Feeding Posture Research Articles

Morphological evolution and changes in foraging behaviour of island and mainland populations of Blue Tit (Parus caeruleus) ? a test of convergence and ecomorphological hypotheses

We study the leg morphology and feeding postures of two subspecies of the Blue Tit (Parus caeruleus; Tenerife island and the Iberian Peninsula) and the Coal Tit (Parus ater; Iberian Peninsula). We search for evidence supporting the hypothesis of convergent evolution in morphological and ecological traits and we discuss the role of ecomorphological hypotheses as predictors of foraging differences at the intraspecific level. To overcome the problems introduced by environmental characteristics not related to locomotion and competition, we make observations under controlled situations to manage food quality and food access. We determine that the island Blue Tit has a longer tarsometatarsus, larger foot span and a more proximal insertion of the tibialis cranialis muscle (flexor of the tarsometatarsus) than the mainland Blue Tit. These morphological differences are consistent with the more frequent use of hanging and clinging ‘head-up’ postures by the Iberian Blue Tit. Several ecomorphological hypotheses obtained at the interspecific level with other taxa, have proved to be of high predictive value for explaining ecological differences considering morphological evolution. The Tenerife Blue Tit and the Iberian Coal Tit clearly show close convergence in both feeding postures and leg structure, although some differences in morphology were found between these two species. Convergence in foraging methods between the island Blue Tit and the mainland Coal Tit can be explained without considering current interspecific competition as a determinant of niche space.

Foraging postures of wapiti ( Cervus elaphus)

We distinguished ten foraging postures of wapiti and explored the ecological contexts in which they were used. Calves and adults had different foraging postures ( P<0.01). In level grassland and forest floor, pre-weaned calves grazed with forelegs apart (68% and 65%) or back arched (32% and 35%). In different habitats, adults used different feeding postures ( P<0.01). Adults grazed while standing when foraging in sedge meadow (61%) in early spring and on sloped grassland (56%) in late spring and summer. On level grassland, they were more mobile and grazed while walking (63%), often turning their heads aside or crossing their forelegs to reach for bites (7%). In the forest, wapiti also grazed while walking in late winter (72%) and summer (65%). In winter, wapiti continued to graze while walking (15%) and standing, (34%) but also browsed (25%) willow margins. Feeding station areas of grazing wapiti depended on head and neck lengths and neck angles. On level grasslands, calves had feeding station areas of 0.06±0.01 m 2. Feeding stations of yearlings and adults were 0.39±0.02 m 2 and 0.56±0.02 m 2 when grazing from a standing posture, and 0.21±0.01 m 2 and 0.30±0.01 m 2 when walking while grazing. The selection of postures seemed to be explained by foraging efficiency as affected by landscape and body proportions.

Neural control of Aplysia feeding posture by the food-arousal neuron C-PR.

Food stimili elicit a characteristic "feeding posture", in which the animal lifts the head and relaxes the anterior part of the foot. A pair of cerebral neuron, C-PR, may function as an important element that evokes a food-arousal state. The C-PR may also mediate the feeding posture by exciting or inhibiting many types of body postural motor neurons. In addition, it has longlasting modulatory effects on the movements of the neck and the anterior foot, which were produced by the motor neurons. These effects may be caused by modulatory neurons receiving monosynaptic excitatory inputs from the C-PR.

Embryonic and neonatal vocal elicitation of parental brooding and feeding responses in american white pelicans

Calls uttered by late-stage embryonic and neonatal American white pelicans, Pelecanus erythrorhynchos, and parental responses to them were observed during natural parent-offspring interactions and during playback experiments. Observations were all made during the hatching period, when the two-egg clutch consisted of various combinations of unpipped or pipped eggs and newly hatched chicks. From pipping onwards, embryos and neonates uttered short harsh squawks, especially when nest contents were exposed to ambient temperatures. Squawks elicited parental brooding responses that were characterized by foot shuffling over the nest, sometimes in association with pushing an egg or chick back towards the centre of the nest. Brooding responses usually ended with the parent resettling over the nest contents. Brooding response frequency increased with the number of squawks uttered per bout of calling, and was the usual response given to playbacks of squawk calls. After hatching, neonates also began to give a distinctive begging call. Long sequences of begging elicited a characteristic parental feeding posture accompanied by feeding. Parental feeding postures, but not actual feedings, were elicited by 1-min playbacks of begging calls. The data indicate that late-stage embryos and neonatal pelicans utter distinctively different calls for thermoregulatory and nutritional needs, and that parents respond appropriately with brooding or feeding responses designed to ameliorate these needs.

Activity Budgets, feeding behavior, and habitat use of pygmy chimpanzees at Lomako, Zaire.

Data from 250 hours of focal animal sampling in the Lomako Forest of central Zaire show pygmy chimpanzees spent 70% of feeding time on fruit and 25% on young leaves. Feeding and resting each accounted for about 40% and traveling less than 20% of the time. Sitting was the most frequent feeding posture. Locomotion was predominantly quadrupedal walking and quadrumanous climbing. Most feeding and resting occurred above 30 m. Pygmy chimpanzees spent most time in primary forest. Activity budgets varied with forest type. Most levels were used in each forest type. Pygmy chimpanzees spent most time in the canopy when in primary and slope (Bolafa) forests, and on the ground in secondary forest. These results show pygmy chimpanzees as arboreal, but habituation may have influenced the results. Pygmy chimpanzees at Lomako and Wamba have similar diets, despite differences in methods of data collection. At Wamba and Lomako, pygmy chimpanzees use secondary forest more and swamp forest less than expected given the abundance of each forest type at both sites.

Studies of Behavioral State in Aplysia.

This paper reviews a series of studies on the neural organization and the cellular mechanisms underlying behavioral states; in these studies, feeding behavior in Aplysia was used as a model system. Feeding in Aplysia has similarities to motivated behaviors in other animals and is modulated by a number of interesting state variables, including arousal. Food-induced arousal manifests itself in two categories of feeding behavior: (1) appetitive responses (e.g., head-up feeding posture and directed head turning), which orient the animal to potential goal objects such as food; and (2) consummatory responses (biting, swallowing), which obtain the goal object. The consummatory responses are rhythmic and relatively stereotyped, whereas the appetitive responses are highly variable. Our evidence suggests that one consummatory response, biting, appears to be controlled by command elements in the cerebral-ganglion, such as neuron CBI-2, which are capable of driving the behavior. One component of the appetitive behavior, head lifting, may be controlled (at least in part) by another cerebral neuron, C-PR. C-PR, however, affects numerous systems in the animal, but all the systems affected seem to be involved in the food-induced arousal state of the animal. We postulate that C-PR is, in some ways, analogous to command neurons that evoke behaviors. The C-PR, however, not only evokes a behavior, but also evokes a central motive state which aids in insuring that behavior is efficiently expressed.

Feeding postures of suspension-feeding larval black flies: the conflicting demands of drag and food acquisition.

We tested whether larval black flies actively control the positioning of their feeding appendages (labral fans), and if so, whether their posture represents a balance between the conflicting demands of drag and feeding. We compared the postures of live larvae with the postures of larvae killed by heat-shock in three different flow regimes in a laboratory experiment; we assumed that the postures of heat-killed larvae approximated a passive response to drag. The average height of the labral fans above the bed declined significantly in faster flows, and was significantly greater in live than dead larvae. There was also a significant interaction effect, since the difference between the fan heights of live and dead larvae was greater in slower flows. Two mechanisms may contribute to this result. Larvae in slower flows have to increase their fan heights more than larvae living in faster flows to achieve comparable increases in velocity and thus particle flux. In addition, muscular strength may limit the feeding postures larvae can assume. The fan heights of live larvae also varied depending on the concentration of food particles: larvae exposed to low food concentrations held their fans higher above the bed than did larvae exposed to high food concentrations in the same flow regime. This change in posture is due neither to an uneven particle concentration in the boundary layer nor to added drag from particles trapped in the labral fans. Collectively, our results indicate that these suspension feeders actively control their feeding posture, and suggest that these varying postures represent a dynamic balance between the conflicting needs of minimizing drag and maximizing feeding.

Appetitive feeding behavior of Aplysia: behavioral and neural analysis of directed head turning

The appetitive phase of feeding behavior in Aplysia consists of a behavioral sequence in which the quiescent animal starts to locomote and then assumes a characteristic feeding posture. In this position, head-turning responses can be elicited by a localized food stimulus (seaweed) delivered to the lips or tentacles. In response to brief (open loop) stimulation with seaweed, the animal turns toward the stimulus but greatly overshoots the target. However, the angular velocity and the final turning angle are a function of the eccentricity of the stimulus, progressively increasing with greater eccentricities. In a food-aroused animal, a brief tactile stimulus evokes turning and biting responses similar to those triggered by seaweed, which provides both tactile and chemical stimulation. Upon repeated tactile stimulation, however, the response magnitude decrements rapidly, whereas the magnitude remains high when turning responses are repeatedly elicited by food stimuli. A purely chemical stimulus sometimes can elicit a turning response, but chemical stimuli alone are much less efficacious than tactile stimuli alone. When the stimulus is maintained in a stationary position (closed loop), the animal turns until its mouth is oriented over the food. A turning response to a lateral stimulus can be reduced by an immediately following medial stimulus. To explain the above findings, we propose a form of response substitution, in which the response to the first, lateral stimulus is substituted by a weaker response to a more medial stimulus. No turning response is evoked when the animal is stimulated while performing spontaneous or evoked bites, though biting per se does not interrupt ongoing turning movements. In animals with lesions of the cerebral-buccal connectives, a food stimulus on the mouth is also followed by a reduction of the capacity of stimuli to elicit turning responses. In these lesioned animals, the food stimulus appears to elicit a bite command, though the biting behavior itself does not occur. Thus, it appears that the bite-related gating of stimuli is of cerebral origin, rather than due to the generation of the buccal motor program. The force necessary to power the turning movements was calculated from the trajectories of the movements. The results indicate that a power phase during the first half of the duration of the total movement is sufficient to generate a turn. The power phase can be followed by a brief gliding phase, and finally the movement appears to be actively terminated.(ABSTRACT TRUNCATED AT 400 WORDS)

Physical modeling of the batocrinid anal tube: functional analysis and multiple hypothesis testing

Baumiller, T. K. 1990 10 15: Physical modeling of the batocrinid anal tube: functional analysis and multiple hypothesis testing. Lethaia, VOL 23, pp. 399–408. Oslo. ISSN 0024–1164. Three hypotheses related to the function of the batocrinid anal tube were tested using physical models: (1) the anal tube served as a ‘rudder’, allowing the crinoid to passively maintain an effective feeding posture in moving water, (2) the tube served as a splitter ‘plate’, reducing the drag on the organism while it was in its feeding posture, and (3) the anal tube functioned as a ‘chimney’ by moving the anus downstream of the arms and thus reducing the risk of the organism ingesting its own wastes and/or gametes. Results of experiments performed in a recirculating flow tank suggested that the tube was well suited for the ‘chimney’ function: it reduced the concentrations of excreted matter in the proximity of the feeding appendages. Differences in rotational torques between models with a tube versus those without a tube implied that a large tube may have increased the rotational stability of the feeding posture in environments with variable current directions. No differences were detected between drag measurements on models with and without the anal tube; thus the ‘splitter-plate’ function of the tube was rejected. ▭Batocrinid anal tube, functional morphology, physical modeling.

Rotational stability in stalked crinoids and the function of wing plates in Pterotocrinus depressus

Baumiller, Tomasz K. & Plotnick, Roy E. 1989 07 15: Rotational stability in stalked crinoids and the function of win2–. plates in Pterotocrinus depressus. Lethaia, Vol. 22, pp. 317–326. Oslo. ISSN 0024–1164. An unusual feature of the Mississippian camerate crinoid Pterotocrinus depressus is its tegmen with five wing-like appendages (wing plates). It has been suggested that the wing plates served as anti-predatory devices, hydrodynamic baffles, or outriggers for stabilization and support on the substrate. We propose two alternative hypotheses. First, the wing plates may have served as splitter plates, which would have acted to reduce drag on the organism. Second. wing plates served as stabilizing fins or rudders, allowing the passive maintenance of an efficient feeding posture in moving water. Experimental analyses of the forces acting on model crinoids, with and without the wing plates, support the hypothesis of the rudder function. A model developed for maintenance of stability in moving water should be applicable to all suspension feeders. *Crinoids, paleobiomechanics, biological rudders.

Multiple measures of hand-use lateralization in the ring-tailed lemur (Lemur catta).

Evaluated a free-ranging matriline of 13 ring-tailed lemurs (Lemur catta) from videotaped records for lateralized hand use with 2 tasks and 4 measures: food reaching, feeding posture, duration of food holding, and manipulation of food between mouth and hand while eating. Binomial z scores determined 7 lemurs to be left preferent in reaching, 3 right, and 3 ambipreferent. Ideographic analyses suggested possible sex-linked and early experience twin effects. When compared to right and ambipreferent lemurs, left reach preferent lemurs used the left hand more but bimanuals grasped less in food holding and also engaged in less hand-mouth food manipulation. The tendency to manipulate food was not correlated with bimanual holding but was inversely related to left hand holding and directly related to right hand holding. These patterns are discussed as possible precursors of human bimanual manipulation.

Risk of predation and foraging behaviour in shoaling banded killifish (Fundulus diaphanus)

While foraging for patchily distributed benthic prey in the laboratory, solitary and shoaling banded killifish reduced their per capita rate of feeding attempts and shortened the duration of their feeding posture (when sampling outside the food patches) in the presence of a predatory brook charr. This presumably allowed more time for predator vigilance and avoidance. Individual feeding rate was independent of shoal size, in either the presence or absence of a predator. Solitary fish thus incurred only a slightly greater predator-mediated relative cost of lost foraging opportunities compared with shoaling fish. Killifish therefore altered their foraging behaviour to reduce risk of predation in the presence of a predator and appeared to trade off risk of mortality and energy gain.

The biology and functional anatomy of Modiolarca tumida (Musculus marmoratus) Bivalvia: Mytilidae

Modiolarca tumida (Hanley, 1843) is a member of the sub‐family Crenellinae (Mytilidae). The preferred habitat of the species is the test of certain ascidians. The shell is dorsally flattened, which prevents it from cutting into the test during dorso‐ventral contraction of the byssal retractors. The use of the byssus enables it to surround itself completely with host tissue. Adoption of the feeding posture involves the anterior‐posterior contraction of the byssal retractors, which elevates the posterior margin above the host's surface using the anterior margin as the fulcrum against the host. Modiolarca tumida are attracted by the tunicin of the host, a process probably facilitated by the host's feeding currents. The smallest individuals are found round the oral aperture. Colonization of other parts of the host may result from surface migration as M. tumida can be highly mobile, crawling by means of the very extensible foot. It is during this process that individuals may be swept away in local currents and be forced to adopt a free‐living existence.

Phagostimulation ofLytechinus variegatus(Lamarck) (Echinodermata: Echinoidea)

Artificial agarose foods containing either starch, glycogen, carragheenan, alginate, casein, gelatin, albumin, or peptones at a concentration of 1% dry weight were not phagostimulatory. Artificial foods containing sugars, especially galactose, at a concentration of 0.005 M were phagostimulatory. Of the common amino acids, only L‐phenylalanine was phagostimulatory at this concentration. The initiation of feeding postures (movement of the spines, tube feet, peristome, and Aristotle's lantern) of Lytechinus variegatus was little affected by the concentration of plant extracts. Many aspects of this behavior were attributable to physical rather than chemical stimulation. Feeding rates of L. variegatus upon artificial agarose foods containing either Thalassia testudinum or Gracilaria verrucosa were directly dependent upon plant tissue concentration. All artificial agarose food‐items were initially moved to the mouth and fed upon, however the time spent feeding was directly dependent upon plant type and tissue c...

Autumn and winter feeding ecology of waterfowl at the Ouse Washes, England

The potential foods available to waterfowl at the Ouse Washes in autumn and winter are described. All were commonly found in the river, pool, marsh and flooded grassland habitats of the washes and in the surrounding arable fields. Gadwall Anas strepera, Wigeon A. penelope, Moorhen Gallinula chloropusand Coot Fulica atramainly consumed vegetative foods, especially the leaves of grasses and in the case of the first named, water plants. Mallard A. platyrhynchos, Pintail A. acuta, Teal A. crecca, Pochard Aythya ferinaand Moorhen fed extensively on fruits and seeds with the first three species supplementing their diets with cereal grains from stubbles. Shoveler A. clypeata, Tufted duck Aythya fuligula, Pochard and Moorhen consumed the largest amounts of invertebrates. Within these three groupings there were further interspecific differences in diet. With most species diets also differed under low and high floods, being most similar under the latter. Amongst the dabbling ducks Anasspp. there were differences, probably minor, in foods taken attributable to differences in the bill lamellae on the outer margins of the upper jaw.The feeding methods used under low and high floods are described and some differences may further serve to ecologically separate the waterfowl. There was a high degree of adaptability, especially amongst the dabbling ducks, with some species changing the feeding postures completely under high floods. All species fed diurnally. Wigeon, Gadwall, Coot and Moorhen all fed for at least 90% of the daylight hours. Shoveler, Teal, Mallard and Pintail were most active in the mornings and afternoons. A partially objective analysis of ecological niches shows that all but two species pairs were clearly separated by either habitat or food factors. There is some overlap between Pochard and Tufted duck and greater overlap between Mallard and Pintail. This may be because they are utilizing the temporarily abundant foods present at this site.

Seasonal dynamics of resource partitioning among foliage-gleaning passerines in northern Finland.

The five most abundant species were included in a year-round study with respect to six foraging niche dimensions. Approximately full multidimensional utilization functions were used for niche metrics. During summer foraging overlaps were invariably high, but in other seasons periodically lower. Foraging site breadth was lower in winter, when fewer sites are profitable for foraging than in summer. Feeding posture versatility, by contrast, was highest in winter. Seasonal foraging shifts were very prominent, as great in fact as between-species differences. Often seasonal trends were parallel in different species. Niche axes of macrohabitat-type (e.g. tree) were more open for foraging variation and axes of microhabitat-type (tree part) more rigid. Among the resident species seasonal variation in foraging was greatest in Regulus regulus and Parus cristatus, whereas the foraging behaviour was more stable for P. montanus (an abundant species with broad niche), perhaps owing to greater intraspecific competition. In these northern forests foliage-gleaners must be versatile generalists to cope with the unpredictable resources, and thus they overlap broadly in their general resource niches which are determined by their genetically fixed cost and benefit relations to each resource type. Anyhow, presumably during periodical food shortage, the actual resource uses adjusted by resource availability and competition may overlap narrowly.

Locomotion and posture in Ateles geoffroyi and Ateles paniscus.

The locomotor and postural behavior of Ateles geoffroyi and Ateles paniscus was studied in Panama and Surinam. Ateles locomotion can be divided into five patterns on the basis of limb usage: quadrupedal walking and running, suspensory locomotion, climbing, bipedalism and leaping. The first three are commonly used in both locomotion during travel and locomotion during feeding, but climbing (especially 'horizontal climbing') is the most important pattern during feeding. Most Ateles locomotion takes place on twigs and branches, with twigs playing a greater role in feeding than in travel. Feeding postures are mainly suspensory and seated, short resting postures are suspensory, seated and standing, and long resting postures are almost entirely seated and reclining. Twigs are the most important supports in feeding postures, but branches are much more important in resting postures. The results of this study indicate that the quadrumanous climbing, forelimb-dominated locomotion during feeding that FLEAGLE considers the primary hominoid adaptation is also characteristic of Ateles.

Biodynamic and phyletic paradigms for sensory organs in camerate crinoids

A Haugh, Bruce N. 1978 04 IS: Biodynamic and phyletic paradigms for sensory organs in camerate crinoids Functional analysis of thecal pores and associated fixed pinnules of camerate crinoids reveals that they may have been organized into an integrated current-sensing biologic system. Paleobiologic, biodynamic, and geometric evidence reveals a potential for sensing the direction and intensity of horizontal water currents. An ahistoric paradigm predicts that the inferred sensory organs could have elicited several alternative feeding postures and a survival posture in response to current intensity. Possession of long anal tubes is judged to be related to the sensory function. By virtue of these adaptations certain camerates may have been discriminatory rheophilic feeders in complex fdter feeding communities. An historically founded phyletic paradigm suggests that a functional change in thecal pores and pinnules occurred in the Early Mississippian as an evolutionary concourse in several independent lineages. This specialized sensory innovation may have signifcantly contributed to the ‘flowering’ of camerates in rheic carbonate environments as well as their demise in terrigenous clastic environments. Phyletic paradigms illustrate the advantage of functional analysis of fossil structures at several points in time and especially at the acme of development when structure and function are commonly most clearly delimited.

Feeding mechanisms and feeding strategies of Atlantic reef corals

The feeding behaviour of 35 species of Atlantic reef corals was examined in the laboratory and in the field. Observations were made during the day and at night, using freshly hatched brine shrimp nauplii and finely ground, filtered fresh fish as food sources. Three feeding strategies were observed: Group I–feeding by tentacle capture only; Group II–feeding by entanglement with a mucus net or mucus filaments; Group III–feeding by a combination of tentacle capture and mucus filament entanglement. Group I included corals of the families Poritidae and Pocilloporidae which were normally expanded during both day and night. Group II included corals of the family Agaricidae which were normally expanded at night and contracted during the day. Group III included corals of the other families examined which, with the exception of Dendrogyra cylindrus, were normally expanded only at night.Feeding responses were elicited by both chemical and tactile stimuli. A preparatory feeding posture was assumed in response to chemical stimuli and consisted of horizontal positioning of the tentacles, elevation of the oral disk to form a cone‐like mouth, a wide mouth opening and secretion of mucus by the epidermis of the oral disk. Following the assumption of the preparatory feeding posture, food capture and ingestive movements were elicited by tactile stimuli. However, food capture and ingestive movements were also elicited by chemical stimuli alone in those species which were normally contracted during the day.While expanded corals captured food with their tentacles or with mucus filaments, contracted corals were able to feed by capturing fine particulate matter with mucus filaments only and thus acted as suspension feeders. By a combination of feeding strategies, reef corals were able to feed both day and night and a wide range of potential food ranging from fine particulate matter to large zooplankton was available to them.

Cleaning behaviour in the centrarchid fishes, Lepomis macrochirus and Micropterus salmoides

Cleaning symbiosis is reported for centrarchid fishes in their natural habitat at Everglades National Park, Florida. Intraspecific cleaning behaviour among conspecifics of the bluegill sunfish Lepomis macrochirus, as well as interspecific cleaning behaviour between L. macrochirus and the largemouth bass Micropterus salmoides, is described. Juveniles of L. macrochirus acted as intraspecific cleaners, adults as interspecific cleaners. Clients displayed a characteristic head-stand pose during cleaning encounters. The evolution of this cleaning invitation pose may be related to an inclined feeding posture frequently utilized by centrarchid fishes. Cleaning stations appeared to exist with regard to interspecific cleaning. Cleaning behaviour may be a seasonal phenomenon in the Everglades.