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Author |
Galloux, P.; Barrey, E. |
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Title |
Components of the total kinetic moment in jumping horses |
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Journal Article |
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Year |
1997 |
Publication |
Equine Veterinary Journal. Supplement |
Abbreviated Journal |
Equine Vet J Suppl |
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Volume |
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Issue |
23 |
Pages |
41-44 |
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Keywords |
Algorithms; Animals; Exertion/*physiology; Female; Gravitation; Horses/*physiology; Kinetics; Locomotion/*physiology; Male; Models, Biological; Movement/*physiology; Video Recording |
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Abstract |
Thirty horses were filmed with a panning camera operating at 50 frames/s as they jumped over a 1.20 x 1.20 m fence. The markers of 9 joints on the horse and 7 joints on the rider were tracked in 2D with the TrackEye system. The centre of gravity and moment of inertia of each segment were calculated using a geometric algorithm and a cylindric model, respectively. The kinetic moment of each part of the horse was calculated after filtering, and resampling of data. This method showed the relative contribution of each body segment to the body overall rotation during the take-off, jump and landing phases. It was found that the trunk, hindlimbs and head-neck had the greatest influence. The coordination between the motion of the body segments allowed the horse to control its angular speed of rotation over the fence. This remained nearly constant during the airborne phase (120 +/- 5 degrees/s). During the airborne phase, the kinetic moment was constant because its value was equal to the moment of the external forces (722 +/- 125 kg x m2/s). |
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Ecole Nationale d'Equitation, Terrefort, Saumur, France |
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PMID:9354287 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3797 |
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Author |
Gonzalez-Fernandez, J.M.; Atta, S.E. |
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Title |
Facilitated transport of oxygen in the presence of membranes in the diffusion path |
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Journal Article |
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Year |
1982 |
Publication |
Biophysical Journal |
Abbreviated Journal |
Biophys J |
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Volume |
38 |
Issue |
2 |
Pages |
133-141 |
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Keywords |
Animals; Biological Transport, Active; Cell Membrane/*metabolism; Diffusion; Dogs; Horses; Humans; Kinetics; Mathematics; *Models, Biological; Muscles/*metabolism; Oxygen/*metabolism |
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Abstract |
Most of the experimental observations on facilitated transport have been done with millipore filters, and all the theoretical studies have assumed homogeneous spatial properties. In striated muscle there exist membranes that may impede the diffusion of the carrier myoglobin. In this paper a theoretical study is undertaken to analyze the transport in the presence of membranes in the diffusion path. For the numerical computations physiologically relevant values of the parameters were chosen. The numerical results indicate that the presence of membranes tends to decrease the facilitation. For the nonlinear chemical kinetics of the reaction of oxygen with the carrier, this decrement also depends on the location of the membranes. At the higher oxygen concentration side of each membrane the flow of combined oxygen is transferred to the flow of dissolved oxygen. The reverse process occurs at the lower concentration side. Jump discontinuities of the concentration of the oxygen-carrier compound at each membrane are associated with these transfers. The decrement of facilitation is due to the cumulative effect of these jump discontinuities. |
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0006-3495 |
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PMID:7093418 |
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Call Number |
Equine Behaviour @ team @ |
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3806 |
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Author |
Santamaria, S.; Bobbert, M.F.; Back, W.; Barneveld, A.; van Weeren, P.R. |
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Title |
Effect of early training on the jumping technique of horses |
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Journal Article |
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Year |
2005 |
Publication |
American Journal of Veterinary Research |
Abbreviated Journal |
Am J Vet Res |
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Volume |
66 |
Issue |
3 |
Pages |
418-424 |
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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 |
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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. |
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Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, NL-3584 CM Utrecht, The Netherlands |
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0002-9645 |
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PMID:15822585 |
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no |
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Call Number |
Equine Behaviour @ team @ |
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4037 |
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Author |
McClearn, G.E. |
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Title |
Behavioral genetics |
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Journal Article |
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Year |
1971 |
Publication |
Behavioral Science |
Abbreviated Journal |
Behav Sci |
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Volume |
16 |
Issue |
1 |
Pages |
64-81 |
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Keywords |
Amino Acid Metabolism, Inborn Errors; Animals; Aptitude; Behavior, Animal; Chromosome Aberrations; Cognition; Cytogenetics; Female; *Genetics, Behavioral; Genetics, Population; Humans; Intelligence; Mental Retardation; Mice; Models, Biological; Personality; Phenylketonurias; Pregnancy; Research; Schizophrenia; Sex Chromosome Aberrations; Twins |
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0005-7940 |
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PMID:5105941 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
4150 |
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Author |
Zhou, W.-X.; Sornette, D.; Hill, R.A.; Dunbar, R.I.M. |
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Title |
Discrete hierarchical organization of social group sizes |
Type |
Journal Article |
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Year |
2005 |
Publication |
Proceedings. Biological sciences / The Royal Society |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
272 |
Issue |
1561 |
Pages |
439-444 |
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Keywords |
Anthropology, Cultural; *Group Structure; Humans; *Models, Biological; *Social Behavior; *Social Environment |
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Abstract |
The 'social brain hypothesis' for the evolution of large brains in primates has led to evidence for the coevolution of neocortical size and social group sizes, suggesting that there is a cognitive constraint on group size that depends, in some way, on the volume of neural material available for processing and synthesizing information on social relationships. More recently, work on both human and non-human primates has suggested that social groups are often hierarchically structured. We combine data on human grouping patterns in a comprehensive and systematic study. Using fractal analysis, we identify, with high statistical confidence, a discrete hierarchy of group sizes with a preferred scaling ratio close to three: rather than a single or a continuous spectrum of group sizes, humans spontaneously form groups of preferred sizes organized in a geometrical series approximating 3-5, 9-15, 30-45, etc. Such discrete scale invariance could be related to that identified in signatures of herding behaviour in financial markets and might reflect a hierarchical processing of social nearness by human brains. |
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State Key Laboratory of Chemical Reaction Engineering, East China University of Science and Technology, Shanghai 200237, China |
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0962-8452 |
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PMID:15734699 |
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refbase @ user @ |
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549 |
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Author |
Cameron, E.Z. |
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Title |
Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism |
Type |
Journal Article |
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Year |
2004 |
Publication |
Proceedings. Biological sciences / The Royal Society |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
271 |
Issue |
1549 |
Pages |
1723-1728 |
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Keywords |
Age Factors; Animals; Body Constitution; *Evolution; Female; Glucose/metabolism/physiology; Litter Size; Male; Mammals/*physiology; *Models, Biological; Reproduction/physiology; Seasons; Sex Factors; *Sex Ratio; Time Factors |
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Abstract |
Evolutionary theory predicts that mothers of different condition should adjust the birth sex ratio of their offspring in relation to future reproductive benefits. Published studies addressing variation in mammalian sex ratios have produced surprisingly contradictory results. Explaining the source of such variation has been a challenge for sex-ratio theory, not least because no mechanism for sex-ratio adjustment is known. I conducted a meta-analysis of previous mammalian sex-ratio studies to determine if there are any overall patterns in sex-ratio variation. The contradictory nature of previous results was confirmed. However, studies that investigated indices of condition around conception show almost unanimous support for the prediction that mothers in good condition bias their litters towards sons. Recent research on the role of glucose in reproductive functioning have shown that excess glucose favours the development of male blastocysts, providing a potential mechanism for sex-ratio variation in relation to maternal condition around conception. Furthermore, many of the conflicting results from studies on sex-ratio adjustment would be explained if glucose levels in utero during early cell division contributed to the determination of offspring sex ratios. |
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Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za |
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0962-8452 |
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PMID:15306293 |
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no |
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Call Number |
refbase @ user @ |
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413 |
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Author |
Brilot, B.O.; Johnstone, R.A. |
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Title |
The limits to cost-free signalling of need between relatives |
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Journal Article |
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Year |
2003 |
Publication |
Proceedings. Biological sciences / The Royal Society |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
270 |
Issue |
1519 |
Pages |
1055-1060 |
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Keywords |
*Animal Communication; Animals; Birds/physiology; Models, Biological; *Social Behavior |
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Abstract |
Theoretical models have demonstrated the possibility of stable cost-free signalling of need between relatives. The stability of these cost-free equilibria depends on the indirect fitness cost of cheating and deceiving a donor into giving away resources. We show that this stability is highly sensitive to the distribution of need among signallers and receivers. In particular, cost-free signalling is likely to prove stable only if there is very large variation in need (such that the least-needy individuals stand to gain much less than the most-needy individuals from additional resources). We discuss whether these conditions are likely to be found in altricial avian breeding systems--the most intensively studied instance of signalling of need between relatives. We suggest that cost-free signalling is more likely to prove stable and will provide parents with more information during the earlier phases of chick growth, when parents can more easily meet the demands of a brood (and chicks are more likely to reach satiation). Later, informative yet cost-free signalling is unlikely to persist. |
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Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. bob21@cam.ac.uk |
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0962-8452 |
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PMID:12803895 |
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refbase @ user @ |
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558 |
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Author |
Flack, J.C.; de Waal, F.B.M.; Krakauer, D.C. |
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Title |
Social structure, robustness, and policing cost in a cognitively sophisticated species |
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Journal Article |
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Year |
2005 |
Publication |
The American Naturalist |
Abbreviated Journal |
Am Nat |
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Volume |
165 |
Issue |
5 |
Pages |
E126-139 |
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Animals; *Behavior, Animal; Cognition; Conflict (Psychology); Female; Macaca nemestrina/*physiology; Male; Models, Biological; *Social Behavior |
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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. |
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Address |
Santa Fe Institute, Santa Fe, New Mexico 87501, USA. jflack@santafe.edu |
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1537-5323 |
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PMID:15795848 |
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no |
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refbase @ user @ |
Serial |
168 |
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Permanent link to this record |
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Author |
Uehara, T.; Yokomizo, H.; Iwasa, Y. |
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Title |
Mate-choice copying as Bayesian decision making |
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Journal Article |
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Year |
2005 |
Publication |
The American naturalist |
Abbreviated Journal |
Am Nat |
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Volume |
165 |
Issue |
3 |
Pages |
403-410 |
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Keywords |
Animals; *Bayes Theorem; *Choice Behavior; Female; Male; *Models, Biological; *Sexual Behavior, Animal |
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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. |
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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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PMID:15729669 |
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1821 |
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Author |
Mettke-Hofmann, C.; Gwinner, E. |
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Title |
Long-term memory for a life on the move |
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Journal Article |
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Year |
2003 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
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Proc. Natl. Acad. Sci. U.S.A. |
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100 |
Issue |
10 |
Pages |
5863-5866 |
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Animals; Germany; Israel; Memory/*physiology; Models, Biological; Periodicity; Songbirds/*physiology |
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Abstract |
Evidence is accumulating that cognitive abilities are shaped by the specific ecological conditions to which animals are exposed. Long-distance migratory birds may provide a striking example of this. Field observations have shown that, at least in some species, a substantial proportion of individuals return to the same breeding, wintering, and stopover sites in successive years. This observation suggests that migrants have evolved special cognitive abilities that enable them to accomplish these feats. Here we show that memory of a particular feeding site persisted for at least 12 months in a long-distance migrant, whereas a closely related nonmigrant could remember such a site for only 2 weeks. Thus, it seems that the migratory lifestyle has influenced the learning and memorizing capacities of migratory birds. These results build a bridge between field observations suggesting special memorization feats of migratory birds and previous neuroanatomical results from the same two species indicating an increase in relative hippocampal size from the first to the second year of life in the migrant but not in the nonmigrant. |
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Max Planck Research Centre for Ornithology, Department of Biological Rhythms and Behaviour, Von-der-Tann-Strasse 7, 82346 Andechs, Germany. mettke-hofmann@erl.ornithol.mpg.de |
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0027-8424 |
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PMID:12719527 |
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refbase @ user @ |
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511 |
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