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Mammals typically process food items more extensively in their oral cavities than do other vertebrates. Dental morphology, jaw-muscle activity patterns, mandibular movements, and tongue manipulation work to facilitate oral fragmentation of dietary items. While processing mechanically challenging foods, mammals modulate mandibular movements and bite forces via recruitment of greater jaw-adductor muscle forces and protracted biting or chewing. Because jaw-loading patterns are influenced by magnitude; frequency; and duration of muscular, bite, and reaction forces during routine feeding behaviors, relatively larger jaws are thought to be more characteristic of mammals that experience higher masticatory loads due to the processing of mechanically challenging foods. The ease of food fracture during post-canine biting and chewing is mainly determined by food stiffness and toughness. Such foods have been associated with increased loading magnitude and/or greater amounts of cyclical loading (i.e., chewing duration). Dietary properties are thought to modulate cyclical loading through changes in chewing frequency and chewing investment. On the other hand, chewing frequency has been found to be independent of dietary properties in rabbits and primates; however, little evidence exists regarding the influence of dietary properties on these parameters in a broader range of mammals. Here, we assessed chewing behavior in seven adult llamas (Llama glama) processing foods with a wide range of mechanical properties (grain, hay, carrots, and dried corn). Each subject was filmed at 60 frames/s, with video slowed for frame-by-frame computer analysis to obtain length of feeding bout and number of chewing cycles for each food type. These parameters were used to calculate chewing frequency (chews/s), chewing investment (chews/g), and chewing duration (s/g). Chewing frequency was not significantly related to mechanical properties of food, but chewing investment and chewing duration were significantly related to dietary stiffness and toughness. Therefore, cyclical loading is positively influenced by stiff and tough foods. This suggests that variation in jaw morphology in extinct and extant mammals is positively related to dietary stiffness and toughness, which requires greater chewing investment and increased chewing duration.

Hatching asynchrony in birds occurs when incubation commences prior to clutch completion and results in broods containing different aged and sized nestlings. The brood reduction hypothesis predicts...

Understanding the dose-response relationship between ingested pathogenic bacteria and infection probability is a key factor for appropriate risk assessment of foodborne pathogens. The objectives of this study were to develop and validate a novel mechanistic dose-response model for Campylobacter jejuni and simulate the underlying mechanism of foodborne illness during digestion. Bacterial behavior in the human gastrointestinal environment, including survival at low pH in the gastric environment after meals, transition to intestines, and invasion to intestinal tissues, was described using a Bayesian statistical model based on the reported experimental results of each process while considering physical food types (liquid versus solid) and host age (young adult versus elderly). Combining the models in each process, the relationship between pathogen intake and the infection probability of C. jejuni was estimated and compared with reported epidemiological dose-response relationships. Taking food types and host age into account, the prediction range of the infection probability of C. jejuni successfully covered the reported dose-response relationships from actual C. jejuni outbreaks. According to sensitivity analysis of predicted infection probabilities, the host age factor and the food type factor have relatively higher relevance than other factors. Thus, the developed “key events dose-response framework” can derive novel information for quantitative microbiological risk assessment in addition to dose-response relationship. The framework is potentially applicable to other pathogens to quantify the dose-response relationship from experimental data obtained from digestion. IMPORTANCE Based on the mechanistic approach called the key events dose-response framework (KEDRF), an alternative to previous nonmechanistic approaches, the dose-response models for infection probability of C. jejuni were developed considering with age of people who ingest pathogen and food type. The developed predictive framework illustrates highly accurate prediction of dose (minimum difference 0.21 log CFU) for a certain infection probability compared with the previously reported dose-response relationship. In addition, the developed prediction procedure revealed that the dose-response relationship strongly depends on food type as well as host age. The implementation of the key events dose-response framework will mechanistically and logically reveal the dose-response relationship and provide useful information with quantitative microbiological risk assessment of C. jejuni on foods.

Academic journals, as well as birding magazines and newsletters, often publish reports of novel and/or unusual feeding behaviors observed by professional and amateur ornithologists. These reports, termed “feeding innovations,” have been used to test predictions in ecology, evolution, cognition, and neuroscience. I present here the latest version of the avian innovation database that has been collated since the mid-1990s, in order to facilitate work by researchers that have up to now had access to smaller versions that contained only innovation frequencies. The database includes descriptions, key words, and references to 4,455 innovations collated for 1,689 species in 166 families, obtained by systematically examining the short notes section and, in some cases, entire issues of 216 ornithology publications over periods that varied between 2 and 84 years. The database is intended as a tool for researchers to further study behavioral plasticity, opportunism, and cognition in birds.

This study examined foraging niche partitioning among coexisting species of shorebirds on a sandy beach dominated by a single food type, Horseshoe Crab ( Limulus polyphemus) eggs, where use of foraging microhabitats of limited variety is temporarily restricted due to tidal cycle. The major goal of the study was to examine whether co-occurring species differed in selection of foraging microhabitats and use of feeding techniques. Ruddy Turnstone ( Arenaria interpres), Red Knot ( Calidris canutus), and Sanderling ( Calidris alba) foraged significantly more on sand and gravel compared to pools and swash zone, Semipalmated Sandpiper ( Calidris pusilla) foraged significantly more on sand and gravel compared to swash zone, but not significantly more compared to pools, while differences in use of microhabitats by Dunlin ( Calidris alpina), and Short-billed Dowitcher ( Limnodromus griseus) were non-significant. Turnstones used digging and turning stones, and pecking significantly more than probing, Semipalmated Sandpipers used pecking significantly more than probing, while all other species used probing significantly more than pecking. Knots and Sanderlings had the highest level of overlap both in use of microhabitats and foraging techniques, while turnstones and dowitchers had the lowest. Ruddy Turnstones were the only birds that used digging and turning stones to obtain food and these two foraging methods seemed to be the most important variables discriminating turnstones from other co-occurring shorebirds. However, despite the slight differences in use of foraging methods and microhabitats by different species, this study documented weak partitioning among shorebirds, particularly between sandpipers and dowitchers. These results indicate that the short-term absence of clear niche partitioning on a local scale may occur in shorebird communities.

Parental roles are highly diverse in animal taxa. Since caring is an important determinant of fitness, understanding the origin and maintenance of various parental care strategies is a key question in evolutionary biology. Here we investigate parental care patterns in birds, which exhibit a remarkable diversity of parental sex roles. By means of phylogenetically informed comparative analyses we investigate whether and how care provisioning is predicted by ecology and social environment. Making use of the most comprehensive dataset including 1101 species that represent 126 avian families, we show that sex differences in parental care are neither related to food type nor to nest type, two key ecological factors. However, we found an effect of the social environment, as males tend to care relatively more in in colonial species than in non-colonial species. Taken together, these results highlight the importance of social effects for evolution of diverse parental sex roles.

Providing food for wild birds is perhaps the most widespread intentional interaction between people and wildlife. In the UK, almost half of households feed wild birds, often as peanuts and seed supplied in hanging feeders. Such food is also taken by the introduced, invasive Grey Squirrel Sciurus carolinensis. Little is known of how Grey Squirrels utilise this resource and how they affect feeder use by wild birds. To assess this we recorded the numbers and time spent by animals visiting experimental feeding stations in suburban gardens, and also asked if exclusionary guards (to prevent Grey Squirrel access), food type (peanut, mixed seed), habitat and weather conditions influenced visits. Using automated cameras, we recorded 24,825 bird and 8577 Grey Squirrel visits. On average >44% of the time feeders were utilised, they were being visited by Grey Squirrels. Grey Squirrel presence prevented birds from feeding at the same time (>99.99%). Feeders where Grey Squirrels were dominant were less likely to be visited by birds, even in their absence. Guards reduced Grey Squirrel use to a minimum on seed feeders, and by approximately half on peanut feeders. Squirrels, food type, guard status, habitat and rainfall all influenced bird activity and timing of feeder visits. Our work suggests that Grey Squirrels reduce the availability of supplementary food to wild birds, while gaining large volumes of food resources with corresponding benefits. Given the ubiquity of supplementary feeding, it is likely that this is an important resource for urban Grey Squirrels; feeder guards mitigate this effect.

Se presentan los resultados de la caracterización de avifauna en cuatro sitios a lo largo del río Fucha y recomendaciones para incrementar su abundancia y diversidad. Mediante recorridos libres se registraron 67 especies (1464 individuos) pertenecientes a 24 familias. Se resalta la presencia de diez especies migratorias boreales y cinco casi-endémicas. Los sitios con mayor riqueza fueron la reserva El Delirio con 46 especies (35 exclusivas) y San Cristóbal con 22 especies, mientras que la de menor riqueza fue Industriales con 16. Los sitios con mayor similitud fueron San Cristóbal y Marsella con 46,37 %, por otra parte el sitio con menos similitud respecto al resto fue la reserva El Delirio (entre el 8 y 15 %). Finalmente, se encontró que 32 especies consumen un solo tipo de alimento y 35 dos tipos, dentro de estos los más representativos fueron insectos pequeños (IP) con 22 especies, seguido de insectos pequeños y frutos (IP-F) con 10 especies. Es necesario proteger, recuperar y fomentar espacios verdes dentro de la ciudad dándole un manejo sostenible al entorno natural para poder conservar las aves y sus hábitats, así como el recurso hídrico, la calidad del aire y el paisaje en general.

This study assessed the performance of L. alexandri postlarvae (2 days after hatching) with different diets (Artemia and Panagrellus redivivus), food amounts (C300-C500-C700), and feeding frequencies (F1-F3-F6) in two experiments lasting 10 days. The best performing food type, Artemia and Artemia with P. redivivus, presented the highest survival rates as well as fish with the greatest weight, length, and specific growth rate (SGR). In the second experiment with Artemia, the weight, length, and SGR presented significant differences, increasing with higher amounts of prey. The best performance was obtained from a daily diet (F1) with the greatest amount of prey (C700).

Laboratory experiments on the New Zealand freshwater mussel Echyridella menziesii were used to investigate the short-term effects (7–8 days) of food type on rates of biodeposition and benthic subst...

Energy acquisition is of fundamental importance to the survival of any organism. Thus, the morphology, or tools, that an organism uses to capture food can be under intense selective pressure. We studied the prey capture mechanics of the central mudminnow (Umbra limi), a benthic-dwelling fish species with a varied diet. A morphology suited for one specific prey type may not be as well suited for another prey type. Thus, we might expect that mudminnow are more successful at capturing one sort of prey over another. Specifically, we sought to determine if there were any changes in prey capture success and underlying prey capture mechanics when faced with highly elusive prey, live feeder fish (guppies), versus a non-elusive invertebrate larvae (midges of the family Chironomidae), commercially known as “blood worms.” Our results indicated that the more elusive prey caused mudminnow to have a slightly slower but a slightly more extreme premaxillary protrusion and expansion events. However, these differe...

Naturalistic feeding methods, such as the provision of whole carcasses to zoo animals, are potentially controversial because zoo visitors might not approve of them. However, since several species of zoo animals feed from large carcasses in the wild, this food type could benefit their welfare in captivity compared to other less-natural food types. Scavengers in particular almost exclusively live on carcasses in nature; therefore, their welfare in captivity could significantly depend on the opportunity to express behaviors related to carcass feeding. In this study, we assessed the frequency of carcass feeding for vultures in North American zoos and investigated the effect of different food types on the behavior of zoo-housed Andean condors (Vultur gryphus). We also evaluated the opinion of North American zoo visitors about carcass feeding. Our results show that small whole carcasses (rats, rabbits) are part of the diet of vultures in most North American zoos, but large whole carcasses (ungulates) are rarely fed. Our behavioral study indicated that Andean condors appear to be more motivated to feed on more natural food types, which also seem to physically engage the birds more and occupy them longer. Most zoo visitors approved of carcass feeding for captive vultures over a range of prey animals, and the majority would also like to observe the vultures eat. Collectively, our results demonstrate that carcass feeding, particularly with larger prey, potentially enriches both zoo-housed vultures as well as the visitor experience. Zoo Biol. 34:118–129, 2015. © 2015 Wiley Periodicals Inc.

Capsule: Providing peanuts on bird feeders was shown to attract more individuals and more species than providing cheese or bread. Aims: To investigate how the provision of different human-derived foods affected visit rates of urban birds at bird feeders. Methods: A fully replicated study design was set up in parkland, offering a binary choice from three food types (peanuts, bread and cheese) on bird tables. Birds were observed by using a scan-sample method. Results: Peanuts attracted more visits, and a greater diversity of bird species, than cheese or bread. This preference was strongest for Blue Tits Cyanistes caeruleus and Great Tits Parus major, whereas European Robins Erithacus rubecula visited all food types equally, and Blackbirds Turdus merula preferred cheese. Bread was the most consumed food type when measured by mass, but this could be linked to varying bite sizes. Conclusion: Our results indicate that birds preferred to visit feeding stations with the most protein- and energy-rich foods, but that some birds still chose the carbohydrate-rich bread. The findings indicate that peanuts, rather than household scraps like bread and cheese, attract the highest number of species and individuals to bird tables. The findings will be of interest to the public and to organizations providing information on bird feeding for recreational purposes.

Capsule Black-headed Gulls along a rural–urban gradient chose a food type most associated with their immediate environment, and showed differences in their response to provisioned food, with more urban birds quicker to respond.Aims To determine whether Black-headed Gulls prefer natural versus anthropogenic food along a rural–urban gradient and so determine whether they select prey primarily according to familiarity.Methods Gulls were allowed to choose between provided anthropogenic and natural foods in 11 locations along a rural–urban gradient. Twenty tests were carried out in each location and the preference and time taken for the birds to select food recorded.Results Black-headed Gulls preferred food types most likely to be found in their immediate environment. Birds in more urban environments were quicker to respond to artificially provisioned food. Across environments, Black-headed Gulls showed the capacity to learn by decreasing the time taken to respond to artificially provisioned food, both within ...

The National Invasive Ant Surveillance is conducted annually around ports and other high-risk areas to detect new ant incursions into New Zealand. Currently, non-sticky food-baited vials are used to trap ants. The ability of a sticky bait trap to trap multiple ant species at baits was tested, under the hypothesis that a sticky trap would reduce the role of competitive exclusion at food sources, a drawback of food baiting. Furthermore, the role of food type, sugar, protein and a combination of both foods, on ant catch was examined. Although only 4% of traps caught multiple species, this incidence was five times greater in the sticky-bait than food-only vials. The combined food source traps caught ants more often than the single food source traps. The refinement of ant monitoring traps will aid surveillance managers in the future.

1. Omnivorous woodland ant species trade off between the ability to find and behaviourally control food resources. Dominant species can limit the ability of subordinates to harvest certain food items. However, subordinate species, by being faster discoverers, could gain access to such food items by arriving at them first. 2. In this study, we tested the hypothesis that resource-directed discovery occurs in ant communities and that good discoverers preferentially discover high value resources. We did this by measuring time to discovery and the number of discoveries of high and low levels of two resource types, crickets and honey, for species occurring in Texas and Arizona woodland ant communities. 3. Ants discovered resources roughly 10 times faster in Texas than in Arizona. They discovered crickets more rapidly than honey in both communities, but there was no difference in the discovery of different resource levels. We also found that species were not biased in their discovery of different resource types or levels. 4. These results provide indirect evidence that discovery is directed by resource stimuli but that such directedness does not impact interspecific exploitative competition.

The food niche partitioning of four species of house snakes (Lamprophis fuliginosus, L. olivaceus, L. lineatus, and L. virgatus) was studied in suburban areas of south‐eastern Nigeria, West Africa. Snakes were captured in the field, and their stomach contents were obtained by forced‐squeezing of the ingested bolus. Pseudo‐community analysis and Monte Carlo simulations, by two different algorithms, were used to investigate whether the community under study was randomly assembled along the trophic niche axis. Four hundred and thirty snake individuals were captured: 52 out of 133 L. fuliginosus (32.1%), 31 of 126 (24.6%) L. lineatus, 30 of 108 (27.8%) L. virgatus, and 20 of 63 (31.7%) L. olivaceus had identifiable food contents in the stomach. Lamprophis fuliginosus appeared as the more generalist species, L. lineatus showed some preference for lizards and frogs, L. virgatus for small mammals (rodents and shrews), and L. olivaceus for nestling birds and small mammals. However, null models showed that the com...

We measured egg hatching times and stage specific naupliar development times of the key calanoid copepods Calanus helgolandicus and C. finmarchicus in response to temperature, food quantity and food type. Calanus helgolandicus development times decreased with increasing temperature and when fed Isochrysis galbana (4.4 μm ESD) rather than Prorocentrum micans (29.5 μm ESD). Nauplii needed higher food carbon concentration to develop past the first feeding stage (N3) when fed I. galbana compared with P. micans. At low food carbon concentrations nauplii developed more slowly past N3 than at more saturated levels. The survival of nauplii fed P. micans increased with temperature, but starved nauplii survival decreased at higher temperatures. We parameterized a temperature-dependent model of development for both species which fitted the observed stage durations under non-limiting food extremely well and demonstrated that C. finmarchicus develops faster than C. helgolandicus. Further data are needed to clarify the effect of food-temperature interactions on development rates.

The manner in which species partition space and time to minimize competition for shared, limited resources has been a major focus of theoretical and empirical ecology. Although numerous examples exist of intra-guild dietary separation among coexisting species, studies of spatio-temporal partitioning among species sharing a single food type are rare. We investigated spatio-temporal patterns of multi-species predation on individually-marked moose Alces alces calves in an Alaskan boreal forest community where moose are the only large herbivore, and constitute the primary prey of coexisting black bears Ursus americanus, brown bears U. arctos and gray wolves Canis lupus. The two most closely related predators, black bears and brown bears, overlapped temporally and spatially in their consumption of moose calves, as indicated by univariate analyses. Moreover, both bear species segregated spatially from wolves when killing moose calves. Hence, our study appears to support key predictions of predator coex...

Background Variation in early nutrition is known to play an important role in shaping the behavioural development of individuals. Parental prey selection may have long-lasting behavioural influences. In birds foraging on arthropods, for instance, the specific prey types, e.g. spiders and caterpillars, matter as they have different levels of taurine which may have an effect on personality development. Here we investigated how naturally occurring variation in the amounts of spiders and caterpillars, provisioned to nestlings at day 4 and 8 after hatching, is related to the response to handling stress in a wild passerine, the great tit (Parus major). Broods were cross-fostered in a split-brood design allowing us to separate maternal and genetic effects from early rearing effects. Adult provisioning behaviour was monitored on day four and day eight after hatching using video recordings. Individual nestlings were subjected to a handling stress test at an age of 14 days, which is a validated proxy for exploratory behaviour as an adult. Results - Variation in handling stress was mainly determined by the rearing environment. We show that, contrary to our predictions, not the amount of spider biomass, but the amount of caterpillar biomass delivered per nestling significantly affected individual performance in the stress test. Chicks provisioned with lower amounts of caterpillars exhibited a stronger stress response, reflecting faster exploratory behaviour later on in life, than individuals who received larger amounts of caterpillars. Conclusions - These results suggest that natural variation in parental behaviour in wild birds modulates the developmental trajectories of their offspring's personality via food provisioning. Since parental provisioning behaviour might also reflect the local environmental conditions, provisioning behaviour may influence how nestlings respond to these local environmental conditions.

In a second-order montane stream of the Hanjiang River basin, Leptophlebia sp.and Ephemera sp. appeared to develop two generations per year, and there was little overlap with the two generations in either species. Leptophlebia sp. pupated in autumn and winter, while Ephemera sp. did so in summer and winter. Annual production of Leptophlebia sp., estimated by the size-frequency method, was 7.23 g (dry weight)/m2. The annual production of Ephemera sp. was 14.45 g/m2. The principal food type and major contributor to this production in both mayflies was amorphous detritus (59.2%), while diatoms contributed 36.4% to the production.

In their natural habitats orangutans and gibbons have to solve spatial problems to find enough food, which is distributed over large areas and available at different times of the year. Therefore both species should evolve spatial memory skills to remember spatial locations and their content. We conducted 2 studies in a 1900-m2 naturalistic outdoor enclosure. In the 1st study, we hid kiwi pieces in 10 different locations and placed kiwi pieces in a visible location. Individuals of both species approached significantly more food locations in the test condition than in the control condition in which no food was hidden. In the 2nd study, we hid 2 types of food in 10 different locations so that individuals had to remember which food type was where. We hid bananas on trees (banana condition) and grapes under bamboo shrubs (grape condition). We also placed oranges in full view (control condition) to rule out the possibility that finding food may automatically trigger an indiscriminate search. Individuals approached the banana locations more often in the banana than in the other 2 conditions. Some orangutans, but not the gibbon, also approached the grape locations more often in the grape than in the other 2 conditions. Individuals often returned to locations in which they previously found food and rarely revisited locations in the same session. We detected little influence of the food quantity and no influence of the distance to each location on the subjects' foraging behavior.

Monomorium orientale Mayr (Hymenoptera: Formicidae) is a common structure- and food-infesting ant in Asia. There is only limited information on the biology and habits of this species, especially on the preferred foods and distribution of nutrients in colonies. We conducted a laboratory study on the distribution of carbohydrates, proteins, and lipids, which were represented by respective food sources, in M. orientale colonies. Three colony conditions were applied: normal, with a balanced ratio of castes, queenless (only workers and brood), and broodless (only queens and workers). Food sources were stained to track the flow of the respective food in the colonies. Results revealed that carbohydrates had rapid distribution, with >60% of the colony indicated in 24 h, in all colony conditions. Queens in all colonies did not feed on protein. Protein showed a more delayed distribution in the brood in all colony conditions

Work against buoyancy during submergence is a large component of the energy costs for shallow diving ducks. For penguins, buoyancy is less of a problem, however they still seem to trade-off levels of oxygen stores against the costs and benefits of buoyant force during descent and ascent. This trade-off is presumably achieved by increasing air sac volume and hence pre-dive buoyancy (Bpre) when diving deeper. Tufted ducks, Aythya fuligula, almost always dive with nearly full oxygen stores so these cannot be increased. However, the high natural buoyancy of tufted ducks guarantees a passive ascent, so they might be expected to decrease Bpre before particularly deep, long dives to reduce the energy costs of diving. Body heat lost to the water can also be a cause of substantial energy expenditure during a dive, both through dissipation to the ambient environment and through the heating of ingested food and water. Thus dive depth (dd), duration and food type can influence how much heat energy is lost during a dive. The present study investigated the relationship between certain physiological and behavioural adjustments by tufted ducks to dd and food type. Changes in Bpre, deep body temperature (Tb) and dive time budgeting of four ducks were measured when diving to two different depths (1.5 and 5.7 m), and for two types of food (mussels and mealworms). The hypothesis was that in tufted ducks, Bpre decreases as dd increases. The ducks did not change Bpre in response to different diving depths, and thus the hypothesis was rejected. Tb was largely unaffected by dives to either depth. However, diving behaviour changed at the greater dd, including an increase in dive duration and vertical descent speed. Behaviour also changed depending on the food type, including an increase in foraging duration and vertical descent speed when mussels were present. Behavioural changes seem to represent the major adjustment made by tufted ducks in response to changes in their diving environment.

Intra-specific colour differences in insects may occur as a result of environmental factors such as food type, temperature and humidity, or may be under genetic control. These colour polymorphisms may result in fitness differences through several mechanisms, including mate selection, camouflage from or warning to natural enemies, and heat absorption. Two colour morphs of adult Chrysophtharta agricola (Chapuis) (Coleoptera: Chrysomelidae: Paropsini) are present in the field in mainland Australia and Tasmania: a common green-brown form, and a rare black form. Tasmanian populations were sampled to assess the frequency of each morph at eight localities. The black form represented less than 3% of beetles (N=1724), with the proportion not significantly different between localities. Crossing tests using the two colour morphs of C. agricola showed that the black form was genetically dominant over the common form. To assess whether colour morphs had any fitness differences, we measured pre-oviposition period, fecu...

Dunking behaviour, the dipping of food in water, has been anecdotally observed in more than 25 species of birds in the wild, but its function and ecology have not been systematically studied. In experiments conducted in the field and in captivity on Carib grackles, Quiscalus lugubris, in Barbados, we showed that: (1) dunking rate in the field was influenced by food type and that moistening dry food seems to be one of the major benefits of dunking; (2) most dunking observed in the field was performed by a minority of individuals, but the vast majority (86%) of grackles tested in captivity were capable of dunking; (3) a higher density of conspecifics at a water source was associated with a lower dunking rate and an increased risk of kleptoparasitism when dunking; and (4) there were consistent individual differences in dunking and stealing frequency. We conclude that dunking is part of the normal behavioural repertoire of Carib grackles in Barbados, and that the low frequency of the behaviour in the field did not result from the inability of some individuals to perform the technique, but more likely from the balance of costs and benefits affecting its expression.

We investigated how the type of food (sucrose or protein) and the presence of brood influence foraging decisions of Lasius niger L. scouts. In particular, we studied whether and how these parameters alter the drinking behaviour of scouts and the allocation of workers to food retrieving and recruiting tasks. We analysed drinking and recruiting behaviour of single scouts from nests with or without brood that encountered a proteinaceous or sucrose droplet. A substantial fraction of scouts encountering a proteinaceous droplet did not ingest it and did not then return to the nest whereas nearly all drank at sugar droplets; brood presence did not influence this decision. Once an ant started drinking, it needed to drink a critical volume before returning to the nest; this critical volume did not depend on the type of food and the presence of brood. Scouts laid a trail only if they returned to the colony. Food type and brood presence altered the proportion of individuals that laid a trail but not the individual trail-laying intensity. We discuss the consequences of this decision system through simple individual assessments and decision rules, with regard to the self-organized foraging patterns of this species and the efficient collective exploitation of natural resources.

Summary This study aimed to evaluate metabolic fingerprinting by Fourier transform infrared (FT-IR) spectroscopy as a technique for investigating microbial communities and their activities in soil. FT-IR spectra from earthworm casts, and other ‘biosamples’, were compared using multivariate cluster analyses. The work formed part of a wider study to quantify the risk of horizontal gene flow and to assess ecological impacts associated with the release of GM crops or recombinant micro-organisms. A range of samples, including pure cultures of similar soil bacteria, plant materials and earthworm casts of various ages and feeding regimes were analysed. A subset of the cast FT-IR data was compared with DGGE analysis of extracted DNA/RNA. Cluster analysis of FT-IR spectra was capable of differentiating between different bacterial, litter and cast samples. There was congruence between FT-IR and DGGE clustering for food type but not for cast age. Further detailed work on the microbial populations will be needed to investigate relationships between microbial and spectroscopy data.

Summary This study aimed to evaluate metabolic fingerprinting by Fourier transform infrared (FT-IR) spectroscopy as a technique for investigating microbial communities and their activities in soil. FT-IR spectra from earthworm casts, and other ‘biosamples’, were compared using multivariate cluster analyses. The work formed part of a wider study to quantify the risk of horizontal gene flow and to assess ecological impacts associated with the release of GM crops or recombinant micro-organisms. A range of samples, including pure cultures of similar soil bacteria, plant materials and earthworm casts of various ages and feeding regimes were analysed. A subset of the cast FT-IR data was compared with DGGE analysis of extracted DNA/RNA. Cluster analysis of FT-IR spectra was capable of differentiating between different bacterial, litter and cast samples. There was congruence between FT-IR and DGGE clustering for food type but not for cast age. Further detailed work on the microbial populations will be needed to investigate relationships between microbial and spectroscopy data.

The dominant paradigm to explain asymmetries in the spatial distribution of foraging animals is that they track the spatial heterogeneity of their environment. However, in social insects, endogenous spatial asymmetries can emerge within a uniform environment as an outcome from the self-organizing process of trail recruitment. We studied how self-organized asymmetries contribute to the exploitation of different food sources (carbohydrate or proteins) in colonies of the aphid-tending ant Lasius niger varying in their nutritional needs (presence or absence of brood). Colonies with brood fed on sucrose sources exhibit a higher mobilization of foragers than the other experimental groups. Foraging patterns differ greatly according to food type: colonies strongly focus their activity on only one droplet of sucrose, whereas they show a rather homogeneous distribution of foragers between proteinaceous sources. In addition, the presence of brood in the colony enhances the asymmetry of collective foraging for both types of food. These spatial differences in self-organized foraging patterns allow efficient exploitation of natural resources and play a role in the competitive strategy of this widespread palearctic ant. Copyright 2002.

How animals locate nutritious but camouflaged prey items with increasing accuracy is not well understood. Olfactory foraging is common in vertebrates and the nutritional desirability of food should influence the salience of odour cues. We used signal detection analysis to test the effect of nutritional value relative to the conspicuousness of food patches on rates of foraging improvement of wild house mice Mus musculus searching for buried food (preferred peanuts or non-preferred barley). Olfactory cues were arranged to make food patches conspicuous or difficult to distinguish using a novel form of olfactory camouflage. Regardless of food type or abundance, mice searching for conspicuous food patches performed significantly better than mice searching for camouflaged patches. However, food type influenced how mice responded to different levels of conspicuousness. Mice searching for peanuts improved by similar rates regardless of whether food was easy or hard to find, but mice searching for barley showed significant differences, improving rapidly when food was conspicuous but declining in accuracy when food was camouflaged. Our results demonstrate a fundamental tenet of olfactory foraging that nutritional desirability influences rates of improvement in odour discrimination, enabling nutritious but camouflaged prey to be located with increasing efficiency.

Predators are known to select food of the same type in non-random sequences or “runs” that are longer than would be expected by chance. If prey are conspicuous, predators will switch between available sources, interleaving runs of different prey types. However, when prey are cryptic, predators tend to focus on one food type at a time, effectively ignoring equally available sources. This latter finding is regarded as a key indicator that animal foraging is strongly constrained by attention. It is unknown whether human foraging is equally constrained. Here, using a novel iPad task, we demonstrate for the first time that it is. Participants were required to locate and touch 40 targets from 2 different categories embedded within a dense field of distractors. When individual target items “popped-out” search was organized into multiple runs, with frequent switching between target categories. In contrast, as soon as focused attention was required to identify individual targets, participants typically exhausted one entire category before beginning to search for the other. This commonality in animal and human foraging is compelling given the additional cognitive tools available to humans, and suggests that attention constrains search behavior in a similar way across a broad range of species., peer-reviewed

The reproductive cycle of the Chilean edible sea urchin, Loxechinus albus , was studied in two areas of the Magellan region, the Cockburn Channel (53°43´S, 70°42´W) and Dawson Island (53°43´S, 72°00´W). Eleven monthly samplings were carried out from April 1996 to May 1997 in each area and samples of between 88 and 100 organisms were collected. Test diameter, total wet weight, and wet gonad weight was measured for each organism. Sex, gonad index, maturity index and gametogenic condition were estimated for each organism through histological analyses. The results indicate that L. albus in the Magellan region has an annual reproductive cycle in which the temporal sequence of different gametogenic processes can not be distinguished accurately due to the rapid and continuous gonadal recovery and gamete production after the spawning period. Although mature organisms were present most of the year, simultaneous spawning of males and females occurred from August to September in Dawson Island and from July to September in the Cockburn Channel. Gametes of those organisms that became mature after the spawning period were resorbed by nutritive phagocytes. Results from this study suggest that small-scale variability of spawning period in the Magellan region may be explained by the differences in food type and availability among areas. Our results also suggest that the Magellan region is an exception to the latitudinal pattern of spawning period reported for most of the Chilean coast. This large-scale variability may be explained by the simultaneous occurrence of low temperatures and short days during late winter and early spring.

A description of the relationship between mean food intake rate (MFIR) and group size is important in assessing the adaptiveness of group living in animals. Several hypotheses argue that foraging in groups can be beneficial in terms of MFIR but an overall assessment of the evidence available thus far was lacking. I examined this relationship in birds using studies that provided a measure of MFIR in groups of different sizes and evaluated the effect of study design and food type. In addition, I noted some of the mechanisms thought to be responsible for changes in MFIR with group size and quantified the impact of the addition of individual foragers. The most common pattern of change in MFIR with group size was a monotonic increase. The different patterns of change in MFIR with group size occurred with similar frequencies in experimental and observational studies despite the fact that observational studies often lacked control for confounding factors. Increases in MFIR were more likely to be associated with seeds as a food type than with fish or invertebrates, and were least likely with carcasses. This finding was related to the ease with which individuals can use aggression to increase their share of resources that are more concentrated in space. Adjustments in vigilance levels and aggression, as well as more subtle changes in speed of search and handling time, were correlated with changes in MFIR with group size. Finally, the addition of three to four individuals appeared to be needed to double the MFIR of a solitary bird. The results suggest that foraging in avian groups is often associated with increased MFIRs and that several ecological factors, including food dispersion, influence the pattern of change with group size.

We analyze the effectiveness, biases and limitations of a poorly-known emetic, apomorphine, for studying the diet of granivorous birds. Apomorphine was tested on three Fringillids yielding an effectiveness of 43-78%, comparable to that reported for the most common emetic, tartar. The effectiveness of the emetic varied significantly among species, probably due to different physiological tolerances. Older chicks and adults were equally sensitive to apomorphine, but it was ineffective in young chicks. The action of the chemical was not independent of food type, and certain food items were underrepresented with this method. However, the importance of most food categories closely resembled the one found through dissection. Mortality caused by exposure to apomorphine was low (< 3%) and successive applications of apomorphine proved to be innocuous, thus allowing for long term studies. Yet, the effectiveness of apomorphine decreased when administered repeatedly within a short time. Apomorphine is an advisable tool for laboratory and field work on granivorous passerines because it is effective, practically harmless, provides reliable results, and can be used repeatedly and easily both with nestlings and adults.

Erosion rates and sources of sediment ingested were quantified for the 2 most abundant parrotfish species on a leeward fringing reef of Bonaire, Netherlands Antilles: Scarus vetula and Sparisoma viride. Direct estimates of erosion by different size classes were obtained from daily feeding rates and grazing scar frequency, scar volume and substrate density. Foraging preference and distribution of fish on the reef were used to examine patterns of bioerosion at 2 spatial scales: reef zones and individual substrates used for grazing. Sediment mass ingested by fish provided an independent check on erosion rates, and was partitioned according to source. S. vetula, employing a scraping feeding mode, removed less material from grazed substrates than similar sized S. viride, which forages by excavating the substrate. Erosion rates increased strongly with fish size in both species. The (indigestible) carbonate derived from epilithic algae accounted for all sediment ingested by juvenile fish. In adult fish, the proportion of freshly eroded carbonate substrate ingested increased with fish size. The distribution of adults of these large scarids over different reef zones determines the rate of bioerosion on a large spatial scale. The highest bioerosional rates occur on the shallow reef (ca 7 kg m(-2) yr(-1)), and they decrease with depth. Parrotfish foraging preferences, and the effects of food type and skeletal density of substrates on the size of the grazing scars, cause large differences in bioerosional rates on a small spatial scale. The highest rates of bioerosion occur on substrates infested with boring algae and of low skeletal density, while high-density substrates and substrates covered with crustose corallines undergo lower rates. Living coral is rarely eaten by scarids, and largely escapes erosion by grazing.

Standardized indices (I) have been created to determine and analyze individual food preferences in choice tests between A types of food presented in the form of N items entirely consumable within the course of one test. For each food type, I represents the ratio between the cumulative area under the curve of the proportion of items consumed as a function of the order in which are consumed the A∙N items, and the sum of the areas for all A items. I varies from 0 (for food in which no item is consumed) to 1 (for food items consumed exclusively); I = 1A for A types of food for which there is no preference; the sum of all indices (I) for all A foods equals 1 in all tests. These standardized indices have been used in tests on Barbary doves (Streptopelia risoria) to study intra-individual coherence and interindividual correspondance in reference to preferences for canary grass (Phalaris canariensis L.), oats (Avena sativa L.), wheat (Triticum vulgare Vill.), hemp (Cannabis sativa L.), and millet (Panicum miliaceum L.).[Translated by the Journal]

The effects of temperature, food type, and sucrose feeding on longevity of house flies, Musca domestica L., were studied. Longevity decreased with increasing temperature. Flies fed cattle manure, poultry manure, or nothing had similar lifespans, which were lower than lifespans of flies fed milk. Sucrose increased longevity for flies on all diets except milk. Addition of poultry feed to a diet of poultry manure also increased longevity. Variation in longevity was highest for flies that were fed milk or sucrose. The intercept (but not the slope) of the relationship between longevity and temperature was affected by diet, indicating that the overall level of the response of fly longevity to temperature was governed by diet. Sugar feeding was detected in 12% of female flies captured in three dairies, and occurred at similar levels among dairies.

Diet of adult House Sparrows Passer domestics was studied by gravimetric analysis of gut contents during August 1988 to July 1989 at Ludhiana, India. Cereals dominated the food forming 83.6% of total diet. Weed seeds and animal matter constituted only 6.2 and 4.3%, respectively. Shannon-Wiener index and Levins' index of food-niche breadth were calculated to be 0.75 and 3.90, respectively. Relative percentage by weight of different food types was significantly positively correlated with their occurrence in the guts (r=0.67, n=16, P

The effect of food and photoperiod on dorado (Salminus brasiliensis) post-larvae growth and survival was investigated using the following treatments: LD (Light: Dark) 24:0 + Artemia nauplii (A), LD 24:0 + fish prey (F), LD 14:10 + A, LD 14:10 + F, LD 0:24 +A and LD 0:24 + F. Prochilodus lineatus larvae were used as fish prey. Higher survival rates were registered in fish prey treatments (PO efeito da alimentação e do fotoperíodo sobre o crescimento e a sobrevivência de pós-larvas de dourado (Salminus brasiliensis) foi investigado utilizando-se os seguintes tratamentos: LE (Luz: Escuro) 24:0 + náuplios de Artemia (A), LE 24:0 + larva forrageira (L), LE 14:10 + A, LE 14:10 + L, LE 0:24 +A e LE 0:24 + L. Larvas de Prochilodus lineatus foram utilizadas como larva forrageira. Taxas de sobrevivência mais elevadas foram registradas nos tratamentos que utilizaram larvas forrageiras (P

Animals often face complex and changing food environments. While such environments are challenging, an animal should make an association between a food type and its properties (such as the presence of a nutrient or toxin). We use information theory concepts, such as mutual information, to establish a theory for the development of these associations. In this theory, associations are assumed to maximize the mutual information between foods and their consequences. We show that associations are invariably imperfect. An association's accuracy increases with the length of a feeding session and the relative frequency of a food type but decreases as time delay between consumption and postingestive consequence increases. Surprisingly, the accuracy of an association is independent of the number of additional food types in the environment. The rate of information transfer between novel foods and a forager depends on the forager's diet. In light of this theory, an animal's diet may have two competing goals: first, the provision of an appropriate balance of nutrients, and second, the ability to quickly and accurately learn the properties of novel foods. We discuss the ecological and behavioral implications of making associational errors and contrast the timescale and mechanisms of our theory with those of existing theory.

Adaptive hypotheses for the evolution of flocking in birds have usually focused on predation avoidance or foraging enhancement. It still remains unclear to what extent each factor has contributed to the evolution of flocking. If predation avoidance were the sole factor involved, flocking should not be prevalent when predation is relaxed. I examined flocking tendencies along with mean and maximum flock size in species living on islands where predation risk is either absent or negligible and then compared these results with matched counterparts on the mainland. The dataset consisted of 46 pairs of species from 22 different islands across the world. The tendency to flock was retained on islands in most species, but in pairs with dissimilar flocking tendencies, island species were less likely to flock. Mean and maximum flock size were smaller on islands than on the mainland. Potential confounding factors such as population density, nest predation, habitat type, food type and body mass failed to account for the results. The results suggest that predation is a significant factor in the evolution of flocking in birds. Nevertheless, predation and other factors, such as foraging enhancement, probably act together to maintain the trait in most species.

We investigated the motivational control of caching behaviour in scrub jays using a two-stage procedure to examine the effects of prefeeding and/or precaching (stage 1) on subsequent caching behaviour (stage 2). Experiment 1 demonstrated that both prefeeding and precaching reduced the subsequent caching of both edible (peanuts) and inedible (stones) items. The reduction in caching was greatest when the items available for storing were the same in the two stages. This item specificity was confirmed in experiment 2 using two food types, peanuts and dog food kibbles. The final experiment demonstrated that the effect of prefeeding on subsequent caching can also be food specific, in that birds that received food in a powdered form that they could eat, but not cache in stage 1, showed a reduction in subsequent caching in stage 2 only when the food type was the same in the two stages. These results suggest that caching behaviour is controlled by both the feeding system and an independent caching system, and that this control is mediated by the incentive value of the specific items rather than by a general motivational state. Copyright 1999 The Association for the Study of Animal Behaviour.

The food habits of animals may be studied in the laboratory or in the field. Field studies describe diet selection of populations but do not permit analysis of the factors causing individual variation in the foraging behaviour of animals. Although numerous indices have been developed to compare use and availability of foods in field diets of animals, little attention has been given to laboratory approaches for comparing food choices. Tests of food choice must account for the order, consumption rate, and total amount of each food type eaten. Current measures fail to account for one or more of these parameters. This often results in highly ambiguous preference rankings, making comparisons among individuals or species difficult. To solve this problem, I propose using the area under the curve of the cumulative proportion eaten versus time for each food type. This index may be used to assess individual variation and determine the relative importance of each major component of the diet selection process in animals.

In the field, Spinachia fed on four types of prey; copepods, isopods, mysids and amphipods. As fish size increased, mysids gradually succeeded amphipods as the most important food type in the diet. Prey dimensions and morphometry of the fish's mouth most accurately predicted capture efficiency for amphipods, whereas for mysids capture efficiency was determined by the prey's escape response and the fish's fast-start capability. Responses to model prey revealed the ability of fish to differentiate among contrasting prey characteristics, resulting in the adoption of appropriate predatory tactics. Amphipods were associated with a shorter gut evacuation time than mysids, although approximately equal proportions of energy were absorbed from each. Similar rations of mysids and amphipods were required to satiate fish. The lower energy content per unit dry mass of amphipods was off set by their lower water content. From pre-digestive behaviour, we predicted that mysids were more profitable than amphipods, and this was reflected in the fish's choice. Conversely, incorporating the net rate of energy uptake by the gut led us to predict that amphipods were more profitable. Although physiological constraints clearly influence the net rate of energy uptake, it appears that dietary preferences are based on pre-digestive predatory behaviour and hence on time minimisation.

Guillemots (Cepphus spp.) feed their chicks a diet that is almost exclusively fish. We observed Pigeon Guillemots (C. columba) at two colonies in Alaska where hermit crabs (Crustacea: Anomura) were a major part of the diet for some nestlings. Hermit crabs were delivered to three of five observed nests at one colony, comprised between 2% and 22% of the items delivered at those nests, and were the second most common food type at one nest. Hermit crabs may be an attractive prey item when lipid-rich forage fish are scarce, and crabs living in gastropod shells that have been softened by encrustations of Suberites sponges may be vulnerable to guillemot predation. Received 11 March 1998, accepted 1 April 1998.