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Author |
McGuigan, M.P.; Wilson, A.M. |
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Title |
The effect of gait and digital flexor muscle activation on limb compliance in the forelimb of the horse Equus caballus |
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Journal Article |
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Year |
2003 |
Publication |
The Journal of Experimental Biology |
Abbreviated Journal |
J Exp Biol |
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Volume |
206 |
Issue  |
Pt 8 |
Pages |
1325-1336 |
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Keywords |
Animals; Biomechanics; Forelimb/anatomy & histology/*physiology; Gait/*physiology; Horses/anatomy & histology/*physiology; Muscle Contraction/*physiology; Running |
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Abstract |
A horse's legs are compressed during the stance phase, storing and then returning elastic strain energy in spring-like muscle-tendon units. The arrangement of the muscle-tendon units around the lever-like joints means that as the leg shortens the muscle-tendon units are stretched. The forelimb anatomy means that the leg can be conceptually divided into two springs: the proximal spring, from the scapula to the elbow, and the distal spring, from the elbow to the foot. In this paper we report the results of a series of experiments testing the hypothesis that there is minimal scope for muscle contraction in either spring to adjust limb compliance. Firstly, we demonstrate that the distal, passive leg spring changes length by 127 mm (range 106-128 mm) at gallop and the proximal spring by 12 mm (9-15 mm). Secondly, we demonstrate that there is a linear relationship between limb force and metacarpo-phalangeal (MCP) joint angle that is minimally influenced by digital flexor muscle activation in vitro or as a function of gait in vivo. Finally, we determined the relationship between MCP joint angle and vertical ground-reaction force at trot and then predicted the forelimb peak vertical ground-reaction force during a 12 m s(-1) gallop on a treadmill. These were 12.79 N kg(-1) body mass (BM) (range 12.07-13.73 N kg(-1) BM) for the lead forelimb and 15.23 N kg(-1) BM (13.51-17.10 N kg(-1) BM) for the non-lead forelimb. |
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Structure and Motion Laboratory, Veterinary Basic Sciences, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK. m.p.mcguigan@leeds.ac.uk |
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0022-0949 |
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PMID:12624168 |
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Equine Behaviour @ team @ |
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3655 |
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Author |
Miklósi, Á.; Kubinyi, E.; Topál, J.; Gácsi, M.; Virányi, Z.; Csányi, V. |
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Title |
A Simple Reason for a Big Difference: Wolves Do Not Look Back at Humans, but Dogs Do |
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Year |
2003 |
Publication |
Current Biology |
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13 |
Issue |
9 |
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763-766 |
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The present investigations were undertaken to compare interspecific communicative abilities of dogs and wolves, which were socialized to humans at comparable levels. The first study demonstrated that socialized wolves were able to locate the place of hidden food indicated by the touching and, to some extent, pointing cues provided by the familiar human experimenter, but their performance remained inferior to that of dogs. In the second study, we have found that, after undergoing training to solve a simple manipulation task, dogs that are faced with an insoluble version of the same problem look/gaze at the human, while socialized wolves do not. Based on these observations, we suggest that the key difference between dog and wolf behavior is the dogs' ability to look at the human's face. Since looking behavior has an important function in initializing and maintaining communicative interaction in human communication systems, we suppose that by positive feedback processes (both evolutionary and ontogenetically) the readiness of dogs to look at the human face has lead to complex forms of dog-human communication that cannot be achieved in wolves even after extended socialization. |
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0960-9822 |
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Equine Behaviour @ team @ |
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4966 |
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Hall, C.A.; Cassaday, H.J.; Derrington, A.M. |
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Title |
The effect of stimulus height on visual discrimination in horses |
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Journal Article |
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Year |
2003 |
Publication |
Journal of Animal Science |
Abbreviated Journal |
J. Anim Sci. |
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Volume |
81 |
Issue |
7 |
Pages |
1715-1720 |
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Keywords |
Animals; *Discrimination Learning/physiology; Female; Horses/physiology/*psychology; Male; Orientation; *Photic Stimulation; Vision/*physiology |
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Abstract |
This study investigated the effect of stimulus height on the ability of horses to learn a simple visual discrimination task. Eight horses were trained to perform a two-choice, black/white discrimination with stimuli presented at one of two heights: ground level or at a height of 70 cm from the ground. The height at which the stimuli were presented was alternated from one session to the next. All trials within a single session were presented at the same height. The criterion for learning was four consecutive sessions of 70% correct responses. Performance was found to be better when stimuli were presented at ground level with respect to the number of trials taken to reach the criterion (P < 0.05), percentage of correct first choices (P < 0.01), and repeated errors made (P < 0.01). Thus, training horses to carry out tasks of visual discrimination could be enhanced by placing the stimuli on the ground. In addition, the results of the present study suggest that the visual appearance of ground surfaces is an important factor in both horse management and training. |
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School of Land-based Studies, Nottingham Trent University, Brackenhurst College Campus, Southwell, Nottinghamshire, England NG25 0QF. carol.hall@ntu.ac.uk |
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0021-8812 |
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PMID:12854807 |
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refbase @ user @ |
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835 |
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Author |
Buechner-Maxwell, V.A.; Elvinger, F.; Thatcher, C.D.; Murray, M.J.; White, N.A.; Rooney, D.K. |
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Title |
Physiological Response of Normal Adult Horses to a Low-Residue Liquid Diet |
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Journal Article |
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Year |
2003 |
Publication |
Journal of Equine Veterinary Science |
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23 |
Issue |
7 |
Pages |
310-317 |
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Abstract The anorexic or dysphagic adult horse often requires nutritional support. Providing nutrients by the enteral route is the safest and most economic choice, but the dietary options available for use in horses are somewhat limited. The objective of this study was to compare the physiologic response of normal horses with a low-residue liquid or normal diet over a 10-day feeding period. Two groups of 6 normal adult horses were maintained on 1 of 2 diets for a 10-day period. Diets were formulated to meet the caloric needs of a horse maintained in a stall. The control group was fed 70% timothy hay and 30% textured concentrate for the test period, and the experimental group received the low-residue liquid diet, similar to liquid nutritional formulas designed for human use. Clinical parameters, body weight, packed cell volume, total plasma solids, blood glucose, and serum electrolytes were recorded daily for each horse during the dietary trial period. On days 1, 5, and 10 of the study, a complete blood count, serum biochemical profile, and urinalysis were performed. Horses' serum total bilirubin concentration and pattern of weight loss differed between groups. All other physical parameters, blood chemistry, complete blood count, and urinalysis results remained within the normal reference interval for the horses regardless of diet, although some statistical differences were observed. Horses returned to pasture and free-choice grass diet without complications at the end of the dietary trial period. These results demonstrate that few differences of biologic significance were observed between horses being fed low-residue diet and horses receiving a normal diet of hay and grain over a 10-day period. (Equine Vet J 2003;23:310-317) |
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Equine Behaviour @ team @ |
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4229 |
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Author |
Brosnan, S.F.; De Waal, F.B.M. |
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Title |
Monkeys reject unequal pay |
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Journal Article |
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Year |
2003 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
425 |
Issue |
6955 |
Pages |
297-299 |
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Keywords |
Aging; Animals; Cebus/*psychology; Choice Behavior; *Cooperative Behavior; Female; Male; *Reward; Social Justice |
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During the evolution of cooperation it may have become critical for individuals to compare their own efforts and pay-offs with those of others. Negative reactions may occur when expectations are violated. One theory proposes that aversion to inequity can explain human cooperation within the bounds of the rational choice model, and may in fact be more inclusive than previous explanations. Although there exists substantial cultural variation in its particulars, this 'sense of fairness' is probably a human universal that has been shown to prevail in a wide variety of circumstances. However, we are not the only cooperative animals, hence inequity aversion may not be uniquely human. Many highly cooperative nonhuman species seem guided by a set of expectations about the outcome of cooperation and the division of resources. Here we demonstrate that a nonhuman primate, the brown capuchin monkey (Cebus apella), responds negatively to unequal reward distribution in exchanges with a human experimenter. Monkeys refused to participate if they witnessed a conspecific obtain a more attractive reward for equal effort, an effect amplified if the partner received such a reward without any effort at all. These reactions support an early evolutionary origin of inequity aversion. |
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Living Links, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA. sbrosna@emory.edu |
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1476-4687 |
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PMID:13679918 |
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refbase @ user @ |
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179 |
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Author |
Rands, S.A.; Cowlishaw, G.; Pettifor, R.A.; Rowcliffe, J.M.; Johnstone, R.A. |
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Title |
Spontaneous emergence of leaders and followers in foraging pairs |
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Journal Article |
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Year |
2003 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
423 |
Issue |
6938 |
Pages |
432-434 |
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Keywords |
Animals; *Energy Metabolism; Food; *Food Chain; *Models, Biological; Motor Activity; *Social Behavior; Time Factors |
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Animals that forage socially often stand to gain from coordination of their behaviour. Yet it is not known how group members reach a consensus on the timing of foraging bouts. Here we demonstrate a simple process by which this may occur. We develop a state-dependent, dynamic game model of foraging by a pair of animals, in which each individual chooses between resting or foraging during a series of consecutive periods, so as to maximize its own individual chances of survival. We find that, if there is an advantage to foraging together, the equilibrium behaviour of both individuals becomes highly synchronized. As a result of this synchronization, differences in the energetic reserves of the two players spontaneously develop, leading them to adopt different behavioural roles. The individual with lower reserves emerges as the 'pace-maker' who determines when the pair should forage, providing a straightforward resolution to the problem of group coordination. Moreover, the strategy that gives rise to this behaviour can be implemented by a simple 'rule of thumb' that requires no detailed knowledge of the state of other individuals. |
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Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. s.rands@zoo.cam.ac.uk |
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0028-0836 |
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PMID:12761547 |
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Equine Behaviour @ team @ |
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5138 |
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Author |
Johnson, D.D.P.; Stopka, P.; Knights, S. |
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Title |
Sociology: The puzzle of human cooperation |
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Journal Article |
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Year |
2003 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
421 |
Issue |
6926 |
Pages |
911-2; discussion 912 |
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Altruism; *Cooperative Behavior; Evolution; Humans; *Models, Biological; Punishment; Reward; Risk |
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Olin Institute for Strategic Studies, Harvard University, Cambridge, Massachusetts 02138, USA. dominic@post.harvard.edu |
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0028-0836 |
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PMID:12606989 |
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refbase @ user @ |
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467 |
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Author |
Conradt, L.; Roper, T.J. |
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Title |
Group decision-making in animals |
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Journal Article |
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Year |
2003 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
421 |
Issue |
6919 |
Pages |
155-158 |
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Keywords |
Animals; Behavior, Animal/*physiology; *Decision Making; Democracy; Group Processes; *Models, Biological; Population Density; Social Behavior |
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Groups of animals often need to make communal decisions, for example about which activities to perform, when to perform them and which direction to travel in; however, little is known about how they do so. Here, we model the fitness consequences of two possible decision-making mechanisms: 'despotism' and 'democracy'. We show that under most conditions, the costs to subordinate group members, and to the group as a whole, are considerably higher for despotic than for democratic decisions. Even when the despot is the most experienced group member, it only pays other members to accept its decision when group size is small and the difference in information is large. Democratic decisions are more beneficial primarily because they tend to produce less extreme decisions, rather than because each individual has an influence on the decision per se. Our model suggests that democracy should be widespread and makes quantitative, testable predictions about group decision-making in non-humans. |
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School of Biological Sciences, University of Sussex, Brighton BN1 9QG, UK. l.conradt@sussex.ac.uk |
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0028-0836 |
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PMID:12520299 |
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Equine Behaviour @ team @ |
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5136 |
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Spadavecchia, C.; Arendt-Nielsen, L.; Andersen, O.K.; Spadavecchia, L.; Doherr, M.; Schatzmann, U. |
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Title |
Comparison of nociceptive withdrawal reflexes and recruitment curves between the forelimbs and hind limbs in conscious horses |
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Journal Article |
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Year |
2003 |
Publication |
American journal of veterinary research |
Abbreviated Journal |
Am J Vet Res |
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64 |
Issue |
6 |
Pages |
700-707 |
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Animals; Consciousness; Female; Forelimb/*physiology; Hindlimb/*physiology; Horses/*physiology; Male; Nociceptors/physiology; Pain/*physiopathology/*veterinary; Pain Threshold/physiology; Recruitment, Neurophysiological/physiology; Reflex/*physiology |
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OBJECTIVE: To compare nociceptive withdrawal reflexes (NWRs) evoked from the distal aspect of the left forelimb and hind limb in conscious standing horses and to investigate NWR recruitment for graded electrical stimulation intensities. ANIMALS: 20 adult horses. PROCEDURE: Surface electromyographic (EMG) activity evoked by transcutaneous electrical stimulation of the digital palmar (or plantar) nerve was recorded from the common digital extensor and cranial tibial muscles. Stimuli consisted of 25-millisecond train-of-5 constant current pulses. Current intensity was gradually increased until NWR threshold intensity was reached. The EMG signal was analyzed for quantification of the NWR. Behavioral responses accompanying the reflex were scored (scale, 0 to 5). The NWR recruitment curves were determined at 0.9, 1.1, 1.2, and 1.3 times the NWR threshold intensity. RESULTS: The NWR threshold was significantly higher for the hind limb (median value, 6.6 mA; range, 3 to 10 mA) than the forelimb (median, 3 mA; range, 1.7 to 5.5 mA). The NWR of the hind limb had a significantly longer latency (median, 122.8 milliseconds; range, 106 to 172 milliseconds), compared with the forelimb (median, 98 milliseconds; range, 86 to 137 milliseconds), and it was associated with significantly stronger behavioral reactions. Gradual increase of NWR amplitude was evident at increasing stimulation intensities and supported by the behavioral observations. CONCLUSIONS AND CLINICAL RELEVANCE: We documented NWRs evoked from the forelimb and hind limb and their recruitment with stimuli of increasing intensity in horses. These results provide a basis for use of NWRs in studies on nociceptive modulation in horses. |
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Department of Clinical Veterinary Sciences, University of Berne, Switzerland |
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0002-9645 |
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PMID:12828255 |
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refbase @ user @ |
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93 |
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Leca, J.-B.; Gunst, N.; Thierry, B.; Petit, O. |
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Title |
Distributed leadership in semifree-ranging white-faced capuchin monkeys |
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Journal Article |
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Year |
2003 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
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Volume |
66 |
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6 |
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1045-1052 |
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We investigated the initiation of group movements in white-faced capuchin monkeys, Cebus capucinus, with the aim of determining whether a single individual with high dominance status consistently leads movements or whether leadership is distributed between group members. The group studied was reared in semifree-ranging conditions. A multivariate analysis followed by univariate analyses demonstrated that leadership was not concentrated on a single individual in this species. All individuals could initiate a collective movement. Nearly half of group members regularly succeeded in recruiting at least three followers. Although both sexes had similar rates of start attempts, females succeeded more frequently than males. We found no significant effect of the dominance status on the percentage of successful attempts. The use of a slow speed, looking back towards the other group members, or trills by the initiator heightened the likelihood of success in group movement initiation. An initiator starting from a core position in a clumped group was more successful than one starting from an edge position in a clumped group or from a dispersed group. Furthermore, the probability of successful start attempts was higher when the group remained stationary for a long period. Leadership in white-faced capuchins appears to be distributed between group members rather than exclusively concentrated on high-ranking individuals. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. |
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