Vigilance Behaviour in Grazing African Antelopes
TL;DR: Time spent looking varied with position within the group; this effect was strongest in closed habitats, where central animals tended to scan least and feed most, and within species, animals inclosed habitats, those with dense vegetation, tended to spend more time in looking than did animals in the open.
Abstract: African antelope may devote a large proportion of their foraging time to looking around. The factors affecting such vigilance behaviour are examined for grazing antelope, five species being studied in detail. The proportion of time spent looking decreased as species body weight increased. Within species, animals in closed habitats, those with dense vegetation, tended to spend more time in looking than did animals in the open. There was some evidence that vigilance, presumably for predators, was shared by group members, but in one species, impala, vigilance apparently increased with group size and with proximity to neighbours. Time spent looking varied with position within the group; this effect was strongest in closed habitats, where central animals tended to scan least and feed most. Vigilance increased as feeding success decreased, partly due to mutual interference between looking and feeding. The possible social, foraging and predator-detection values of vigilance are discussed. A simple model is introduced to help explain the effects of cover and to facilitate further discussion.
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TL;DR: It is clear that both brain hemispheres play significant roles in social responses, while their relative contribution is likely determined by a complex set of motivational and emotional factors rather than a simple dichotomous distinction such as approach versus withdrawal motivation.
Abstract: Two brain hemispheres are unequally involved in the processing of social stimuli, as demonstrated in a wide range of vertebrates. A considerable number of studies have shown the right hemisphere advantage for social processing. At the same time, an approach–withdrawal hypothesis, mainly based on experimental evidence, proposes the involvement of both brain hemispheres according to approach and withdrawal motivation. The present study aimed to test the relative roles of the two hemispheres in social responses displayed in a natural context. Visual biases, implicating hemispheric lateralization, were estimated in the social interactions of saiga antelope in the wild. In individually identified males, the left/right visual field use during approach and withdrawal responses was recorded based on the lateral head/body position, relative to the conspecific. Lateralized approach responses were investigated in three types of interactions, with left visual field bias found for chasing a rival, no bias—for attacking a rival, and right visual field bias—for pursuing a female. In two types of withdrawal responses, left visual field bias was found for retreating after fighting, while no bias was evident in fight rejecting. These findings demonstrate that neither the right hemisphere advantage nor the approach–withdrawal distinction can fully explain the patterns of lateralization observed in social behaviour. It is clear that both brain hemispheres play significant roles in social responses, while their relative contribution is likely determined by a complex set of motivational and emotional factors rather than a simple dichotomous distinction such as, for example, approach versus withdrawal motivation.
11 citations
Cites background from "Vigilance Behaviour in Grazing Afri..."
...Such chasing, often referred as herding behaviour (Underwood 1982), helps males to keep females together and is observed throughout the year, while the mating itself takes place only during the rut in winter (Bekenov et al....
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...Such chasing, often referred as herding behaviour (Underwood 1982), helps males to keep females together and is observed throughout the year, while the mating itself takes place only during the rut in winter (Bekenov et al....
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Dissertation•
01 Jan 2013
TL;DR: The findings of this study indicate that a population at the edge of their species’ ecological tolerance are forced to considerably adapt behaviourally to seasonally and spatially varying resources and risk.
Abstract: Food acquisition and predator avoidance are principal components of the survival strategies of all primates. However, for primates, maximising food acquisition whilst minimising predation risk is often impossible. This leads to the existence of the foraging/risk trade-off, a mechanism fundamental in shaping life histories, species interactions and ultimately community assemblage. The principal aim of this study was to investigate how samango monkeys (Cercopithecus mitis erythrarchus) strategically balance the foraging/risk trade-off when exposed to spatially and temporally varying resources and risk.
Data were collected on a habituated group of samango monkeys over a 12 months observational period at the Lajuma Environmental Research Centre, South Africa. The focal group are part of a population near the southerly limit of the most southerly ranging African, primarily arboreal, monkey species. A biogeographical approach was also used, utilising ecological data from 12 different populations of C. mitis from a number of field sites across the species’ distribution.
Cold, dry winter periods were associated with increased time spent feeding and decreased in time spent resting. During winter months the samangos supplement their diet with foliar material, most likely due to the increased energetic requirements of maintaining body temperature. On a geographical scale, southern populations of samango have significantly more fruit in their diet than their more equatorial relations; whilst the opposite pattern is apparent involving the amount of animal matter consumed. On a spatial scale resources appear to be less important in determining samango ranging behaviour than the risk of predation. The study group actively avoid areas of perceived eagle predation risk, even though resources, such as food, are available in those areas. Similarly, the samangos increase time spent vigilant when in areas of high perceived eagle predation risk, but environmental factors such as visibility or food availability have little effect on vigilance.
The findings of this study indicate that a population at the edge of their species’ ecological tolerance are forced to considerably adapt behaviourally to seasonally and spatially varying resources and risk. In particular, great effort is put into avoiding predation risk; by avoiding high risk areas and maintaining an adequate level of vigilance. All of this must be achieved whilst combating rival groups and maintaining a territory, ensuring adequate food can be foraged and ensuring the successful raising of the next generation.
10 citations
Cites background from "Vigilance Behaviour in Grazing Afri..."
...For example, most animals are unable to forage and remain vigilant for predators at the same time (Underwood 1982, Lima 1998)....
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TL;DR: In this paper, the effects of visual obstruction on white-tailed deer (Odocoileus virginianus) include enhanced vigilance and flight-initiation distances, and increased alert behavior (e.g., head held above horizontal, ears erect, body posture noticeably stiff and animal paused, directed attention, tail flagging, or fleeing) by deer using the stations.
Abstract: Effects of visual obstruction on white-tailed deer (Odocoileus virginianus) include enhanced vigilance and flight-initiation distances. Prior work suggests that artificial visual barriers might enhance perceived risk of predation to deer. During 2008–2010 at the National Aeronautics and Space Administration's Plum Brook Station (Erie County, OH), we tested the hypotheses that visual obstruction of winter feeding stations would result in fewer white-tailed deer visiting treatment stations and increased vigilance exhibited relative to deer using control stations. When feeding stations were bounded on 3 sides by a 22.5-m-long, 1.5-m-high, continuous, polyethylene visual barrier (including a 5-m opening on the fourth side), and offset from the food resource by 22.5 m, we observed no differences in deer use or vigilance compared with control stations (4.5-cm mesh, snow fencing only). In a second experiment, feeding stations bounded by individual, 1.5-m-high, polyethylene visual barriers, positioned on 3 sides only and offset from the food resource by only 7.6 m each, were characterized by 1) fewer deer, 2) increased alert behavior (e.g., head held above horizontal, ears erect, body posture noticeably stiff and animal paused, directed attention, tail flagging, or fleeing) by deer using the stations, and 3) fewer deer using stations at night, relative to control stations. Visual barriers offset at most by 7.6 m from a food resource (e.g., crops), or located randomly within target areas frequented by deer can offer temporary and easily manipulated means of diminishing deer use of resources on unfenced General Aviation airports or depredation of agricultural crops, and ready integration with other management methods. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
10 citations
Cites background from "Vigilance Behaviour in Grazing Afri..."
...In numerous ungulate species, time spent vigilant in response to potential risk increases as distance to visual obstruction (i.e., cover characteristics that might conceal a predator) decreases (e.g., Underwood 1982, Isvaran 2007, Moser et al. 2008)....
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TL;DR: Ass associations between social dominance, body condition and interruptions to foraging behaviour in a cross-sectional study of 116 domestic horses and ponies are investigated, demonstrating that factors other than social dominance can result in stable differences in winter body condition.
Abstract: Individual animals experience different costs and benefits associated with group living, which may impact on their foraging efficiency in ways not yet well specified. This study investigated associations between social dominance, body condition and interruptions to foraging behaviour in a cross-sectional study of 116 domestic horses and ponies, kept in 20 discrete herds. Social dominance was measured for each individual alongside observations of winter foraging behaviour. During bouts of foraging, the duration, frequency and category (vigilance, movement, social displacements given and received, scratching and startle responses) of interruptions were recorded, with total interruption time taken as a proxy measure of foraging efficiency. Total foraging time was not influenced by body condition or social dominance. Body condition was associated with social dominance, but more strongly associated with foraging efficiency. Specifically, lower body condition was associated with greater vigilance. This demonstrates that factors other than social dominance can result in stable differences in winter body condition.
10 citations
Cites background from "Vigilance Behaviour in Grazing Afri..."
...Vigilance may serve a range of functions in group living animals (Fattorini & Ferretti, 2019), including anti-predatory behaviour (Elgar, 1989; Hunter & Skinner, 1998), monitoring of other herd members and scanning the environment for resources (Underwood, 1982)....
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TL;DR: The results support the assumption that individuals scan independently of each other in this solitary species of wombats, which tolerates the presence of conspecifics within their home range.
Abstract: We studied vigilance activity in a wild population of the common wombat (Vombatus ursinus), a large, solitary, burrow-using, marsupial prey species in which individuals tolerate the presence of conspecifics within their home range. For the first time, we report postures and rates of vigilance in common wombats; our results show a limited repertoire of vigilant postures and low overall rates of vigilance. Because few studies of birds and mammals that have reported the effect of distance to conspecifics on the vigilance of focal animals have considered solitary prey species, we tested this effect in wombats. Our results show that a model including distance to cover and distance to the nearest conspecific, but not time of day, best explained the variation in the proportion of time that focal individuals spent in vigilance. Individual vigilance decreased when distance to cover increased. Vigilance of wombats increased when there was a conspecific within a radius of 70 m of the focal individual. In addition, we tested whether pairs of nearby wombats scanned independently of one another, coordinated their activity in non-overlapping bouts of vigilance or synchronised their bouts of vigilance. Wombats in close proximity exhibited independent bouts of individual vigilant and foraging activity. Thus, in this solitary species, our results support the assumption that individuals scan independently of each other.
10 citations
References
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TL;DR: Seven major types of sampling for observational studies of social behavior have been found in the literature and the major strengths and weaknesses of each method are pointed out.
Abstract: Seven major types of sampling for observational studies of social behavior have been found in the literature. These methods differ considerably in their suitability for providing unbiased data of various kinds. Below is a summary of the major recommended uses of each technique: In this paper, I have tried to point out the major strengths and weaknesses of each sampling method. Some methods are intrinsically biased with respect to many variables, others to fewer. In choosing a sampling method the main question is whether the procedure results in a biased sample of the variables under study. A method can produce a biased sample directly, as a result of intrinsic bias with respect to a study variable, or secondarily due to some degree of dependence (correlation) between the study variable and a directly-biased variable. In order to choose a sampling technique, the observer needs to consider carefully the characteristics of behavior and social interactions that are relevant to the study population and the research questions at hand. In most studies one will not have adequate empirical knowledge of the dependencies between relevant variables. Under the circumstances, the observer should avoid intrinsic biases to whatever extent possible, in particular those that direcly affect the variables under study. Finally, it will often be possible to use more than one sampling method in a study. Such samples can be taken successively or, under favorable conditions, even concurrently. For example, we have found it possible to take Instantaneous Samples of the identities and distances of nearest neighbors of a focal individual at five or ten minute intervals during Focal-Animal (behavior) Samples on that individual. Often during Focal-Animal Sampling one can also record All Occurrences of Some Behaviors, for the whole social group, for categories of conspicuous behavior, such as predation, intergroup contact, drinking, and so on. The extent to which concurrent multiple sampling is feasible will depend very much on the behavior categories and rate of occurrence, the observational conditions, etc. Where feasible, such multiple sampling can greatly aid in the efficient use of research time.
12,470 citations
TL;DR: An antithesis to the view that gregarious behaviour is evolved through benefits to the population or species is presented, and simply defined models are used to show that even in non-gregarious species selection is likely to favour individuals who stay close to others.
3,343 citations
Additional excerpts
...The 'selfish herd' (HAMILTON, 1971)...
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TL;DR: The paper describes different feeding styles among antelope, in terms of selection of food items and coverage of home ranges, and argues that these feeding styles bear a relationship to maximum group size of feeding animals through the influence of dispersion ofFood items upon group cohesion.
Abstract: The types of social organisation displayed by the African antelope species have been assigned in this paper to five classes, distinguished largely by the strategies used by the reproductively active males in securing mating rights, and the effects of those strategies on other social castes. The paper attempts to show that these strategies are appropriate to each class because of the effects of other, ecological, aspects of their ways of life. The paper describes different feeding styles among antelope, in terms of selection of food items and coverage of home ranges. It argues that these feeding styles bear a relationship to maximum group size of feeding animals through the influence of dispersion of food items upon group cohesion. The feeding styles also bear a relationship to body size and to habitat choice, both of which influence the antelope species' antipredator behaviour. Thus feeding style is related to anti-predator behaviour which, in many species, influences minimum group size. Group size and the pattern of movement over the annual home range affect the likelihood of females being found in a given place at a given time, and it is this likelihood which, to a large extent, determines the kind of strategy a male must employ to achieve mating rights. The effects of the different strategies employed by males can be seen in such aspects of each species' biology as sexual dimorphism, adult sex ratio, and differential distribution of the sexes.
2,088 citations
"Vigilance Behaviour in Grazing Afri..." refers background in this paper
...Such habitat differences may have influenced the evolution of social and anti-predator behaviour in antelope (GEIST, 1974; JARMAN, 1974; ESTES, 1974) and may also affect both predator and prey behaviour on a day to day basis (SCHALLER, 1972; KRUUK, 1972; CURIO, 1976; EDMUNDS, 1974)....
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...If scanning reduces predation, it may take up less of the large animals' time either because both the number and the range of potential predators are smaller (JARMAN, 1974; GEIST, 1974), or because these antelope, being found in large groups, either are (a) less easy for a predator to find, (b) share vigilance with other group members (CARACAO et al....
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...The smaller and, according to JARMAN (1974), the more selective species are those which show significant correlations between the rate of looking and indices of feeding success, supporting the possibility that scanning forms a part of foraging behaviour....
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1,193 citations
Book•
21 Sep 1976
TL;DR: This chapter discusses hunting for Prey, the Diversity of Hunting Methods, and the Motivation Underlying Feeding Responses of Predator-Prey Interactions.
Abstract: 1 Internal Factors.- A. Hunger: Expression through Overt behavior.- I. Predatory Schedules.- 1. Patterns of Satiation.- 2. Feast and Famine.- II. Hunger and Diel Rhythms.- III. The Ramification of Hunger Effects.- 1. Capture-eliciting Prey Stimuli.- 2. Search behavior.- IV. The Motivation Underlying Feeding Responses.- 1. Hunger Thresholds of Feeding Response Components.- 2. The Complexity of Predatory Motivation.- V. The Diversity of Foraging Tactics.- VI. Feeding Components Affected and not Affected by Hunger.- B. The Control of Feeding Responses by Factors Other than Hunger.- I. The Readiness to Hunt.- II. Prey Storing.- III. Providing Food for Dependent Family Members.- C. The Problem of Specific Hungers.- I. Switching of Prey.- II. The Prey-density Predation Curve.- III. Swamping the Appetite of Predators.- D. Daily and Annual Rhythms in Predator-Prey Interactions.- I. Daily Rhythm of Predation.- II. Daily Activity Patterns of the Prey.- III. Annual Rhythm of Predation.- 2 Searching for Prey.- A. Path of Searching and Scanning Movements.- B. Area-concentrated Search.- I. Short-term Area Concentration.- 1. Living Scattered and Area-concentrated Search.- 2. The Nature of the Path Changes.- 3. Search Behavior after the Disappearance of Prey.- II. Long-term Area Concentration.- III. One-prey : One-place Association.- C. Object-concentrated Search.- I. Existence and Properties of "Searching Image".- 1. Ecological Evidence.- 2. Experimental Evidence.- II. Social Facilitation of Searching Image Formation.- III. Searching Image and "Training Bias".- IV. Searching Image and Profitability of Hunting.- 1. Ecological Evidence for Profitability of Hunting.- 2. Experimental Evidence for Profitability of Hunting.- V. Prey-specific Expectation.- VI. Ecological Implications of Searching Image.- 3 Prey Recognition.- A. The Stimulus-specificity of Prey Capture.- I. Capture-eliciting Prey Stimuli.- II. Capture-inhibiting Prey Stimuli.- B. One-prey : One-response Relationships.- C. The Assessment of the Circumstances of a Hunt.- D. Prey Recognition by Prey-related Signals.- E. Prey Stimulus Summation.- F. Novelty Versus Familiarity.- I. The Rejection of Novel Prey.- II. Familiarization with Prey and Its Consequences.- G. The Multi-channel Hypothesis of Prey Recognition.- 4 Prey Selection.- A. Preying upon the Weak and the Sick.- B. Preying upon the Odd and the Conspicuous.- C. The Mechanics of Prey Selection.- D. Evolutionary Implications.- 5 Hunting for Prey.- A. Modes of Hunting.- I. Hunting by Speculation.- II. Stalking and Ambushing.- 1. Stalking.- 2. Ambushing.- III. Prey Attack under Disguise.- IV. Pursuit of the Prey.- 1. Changes of Velocity of Attack (Pursuit).- 2. Interception of the Flight Path.- 3. Counteradaptations of the Prey.- V. Exhausting Dangerous Prey.- VI. Insinuation.- VII. Scavenging and Cleptoparasitism.- 1. Modes and Extent.- 2. Cleptoparasitism and Competition.- 3. Counter-measures of the Robbed.- VIII. Tool-use.- IX. Mutilation.- B. The Diversity of Hunting Methods.- I. Prey-specific Methods.- II. Situation-specific Methods.- III. Mechanisms and Causes of Predatory Versatility.- 1. General.- 2. Individual Predatory Repertories.- 3. The Persistence of Individual Traits.- 4. Predatory Specialization and Structural Modification.- 5. Predatory Versatility in Relation to Prey Availability.- C. Behavioral Aspects of Hunting Success.- I. A Comparison of Hunting Success across Predator Species.- II. Variables Influencing Hunting Success within Predator Species.- III. Aspects of Communal Hunting.- 1. Modes and Properties of Communal Hunting.- 2. Factors Conducive to Communal Hunting.- 3. Benefits of Communal Hunting.- References.- Scientific Names of Animals and Plants.
919 citations
"Vigilance Behaviour in Grazing Afri..." refers background in this paper
...Such habitat differences may have influenced the evolution of social and anti-predator behaviour in antelope (GEIST, 1974; JARMAN, 1974; ESTES, 1974) and may also affect both predator and prey behaviour on a day to day basis (SCHALLER, 1972; KRUUK, 1972; CURIO, 1976; EDMUNDS, 1974)....
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