| Records |
| Author |
Hernandez, J.; Hawkins, D.L. |
| Title |
Training failure among yearling horses |
Type |
Journal Article |
| Year |
2001 |
Publication |
American Journal of Veterinary Research |
Abbreviated Journal  |
Am J Vet Res |
| Volume |
62 |
Issue |
9 |
Pages |
1418-1422 |
| Keywords |
Animals; Female; Florida; Horses/*physiology; Lameness, Animal/*economics; Male; Physical Conditioning, Animal/adverse effects/economics; Respiratory Tract Diseases/economics/*veterinary; Statistics, Nonparametric |
| Abstract |
OBJECTIVE: To compare financial returns between pinhooked yearling horses (ie, bought and trained for approximately 5 months with the goal of selling the horse at “2-year-olds in training” sales) that had mild or severe training failure and horses that had planned versus nonplanned training failure. ANIMALS: 40 Thoroughbred pinhooked yearling horses. PROCEDURE: During the period from September 1998 through and April 1999, 20 horses had mild training failure (1 to 11 days lost), and 20 horses had severe training failure (13 to 108 days lost). Horses were assigned to these 2 groups on the basis of frequency distribution (median) of days lost during training. Horses were also categorized on the basis of type of training failure (planned vs nonplanned training failure). The outcome of primary interest was financial return. Median financial returns were compared among groups by use of the Mann-Whitney U test. RESULTS: Median financial returns for horses that had severe training failure ($1,000) were significantly different, compared with horses that had mild training failure ($24,000). Analysis of results also indicated that median returns were significantly different among horses that had planned training failure (-$2,000; eg, horses with radiographic abnormalities detected during routine prepurchase examinations that required surgical treatment, resulting in days lost during training), compared with horses that did not ($10,000). CONCLUSIONS AND CLINICAL RELEVANCE: Training failure has an economic impact on revenues in pinhooked yearling horses. Lameness, planned training failure, respiratory disease, and ringworm were common and important causes of training failure. |
| Address |
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610-0136, USA |
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0002-9645 |
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| Notes |
PMID:11560271 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
4051 |
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| Author |
Bottoms, G.D.; Roesel, O.F.; Rausch, F.D.; Akins, E.L. |
| Title |
Circadian variation in plasma cortisol and corticosterone in pigs and mares |
Type |
Journal Article |
| Year |
1972 |
Publication |
American Journal of Veterinary Research |
Abbreviated Journal |
Am J Vet Res |
| Volume |
33 |
Issue |
4 |
Pages |
785-790 |
| Keywords |
Animals; *Circadian Rhythm; Corticosterone/*blood; Female; Horses/*metabolism; Hydrocortisone/*blood; Methods; Swine/*metabolism; Time Factors |
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0002-9645 |
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| Notes |
PMID:5017871 |
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no |
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Equine Behaviour @ team @ |
Serial |
4074 |
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| Author |
Flack, J.C.; de Waal, F.B.M.; Krakauer, D.C. |
| Title |
Social structure, robustness, and policing cost in a cognitively sophisticated species |
Type |
Journal Article |
| Year |
2005 |
Publication |
The American Naturalist |
Abbreviated Journal |
Am Nat |
| Volume |
165 |
Issue |
5 |
Pages |
E126-139 |
| Keywords |
Animals; *Behavior, Animal; Cognition; Conflict (Psychology); Female; Macaca nemestrina/*physiology; Male; Models, Biological; *Social Behavior |
| Abstract |
Conflict management is one of the primary requirements for social complexity. Of the many forms of conflict management, one of the rarest and most interesting is third-party policing, or intervening impartially to control conflict. Third-party policing should be hard to evolve because policers personally pay a cost for intervening, while the benefits are diffused over the whole group. In this study we investigate the incidence and costs of policing in a primate society. We report quantitative evidence of non-kin policing in the nonhuman primate, the pigtailed macaque. We find that policing is effective at reducing the intensity of or terminating conflict when performed by the most powerful individuals. We define a measure, social power consensus, that predicts effective low-cost interventions by powerful individuals and ineffective, relatively costly interventions by low-power individuals. Finally, we develop a simple probabilistic model to explore whether the degree to which policing can effectively reduce the societal cost of conflict is dependent on variance in the distribution of power. Our data and simple model suggest that third-party policing effectiveness and cost are dependent on power structure and might emerge only in societies with high variance in power. |
| Address |
Santa Fe Institute, Santa Fe, New Mexico 87501, USA. jflack@santafe.edu |
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English |
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Edition |
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| ISSN |
1537-5323 |
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| Notes |
PMID:15795848 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
168 |
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| Author |
Cameron, E.Z.; du Toit, J.T. |
| Title |
Winning by a neck: tall giraffes avoid competing with shorter browsers |
Type |
Journal Article |
| Year |
2007 |
Publication |
The American naturalist |
Abbreviated Journal |
Am Nat |
| Volume |
169 |
Issue |
1 |
Pages |
130-135 |
| Keywords |
Acacia/growth & development; Animals; Feeding Behavior/*physiology; Neck/*anatomy & histology; Plant Leaves/growth & development; Ruminants/*anatomy & histology/*physiology; South Africa |
| Abstract |
With their vertically elongated body form, giraffes generally feed above the level of other browsers within the savanna browsing guild, despite having access to foliage at lower levels. They ingest more leaf mass per bite when foraging high in the tree, perhaps because smaller, more selective browsers deplete shoots at lower levels or because trees differentially allocate resources to promote shoot growth in the upper canopy. We erected exclosures around individual Acacia nigrescens trees in the greater Kruger ecosystem, South Africa. After a complete growing season, we found no differences in leaf biomass per shoot across height zones in excluded trees but significant differences in control trees. We conclude that giraffes preferentially browse at high levels in the canopy to avoid competition with smaller browsers. Our findings are analogous with those from studies of grazing guilds and demonstrate that resource partitioning can be driven by competition when smaller foragers displace larger foragers from shared resources. This provides the first experimental support for the classic evolutionary hypothesis that vertical elongation of the giraffe body is an outcome of competition within the browsing ungulate guild. |
| Address |
Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za |
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1537-5323 |
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Conference |
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| Notes |
PMID:17206591 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
410 |
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| Author |
Uehara, T.; Yokomizo, H.; Iwasa, Y. |
| Title |
Mate-choice copying as Bayesian decision making |
Type |
Journal Article |
| Year |
2005 |
Publication |
The American naturalist |
Abbreviated Journal |
Am Nat |
| Volume |
165 |
Issue |
3 |
Pages |
403-410 |
| Keywords |
Animals; *Bayes Theorem; *Choice Behavior; Female; Male; *Models, Biological; *Sexual Behavior, Animal |
| Abstract |
Mate-choice copying by females has been reported in fishes (e.g., guppies) and lekking birds. Presumably, females assess males' quality using both information from direct observation of males and information acquired by observing other females' choices. Here, we study mathematically the conditions under which mate-choice copying is advantageous on the basis of Bayesian decision theory. A female may observe the mate choice of another female, called the model female, who has performed an optimal choice based on her own judgment. The conditions required for the focal female to choose the same mate as that chosen by the model female should depend on the male's appearance to her, the reliability of her own judgment of male quality, and the reliability of the model females. When three or more females are involved, the optimal mate choice critically depends on whether multiple model females make decisions independently or they themselves copy the choices of others. If two equally reliable females choose different males, the choice of the second female, made knowing the choice of the first, should have a stronger effect on the choice of the third (focal) female. This “last-choice precedence” should be tested experimentally. |
| Address |
Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan. uehara@bio-math.biology.kyushu-u.ac.jp |
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1537-5323 |
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| Notes |
PMID:15729669 |
Approved |
no |
| Call Number |
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Serial |
1821 |
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| Author |
Dubois, F.; Giraldeau, L.-A.; Hamilton, I.M.; Grant, J.W.A.; Lefebvre, L. |
| Title |
Distraction sneakers decrease the expected level of aggression within groups: a game-theoretic model |
Type |
Journal Article |
| Year |
2004 |
Publication |
The American Naturalist |
Abbreviated Journal |
Am Nat |
| Volume |
164 |
Issue |
2 |
Pages |
E32-45 |
| Keywords |
*Aggression; Animals; Behavior, Animal/*physiology; Columbidae/*physiology; Competitive Behavior; Cooperative Behavior; *Game Theory; Hawks/*physiology; Models, Biological |
| Abstract |
Hawk-dove games have been extensively used to predict the conditions under which group-living animals should defend their resources against potential usurpers. Typically, game-theoretic models on aggression consider that resource defense may entail energetic and injury costs. However, intruders may also take advantage of owners who are busy fighting to sneak access to unguarded resources, imposing thereby an additional cost on the use of the escalated hawk strategy. In this article we modify the two-strategy hawk-dove game into a three-strategy hawk-dove-sneaker game that incorporates a distraction-sneaking tactic, allowing us to explore its consequences on the expected level of aggression within groups. Our model predicts a lower proportion of hawks and hence lower frequencies of aggressive interactions within groups than do previous two-strategy hawk-dove games. The extent to which distraction sneakers decrease the frequency of aggression within groups, however, depends on whether they search only for opportunities to join resources uncovered by other group members or for both unchallenged resources and opportunities to usurp. |
| Address |
Departement des Sciences Biologiques, Universite du Quebec a Montreal, Case postale 8888 Succursale Centre-Ville, Montreal, Quebec H3C 3P8, Canada. frede_dubois@yahoo.fr |
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English |
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1537-5323 |
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Conference |
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| Notes |
PMID:15278850 |
Approved |
no |
| Call Number |
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Serial |
2130 |
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| Author |
Dubois, F.; Giraldeau, L.-A. |
| Title |
The forager's dilemma: food sharing and food defense as risk-sensitive foraging options |
Type |
Journal Article |
| Year |
2003 |
Publication |
The American Naturalist |
Abbreviated Journal |
Am Nat |
| Volume |
162 |
Issue |
6 |
Pages |
768-779 |
| Keywords |
Animals; Competitive Behavior/*physiology; *Environment; Feeding Behavior/*physiology; *Game Theory; *Models, Biological; Population Density; Population Dynamics |
| Abstract |
Although many variants of the hawk-dove game predict the frequency at which group foraging animals should compete aggressively, none of them can explain why a large number of group foraging animals share food clumps without any overt aggression. One reason for this shortcoming is that hawk-dove games typically consider only a single contest, while most group foraging situations involve opponents that interact repeatedly over discovered food clumps. The present iterated hawk-dove game predicts that in situations that are analogous to a prisoner's dilemma, animals should share the resources without aggression, provided that the number of simultaneously available food clumps is sufficiently large and the number of competitors is relatively small. However, given that the expected gain of an aggressive animal is more variable than the gain expected by nonaggressive individuals, the predicted effect of the number of food items in a clump-clump richness-depends on whether only the mean or both the mean and variability associated with payoffs are considered. More precisely, the deterministic game predicts that aggression should increase with clump richness, whereas the stochastic risk-sensitive game predicts that the frequency of encounters resulting in aggression should peak at intermediate clump richnesses or decrease with increasing clump richness if animals show sensitivity to the variance or coefficient of variation, respectively. |
| Address |
Departement des Sciences Biologiques, Universite du Quebec a Montreal, Case postale 8888, Succursale Centre-Ville, Montreal, Quebec H3C 3P8, Canada. fdubois@u-bourgogne.fr |
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English |
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0003-0147 |
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| Notes |
PMID:14737714 |
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no |
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Serial |
2132 |
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Conradt, L.; Krause, J.; Couzin, I. D.; Roper, T. J. |
| Title |
“Leading According to Need” in Self-Organizing Groups |
Type |
Journal Article |
| Year |
2009 |
Publication |
The American Naturalist |
Abbreviated Journal |
Am Nat |
| Volume |
173 |
Issue |
3 |
Pages |
304-312 |
| Keywords |
behavioral synchrony, collective group decisions, democracy and egalitarianism in animals, public goods experiments, sexual segregation, social choice theory |
| Abstract |
Self‐organizing‐system approaches have shed significant light on the mechanisms underlying synchronized movements by large groups of animals, such as shoals of fish, flocks of birds, or herds of ungulates. However, these approaches rarely consider conflicts of interest between group members, although there is reason to suppose that such conflicts are commonplace. Here, we demonstrate that, where conflicts exist, individual members of self‐organizing groups can, in principle, increase their influence on group movement destination by strategically changing simple behavioral parameters (namely, movement speed, assertiveness, and social attraction range). However, they do so at the expense of an increased risk of group fragmentation and a decrease in movement efficiency. We argue that the resulting trade‐offs faced by each group member render it likely that group movements are led by those members for which reaching a particular destination is most crucial or group cohesion is least important. We term this phenomenon leading according to “need” or “social indifference,” respectively. Both kinds of leading can occur in the absence of knowledge of or communication about the needs of other group members and without the assumption of altruistic cooperation. We discuss our findings in the light of observations on fish and other vertebrates. |
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Equine Behaviour @ team @ |
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5121 |
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Nettle, D. |
| Title |
The evolution of personality variation in humans and other animals |
Type |
Journal Article |
| Year |
2006 |
Publication |
The American Psychologist |
Abbreviated Journal |
Am Psychol |
| Volume |
61 |
Issue |
6 |
Pages |
622-631 |
| Keywords |
Animals; Birds; *Evolution; Female; Fishes; Humans; Insects; Male; Personality/*genetics/*physiology |
| Abstract |
A comprehensive evolutionary framework for understanding the maintenance of heritable behavioral variation in humans is yet to be developed. Some evolutionary psychologists have argued that heritable variation will not be found in important, fitness-relevant characteristics because of the winnowing effect of natural selection. This article propounds the opposite view. Heritable variation is ubiquitous in all species, and there are a number of frameworks for understanding its persistence. The author argues that each of the Big Five dimensions of human personality can be seen as the result of a trade-off between different fitness costs and benefits. As there is no unconditionally optimal value of these trade-offs, it is to be expected that genetic diversity will be retained in the population. |
| Address |
University of Newcastle, Newcastle, United Kingdom. daniel.nettle@ncl.ac.uk |
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0003-066X |
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PMID:16953749 |
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no |
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Equine Behaviour @ team @ |
Serial |
4105 |
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| Author |
Neuringer, A. |
| Title |
Reinforced variability in animals and people: implications for adaptive action |
Type |
Journal Article |
| Year |
2004 |
Publication |
The American Psychologist |
Abbreviated Journal |
Am Psychol |
| Volume |
59 |
Issue |
9 |
Pages |
891-906 |
| Keywords |
Animals; Behavior, Animal; *Choice Behavior; Conditioning, Operant; Creativeness; Discrimination (Psychology); Humans; Memory; Problem Solving; *Reinforcement (Psychology) |
| Abstract |
Although reinforcement often leads to repetitive, even stereotyped responding, that is not a necessary outcome. When it depends on variations, reinforcement results in responding that is diverse, novel, indeed unpredictable, with distributions sometimes approaching those of a random process. This article reviews evidence for the powerful and precise control by reinforcement over behavioral variability, evidence obtained from human and animal-model studies, and implications of such control. For example, reinforcement of variability facilitates learning of complex new responses, aids problem solving, and may contribute to creativity. Depression and autism are characterized by abnormally repetitive behaviors, but individuals afflicted with such psychopathologies can learn to vary their behaviors when reinforced for so doing. And reinforced variability may help to solve a basic puzzle concerning the nature of voluntary action. |
| Address |
Department of Psychology, Reed College, Portland, OR 97202, USA. allen.neuringer@reed.edu |
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0003-066X |
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PMID:15584823 |
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no |
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Equine Behaviour @ team @ |
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4106 |
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