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Author C. K. Hemelrijk, doi  openurl
  Title An individual-orientated model of the emergence of despotic and egalitarian societies Type Journal Article
  Year 1999 Publication Proceedings of the Royal Society B: Biological Sciences Abbreviated Journal Proc. Roy. Soc. Lond. B Biol. Sci.  
  Volume 266 Issue 1417 Pages 361-361  
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  Abstract Single behavioural differences between egalitarian and despotic animal societies are often assumed to reflect specific adaptations. However, in the present paper, I will show in an individual-orientated model, how many behavioural traits of egalitarian and despotic virtual societies arise as emergent characteristics. The artificial entities live in a homogeneous world and only aggregate, and upon meeting one another and may perform dominance interactions in which the effects of winning and losing are self-reinforcing. The behaviour of these entities is studied in a similar way to that of real animals. It will be shown that by varying the intensity of aggression only, one may switch from egalitarian to despotic virtual societies. Differences between the two types of society appear to correspond closely to those between despotic and egalitarian macaque species in the real world. In addition, artificial despotic societies show a clearer spatial centrality of dominants and, counter-intuitively, more rank overlap between the sexes than the egalitarian ones. Because of the correspondence with patterns in real animals, the model makes it worthwhile comparing despotic and egalitarian species for socio-spatial structure and rank overlap too. Furthermore, it presents us with parsimonious hypotheses which can be tested in real animals for patterns of aggression, spatial structure and the distribution of social positive and sexual behaviour.  
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  Call Number refbase @ user @ Serial 862  
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Author Hemelrijk, C.K. url  doi
openurl 
  Title Towards the integration of social dominance and spatial structure Type Journal Article
  Year 2000 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 59 Issue 5 Pages 1035-1048  
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  Abstract My aim was to show how individual-oriented (or artificial life) models may provide an integrative background for the development of theories about dominance by including effects of spatial structure. Dominance interactions are thought to serve two different, contrasting functions: acquisition of high rank and reduction of aggression. The model I present consists of a homogeneous virtual world inhabited by artificial agents whose actions are restricted to grouping and dominance interactions in which the effects of winning and losing are self-reinforcing. The two functions are implemented as strategies to initiate dominance interactions and the intensity of aggression and dominance perception (direct or memory based) are varied experimentally. Behaviour is studied by recording the same behavioural units as in real animals. Ranks appear to differentiate more clearly at high than at low intensity of aggression and also more in the case of direct than of memory-based rank perception. Strong differentiation of rank produces a cascade of unexpected effects that differ depending on which function is implemented: for instance, a decline in aggression, spatial centrality of dominants and a correlation between rank and aggression. Insight into the origination of these self-organized patterns leads to new hypotheses for the study of the social behaviour of real animals.  
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  Call Number refbase @ user @ Serial 863  
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Author Hemelrijk, C.K. doi  openurl
  Title Despotic societies, sexual attraction and the emergence of male 'tolerance': an agent-based model Type Journal Article
  Year 2002 Publication Behaviour Abbreviated Journal Behaviour  
  Volume 139 Issue 6 Pages 729-747  
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  Abstract During the period when females are sexually attractive – but only then – males of certain species of primates, such as chimpanzees, allow females access to resources. Because males are usually dominant over females, such male 'tolerance' is explained as a special, reproductive strategy to gain access to females. In this paper a simpler hypothesis is proposed on the basis of an individual-based model (called DomWorld): male 'tolerance' towards females arises in 'despotic' artificial societies as a kind of 'respectful timidity', because sexual attraction automatically increases female dominance over males as a side-effect. The model consists in a homogeneous, virtual world with agents that group and perform dominance-interactions in which the effects of victory and defeat are self-reinforcing. The artificial sexes differ in that VirtualMales have a higher intensity of aggression, they start with a greater capacity to win conflicts than VirtualFemales and they are especially attracted to the opposite sex during certain periods, whereas VirtualFemales are not. I shall explain how the introduction into DomWorld of the attraction of VirtualMales by VirtualFemales leads to female dominance, why it does so only in despotic, but not in egalitarian societies, and how it leads to other phenomena that are relevant to the study of primate behaviour.  
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  Call Number refbase @ user @ Serial 864  
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Author Karavanich, C.; Atema, J. url  doi
openurl 
  Title Individual recognition and memory in lobster dominance Type Journal Article
  Year 1998 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 56 Issue 6 Pages 1553-1560  
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  Abstract American lobsters,Homarus americanus, form stable dominance relationships in captivity. Size, sex and stage in the moult cycle are important determinants for dominance. Other factors, such as recent agonistic experience play a role. This paper investigates how lobsters maintain their stable dominance relationships: they may recognize individuals or alternatively, recognize overall dominance status. We paired lobsters in two consecutive `boxing matches'. Results indicate that lobsters remember familiar opponents when kept either in isolation or in communal tanks for 24 h between their first and second fights. Subordinates immediately backed away from familiar dominants, avoiding a second fight. In some animals, this memory lasted between 1-2 weeks if pairs were kept separate between the first and second fights. When paired for the second fight against unfamiliar dominant lobsters, subordinate lobsters from first fights actively fought and won the encounter. These results suggest that lobsters are capable of `individual recognition'. In nature, the observed social organization of lobsters may be maintained by individual recognition of a small number of residents inhabiting separate, nearby shelters.  
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  Call Number refbase @ user @ Serial 866  
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Author Thouless, C.R.; Guinness, F.E. url  openurl
  Title Conflict between red deer hinds: the winner always wins Type Journal Article
  Year 1986 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 34 Issue 4 Pages 1166-1171  
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  Abstract Dominance relations between free-living, female red deer (hinds) (Cervus elaphus L.) on the Isle of Rhum, Scotland, were investigated. Most interactions were won by the older hind of the pair and this was the case even when both individuals had reached full body size. The younger hind was more likely to be the winner if the conflict was escalated or if the two hinds were strangers, in which case escalation was more frequent than usual. When outside their normal home range, older hinds were much more likely to lose, and younger ones more likely to win, than usual. These results can be best explained by the hinds using previous experience as a cue for conventional resolution of conflict, with the result that dominance relationships established early in life are perpetuated. No such cue is available if the hinds have not previously met.  
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  Call Number refbase @ user @ Serial 868  
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Author De Vries, H.; Appleby, M.C. url  doi
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  Title Finding an appropriate order for a hierarchy: a comparison of the I&SI and the BBS methods Type Journal Article
  Year 2000 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 59 Issue 1 Pages 239-245  
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  Call Number refbase @ user @ Serial 869  
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Author Chase, I.D.; Bartolomeo, C.; Dugatkin, L.A. url  doi
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  Title Aggressive interactions and inter-contest interval: how long do winners keep winning? Type Journal Article
  Year 1994 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 48 Issue 2 Pages 393-400  
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  Abstract Abstract. Considerable evidence across many taxa demonstrates that prior social experience affects the outcome of subsequent aggressive interactions. Although the 'loser effect', in which an individual losing one encounter is likely to lose the next, is relatively well understood, studies of the 'winner effect', in which winning one encounter increases the probability of winning the next, have produced mixed results. Earlier studies differ concerning whether a winner effect exists, and if it does, how long it lasts. The variation in results, however, may arise from different inter-contest intervals and procedures for selecting contestants employed across previous studies. These methodological differences are addressed through a series of experiments using randomly selected winners and three different inter-contest intervals in the pumpkinseed sunfish, Lepomis gibbosus. The results indicate that a winner effect does in fact exist in pumpkinseed sunfish, but that it only lasts between 15 and 60 min. Based on these results, predictions about the behavioural dynamics of hierarchy formation are discussed, and it is suggested that it may be impossible, in principle, to predict the outcome of dominance interactions between some individuals before they are actually assembled to form a group. Finally, the possible mechanisms underlying the winner effect are explored.  
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  Call Number refbase @ user @ Serial 873  
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Author Asa, C.S.; Goldfoot, D.A.; Garcia, M.C.; Ginther, O.J. url  doi
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  Title Dexamethasone suppression of sexual behavior in the ovariectomized mare Type Journal Article
  Year 1980 Publication Hormones and Behavior Abbreviated Journal Horm Behav  
  Volume 14 Issue 1 Pages 55-64  
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  Abstract The influence of steroids of adrenal cortical origin on estrous behavior in the ovariectomized mare was evaluated by adrenal suppression via dexamethasone (DEX) administration in two experiments. In Experiment I, 12 mares (six DEX, six control) were tested for sexual behavior in harem groups (two DEX and two control mares plus one stallion per group) for 9 consecutive days. In Experiment II, estradiol (E2) was given to a group of DEX-treated mares as an additional control. Twelve mares (four DEX, four DEX + E2, and four control) were tested in harem groups (one DEX, one DEX + E2, and one control mare plus one stallion per group) for 10 days. All DEX mares showed a clear suppression of sexual response compared to control or DEX + E2 mares, indicating that the estrous behavior seen in ovariectomized mares may be due to steroids from the adrenal cortex. The control and DEX + E2 mares were similar in all measures of proceptivity. Despite being more receptive, as indicated by fewer negative responses, the DEX + E2 mares received fewer intromissions and ejaculations than did the control animals. The ability of estradiol to induce estrous behavior in the dexamethasone-suppressed mare notwithstanding, other adrenal steroids, e.g., androgens, may be involved in estrous behavior in the untreated, ovariectomized mare.  
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  ISSN 0018-506x ISBN Medium  
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  Notes Approved (up) no  
  Call Number Equine Behaviour @ team @ Serial 5360  
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Author Asa, C.S.; Goldfoot, D.A.; Ginther, O.J. url  doi
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  Title Sociosexual behavior and the ovulatory cycle of ponies (Equus caballus) observed in harem groups Type Journal Article
  Year 1979 Publication Hormones and Behavior Abbreviated Journal Horm Behav  
  Volume 13 Issue 1 Pages 49-65  
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  Abstract Observations of sociosexual behavior of adult ponies, made on two harem groups (each comprised of one vasectomized male and three females), were correlated with follicular development and ovulation for a total of 15 cycles (minimum of 2 cycles per female). Mean cycle length (interovulatory interval) was found to be 19.7 days, with behavioral estrus lasting 7-8 days (5.5 days preovulatory; 2.3 days postovulatory). Estrous females typically showed increased frequencies of approaching and following the stallion, urinating, presenting, clitoral winking, and tail raising. Approaching and following the stallion appeared earlier and persisted longer than other estrous responses. Deviations from the modal estrous pattern included cycles with subestrus, continual estrus, behavioral estrus in the absence of ovulation, and displays of female mounting. Dominance tests revealed that a mare's status was unaffected by the phases of the estrous cycle. The presence of more than one estrous female affected the copulatory performance of both stallions, most notably in reduced latencies to first mount, intromission, and ejaculation, in spite of differences between the stallions in sexual vigor. Each stallion usually selected the dominant mare for copulation when there were multiple estrous females present, but mounts were not displayed exclusively to one female per test. The social testing situation made apparent the importance of use of space in sociosexual communication in this species, particularly in avoidance of the stallion by diestrous mares and standing alone or in proximity to him by estrous mares.  
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  Notes Approved (up) no  
  Call Number Equine Behaviour @ team @ Serial 5363  
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Author Campitelli, S.; Carenzi, C.; Verga, M. doi  openurl
  Title Factors which influence parturition in the mare and development of the foal Type Journal Article
  Year 1982 Publication Applied Animal Ethology Abbreviated Journal Appl. Animal. Ethol.  
  Volume 9 Issue 1 Pages 7-14  
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  Abstract Observations are reported of 127 foals born to 127 mares. In particular, comparisons are made between the mare's tendency to foal at night, the length of gestation, the weight of the foal and the weight of the foetal membrane, the time taken by the foal to attain a standing position and the time taken by the mare to expel the foetal membrane and the age of the mare and the season.

The new facts that emerge from the results are: (a) foals from middle-aged (6–11 years) mares are heavier; (b) variations of gestation length are related to the month of conception (just a trend, not a statistically significant result); (c) time for the foal to stand is related to the foal sex (females: 56.3 minutes; males 70.6 minutes, on average), and to the time taken by the mare to expel the foetal membrane; (d) parturitions take place mainly (80%) during the hours of darkness. In spring, the percentage of night births (85%) is higher than in winter (78%).
 
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  Notes from Professor Hans Klingels Equine Reference List Approved (up) no  
  Call Number Serial 984  
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