and shrubs in the New Zealand flora and in the flora of the Orongorongo Valley, southern Rimutaka Range, were compared with those known to be eaten by possums to assess the degree of food selection by possums. Colour and diameter of fruits had little effect on whether they were selected by possums, but the size of the enclosed seed affected feeding behaviour. Fruits with seeds < 10 mm were eaten whole, whereas usually only the skin and flesh were eaten from fruits with larger seeds. An analysis of the wet and dry weights of the flesh and seeds of fruits growing in the Orongorongo Valley suggested that possums could maximise their dry matter intake from fruits by feeding preferentially on the larger fruits. Although this suggestion was supported in general by field observations, other studies suggest that annual variations in the abundance of fruits of the various species and their accessibility are also important in determining the contribution of fruits to the diet of possums.     

Feeding of an Iberian stream cyprinid assemblage: seasonality of resource use in a highly variable environment

Food resource use by seven cyprinids from an Iberian stream was analysed over 9 months. Differences in food resource use were found both between species and within species between seasons. Plant material was a more important food for carp, nase, goldfish and barbel than for gudgeon, roach and chub, irrespective of the season. Chironomid larvae were the staple animal food for the former five species throughout the year. Roach and chub, especially the latter, displayed large seasonal variations in prey use, with chironomid larvae only being important during autumn. Ephemerellid nymphs and ephemeropteran imagos dominated the animal diet of chub during spring and summer, respectively. Dipteran adults and Formicidae were the most important prey for roach during spring and summer, with other common prey being ephemerellid nymphs and hydropsychid larvae. Food resource overlap among the three dominant species (roach, barbel and chub) displayed a large seasonal variation. High overlaps were observed during autumn when these species used the same resources. During summer overlaps were much lower with each species specialising on different prey. The remaining less abundant species had large diet overlaps amongst themselves and with barbel, over all seasons. It is suggested that morphological constraints, habitat partitioning and temporal changes in food resource limitation may be involved in producing these patterns of food resource use.     

Food- and habitat-segregation in sympatric grayling and brown trout

Grayling in the large reservoir Aursjøen, Norway, did not use the pelagic habitat and only trout larger than 187 mm and older than 4+ were caught there. Both species preferred the upper 8 m in the benthic habitat, but grayling were caught deeper than trout in August and September. Grayling were more closely associated with soft substratum than trout. Association with soft substratum decreased with increasing size in grayling, whereas this relationship was reversed in trout. A low number of empty stomachs indicated a low degree of food competition, but despite this the two species segregated in different key prey items—probably due to differences in mouth shapes. The key prey item for grayling was the benthic Eurycercus lamellatus , with zooplankton dominating the diet of the smallest individuals. Large trout (>300 mm) preferred the benthic Lepidurus arcticus , whereas medium trout (160–300 mm) ate predominantly the limnic-pelagic Bythotrephes longimanus , irrespective of habitat. The distribution of key prey items seemed to be the major factor controlling the habitat use, except in small trout which showed a generalist feeding pattern throughout the period. A generalist feeding pattern, a close association to coarse substratum and absence from the pelagic habitat indicated that small trout were negatively influenced by large individuals. Small grayling seemed less affected by aggressive encounters as they were less associated with coarse substratum and ate predominantly high-risk food such as zooplankton. These individuals probably did shoal in order to reduce predation risk.     

The growth, reproduction and food of the roach Rutilus rutilus (L.), of the River Lugg, Herefordshire

Checks were formed on the scales in June and July. A dominant 1959 year class accounted for half the population present in 1964. Females grew faster than males and attained greater ultimate size. Growth in the River Lugg was good in comparison with rates in other British waters. The sex ratio was found to change with age; a predominance of males in the youngest age classes changed to a preponderance of females in the older classes. The youngest fishes caught (3+) were already sexually mature. The gonads were found to be a constant proportion of the body weight for fishes of all sizes at a given season. Spawning was completed by June; males were ripe in May. The ovaries recovered more rapidly than the testes after spawning. Seasonal variation in feeding activity, with higher activity in summer, was observed and could be correlated with temperature. Seasonal changes in the diet could be related to availability. The diet was predominantly vegetable; the most important animal component, aquatic insect larvae, accounted for 11 % of the total diet. Aerial insects were rarely eaten. Diet varied with age: molluscs being particularly important to older roach; younger roach consumed large amounts of substrate material. There is some evidence that young roach indiscriminately ingest substrate material but older roach are more selective and reject inert material.     

The trophic ecology of Atlantic cod: insights from tri-monthly, localized scales of sampling

The meso-scale trophic dynamics of cod Gadus morhua were examined based upon tri-monthly stomach sample collections from a nearshore, localized ( c. 800 km²) region off Cape Cod, Massachusetts, U.S.A. The major objective for this work was to relate any changes in cod diet and amount of food eaten to seasonal variations in prey availability, water temperature and spawning at a spatial scale between broad-scale and laboratory studies. Results suggested that the type and amount of food eaten by cod was generally consistent throughout a year and repeatable across years. Cod feeding was marked by two periods of increased feeding, corresponding to the arrival of small pelagic fishes in the area. This pelagic migration and subsequent increased feeding by cod occurred during important periods in the life history of cod ( e.g . spawning and overwintering). Similar annual patterns in food consumption and diet composition were remarkably consistent over the 2·5 years of the project, suggesting important feeding periods for cod that correspond to environmental and biological events. The diet of cod was composed primarily of several species of forage fishes [ e.g. herrings (predominantly Atlantic herring Clupea harengus ), sand lance Ammodytes sp. and Atlantic mackerel Scomber scombrus ], ophiuroids, Cancer sp. crabs and other small crustaceans. It was inferred that cod exhibited a maintenance diet on local forage fishes and benthic macroinvertebrates, augmenting their diet by seasonally gorge feeding upon migrating pelagic species.     

Some observations on the food of the gwyniad Coregonus clupeoides pennantii Valenciennes of Llyn Tegid (Lake Bala), North Wales

The seasonal variations in the diet of adult gwyniad Coregonus clupeoides pennantii=C. lavaretus from Llyn Tegid, North Wales were studied. Stomachs were examined to determine fullness, volume and identity of contents.
A clear seasonal cycle in food intake was found. Feeding rates were low from January to April but increased during the summer (May-June) and remained at a high level until December. The period of low feeding intensity coincided with the time of spawning and the time of annulus formation of both scales and otoliths. The diet showed seasonal changes and two main periods were distinguished : December to July, when the fish fed mainly on bottom fauna, and August to November, when the diet included both bottom fauna and midwater and surface foods.
The gwyniad were shown to be opportunistic in feeding, the composition of the diet reflecting availability of food items rather than selective feeding on the part of the fish.     

Food habits and habitat selection of suburban badgers (Meles meles) in Japan

A study of the Japanese badger Meles meles anakuma was undertaken in Hinode, a suburb of Tokyo, between 1992 and 1998. Faecal analysis, based on 82 samples, revealed that during spring and summer, earthworms ( Megaseolocidae spp.) occurred at high frequency in the diet, with berries ( Rubus spp.), beetles and persimmon Dymopyrus kaki also eaten during summer months. Scavenged food was eaten in early spring when earthworm availability was low, and badgers switched from worms when persimmon became abundant in autumn. Twenty-one Japanese badgers (14 males and seven females) were radio-tracked. Adult badger home ranges were stable, and those of males [40±19 ( sd ) ha, n =7] were larger than those of females [11±6 ( sd ) ha, n =4]. Badger resting sites in each home range were located within 630 m of each other and categorized as setts or couches. Setts were sited within core areas (30% adaptive kernel method) of home ranges. Most setts were on a sub-ridge and avoided west-facing slopes. Couches, mainly in deciduous forest and forest edge, were generally sited towards the periphery of home ranges. Most badger foods were distributed along ecotones between forestry plantations and farmland; earthworms, their main food from late spring to summer, and berry thickets were both concentrated at the edge of conifer plantations. Persimmon trees, the main food source for badgers in autumn, were also found in agricultural land bordering forest edge. Badger home range size was related to forest edge density.     

Selection for nutrients by red deer hinds feeding on a mixed forest edge

We studied the nutritional behaviour of hinds foraging on a mixed-forest edge by direct observation of their choices at each season and by measuring nutrient concentration in the plants. We compared nutrient concentrations in the observed diets with those in the total available vegetation, and with those of 1,000 randomly simulated diets in which we included only those plants that were actually eaten by the animal. Whether the available or the consumed feeds were used as the basis for comparisons had important consequences due to the presence of conifers and ferns, which were high in soluble sugars but were never eaten by the animals (potentially due to their toxicity). The selected diets were lower in sugars than the total available vegetation in summer, but were actually higher in sugars than the random diets generated from consumed forage species only. Hind diets contained more soluble sugars but not more protein than simulated diets in all seasons. Contrary to our prediction, anti-nutritional compounds (ADL and tannins) were avoided only in winter. Compared to simulated diets, hinds consumed more tannins in spring and summer and more ADL in summer and autumn. We suggest that this was a consequence of selection for soluble sugars, because the preferred plant species, which had high soluble sugar concentrations, also contained a large proportion of the anti-nutritional compounds eaten. In winter, the grass-dominated diets contained more fibre (NDF) and less ADL than the simulated diets, indicating that hinds orient their feeding towards digestible fibres. The switch from a browser to a grazer diet was related to a change in the availability of the nutrients, mainly soluble sugars. In our study, grasses contained more soluble sugars and proteins than deciduous browse during winter. This calls into question the dichotomy usually assumed in the literature between grass and browse in terms of nutrient content. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Food habits of the American mink Mustela vison in the Mazurian Lakeland, Northeastern Poland

Food habits of the American mink Mustela vison were studied based on the analysis of 2364 scat samples, collected at three lakes in Northeastern Poland. The mink preyed on a wide range of prey, but two types of prey, amphibians and fish, dominated in the diet of the mink during all the seasons. Frogs, and first and foremost, the common frog Rana temporaria, were hunted by the mink, mainly from the late autumn until the early spring, and comprised up to 83.9% of the prey biomass (the multiannual average for November–December at the Majcz Wielki Lake). The most frequently eaten fish were cyprinids and percids. Seasonality of fish consumption by mink was not as well pronounced as in the case of amphibians. At the first two lakes, fish were hunted mainly in the winter and in the early spring, whereas at the third lake in the summer. The highest multiannual average share of fish in the diet of the mink was recorded in March–April at Lake Tuchlin (69.2% of the prey biomass). Crayfish, which were recorded in the diet mainly in the late spring and in the summer, comprised up to 59.6% of the prey biomass for May–June at the Majcz Wielki Lake. Birds, mammals and insects were supplementary food for the mink. During the breeding season, mink predation on waterfowl and their broods was correlated with the abundance of crested grebe Podiceps cristatus and coot Fulica atra nests in the area. The diet of individual mink varied considerably and the share of birds in the diet of the mink was related to the distance from individual mink dens to the colonies of waterfowl. In May–June, adult birds, chicks and eggs comprised up to 73.6% of the prey biomass of a female mink that inhabited a den located 100 m from the colony's edge. At all three lakes, the diet of the mink was the most diverse in the late spring and in the summer. In May–August, the values of the mink food niche breadths were about twice those noted in winter months.