Cercocebus torquatus: Adaptive feeding and ranging behaviors related to seasonal fluctuations of food resources in the tropical rain forest of south-western Cameroon

The feeding and ranging behaviors of mangabeys,Cercocebus torquatus torquatus Kerr (1792), were studied over two periods for a total of 15 months in south-western Cameroon between 1983 and 1986. The mangabeys showed stable food acquisition, mainly of fruits produced by canopy trees. Their ranging area, especially the core area, shifted seasonally. The fruiting trees revealed a clumped distribution in space, and provided a fluctuating food resource for frugivores, including the mangabeys. The core area of the mangabeys possibly shifted due to the spatial distribution of fruiting trees, their highest ranking food items. Mangabeys are well adapted to such a fluctuating food distribution, regulating their ranging behaviors to ensure stable food acquisition.     

Hand preference in unimanual and bimanual tasks and postural effect on manual laterality in captive red-capped mangabeys (Cercocebus torquatus torquatus)

Hand preference in 11 captive red-capped mangabeys (Cercocebus torquatus torquatus) was examined under different conditions: a free situation during spontaneous food processing, three different postural conditions (brachiating, and bipedal and tripedal standing), and a situation involving bimanual processing. Generally, individual laterality was found regardless of the task and behavior involved. However, the number of monkeys with hand preferences and the strength of the preference increased with the complexity of the tasks. The monkeys exhibited a significantly higher and positive mean manual preference index (HI) when they were hanging than when they were quadrupedal or sitting. The strength of manual preference (ABS-HI) was in turn higher when the monkeys were hanging or bipedal than when they were quadrupedal. The strength of manual preference was higher for both the bimanual and experimental tasks than for unimanual tasks and spontaneous activities. Although our sample was too small to allow us to make any generalizations concerning lateral preferences in red-capped mangabeys, we propose some hypotheses about the influence of posture stability and task complexity.     

Evidence for sexually selected infanticide in captiveCercopithecus mitis,Cercocebus torquatus,andMandrillus leucophaeus

Adult resident males of one-male-multi-female primate groups housed at the Hannover Zoo exhibited aggression, when confronted with nonadult individuals, which were fathered by other males: (1) a new adult resident male in a group of blue monkeys killed a 5.8-month-old female infant: (2) a new adult resident male in a group of white collared mangabeys injured a 24.0-month-old female and an 18.9-month-old male severely; they would have died without veterinary care; and (3) the resident male of a group of drills threatened an 1.8-month-old foreign female infant seriously; efforts to introduce the infant were discontinued. Pathological explanations are unlikely because the adult males showed no aggression towards own nonadult offspring under the same captive conditions. By and large, the events support the theory that infanticide is the result of sexual selection among males.     

Observations on the activity patterns and social interactions of a captive group of blackcapped or brown capuchin monkeys (Cebus apella)

Studies were conducted on a captive group of 16 blackcapped capuchin monkeys (Cebus apella), with observations being carried out for a total of 75 hr over a 6 month period. Records were kept of their activities and spatial distribution according to weather type and time of day. Evidence of a social hierarchy was sought and was characterized primarily by the stability of the environment in which the animals live, dominance playing little part. The behaviour of the blackcapped capuchin has been studied previously in captivity (Dobruruka, 1972;Weigel, 1979); this study is, however, unique in that the troop under observation enjoys more freedom. Weather had no effect on the rank order of behavioural activities but did affect both activity levels and distribution of individuals. TheCebus apella troop spent around 50% of its active time foraging and eating, 7–10% of this time walking and around 30% of the time inactive. These values lie between those reported for caged and wild animals. Social interactions contributed more than 10% of the time budget, which is greater than wild populations. The study here thus provides an interesting link between information collected from wildCebus apella populations and that from rather more restricted troops.     

Effects of location of food delivery and social status on foraging-site selection by juvenile Atlantic salmon

Synopsis Experiments were conducted to investigate the response of juvenile Atlantic salmon,Salmo salar, to changes in the location at which food entered a stream tank. Experience with the location of food input into the system significantly influenced foraging-site selection by the dominant fish. Dominant fish changed location of their foraging site in response to a change in the location of food input, and occupied, aggressively defending, sites just downstream of the location of food introduction. In contrast, subordinate fish occupied foraging sites at the downstream end of the stream tank, regardless of location of food input. As a result of both site selection and social status, dominant fish captured significantly more prey than subordinates. Our results support the contention that salmonids choose foraging sites to maximize foraging opportunities. Our results also provide a possible explanation for the use of atypical foraging sites by individual fish within their home range over the course of a single day, as observed in a number of salmonid species in the field.     

Annual changes in body mass in captive Svalbard ptarmigan: role of changes in locomotor activity and food intake

The influence of changes in the amount of locomotor activity on the annual body mass cycle was investigated in captive Svalbard ptarmigan kept indoors at thermoneutrality and exposed to seasonal changes in daylength or continuous light from the summer onwards. In both groups there was a close correlation between locomotor activity and metabolic rate. Only birds exposed to changes in daylength showed an annual cycle in locomotor activity, with low activity in autumn and mid-winter and a peak in spring. The birds permanently exposed to continuous light had a relatively low activity throughout the year with no systematical changes. Body mass began to increase in both groups in early autumn and the food intake was elevated during most of the following fattening period. It is concluded that elevated food intake is the prime factor involved in autumnal fattening in captive Svalbard ptarmigan. Body mass increased significantly faster under decreasing daylength compared with continuous light, associated with a lower activity as well as a higher food intake. The birds exposed to continuous light maintained a high body mass and a relatively low activity level during spring. In birds exposed to changing daylength, body mass fell from late February onwards, which is about 3 months later than in outdoor caged or free-living Svalbard ptarmigan. In the birds exposed to increasing daylength a fourfold increase in the amount of locomotor activity occurred from February to April. This increased activity was correlated with a negative energy balance and may be casually associated with the fall in body mass in these birds. Under outdoor conditions, elevated locomotor activity in spring may be responsible for a continuation of the decline in body mass commencing in November, despite a slight tendency for an increased food intake towards the end of this period.Abbreviations BM body mass - CE_f caloric equivalent of food - EAE energy assimilation efficiency - EE energy expenditure - FI food intake - LA locomotor activity - LL continuous light - LD simulated annual changes in daylength - MEI metabolizable energy intake - MR metabolic rate - RQ respiratory quotient     

Influence of probiotic feeding duration on disease resistance and immune parameters in rainbow trout

The effect of feeding the probiotic Kocuria SM1 to rainbow trout (Oncorhynchus mykiss, Walbaum) on disease resistance was evaluated. Thus, rainbow trout were fed Kocuria SM1 supplemented diets at concentrations of 10⁸ cells g⁻¹ feed for up to four weeks, and then challenged intraperitoneally with Vibrio anguillarum at weekly intervals. A two-week feeding regime led to the maximum reduction in mortalities, i.e. 16%, compared to mortalities of 62, 30 and 22% for one, three and four week feeding regimes, respectively. These compared to 70–90% mortalities of the controls. An enhanced cellular and humoral immune response, notably greater head kidney macrophage phagocytic and peroxidase activities, and higher serum lysozyme and total protein levels were recorded after two weeks of probiotic administration. These results reveal that a two-week feeding regime with Kocuria SM1 leads to higher disease protection in rainbow trout, with protection linked to stimulation of immune parameters.     

The effect of randomly altering the time and location of feeding on the behaviour of captive coyotes (Canis latrans)

Captive carnivores appear highly susceptible to the negative effects of predictable feeding routines. Current research and reviews suggest feeding unpredictably may increase species typical behaviour, but positive results have been limited to a few species. Our objectives were to determine whether randomly altering the time and location of feeding increased species typical behaviour, or affected the temporal distribution of captive coyote (Canis latrans) behaviour. We assigned 12 coyotes individually to either a predictable or an unpredictable (in time and location) feeding condition and measured behaviours in the morning and evening. Overall, mean time spent foraging, travelling, resting or standing was similar in both conditions, but coyotes in the unpredictable condition marked (118 vs. 42; P = 0.01, one-tailed) and howled (81 vs. 24; P = 0.05, one-tailed) significantly more than coyotes in the predictable condition. There were also significant temporal differences (a.m. vs. p.m.) in behaviour between conditions. Specifically, coyotes fed predictably foraged (P = 0.03) and travelled (P = 0.03) more in the morning and rested (P = 0.03) more in the evening, whereas coyotes fed unpredictably howled (62 vs. 19; P = 0.03) and stood (P = 0.05) more in the morning and foraged (P = 0.03) more in the evening. Optimum predictability for captive carnivores should be based on species-specific captive study results and relevant ecological data. Our results suggest coyote feeding regimes may be improved by including unpredictable elements nested within a predictable framework to mirror seasonal fluctuations in resources and increase species-specific behaviour in captivity.     

Plasma ghrelin levels in rainbow trout in response to fasting, feeding and food composition, and effects of ghrelin on voluntary food intake

Ghrelin, a peptide hormone which stimulates growth hormone (GH) release, appetite and adiposity in mammals, was recently identified in fish. In this study, the roles of ghrelin in regulating food intake and the growth hormone (GH)-insulin-like growth factor I (IGF-I) system of rainbow trout (Oncorhynchus mykiss) were investigated in three experiments: 1) Pre- and postprandial plasma levels of ghrelin were measured in relation to dietary composition and food intake through dietary inclusion of radio-dense lead-glass beads, 2) the effect of a single intraperitoneal (i.p.) injection with rainbow trout ghrelin on short-term voluntary food intake was examined and 3) the effect of one to three weeks fasting on circulating ghrelin levels and the correlation with plasma GH and IGF-I levels, growth and lipid content in the liver and muscle was studied. There was no postprandial change in plasma ghrelin levels. Fish fed a normal-protein/high-lipid (31.4%) diet tended to have higher plasma ghrelin levels than those fed a high-protein/low-lipid (14.1%) diet. Plasma ghrelin levels decreased during fasting and correlated positively with specific growth rates, condition factor, liver and muscle lipid content, and negatively with plasma GH and IGF-I levels. An i.p. ghrelin injection did not affect food intake during 12-hours post-injection. It is concluded that ghrelin release in rainbow trout may be influenced by long-term energy status, and possibly by diet composition. Further, in rainbow trout, ghrelin seems to be linked to growth and metabolism, but does not seem to stimulate short-term appetite through a peripheral action.     

Factors affecting feeding decisions in a group of black lemurs confronted with novel food

The behavior of black lemurs presented with novel and familiar food in the presence or absence of the dominant female was analyzed in order to examine the influence of the latter on feeding decisions at a group level. Results showed that individual learning occurred with high quality food, while the dominant female influenced the eating behavior of other group members when food was of low attractiveness or unfamiliar.     

Sex differences in food acquisition and aggression in captive common marmosets (Callithrix jacchus)

Competition for food within the social group has been postulated as an important factor affecting primate social organization. This study examined how factors such as sex, aggression, dispersion of food, and amount of difficulty involved in obtaining food affect the distribution of food in common marmoset (Callithrix jacchus) social groups. Mated pairs of adultC. jacchus were presented with food that was either dispersed or concentrated, and either difficult or easy, to obtain. The number of food pieces obtained, aggressive displays, incidents of physical aggression, and amount of time spent searching for food were recorded for each animal. Neither dispersion nor difficulty in obtaining food had significant effects on the distribution of food or any of the other behaviors examined. The primary factors affecting food distribution were aggression and amount of time spent searching. Females obtained more food than males in all situations because they were more aggressive and apparently more motivated to search for food than were males.     

Responses of foster-mothers and troop members to adopted newborns in a captive group of rhesus monkeys

Two rhesus monkey males and two females, born to females caged singly, were exchanged with same-sex infants born to females in a large troop which was held in an enclosure in a different building. The ages of the infants were between 24 and 120 hr. The selected foster mothers (FMs) immediately accepted the foreign infants, allowed them to suckle and treated them as their own offspring. Compared with interactions with previous offspring, the FMs initially tended to be more possessive and restrictive of their foster infants: generally they took longer before they allowed the infants to sit at a distance from them and more readily retrieved them. The foster infants tended to be more active (‘fidgety’) than natural (control) offspring born to the troop. Non-related members of the troop, differentiated between foster and control groups. These troop animals more frequently approached and sat in proximity, often in fur-contact with, touched, groomed, and lipsmacked to, foster infants than control infants. The attractiveness of the fostered infants seemed to be slightly associated with the FMs' dominance rank. The foster infants were therefore viewed by others as having assumed the role afforded by the FMs' rank. Thus both FMs and other troop members recognized the unfamiliarity and novelty of the foster infant but the infants were still accepted into the group. We suggest that the different treatment of the foster infants by the troop may have consequences on the infants' future social development.     

Wound-induced changes in tomato leaves and their effects on the feeding patterns of larval lepidoptera

Several studies have shown changes in the patterns of damage from feeding insects associated with changes in palatability and overall consumption as a result of wound-induced chemical changes in plants. This paper describes how the pattern of feeding damage made by the larvae of Spodoptera littoralis Boisd. (Lepidoptera: Noctuidae) on tomato is affected by changes in palatability of the leaves. Two sorts of responses to leaves from plants that had received prior damage were observed. Larvae offered a choice of leaves tended to take fewer meals on leaves from previously-wounded plants than on control leaves, frequently rejecting the former after sampling them. On wounded plants this rejection behaviour was associated with a shift in feeding site towards the base of the plant. However, starved larvae offered only a single excised leaf readily ate leaves from wounded plants but took shorter meals on these leaves than on controls. Although it was not directly tested it is possible that this difference in response reflected changes in food selectivity with a differing level of satiation. The results are considered in relation to the adaptive significance of the plant of changes in within-plant distributions of herbivore damage.     

Variations in competitive mechanisms of captive male hamadryas-like baboons in two feeding situations

Experiments were carried out to determine the influence of food distribution (clumped vs dispersed) on processes of competition among seven captive male hamadryas-like baboons. Spatial cohesion, cohesive behaviours that males performed and received from their females, and aggressive and feeding behaviours of the males were collected during 35 min after food supply. Median values and variability of these variables were compared in both the feeding situations. Food distribution influenced both asymmetries in access and the form of competition. When food was clumped, those with less access fed by means of compensatory or alternative strategies (away from the main source and/or by feeding supplants), and they were more aggressive towards other males. When food was dispersed, all individuals could feed simultaneously, males that were more aggressive were those with less cohesive OMUs, despite the fact that cohesive behaviours remained constant. Females appeared to contribute to variation in the OMU's cohesion through their responses to both food distribution and males' competitive ability.     

Habitat use and feeding behavior of thirteen species of benthic stream fishes

Synopsis The densities, habitat use, and feeding behaviors of 13 fish species belonging to the benthic invertebrate-feeding guild were studied by snorkeling at three localities in the Little River of eastern Tennessee, U.S.A. Resource partitioning occurred by habitat, feeding behavior and time of activity. Differences were also found at the generic level.Cottus was a nocturnal feeder, whereasPercina andEtheostoma were, for the most part, diurnally active.Percina moved about rapidly and spent most of its time above the bottom. In contrast,Etheostoma varied considerably in the amount of time spent under cover, spent little time above the bottom, and exhibited low levels of swimming activity. Nearly all species sought cover at night, suggesting they may be particularly sensitive to predation at night. Species with small adult sizes (Etheostoma, Cottus andP. evides) were concentrated in shallow water habitats, whereas species with large adult sizes (Percina) were more abundant in deep water habitats. The habitat use data are consistent with the hypothesis that size-selective predation by centrarchid bass may cause smaller fish to avoid deep water areas. Large species should have a lower risk of predation due to their size and behavior.     

Metabolic response to feeding in the Chinese striped-necked turtle, Ocadia sinensis

We measured oxygen consumption in juvenile Chinese striped-necked turtles (Ocadia sinensis) after they ingested food, either as a single meal or as double meals, to examine the influence of meal type and feeding frequency on specific dynamic action (SDA). Temporal variation in oxygen consumption after feeding was evident in the ingesting turtles but not in the unfed control turtles. In the single-meal experiment, the peak metabolic rate and the integrated SDA response (the whole energetic cost for the processes of digestion) both did not differ between turtles ingesting mealworms and shrimps when the influence of variation in ingested energy was removed, and the time to reach peak metabolic rate was not affected by meal type and the amount of food ingested. Turtles in the double-meal experiment ingested more energy and hence had a prolonged duration of SDA response than did those in the single-meal experiment, but the integrated SDA response did not differ between both experimental treatments when the influence of variation in ingested energy was removed. Our results show that meal type and feeding frequency have important consequences on the SDA response of juvenile O. sinensis. As the integrated SDA response remained remarkably constant either between turtles ingesting different food or between turtles ingesting the same food but at different frequencies when the influence of variation in ingested energy was removed, we therefore conclude that the energetic cost associated with ingestion is primarily determined by energy content of food ingested in juvenile O. sinensis.     

Larval parasitism of the autumnal moth reduces feeding intensity on the mountain birch

Plants respond to grazing by herbivorous insects by emitting a range of volatile organic compounds, which attract parasitoids to their insect hosts. However, a positive outcome for the host plant is a necessary precondition for making the attraction beneficial or even adaptive. Parasitoids benefit plants by killing herbivorous insects, thus reducing future herbivore pressure, but also by curtailing the feeding intensity of the still living, parasitised host. In this study, the effect of parasitism on food consumption of the 5th instar larvae of the autumnal moth (Epirrita autumnata) was examined under laboratory conditions. Daily food consumption, as well as the duration of the 5th instar, was measured for both parasitised and non-parasitised larvae. The results showed that parasitism by the solitary endoparasitoid Zele deceptor not only reduced leaf consumption significantly but also hastened the onset of pupation in autumnal moth larvae. On the basis of the results, an empirical model was derived to assess the affects on the scale of the whole tree. The model suggests that parasitoids might protect the tree from total defoliation at least at intermediate larval densities. Consequently, a potential for plant–parasitoid chemical signalling appears to exist, which seems to benefit the mountain birch (Betula pubescens ssp. czerepanovii) by reducing the overall intensity of herbivore defoliation due to parasitism by this hymenopteran parasitoid.     

Influence of food size and food quantity on the feeding of the mussel Dreissena polymorpha

Summary In common with many other suspension feeders, the freshwater mussel Dreissena polymorpha has a maximum filtration rate at low food concentrations and a maximum ingestion rate at high food concentrations. These high rates, which reflect the potential maximum food uptake of the animal, are called the filtration capacity and the ingestion capacity respectively. The ingestion capacity was attained without forming pseudofaeces with Chlamydomonas reinhardii as food. The incipient limiting level could be calculated as the quotient of these two values. A decrease of the filtration rate at high food concentrations was correlated with changes in pumping activity, which showed more frequent interruptions, or a lower level of water transport. Dreissena can filter out particles of diameter greater than 0.7 m from the water. Retention reaches a plateau at about 5 m particle diameter. Scanning electron micrographs of the arrangement of the cilia on the gill filaments are given.     

Resolving within- and between-population variation in feeding ecology with a biomechanical model

Studies of phenotypic plasticity have emphasized the effect of the environment on the phenotype, but plasticity can also be used as a tool to study the functional significance of key traits. By inducing variation in phenotypes and testing quantitative models that predict performance based on biological mechanisms, we can develop functionally general models of performance. Pumpkinseed sunfish from lakes with high snail availability have large levator posterior muscles (which are used to crush snail shells), whereas fish from lakes with few snails have relatively small muscles. Here we: (1) quantify differences in the feeding ability of an ontogenetic series of pumpkinseed from two populations; and (2) evaluate whether a biomechanical model can resolve the observed ontogenetic and between-population variation in feeding ecology. Mass, but not length, of the levator posterior muscle in fish from Three Lakes (a lake rich in snails) was greater than for comparably sized fish from Wintergreen Lake (a lake with few snails). Handling times were shorter, crushing strengths were 71% greater, and foraging rate (snail tissue mass consumed per time) and the fraction of thick-shelled snails in the diet were approximately 100% greater for fish from Three Lakes compared to comparably sized fish from Wintergreen. These between-lake differences were not significant after adjusting for variation in pharyngeal morphology, suggesting that the biomechanical model of snail crushing resolved observed ontogenetic and population-level variation in the feeding ecology of pumpkinseed.     

Ontogenetic changes in diel activity,food habits and spatial distribution of juvenile and adult creek chub,Semotilus atromaculatus

Synopsis Juvenile creek chub, Semotilus atromaculatus, differed ecologically from adults. They were essentially diurnal, fed on small prey (adult diptera and aquatic adult coleoptera) and were found mainly in shallow littoral water (0.8 m depth) of a Québec oligotrophic lake. In contrast, adults were principally nocturnal, fed on larger prey (Gammaridae, diptera larvae, diptera pupae and ephemeroptera larvae) and were found in deeper water (1.2, 2.0 and 2.9 m depth). The overlap in diet between juvenile and adult fish was 10 percent. We found that predation by brook charr, Salvelinus fontinalis, upon creek chub was low, as only 5 chart stomachs of the 302 examined contained a total of 16 juvenile chub and none contained adult chub. Laboratory observations revealed that under low light intensity (0.17 lux) adult creek chub fed as efficiently as under high light intensity (22 lux). Several possible hypotheses to explain the evolution of the two different strategies exhibed by adult and juvenile creek chub are discussed.