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Author |
Viscido, S.V.; Miller, M.; Wethey, D.S. |
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Title  |
The dilemma of the selfish herd: the search for a realistic movement rule |
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Journal Article |
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Year |
2002 |
Publication |
Journal of theoretical biology |
Abbreviated Journal |
J. Theor. Biol. |
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Volume |
217 |
Issue |
2 |
Pages |
183-194 |
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Keywords |
Animals; *Behavior, Animal; *Mass Behavior; Models, Biological; *Motor Activity; Predatory Behavior |
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Abstract |
The selfish herd hypothesis predicts that aggregations form because individuals move toward one another to minimize their own predation risk. The “dilemma of the selfish herd” is that movement rules that are easy for individuals to follow, fail to produce true aggregations, while rules that produce aggregations require individual behavior so complex that one may doubt most animals can follow them. If natural selection at the individual level is responsible for herding behavior, a solution to the dilemma must exist. Using computer simulations, we examined four different movement rules. Relative predation risk was different for all four movement rules (p<0.05). We defined three criteria for measuring the quality of a movement rule. A good movement rule should (a) be statistically likely to benefit an individual that follows it, (b) be something we can imagine most animals are capable of following, and (c) result in a centrally compact flock. The local crowded horizon rule, which allowed individuals to take the positions of many flock-mates into account, but decreased the influence of flock-mates with distance, best satisfied these criteria. The local crowded horizon rule was very sensitive to the animal's perceptive ability. Therefore, the animal's ability to detect its neighbors is an important factor in the dynamics of group formation. |
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Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA. viscido@u.washington.edu |
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0022-5193 |
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PMID:12202112 |
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refbase @ user @ |
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554 |
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Author |
Viscido, S.V.; Miller, M.; Wethey, D.S. |
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Title |
The response of a selfish herd to an attack from outside the group perimeter |
Type |
Journal Article |
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Year |
2001 |
Publication |
Journal of theoretical biology |
Abbreviated Journal |
J. Theor. Biol. |
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Volume |
208 |
Issue |
3 |
Pages |
315-328 |
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Keywords |
Animals; *Behavior, Animal; *Computer Simulation; Models, Biological; *Movement; Predatory Behavior |
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Abstract |
According to the selfish herd hypothesis, animals can decrease predation risk by moving toward one another if the predator can appear anywhere and will attack the nearest target. Previous studies have shown that aggregations can form using simple movement rules designed to decrease each animal's Domain of Danger. However, if the predator attacks from outside the group's perimeter, these simple movement rules might not lead to aggregation. To test whether simple selfish movement rules would decrease predation risk for those situations when the predator attacks from outside the flock perimeter, we constructed a computer model that allowed flocks of 75 simulated fiddler crabs to react to one another, and to a predator attacking from 7 m away. We attacked simulated crab flocks with predators of different sizes and attack speeds, and computed relative predation risk after 120 time steps. Final trajectories showed flight toward the center of the flock, but curving away from the predator. Path curvature depended on the predator's size and approach speed. The average crab experienced a greater decrease in predation risk when the predator was small or slow moving. Regardless of the predator's size and speed, however, predation risk always decreased as long as crabs took their flock-mates into account. We conclude that, even when flight away from an external predator occurs, the selfish avoidance of danger can lead to aggregation. |
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Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, U.S.A. viscido@u.washington.edu |
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0022-5193 |
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PMID:11207093 |
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555 |
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Author |
Burke, D.; Cieplucha, C.; Cass, J.; Russell, F.; Fry, G. |
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Title |
Win-shift and win-stay learning in the short-beaked echidna (Tachyglossus aculeatus) |
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Journal Article |
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Year |
2002 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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Volume |
5 |
Issue |
2 |
Pages |
79-84 |
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Keywords |
Animals; Echidna/*psychology; Ecology; Female; *Learning; *Memory; *Predatory Behavior; Reinforcement (Psychology) |
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Abstract |
Numerous previous investigators have explained species differences in spatial memory performance in terms of differences in foraging ecology. In three experiments we attempted to extend these findings by examining the extent to which the spatial memory performance of echidnas (or “spiny anteaters”) can be understood in terms of the spatio-temporal distribution of their prey (ants and termites). This is a species and a foraging situation that have not been examined in this way before. Echidnas were better able to learn to avoid a previously rewarding location (to “win-shift”) than to learn to return to a previously rewarding location (to “win-stay”), at short retention intervals, but were unable to learn either of these strategies at retention intervals of 90 min. The short retention interval results support the ecological hypothesis, but the long retention interval results do not. |
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Department of Psychology, University of Wollongong, Wollongong, NSW 2522, Australia. darren_burke@uow.edu.au |
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1435-9448 |
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PMID:12150039 |
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Equine Behaviour @ team @ |
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2605 |
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Author |
Isenbugel, E. |
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Title |
[From wild horse to riding horse] |
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Journal Article |
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Year |
2002 |
Publication |
Schweizer Archiv fur Tierheilkunde |
Abbreviated Journal |
Schweiz Arch Tierheilkd |
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Volume |
144 |
Issue |
7 |
Pages |
323-329 |
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Keywords |
Animal Husbandry/*history; Animals; Animals, Domestic; Animals, Wild; *Bonding, Human-Pet; Breeding/history; Evolution; Female; History, 15th Century; History, 16th Century; History, 17th Century; History, 18th Century; History, 19th Century; History, 20th Century; History, Ancient; History, Medieval; *Horses/physiology/psychology; Humans; Male; Paintings; Predatory Behavior; Sculpture; Sports/history |
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Over 45 million years of evolution the horse developed to a highly specialized animal in anatomy, physiology and behavior. No other animal had influenced the economic and cultural history of men to such extent. Hunting prey since the ice age, domesticated 4000 B.C. and used for thousands of years as unique animal all over the world has attained a new role today as partner in sport, as companion animal and even as cotherapeutic. The well known behavioral demands in use and keeping are still often not fulfilled. |
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Zoologischer Garten Zurich |
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German |
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Original Title |
Vom Wildpferd zum Reitpferd |
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0036-7281 |
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Notes |
PMID:12174680 |
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no |
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Call Number |
refbase @ user @ |
Serial |
1913 |
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