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	Author	Santamaria, S.; Bobbert, M.E.; Back, W.; Barneveld, A.; van Weeren, P.R.
	Title	Variation in free jumping technique within and among horses with little experience in show jumping			Type	Journal Article
	Year	2004	Publication	American Journal of Veterinary Research	Abbreviated Journal	Am J Vet Res
	Volume	65	Issue	7	Pages	938-944
	Keywords	Acceleration; Analysis of Variance; Animals; Biomechanics; Forelimb/physiology; Gait/physiology; Hindlimb/physiology; Horses/physiology; Locomotion/physiology; Models, Biological; Video Recording
	Abstract	OBJECTIVE: To quantify variation in the jumping technique within and among young horses with little jumping experience, establish relationships between kinetic and kinematic variables, and identify a limited set of variables characteristic for detecting differences in jumping performance among horses. ANIMALS: Fifteen 4-year-old Dutch Warmblood horses. PROCEDURE: The horses were raised under standardized conditions and trained in accordance with a fixed protocol for a short period. Subsequently, horses were analyzed kinematically during free jumping over a fence with a height of 1.05 m. RESULTS: Within-horse variation in all variables that quantified jumping technique was smaller than variation among horses. However, some horses had less variation than others. Height of the center of gravity (CG) at the apex of the jump ranged from 1.80 to 2.01 m among horses; this variation could be explained by the variation in vertical velocity of the CG at takeoff (r, 0.78). Horses that had higher vertical velocity at takeoff left the ground and landed again farther from the fence, had shorter push-off phases for the forelimbs and hind limbs, and generated greater vertical acceleration of the CG primarily during the hind limb push-off. However, all horses cleared the fence successfully, independent of jumping technique. CONCLUSIONS AND CLINICAL RELEVANCE: Each horse had its own jumping technique. Differences among techniques were characterized by variations in the vertical velocity of the CG at takeoff. It must be determined whether jumping performance later in life can be predicted from observing free jumps of young horses.
	Address	Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 12, NL-3584 CM Utrecht, The Netherlands
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0002-9645	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:15281652			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	3772
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	Author	Santamaria, S.; Bobbert, M.F.; Back, W.; Barneveld, A.; van Weeren, P.R.
	Title	Effect of early training on the jumping technique of horses			Type	Journal Article
	Year	2005	Publication	American Journal of Veterinary Research	Abbreviated Journal	Am J Vet Res
	Volume	66	Issue	3	Pages	418-424
	Keywords	Age Factors; Analysis of Variance; Animals; Biomechanics; Forelimb/physiology; Gait/physiology; Hindlimb/physiology; Horses/growth & development/physiology; Locomotion/physiology; Models, Biological; Physical Conditioning, Animal/methods
	Abstract	OBJECTIVE: To investigate the effects of early training for jumping by comparing the jumping technique of horses that had received early training with that of horses raised conventionally. ANIMALS: 40 Dutch Warmblood horses. PROCEDURE: The horses were analyzed kinematically during free jumping at 6 months of age. Subsequently, they were allocated into a control group that was raised conventionally and an experimental group that received 30 months of early training starting at 6 months of age. At 4 years of age, after a period of rest in pasture and a short period of training with a rider, both groups were analyzed kinematically during free jumping. Subsequently, both groups started a 1-year intensive training for jumping, and at 5 years of age, they were again analyzed kinematically during free jumping. In addition, the horses competed in a puissance competition to test maximal performance. RESULTS: Whereas there were no differences in jumping technique between experimental and control horses at 6 months of age, at 4 years, the experimental horses jumped in a more effective manner than the control horses; they raised their center of gravity less yet cleared more fences successfully than the control horses. However, at 5 years of age, these differences were not detected. Furthermore, the experimental horses did not perform better than the control horses in the puissance competition. CONCLUSIONS AND CLINICAL RELEVANCE: Specific training for jumping of horses at an early age is unnecessary because the effects on jumping technique and jumping capacity are not permanent.
	Address	Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, NL-3584 CM Utrecht, The Netherlands
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0002-9645	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:15822585			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	4037
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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
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1537-5323	ISBN		Medium
	Area		Expedition		Conference
	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
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1537-5323	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:15729669			Approved	no
	Call Number				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
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1537-5323	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:15278850			Approved	no
	Call Number				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
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0003-0147	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:14737714			Approved	no
	Call Number				Serial	2132
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	Author	Aureli, F.; de Waal, F.B.
	Title	Inhibition of social behavior in chimpanzees under high-density conditions			Type	Journal Article
	Year	1997	Publication	American journal of primatology	Abbreviated Journal	Am. J. Primatol.
	Volume	41	Issue	3	Pages	213-228
	Keywords	Aggression/psychology; Animals; Behavior, Animal; Crowding; Female; Male; Pan troglodytes/psychology; Population Density; *Social Environment; Stress, Psychological
	Abstract	This is the first study to investigate the short-term effects of high population density on captive chimpanzees (Pan troglodytes). Subjects of the study were 45 chimpanzees living in five different groups at the Yerkes Regional Primate Research Center. The groups were observed under two conditions: 1) when they had access to both the indoor and outdoor sections of their enclosures; 2) during cold days when they were locked into the indoor runs, which reduced the available space by more than half. Under the high-density condition, allogrooming and submissive greetings decreased, but juvenile play increased. Remarkably, the rate of various forms of agonistic behavior, such as aggression, bluff charge, bluff display, and hooting, occurred less frequently under the high-density condition. This general decrease in adult social activity, including agonistic behavior, can be interpreted as an inhibition strategy to reduce opportunities for conflict when interindividual distances are reduced. This strategy is probably effective only in the short run, however. Behavioral indicators of anxiety, such as rough scratching and yawning, showed elevated rates, suggesting increased social tension under the high-density condition.
	Address	Yerkes Regional Primate Research Center, Emory University, Atlanta, GA 30322, USA
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0275-2565	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:9057966			Approved	no
	Call Number	refbase @ user @			Serial	203
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	Author	Izar, P.; Ferreira, R.G.; Sato, T.
	Title	Describing the organization of dominance relationships by dominance-directed tree method			Type	Journal Article
	Year	2006	Publication	American journal of primatology	Abbreviated Journal	Am. J. Primatol.
	Volume	68	Issue	2	Pages	189-207
	Keywords	Animals; Cebus/physiology; Models, Biological; Social Dominance
	Abstract	Methods to describe dominance hierarchies are a key tool in primatology studies. Most current methods are appropriate for analyzing linear and near-linear hierarchies; however, more complex structures are common in primate groups. We propose a method termed “dominance-directed tree.” This method is based on graph theory and set theory to analyze dominance relationships in social groups. The method constructs a transitive matrix by imposing transitivity to the dominance matrix and produces a graphical representation of the dominance relationships, which allows an easy visualization of the hierarchical position of the individuals, or subsets of individuals. The method is also able to detect partial and complete hierarchies, and to describe situations in which hierarchical and nonhierarchical principles operate. To illustrate the method, we apply a dominance tree analysis to artificial data and empirical data from a group of Cebus apella.
	Address	Department of Experimental Psychology, University of Sao Paulo, Brazil. patrizar@usp.br
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0275-2565	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:16429416			Approved	no
	Call Number	refbase @ user @			Serial	723
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	Author	Smith, J.E.; Kolowski, J.M.; Graham, K.E.; Dawes, S.E.; Holekamp, K.E.
	Title	Social and ecological determinants of fission-fusion dynamics in the spotted hyaena			Type	Journal Article
	Year	2008	Publication	Animal Behaviour.	Abbreviated Journal	Anim. Behav.
	Volume	76	Issue	3	Pages	619-636
	Keywords	competition; conflict resolution; cooperative hunting; Crocuta crocuta; ecological constraints; group living; social rank
	Abstract	Theory predicts that individuals living in fission-fusion societies, in which group members frequently change subgroups, should modify grouping patterns in response to varying social and environmental conditions. Spotted hyaenas, Crocuta crocuta, are long-lived carnivores that reside in permanent social groups called clans. Clans are complex, fission-fusion societies in which individual members travel, rest and forage in subgroups that frequently change composition. We studied two clans in Kenya to provide the first detailed description of fission-fusion dynamics in this species. Because social and ecological circumstances can influence the cohesiveness of animal societies, we evaluated the extent to which specific circumstances promote the formation of subgroups of various sizes. We found that cooperative defence of shared resources during interclan competition and protection from lions were cohesive forces that promoted formation of large subgroups. We also tested hypotheses suggesting factors limiting subgroup size. Mothers with small cubs avoided conspecifics, thereby reducing infanticide risk. Victims of aggression either reconciled fights or separated from former opponents to reduce the immediate costs of escalated aggression in the absence of food. As predicted by the ecological constraints hypothesis, hyaenas adjusted their grouping patterns over both short and long time scales in response to feeding competition. Crocuta were most gregarious during periods of abundant prey, joined clanmates at ephemeral kills in numbers that correlated with the energetic value of the prey and gained the most energy when foraging alone because cooperative hunting attracted numerous competitors. Overall, our findings indicate that resource limitation constrains grouping in this species.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	Equine Behaviour @ team @			Serial	4676
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	Author	Smith, L.A.; Wells, K.L.; Marion, G.; Swain, D.L.; Hutchings, M.R.
	Title	Effects of group composition on the grazing behaviour of herbivores			Type	Journal Article
	Year		Publication	Animal Behaviour.	Abbreviated Journal	Anim. Behav.
	Volume	In Press, Corrected Proof	Issue		Pages
	Keywords	grazing; group composition; herbivore; individual behaviour; physiological state
	Abstract	Animal behaviour is often a function of the animal's physiological state. Groups of animals will often contain individuals with a range of physiological states and the grazing behaviour of herbivores is affected by their physiological state. This study compared the grazing decisions of animals in groups of single and mixed physiological states. Using a grazing model that simulated individual herbivore behaviour in relation to environmental distributions of forage resource (grass) and parasites (faeces), we tested the hypothesis that an animal's level of parasite exposure via the faecal-oral route is affected by the composition of physiological states in the group. Four physiological states were considered: parasite-naïve, parasitized, lactating and parasite-immune animals. Baseline parasite exposure levels for each state were generated by simulating single-state groups and were compared to simulations of each of the six two-state combinations. In single-state groups parasitized animals had the least and lactating animals had the greatest levels of parasite exposure. When co-grazing with lactating animals, parasitized, immune and naïve animals increased their parasite exposure, relative to single-state groups. When co-grazing with parasitized animals, lactating, immune and naïve animals reduced their parasite exposure, relative to single-state groups. There was no difference in parasite exposure of the immune or naïve animals co-grazing together when compared to the single-state groups. These results highlight the need to recognize the impact of the individual when studying group-living animals.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0003-3472	ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	Equine Behaviour @ team @			Serial	5155
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