The effects of ambient flow velocity,colony size,and upstream colonies on the feeding success of bryozoa. I. Bugula stolonifera Ryland,an arborescent species

The effects of ambient flow velocity, colony size, and the presence of upstream colonies on the feeding success of the arborescent bryozoan, Bugula stolonifera (Ryland), were studied. Faster ambient flow velocities were found to reduce feeding of zooids of small colonies but not of large colonies. Zooids from different regions of colonies dominated in feeding at different ambient flow velocities: upstream zooids dominated in feeding from slow ambient flow: zooids from central regions dominated in feeding from fast ambient flow. These results are interpreted with respect to the branching morphology of colonies. Finally, evidence that upstream colonies interfere with the feeding success of zooids of colonies downstream was obtained.     

Interactions between red-billed oxpeckers, Buphagus erythrorhynchus, and domestic cattle, Bos taurus, in Zimbabwe

Many apparent interspecific mutualisms are poorly understood. Although theory has focused on the various evolutionary problems peculiar to mutualism, especially the need to identify mechanisms that protect a mutualism from cheating or exploitation, there are relatively few quantified examples of how organisms actually interact. Oxpeckers are believed to benefit their mammalian hosts by reducing tick loads, an assumption based on the fact that the birds include ticks in their diet. I watched red-billed oxpeckers foraging on domestic cattle in the Limpopo Valley between August 1996 and September 1997. From focal watches of 41 individually colour-ringed oxpeckers, I found that birds fed mainly on wounds, in ears and by 'scissoring' with the bill (a distinctive feeding technique). Observable tick feeding represented a very small percentage of their foraging time. Based on oxpecker behaviour at feeding sites, blood from open wounds appeared to be the favoured food: oxpeckers displaced each other significantly more, and were significantly less likely to be deterred by the cows' attempts to remove them, when feeding on a wound than at other feeding sites. The preference for blood, the inability of cows to prevent oxpeckers feeding on blood and the relatively small amount of visible tick feeding suggest that, certainly for cattle, oxpeckers may not be beneficial. However, as cows have not coevolved with oxpeckers, these results may not be representative of oxpecker relations with native African mammalian hosts. Copyright 1999 The Association for the Study of Animal Behaviour.     

Starvation tolerance of macropter brown planthopper, Nilaparvata lugens, from temperate, subtropical, and tropical populations in East and South-East Asia

We compared the starvation tolerance of macropter brown planthopper, Nilaparvata lugens Stål (Homoptera: Delphacidae), a characteristic favoring long-distance migration, among populations collected from subtropical and temperate East Asia, tropical Indochina, and the Malay Peninsula. Starvation tolerance of planthoppers was significantly affected by climatic zone in which the planthoppers had been collected and by feeding duration after adult eclosion. After 24 h feeding on rice, newly emerged macropters originating from East Asia lived longer without feeding (starvation tolerance) than macropters from the tropical populations. The difference in longevity between the two groups of populations became more conspicuous when macropters fed on rice for 48 or 72 h, indicating that post-eclosion feeding markedly increased starvation tolerance in East Asian populations relative to the tropical populations. These facts provide evidence that N. lugens populations that are adapted for long-distance migration are distributed in subtropical and temperate East Asia. From the data on post-eclosion feeding together with starvation tolerance, we discuss the timing of planthopper takeoff from paddies and the difference in resource allocation (vitellogenesis or stored resources) between East Asian and tropical populations.     

Breast feeding,nutritional state,and child survival in rural Bangladesh

The effect of breast feeding on nutritional state, morbidity, and child survival was examined prospectively in a community in rural Bangladesh. Every month for six months health workers inquired about breast feeding and illness and measured arm circumference in an average of 4612 children aged 12-36 months. Data from children who died within one month of a visit were compared with those from children who survived. Roughly one third of the deaths in the age range 18-36 months were attributable to absence of breast feeding. Within this age range protection conferred by breast feeding was independent of age but was evident only in severely malnourished children.In communities with a high prevalence of malnutrition breast feeding may substantially enhance child survival up to 3 years of age.     

Effects of feeding regime on food consumption, growth rates and tissue nucleic acids in juvenile Arctic charr, Salvelinm alpinus, with particular respect to compensatory growth

Juvenile Arctic charr responded to a change from restricted to satiation feeding by showing a growth spurt (compensatory growth). During this period of rapid growth the fish became hyper-phagic and in the days immediately following transfer from restricted to satiation feeding showed improved food conversion efficiency compared to their counterparts raised on a liberal feeding regime. Tissue (liver and muscle) nucleic acid concentrations were influenced by feeding regime, and RNA : DNA ratios were low in both starved fish and those fed restricted rations. Following transfer from restricted to satiation feeding, tissue RNA : DNA ratios were rapidly restored to initial levels. The uses of tissue RNA: DNA ratios both in evaluating nutritional status and as growth indices are discussed.     

Glucose, Insulin, and Adrenaline Effects on Some Aspects of Fish Feeding Behavior

Effects of glucose, insulin, and adrenaline on the feeding latent time and the ration in 3 species of fresh-water teleost fish were studied. There has been shown a significant and uniform effect of glucose (an increase of the feeding latent period, a decrease of the ration) and of adrenaline (an increase of the feeding latent period) at initial stages of exotrophia in fish. The insulin effect on the fish feeding reaction rate is not uniform: apart from a statistically significant decrease of the feeding latent period, there were recorded opposite effects.     

Female feeding priority in bonobos, Pan paniscus, and the question of female dominance

The question of whether bonobos show feeding priority and female dominance has been proposed and examined, both in the wild and in captive studies, with differing results. The relationship between female dominance and female feeding priority has been best studied in prosimian primates. These studies use established criteria of females consistently evoking submissive behavior from males in dyadic encounters for determining female dominance. Although the relationship is complex, female dominance in prosimians is associated with preferential access to food. Data from studies of wild habituated bonobos in the Lomako Forest, Democratic Republic of the Congo, are examined for evidence of both female feeding priority and female social dominance using similar criteria as used for prosimians. Bonobos showed evidence of female feeding priority in small, but not in large, food patches. Male-male competition for mating opportunities at the start of the food bout was related to some, but not all, differences in time spent feeding between the sexes. Female dominance similar to that seen in prosimians was not observed in these bonobos. Males were consistently dominant in dyadic interactions. Female feeding priority with male dyadic social dominance implies that male deference during feeding cannot be excluded as one explanation of interpretations of female dominance in bonobos. Additionally, dominance of male bonobos by females appears to require the presence of female coalition partners. As in other primates with female feeding priority, bonobo females express this trait where food is economically defendable. Unlike prosimians, however, bonobo female feeding priority may result from male deference and the importance of female coalitions in nondyadic interactions.     

The effects of ambient flow velocity,colony size,and upstream colonies on the feeding success of Bryozoa. II. Conopeum reticulum (Linnaeus), an encrusting species

The effects of ambient flow velocity, colony size, and the presence of an actively-feeding colony upstream on the feeding success of the encrusting bryozoan Conopeum reticulum (Linnaeus) were studied. Zooids from both large and small colonies showed a reduction in feeding as flow velocity increased, however, the reduction in feeding was less for zooids from large colonies except at very fast ambient flow velocities. The greater pumping capacity of large colonies may result in a relatively greater per zooid feeding success from moving water. The presence of an actively-feeding colony upstream was found to enhance the feeding of zooids on downstream colonies. Diversion of flowing water by actively-feeding colonies upstream may account for the observed enhancement of feeding by zooids on colonies downstream.The results from this study on an encrusting species are compared with results from a previous study on feeding from flow by an arborescent bryozoan, and the feeding performances of these two colony types are related to their respective flow microhabitats.     

Embryogenesis and early larval development in wild-caught Levantine scraper,Capoeta damascina (Valenciennes, 1842)

Levantine scraper, Capoeta damascina is a candidate species for future stock assessments, conservation studies, and hatchery efforts. Herein, we documented embryonic and early larval development, from egg activation to the exogenous feeding period, using morphological and histological landmarks. Embryos were obtained by in vitro fertilization from hormonally induced wild-caught broodstock, and subsequent development was monitored at temperatures coinciding with native conditions. Embryonic development from fertilization to hatch lasted ~105–110 hr. Larvae emerged with unpigmented eyes and body morphology, as well as an undifferentiated digestive tract. The mouth was closed at hatch by the oropharyngeal membrane and opened by the early endogenous feeding period. Trabeculae cartilage, quadrate bone, and Meckel's cartilage of the endoskeleton were present during the endogenous feeding period. During this period, the larvae underwent considerable changes in craniofacial morphology, locomotion, and organogenesis of the digestive tract. The cartilaginous floor of the neurocranium developed and the first four ceratobranchials appeared simultaneously at the end of endogenous feeding period. The digestive tract was differentiated into buccopharynx, esophagus, and small intestine during the endogenous feeding period. The intestinal valve and numerous longitudinal folds at the posterior region of the intestine formed together by the endo–exogenous feeding period. Major developmental events in retinogenesis occurred during the endogenous feeding period. When larvae entered exogenous feeding the mouth was fully-functional. Additionally, liver size and eye diameter increased. Our analysis of embryonic and early larval development in Levantine scraper aligned with other freshwater fishes.     

Blood,sweat, and tears: a review of the hematophagous,sudophagous, and lachryphagous Lepidoptera

Although adult Lepidoptera are not often considered medically relevant, some butterflies and moths are notorious for their consumption of mammalian body fluids. These Lepidoptera can be blood‐feeding (hematophagous), tear‐feeding (lachryphagous), or sweat‐feeding (we use the term “sudophagous”). Blood‐feeding Lepidoptera have been observed piercing the skin of their hosts during feeding, while tear‐feeding Lepidoptera have been observed frequenting the eyes of hosts in order to directly obtain lachrymal fluid. These behaviors have negative human health implications and some potential for disease transmission. In this study, articles concerning feeding behavior of blood, sweat, and tear‐feeding Lepidoptera were reviewed, with emphasis on correlations between morphological characters and feeding behaviors. Harmful effects and vector potential of these Lepidoptera are presented and discussed.     

Particulate and filter feeding in threadfin shad, Dorosoma petenense, at different light intensities

Previous workers inferred from stomach analyses that threadfin shad ( Dorosoma petenense ) ate plankton by both filter and particulate feeding. These inferences were confirmed in this study by laboratory experiments in which both types of feeding were observed. Threadfin shad consumed relatively small food particles (≤ 0.39 mm) by filtration, while larger prey (7.5 mm) were eaten individually. The shad were able to filter feed on small foods (brine shrimp nauplii and phytoplankton) at all light intensities from 0 to 9 × 10¹ fL. These data indicate that under natural conditions shad can filter feed at any time of the 24 h period if food conditions are sufficient to trigger feeding. Filter feeding is probably induced by chemoreception rather than vision. The particulate feeding rate decreased as light intensity decreased, reaching a minimum between 9 × 10⁻⁴ and 9 × 10⁻⁵ fL. From these data it is inferred that particulate feeding is a visual process in this species, requiring intensities equivalent to bright moonlight or greater. Filter and particulate feeding abilities allow threadfin shad to consume most of the different types of plankton and to change their diet with seasonal changes in the composition of the plankton.     

Feeding Kinematics,Suction, and Hydraulic Jetting Performance of Harbor Seals (Phoca vitulina)

The feeding kinematics, suction and hydraulic jetting capabilities of captive harbor seals (Phoca vitulina) were characterized during controlled feeding trials. Feeding trials were conducted using a feeding apparatus that allowed a choice between biting and suction, but also presented food that could be ingested only by suction. Subambient pressure exerted during suction feeding behaviors was directly measured using pressure transducers. The mean feeding cycle duration for suction-feeding events was significantly shorter (0.15±0.09 s; P<0.01) than biting feeding events (0.18±0.08 s). Subjects feeding in-water used both a suction and a biting feeding mode. Suction was the favored feeding mode (84% of all feeding events) compared to biting, but biting comprised 16% of feeding events. In addition, seals occasionally alternated suction with hydraulic jetting, or used hydraulic jetting independently, to remove fish from the apparatus. Suction and biting feeding modes were kinematically distinct regardless of feeding location (in-water vs. on-land). Suction was characterized by a significantly smaller gape (1.3±0.23 cm; P<0.001) and gape angle (12.9±2.02°), pursing of the rostral lips to form a circular aperture, and pursing of the lateral lips to occlude lateral gape. Biting was characterized by a large gape (3.63±0.21 cm) and gape angle (28.8±1.80°; P<0.001) and lip curling to expose teeth. The maximum subambient pressure recorded was 48.8 kPa. In addition, harbor seals were able to jet water at food items using suprambient pressure, also known as hydraulic jetting. The maximum hydraulic jetting force recorded was 53.9 kPa. Suction and hydraulic jetting where employed 90.5% and 9.5%, respectively, during underwater feeding events. Harbor seals displayed a wide repertoire of behaviorally flexible feeding strategies to ingest fish from the feeding apparatus. Such flexibility of feeding strategies and biomechanics likely forms the basis of their opportunistic, generalized feeding ecology and concomitant breadth of diet.     

Initial feeding time of Atlantic salmon,Salmo salar,alevins compared to river flow and water temperature in Norwegian streams

Synopsis The time of initial feeding of Atlantic salmon,Salmo salar, alevins in ten geographically widespread Norwegian streams was estimated theoretically by combining data on spawning time and models describing the time from fertilization to hatching and from hatching to initial feeding at different temperatures. The point of initial feeding was correlated with water flow and water temperature regimes. Initial feeding was avoided in all rivers during spring peak flow, and before water temperature reached 8°C. Two different strategies were indicated: (1) initial feeding may take place before the culmination of the spring flow or (2) after the peak spring flow. The choice of strategy depends on temperature and flow regimes in each river.     

Influences on the feeding behavior of three mammals in the Maruyama Zoo: bears, elephants, and chimpanzees

Modifications of feeding conditions are essential to the establishment of environmental enrichment in zoos. In this study, we attempted to increase the duration of feeding by varying feeding conditions, such as the spatial or temporal distribution of foods, while keeping the sorts and amounts of food the same. Subjects included nonhuman animals reared at the Maruyama Zoo in Sapporo, Japan: 3 bears (Ursus arctos), 2 elephants (Elephas maximus), and 5 chimpanzees (Pan troglodytes). Considering that the feeding ecologies of these animals differed a great deal from those in the wild, we used the focal animal sampling method. Consisting of the spatial dispersive and massed feeding conditions, the experiment with bears found feeding time increased more in the dispersive condition. In addition, the behavioral rhythm of alternate feeding and sleeping appeared. The experiment with elephants, consisting of the temporal dispersive and massed condition, increased feeding time under the massed condition. The experiment using chimpanzees reversed conditions used in the elephant study and increased feeding time under the dispersive condition. Results indicated that these simple modifications both influenced an increasing duration of feeding and affected behavioral patterns in a day.     

Influences on the Feeding Behavior of Three Mammals in the Maruyama Zoo: Bears,Elephants, and Chimpanzees

Modifications of feeding conditions are essential to the establishment of environmental enrichment in zoos. In this study, we attempted to increase the duration of feeding by varying feeding conditions, such as the spatial or temporal distribution of foods, while keeping the sorts and amounts of food the same. Subjects included nonhuman animals reared at the Maruyama Zoo in Sapporo, Japan: 3 bears (Ursus arctos), 2 elephants (Elephas maximus), and 5 chimpanzees (Pan troglodytes). Considering that the feeding ecologies of these animals differed a great deal from those in the wild, we used the focal animal sampling method. Consisting of the spatial dispersive and massed feeding conditions, the experiment with bears found feeding time increased more in the dispersive condition. In addition, the behavioral rhythm of alternate feeding and sleeping appeared. The experiment with elephants, consisting of the temporal dispersive and massed condition, increased feeding time under the massed condition. The experiment using chimpanzees reversed conditions used in the elephant study and increased feeding time under the dispersive condition. Results indicated that these simple modifications both influenced an increasing duration of feeding and affected behavioral patterns in a day.     

Adaptive significance of winter pair bond in male pintail, Anas acuta

To test the female-advantage hypothesis that has been proposed to explain the adaptive significance of winter pair bonds in ducks, we examined the feeding and social behaviors of the northern pintail, Anas acuta. The female-advantage hypothesis assumes that male attendance offers paired females the benefits of increased social status and access to food, as well as less harassment from conspecifics, allowing them to spend more time feeding. Paired females dominated unpaired females, but neither time budgets of feeding nor frequency of feeding was significantly different between unpaired and paired females. The female-advantage hypothesis predicts that paired males spend less time feeding because they must closely guard their partners from harassment by male conspecifics. Paired males defended their mates by chasing and pecking the unpaired males. However, both time budgets of feeding and frequency of feeding were significantly higher in paired males than in unpaired males. Unpaired males frequently approached females while swimming. They performed courtship displays, mostly toward unpaired females. Paired males spent more time feeding by saving time and energy in courtship. We consider that the advantage of winter pairing for males comes from having a mate plus having an increase in feeding frequency. Received: February 20, 2000 / Accepted: May 22, 2000     

Anthropogenic food provisioning and immune phenotype: Association among supplemental food,body condition,and immunological parameters in urban environments

Direct or indirect supplemental feeding of free‐ranging animals occurs worldwide, resulting in significant impacts on population density or altered demographic processes. Another potential impact of increased energy intake from supplemental feeding is altered immunocompetence. As immune system maintenance is energetically costly, there may be trade‐offs between immune responses and other energy‐demanding physiological processes in individual animals. Although increased availability of food sources through supplemental feeding is expected to increase the overall immunocompetence of animals, empirical data verifying the association between supplemental feeding and different immune parameters are lacking. Understanding the potential influence of supplemental feeding on immune phenotypes is critical, as it may also impact host–pathogen dynamics in free‐ranging animals. Using urban stray cats as a study model, we tested for associations between the intensity of supplemental feeding due to cat caretaker activity (CCA); body condition; and immune phenotype (bacterial killing assay (BKA), immunoglobulin G (IgG) concentration, and leukocyte counts). Significantly higher bacterial killing ability was observed in cats from high CCA districts, whereas higher IgG concentration and eosinophil counts were observed in cats from low CCA districts. Other leukocyte counts and body condition indices showed no significant association with CCA. We observed varying patterns of different immune components in relation to supplemental feeding. Out data suggest that supplemental feeding influences immune phenotype, not only by means of energy provisioning, but also by potentially reducing exposure rates to parasite infections through stray cat behavioral changes.     

Feeding mechanisms, and their variation in form, of some adult ground-beetles (Coleoptera: Caraboidea)

The structure of the mouthparts and foregut of some caraboid beetles has been correlated with their type of feeding mechanism. These may be adapted to fragmentary feeding, fluid feeding (where pre-oral digestion is important), or to mixed feeding (a large category which ranges from a mainly fluid to a mainly solid intake). Head structures concerned with feeding have been discussed in relation to these methods; they include the mandibles, maxillae, labrum-epipharynx and anterior foregut, proventriculus, labium-hypopharynx and the head floor. Different types of head floor were denned in relation to gular structure, in particular the presence or absence of the mid-gular apodeme. Convergent evolution of feeding mechanisms was noted amongst both fragmentary feeders and fluid feeders; in the latter group, sucking pumps have been evolved in the Carabitae, Scarites , Cicindelidae, Paussini and some other caraboids. It was suggested that head shape in caraboids may reflect locomotory adaptations more frequently than feeding adaptations.     

Validation of bone surface modification models for inferring fossil hominin and carnivore feeding interactions, with reapplication to FLK 22, Olduvai Gorge, Tanzania

Resolving the issue of how Early Stone Age hominins acquired large mammal carcasses requires information on their feeding interactions with large carnivores. This ecological information and its behavioral and evolutionary implications are revealed most directly from the tooth, cut, and percussion marks on bone surfaces generated by hominin and carnivore feeding activities. This paper employs a bootstrap method, a form of random resampling with replacement, to refine published neotaphonomic models that use the assemblage-wide proportions of long bones bearing feeding traces to infer the sequences in which Plio-Pleistocene hominins and carnivores accessed flesh, marrow, and/or grease from carcasses. Results validate the sensitivity of the models for inferring hominin feeding ecology, which have been questioned on grounds shown here to be unfounded. The bootstrapped feeding trace models are applied to the late Pliocene larger mammal fossil assemblage from FLK 22 (Zinjanthropus site), Olduvai Gorge, Tanzania. High frequencies of tooth and percussion marking on long bone midshaft fragments from FLK 22 are most consistent with those feeding trace models that simulate hominin scavenging from carcasses defleshed by carnivores, while cut mark data indicate that hominins more often had access to upper forelimb flesh than upper hind limb flesh. Together, the bone surface modification data indicate that hominins typically gained secondary access to partially defleshed carnivore kills, but they also allow for the possibility of some carcasses being processed only by carnivores and only by hominins.     

How zooplankton feed: mechanisms,traits and trade‐offs

Zooplankton is a morphologically and taxonomically diverse group and includes organisms that vary in size by many orders of magnitude, but they are all faced with the common problem of collecting food from a very dilute suspension. In order to maintain a viable population in the face of mortality, zooplankton in the ocean have to clear daily a volume of ambient water for prey particles that is equivalent to about 10⁶ times their own body volume. While most size‐specific vital rates and mortality rates decline with size, the clearance requirement is largely size‐independent because food availability also declines with size. There is a limited number of solutions to the problem of concentrating dilute prey from a sticky medium: passive and active ambush feeding; feeding‐current feeding, where the prey is either intercepted directly, retained on a filter, or individually perceived and extracted from the feeding current; cruise feeding; and colonization of large particles and marine snow aggregates. The basic mechanics of these food‐collection mechanisms are described, and it is shown that their efficiencies are inherently different and that each of these mechanisms becomes less efficient with increasing size. Mechanisms that compensate for this decline in efficiency are described, including inflation of feeding structures and development of vision. Each feeding mode has implications beyond feeding in terms of risk of encountering predators and chance of meeting mates, and they partly target different types of prey. The main dichotomy is between (inefficient) ambush feeding on motile prey and the more efficient active feeding modes; a secondary dichotomy is between (efficient) hovering and (less efficient) cruising feeding modes. The efficiencies of the various feeding modes are traded off against feeding‐mode‐dependent metabolic expenses, predation risks, and mating chances. The optimality of feeding strategies, evaluated as the ratio of gain over risk, varies with the environment, and may explain both size‐dependent and spatio‐temporal differences in distributions of various feeding types as well as other aspects of the biology of zooplankton (mating behaviour, predator defence strategies).