Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Foraging”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28Linked to original sources
PubMed1976

The foraging behavior of the ant Myrmica laevinodis nyl.

The foraging territory is not divided among particular foragers, at least in the young, small families of M. laevinodis. The same individuals may be observed repeatedly only at the aphides over a period of several days, which may be explained by a transient memorizing of the source of attractive food. Along with the faculty of these ants to inform their nestmates of the food source, a certain continuity in care of the aphides is ensured. Various forms of behavior among particular foragers coming in contact with the trophy exceeding their strength were noted. The less time the ant hesitates before to the nest, the sooner and more efficiently it recruits helpers and the smaller is its dependence on its own odor trails when moving on the terrain. Since there exist transitory forms between diametrically opposite manifestations of such behavior, possibly the process of individual acquirement of capabilities necessary for fulfilling foraging function occurs.

Animals↗
PubMed1975

Ethological studies in the ant Tetramorium caespitum Mayr. I. Foraging and building behavior.

Carrying heavy objects is a common element in the foraging and building behavior of ants. The initial stages of this behavior, i.e., lifting and moving in T. caespitum displayed as stereotyped patterns of movement. These patterns do not improve as the ants become older and more experienced, which suggest their congenital nature. Growing experience of ants is manifested in the later stages of the transportation of heavy objects, and especially in entering the correct opening of the nest with the carried prey. When a foraging ant leaves its nest to return to the prey it initially moves in the general direction of its objective. It is not until a certain distance from the nest is reached, that the ant is able to use olfactory stimuli to locate and follow its previous path. These observations indicate that the representatives of this species do not learn an exact way to and from the nest but instead have a memory for direction. The congenital character of these basic elements of foraging and building behavior allows the existence of a social organization without a division of work and foraging areas.

Animals↗
PubMed2001

Accumulation of DDT and mercury in prothonotary warblers (Protonotaria citrea) foraging in a heterogeneously contaminated environment.

Foraging areas of adult prothonotary warblers (Protonotaria citrea) were determined using standard radiotelemetry techniques to determine if soil concentrations of p,p'dichlorodiphenyltrichloroethane (p,p'DDT) and mercury in foraging areas could be used to predict contaminant levels in diets and tissues of nestling warblers. Adult warblers were fitted with transmitters and monitored for approximately 2 d while foraging and feeding 6- to 8-d-old nestlings. Foraging ecology data were integrated with contaminant levels of soil, diets, and tissues into a comprehensive analysis of geographic variation in contaminant exposure and uptake using linear regression. Concentrations of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and mercury in nestling tissues varied considerably across the study site. Mean concentration of DDE was greater in eggs than all other tissues, with individual samples ranging from 0.24 to 8.12 microgram/kg. In general, concentrations of DDT in soil were effective in describing the variation of contaminants in adipose samples. Concentrations of mercury in soils accounted for 78% of the variation in kidney samples. This was the best relationship of any of the paired variables. All other relationships showed relatively poor predictive ability.

Animals↗
PubMedDate not supplied

Dimorphic foraging behaviors and the evolution of hominid hunting.

In contemporary foraging societies men typically hunt more than women. This observation has played an important role in many reconstructions of hominid evolution. The gender difference in human hunting, likely a product of both ecological and cultural factors, is mirrored by a similar sex difference among nonhuman primates. Existing explanations of such primate behavioral dimorphism are augmented by the recognition of an additional factor that may contribute to differences between males and females in the value of meat. Episodic female immunosuppression is a normal part of reproduction. Because meat is a source of pathogens, females can be expected to exhibit less constant attraction to meat. Sexual dimorphism in the attraction to meat may then contribute to dimorphic foraging specializations, a divergence that is likely augmented by the differential value of insectivory across the sexes. With the rise of cultural transmission of foraging knowledge, dimorphic foraging behaviors would have been reinforced, creating a more comprehensive gender-based division of labor.

Animals↗
PubMed2004

[Research advance in characteristics of molybdenum, boron and selenium in red soils of South China and effects of their reasonable application on forage grass growth].

Reasonable fertilization and fertility improvement of red soils are the important measures to develop the forage industry in hilly regions of South China. This paper summarized the existing form, chemical feature, availability and content of molybdenum, boron and selenium in red soils of South China. The lack of these three microelements in red soils was in common, and their reasonable application could significantly improve the growth of forage grass and its yield. The authors discussed the effects of molybdenum, boron and selenium application on the uptake and accumulation of available nutrients by forage grass and relevant physiological functions, described the molybdenum, boron and selenium deficiency symptoms of forage grass, their diagnostic methods and correcting measures, and put forward some suggestions for deepening the study.

Boron↗
PubMed2002

[Progress in the biotechnology of legume forage plants].

As important forage crops,legume forage plants can play an important role in improving natural environment, maintenins water and soil. With development of molecular biology and improvement of plant transformation techniques,molecular breeding of legume forage plants by biotechnology is possible. This review summarized recent progress on improvement of several forage crops,including improvement of nutrient quality, increase of biomass,enhancement of the assimilation and efficient absorb of nutrient element, and enhancement of abiotic and biotic stress resistance.

English Abstract↗
PubMed2006

[Soil carbon and nitrogen sequestration following cropland to forage grassland conversion in the marginal land in the middle of Heihe River basin, northwest China].

Changes in soil organic carbon (SOC) and total nitrogen (TN) stocks were studied following croplands were converted to forage grasslands (alfalfa) for five years on the marginal land at the edge of oasis in the middle reaches of Heihe river basin. Soil from 12 paired forage land/adjacent cropland on the two soil types (Typic Torripsamments and Typic Calciorthids) was sampled at the three depths of 0-5, 5-10 and 10-20 cm and analyzed for SOC and TN, particulate organic carbon (POC) and nitrogen (PON). The studied soils had very low SOC and N concentrations. SOC stock at the 0-20 cm depth increased by 22.1%-27.8% after conversion of annually crop to perennial alfalfa for four years, and carbon sequestration rate was estimated to be on average 0.47 Mg/(hm2 x a). The greatest change in SOC stock occurred at the 0-5 cm surface layer with an increase of 32%-66%. No significant TN stock was found at the 0-20 cm depth, however, it increased at the 0-5 cm surface layer by 12.8% and 48.1% for Typic Torripsamments and Typic Calciorthids, respectively. Changes in POC and PON stocks were more significant than those in SOC and total N following conversion of crop to forage, and the percentage of distributions of POC and PON increased. POC and PON stocks at the 0-20 cm depth increased by 22.8%-42.7% and 18.6%-57.6% with the greatest increases at the 0-5 cm layer. The increase in soil C pool was mainly attributed to the increase of POC formation after the marginal lands converted to perennial forage cover. Typic Calciorthids with lower SOC concentration had relatively lower C sequestration rate but more significant effects of C and N sequestration compared with Typic Torripsamments.

Carbon↗
PubMedDate not supplied

Determination of acid-detergent fiber and crude protein in forages by near-infrared reflectance spectroscopy: collaborative study.

A collaborative study was conducted to determine the standard error of difference among laboratories for near-infrared reflectance spectroscopic (NIRS) determination of acid-detergent fiber (ADF) and crude protein in forages. The 6 participating laboratories were members of the USDA/ARS National Near-Infrared Reflectance Spectroscopy Forage Research Project. The NIRS calibration equations were developed in the Associate Referee's laboratory for crude protein and ADF and were transferred to the instrument in each of the other collaborating laboratories. The calibration set included over 650 diverse forage samples with crude protein and ADF calibration data; the validation set included 94 samples of bermudagrass. Among-laboratory reproducibility for the NIRS method, calculated as the relative standard deviation for reproducibility (RSDR), was 1.14% for ADF and 0.42% for crude protein. The variance component for among-laboratory variation (coefficient of variation) was 2.54% for ADF and 2.89% for crude protein. These results confirm that it is possible to calibrate, validate, and transfer (NIRS) equations and data among laboratories for the accurate determination of ADF and crude protein, and thereby demonstrate that NIRS can be used as a standard method for the analysis of forages. The method has been adopted official first action.

Detergents↗
PubMedDate not supplied

Determination of water in forages and animal feeds by Karl Fischer titration.

Oven methods for determining moisture (volatiles) in forages and other animal feeds are empirical. The moisture concentration obtained depends upon the time and temperature the sample was dried and is influenced by the presence of other volatiles than water. A validated reference method to measure water in forages and animal feeds could be used to evaluate the appropriateness of oven methods for various types of animal feeds and forages. Karl Fischer titration is a well-established method for determining water. However, thorough extraction of water from forages and feeds is a challenge because they often contain cellular structures that release water slowly. Water was successfully extracted into methanol-formamide (50 + 50) by high-speed homogenization and then titrated directly at 50 degrees C with a one-component Karl Fischer reagent based on imidazole. The method is described in detail, results of day-to-day repeatability and laboratory-to-laboratory reproducibility are reported, and preliminary comparison data between oven methods are provided.

Analysis of Variance↗
PubMed2000

Recruiters and Joiners: Using Optimal Skew Theory to Predict Group Size and the Division of Resources within Groups of Social Foragers.

I apply skew theory to the division of resources within multimember social foraging and antipredator groups. Resource division is modeled as a game between an individual controlling resources (recruiter) and a potential joiner to the group. If a recruiter benefits from the presence of a joiner, it will allocate sufficient resources to the joiner so that the joiner gains as much from group foraging as it would from foraging alone. Joiners should receive a greater proportion of resources controlled by the recruiter when benefits to grouping are low. If group success is a concave-down function of group size, this framework can be used to predict the stable group size. The stable group size is larger than the optimal group size, given equal division of resources, and smaller than the stable group size, given equal division of resources. Furthermore, both current group members and potential joiners agree on the stable group size, so long as the recruiter is able to control resource division. If the recruiter cannot control resource division, there may be conflict over group size and the opportunity for group members to contribute less to group success than they are able.

dominance↗
PubMed1999

Variability and Parasitoid Foraging Efficiency: A Case Study of Pea Aphids and Aphidius ervi.

When a parasitoid is searching for hosts, not all hosts are equally likely to be attacked. This variability in attack probability may affect the parasitoid functional response. Using a collection of experiments, we quantified the functional response of Aphidius ervi (Hymenoptera: Braconidae), an insect parasitoid of the pea aphid Acyrthosiphon pisum (Homoptera: Aphididae). We measured variability in the number of hosts attacked by a foraging parasitoid both among plants and within plants. At the first scale, A. ervi, searching among plants containing different numbers of aphids, showed both aphid-density-dependent and aphid-density-independent variability in the number of aphids attacked per plant. Within plants, A. ervi selectively attacked second and third instar aphids relative to other instars. Furthermore, there was variability in the susceptibility of attack among aphids independent of instar. Variability in attack rates among aphids both among and within plants decreased parasitoid foraging efficiency, with the greatest decrease caused by among-plant variability. Furthermore, the decrease in foraging efficiency was greatest when the average number of aphids per plant was low, thereby transforming a strong Type II functional response into one approaching Type I.

host‐parasitoid interactions↗
PubMed1998

Cerebrospinal fluid concentrations of somatostatin and biogenic amines in grown primates reared by mothers exposed to manipulated foraging conditions.

BACKGROUND: In an earlier study, infant primates were nursed by mothers randomly assigned to variable foraging demand (VFD) or nonvariable foraging conditions (non-VFD). A group of grown VFD-reared subjects demonstrated elevations of cisternal cerebrospinal fluid (CSF) corticotropin-releasing factor concentrations and decreased CSF cortisol levels vs non-VFD counterparts. To further characterize neurobiological sequelae of disturbed early rearing, CSF concentrations of serotonin, dopamine, and norepinephrine metabolites (5-hydroxyindoleacetic acid, homovanillic acid, and 3-methoxy-4-hydroxyphenethyleneglycol [MHPG], respectively) and of somatostatin were determined. METHODS: Second CSF taps were obtained from the previously studied cohort of 30 subjects and from 28 age-matched ad libitum-reared control subjects. Relevant assays were performed. RESULTS: All neurochemicals assayed except MHPG were elevated in the VFD-reared compared with non-VFD subjects. In the VFD group, statistically significant positive correlations between corticotropin-releasing factor and each neurochemical was found, except for MHPG. In the non-VFD subjects, no significant correlations with corticotropin-releasing factor were observed. No effect of age was evident. CONCLUSIONS: Reducing the predictability of maternal foraging demand during early rearing was associated with elevations of cisternal somatostatin and of serotonin and dopamine metabolite concentrations in grown offspring. The corticotropin-releasing factor elevations reported previously were positively correlated with all the elevated CSF parameters of the current study. The findings support the notion that adverse early rearing experiences in primates have longstanding and complex effects on a range of neurochemicals relevant to emotional regulation. Replication in prospective age-controlled studies is warranted.

Animals↗
PubMed2000

Foraging ecology of the mountain monkey (Cercopithecus l'hoesti): implications for its evolutionary history and use of disturbed forest.

We present the first systematic field study on the feeding ecology of the mountain monkey (Circopithecus l'hoesti), a semi-terrestrial guenon. We compare our results with findings from a concurrent study of blue monkeys (C. mitis doggetti, which have an overlapping home range) conducted over ten months in the Nyungwe Forest Reserve, Rwanda. The mountain monkeys spent 35% of observation time feeding on terrestrial herbaceous vegetation. Thirty-five fruit and seed species comprised 42% of their diet, and invertebrates composed 9%. They spent 38% of observation time on the ground and 27% of observation time in canopy trees. Individuals were observed for equivalent proportions of time foraging on the ground for herbs and in canopy trees for fruits. Although mountain monkeys primarily foraged in undisturbed open areas, they also used disturbed open habitats for this purpose. Synthesizing our results with Pleistocene forest history and C. l'hoesti evolutionary history, we suggest that, although these monkeys readily use disturbed forest for herb foraging, they are a forest-adapted species which has adopted a terrestrial lifestyle to exploit the abundant herb layer common to montane forests.

Animals↗
PubMed2004

Changes in locomotor and foraging skills in captive-born, reintroduced golden lion tamarins (Leontopithecus rosalia rosalia).

The behavior of reintroduced, captive-born animals is understudied, limiting the scientific understanding and utility of reintroduction as a conservation tool. This work describes changes in locomotor and foraging behaviors in captive-born golden lion tamarins over the first 18 months after their release into the wild. The subjects included 73 individuals living in and around the Poco das Antas Biological Reserve in Brazil between 1984 and 1996. The differences between animals that survived 6 months after release and those that did not indicate that initial deficiencies in locomotor and foraging abilities are related to survival. Behavioral changes in both juvenile and adult individuals during the first 6 and 18 months after release appear to be primarily related to locomotor abilities; however, the effect of provisioning on foraging abilities is unknown. Juvenile animals showed a larger number of changes relative to adults during the first 6 and 18 months, suggesting that placing tamarins into complex environments early in development may promote the expression of natural behaviors and increase survival opportunities after their release. However, when this is not possible, the best mechanism for reintroducing adult members of this species involves intensive post-release support rather than pre-release training, which confers few behavioral advantages. Recommendations for future reintroductions with this and other species include introducing animals to complex environments early in development, and collecting data systematically.

Acclimatization↗
PubMed2004

Use of spatial, visual, and olfactory information during foraging in wild nocturnal and diurnal anthropoids: A field experiment comparing Aotus, Callicebus, and Saguinus.

Early in their evolution, the ancestors of anthropoid primates radiated from a nocturnal to a diurnal niche. Foraging during the night differs from foraging during the day in terms of the availability of light and color cues, and in the movement of odor molecules through the canopy. In this study, we compared the ability of nocturnal and diurnal New World monkeys to use perceptual cues (i.e., the sight or smell of food) and spatial information (place predictability) in within-patch foraging decisions. An experimental field study was conducted on wild groups of night monkeys (Aotus nigriceps), tamarins (Saguinus imperator imperator and S. fuscicollis weddelli), and titi monkeys (Callicebus cupreus) at the Zoobotanical Park/UFAC, Rio Branco, Brazil. Our research design included the construction of feeding stations located in the home range of the study groups. Each feeding station consisted of eight visually identical feeding platforms located in a circular arrangement. In all test settings, two platforms at each feeding station contained a food reward (banana), and the remaining six platforms contained a sham reward (yellow plastic or inaccessible banana). In the night-monkey experiments, each feeding platform was illuminated by a 40-W red bulb to aid the researcher in observing their behavior. When the location of reward sites was predictable over time, individuals in all four species successfully relocated food rewards based solely on spatial information. Each species was also successful in using visual information to distinguish real from sham food rewards. However, only night monkeys and one group of emperor tamarins used olfactory information alone to locate food rewards. Overall, the species' performances did not clearly differentiate Aotus from diurnal New World primates in these experiments.

Animals↗
PubMed2006

Weaning age among foragers at Matjes river rock shelter, South Africa, from stable nitrogen and carbon isotope analyses.

Matjes River Rock Shelter is a large shell midden on the southern coast of South Africa. Stable nitrogen (delta(15)N) and carbon (delta(13)C) isotope ratios were measured in bone collagen and dentine from human skeletons excavated from this site in order to establish a weaning curve in mid-Holocene hunter-gatherers. delta(15)N results show a progressive increase in individuals from birth to 1.5 years old. delta(13)C results are more tightly clustered and mirror the steady progressive change seen for delta(15)N. We deduce that children at Matjes River Rock Shelter were breastfed for at least the first 1.5 years after birth, and were weaned sometime between 2-4 years of age. A similar pattern was documented for historic-era Kalahari foraging people, where the interbirth spacing was approximately 3 years. This study provides the first direct evidence for an extended period of breastfeeding, and thus long interbirth intervals, among prehistoric foragers, even when those foragers lived in an environment with abundant food resources.

Age Factors↗
PubMed1999

Foraging strategy in a social bird, the alpine chough: effect of variation in quantity and distribution of food.

I conducted feeding experiments to determine the effect of variations in food availability on individual flocking behaviour and foraging efficiency in a social corvid, the alpine chough Pyrrhocorax graculus, which lives in large flocks all year round. In 37 trials I varied both food quantity and the number of food patches. A decrease in the amount of available food reduced the mean flock size, the proportion of birds that had access to food, and their mean pecking rate. A decrease in the number of patches, on the other hand, reduced only the proportion of birds that had access to food. The number of choughs foraging was not influenced by food competition but depended only on the number visiting the site. Females competed less well than males: when food was made scarce, they frequented the site in the same proportion as did males, but had less access to food. I suggest that in this social corvid, long-term advantages to flocking related to social bonds, such as the maintenance of pair bonds, may compensate for short-term costs such as a reduction in foraging efficiency. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Foraging innovation in the guppy.

When novel behaviour patterns spread through animal populations, typically one animal will initiate the diffusion. It is not known whether such 'innovators' are particularly creative individuals, individuals exposed to the appropriate environmental contingencies, or individuals in a particular motivational state. We describe three experiments that investigated the factors influencing foraging innovation in the guppy Poecilia reticulata. We exposed small laboratory populations of fish to novel foraging tasks, which involved exploration and problem solving to locate a novel food source. Experiments 1 and 2 found that (1) females were more likely to innovate than males, (2) food-deprived fish were more likely to innovate than nonfood-deprived subjects, and (3) smaller fish were more likely to innovate than larger fish. We suggest that the sex difference may reflect parental investment asymmetries in males and females. Experiment 3 found that past innovators were more likely to innovate than past noninnovators. Collectively, the results suggest that differences in foraging innovation in guppies are best accounted for by differences in motivational state, but, in addition, guppies may vary in their predisposition to innovate. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗