| Records |
| 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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| Language |
English |
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Edition |
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| ISSN |
1537-5323 |
ISBN |
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| Notes |
PMID:17206591 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
410 |
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| Author |
Linton, M.L. |
| Title |
Washoe the chimpanzee |
Type |
Journal Article |
| Year |
1970 |
Publication |
Science (New York, N.Y.) |
Abbreviated Journal |
Science |
| Volume |
169 |
Issue |
943 |
Pages |
328 |
| Keywords |
Animals; Animals, Newborn; Cognition; Cultural Deprivation; *Hominidae; Humans; Infant; *Language Development; Psychology, Comparative |
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English |
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Edition |
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| ISSN |
0036-8075 |
ISBN |
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| Notes |
PMID:5450363 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
2849 |
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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 |
ISBN |
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Conference |
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| Notes |
PMID:15795848 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
168 |
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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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English |
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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 |
Golland, L.C.; Evans, D.L.; McGowan, C.M.; Hodgson, D.R.; Rose, R.J. |
| Title |
The effects of overtraining on blood volumes in standardbred racehorses |
Type |
Journal Article |
| Year |
2003 |
Publication |
Veterinary Journal (London, England : 1997) |
Abbreviated Journal |
Vet J |
| Volume |
165 |
Issue |
3 |
Pages |
228-233 |
| Keywords |
Animals; *Blood Volume; Erythrocytes/*physiology; Hematocrit/veterinary; Horse Diseases/etiology/*physiopathology; Horses; Male; *Physical Conditioning, Animal; Physical Endurance |
| Abstract |
Red blood cell hypervolaemia has been used for diagnosis of overtraining in racehorses, and has been suggested as a mechanism of this cause of loss of racing performance. The effects of overload training (OLT) on the plasma, blood and red cell volumes were investigated in a prospective study in 12 Standardbred horses. Measurements of blood volumes were made after eight and 32 weeks of an exercise training study. Horses were randomly allocated to OLT and control groups (n=6) after 16 weeks of training. Training duration and intensity were increased more rapidly for the OLT group from week 16, until overtraining was diagnosed in week 32.There were no significant effects of OLT on plasma, blood or total red cell volumes between weeks eight and 32. These volumes significantly decreased with time. Maximal haematocrit after exercise was lower (P<0.05) in the OT group in week 32 (0.57+/-0.003% L/L) than in week eight (0.59+/-0.004 L/L). It was concluded that red cell hypervolaemia was not a mechanism for the decrease in capacity for exercise that occurs with overtraining. |
| Address |
Faculty of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia |
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English |
Summary Language |
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Edition |
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| ISSN |
1090-0233 |
ISBN |
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Expedition |
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Conference |
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| Notes |
PMID:12672368 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
4045 |
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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 |
Summary Language |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
1537-5323 |
ISBN |
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Medium |
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Expedition |
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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 |
ISBN |
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| Notes |
PMID:14737714 |
Approved |
no |
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Serial |
2132 |
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| Author |
Robinson, H.C. |
| Title |
Equine interspecies aggression |
Type |
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| Year |
2007 |
Publication |
The Veterinary record |
Abbreviated Journal |
Vet. Rec. |
| Volume |
160 |
Issue |
7 |
Pages |
244 |
| Keywords |
*Aggression; Animals; Behavior, Animal; Equidae; Horses/*physiology/*psychology |
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English |
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| ISSN |
0042-4900 |
ISBN |
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| Notes |
PMID:17308028 |
Approved |
no |
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Serial |
1773 |
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| Author |
Huxley, J. |
| Title |
Equine interspecies aggression |
Type |
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| Year |
2006 |
Publication |
The Veterinary record |
Abbreviated Journal |
Vet. Rec. |
| Volume |
159 |
Issue |
25 |
Pages |
860 |
| Keywords |
*Aggression; Animals; *Behavior, Animal; Horses; Male; Sheep |
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0042-4900 |
ISBN |
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| Notes |
PMID:17172489 |
Approved |
no |
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Serial |
1776 |
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| Author |
Burden, F.; Trawford, A. |
| Title |
Equine interspecies aggression Comment on |
Type |
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| Year |
2006 |
Publication |
The Veterinary record |
Abbreviated Journal |
Vet. Rec. |
| Volume |
159 |
Issue |
25 |
Pages |
859-860 |
| Keywords |
*Aggression; Animals; *Behavior, Animal; Cats; Dogs; Equidae |
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English |
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Edition |
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0042-4900 |
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| Notes |
PMID:17172484 |
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no |
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Serial |
1777 |
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