Dugatkin, L. A. (1991). Dynamics of the TIT FOR TAT strategy during predator inspection in the guppy (Poecilia reticulata). Behav. Ecol. Sociobiol., 29(2), 127–132.
Abstract: One well-known solution to the iterated Prisoner's Dilemma is the TIT FOR TAT strategy. This strategy has three “characteristics” associated with it. TIT FOR TAT is nice (cooperates on the first move of a game), retaliatory (plays defect against an individual that defected on the prior move), and forgiving (cooperates with an individual which has defected in the past but cooperates in the present). Predator inspection behavior in guppies (Poecilia reticulata) was examined in order to determine whether guppies displayed these three characteristics. Results indicate that while it can be quite difficult to translate the abstract concepts of niceness, retaliation, and forgiveness into measurable behaviors, the data support the hypothesis that guppies display the three characteristics associated with the TIT FOR TAT strategy.
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Judge, P. J. (1991). Dyadic and triadic reconciliation in pigtail macaques (Macaca nemestrina). Am. J. Primatol., 23, 225–237.
Abstract: The tendency in primates for former antagonists to approach and affiliate following aggression has been termed reconciliation because the response is thought to resolve social conflicts produced by aggression. In primate societies, however, an aggressive interaction between two individuals often spreads to include other group members, especially the kin of the combatants. If post conflict affiliation resolves aggressive conflicts in a group, then affiliative increases might occur between combatants and the kin of their opponents following aggression as well as between former opponents. This hypothesis was tested in a captive group of 39 pigtail macaques (Macaca nemestrina) by comparing affiliative response frequencies of combatants during the 5 minute period following aggression to affiliative response frequencies during 5 minute baseline periods not preceded by aggressive activity. Following aggression, affiliation rates increased between combatants and their opponents, aggressors and the kin of their opponents, and aggressors and their own kin. Additional analyses showed that aggression among kin was reconciled more often than aggression among nonkin. Recipients of aggression reconciled with their attackers more often than aggressors reconciled with their victims. Animals with similar dominance ranks reconciled proportionately more often than those with large rank disparities and aggressive infractions of a calculated dominance hierarchy were reconciled more often than attacks consistent with the hierarchy. Results suggest that both dyadic and triadic reconciliations occur in M. nemestrina and that compared to other primate species M. nemestrina exhibit a moderate-to-high conciliatory tendency.
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Deutsch, J., & Lee, P. (1991). Dominance and feeding competition in captive rhesus monkeys. Int. J. Primatol., 12(6), 615–628.
Abstract: The feeding behavior of 16 adult female rhesus monkeys living in three captive social groups was observed. Estimates of relative food intake, feeding rate, and location of feeding in relation to food sources were compared between females of different dominance ranks. Higher-ranking females had greater access to feeding sites and were supplanted or threatened less frequently while feeding than subordinates. However, no consistent differences in estimates of total intake were found between females of high and females of low rank. The effects of dominance on feeding behavior were most pronounced in the group receiving the least food relative to estimates of overall group nutritional requirements. Higher-ranking females, both over the long term and during the study period, tended to produce more surviving offspring. The effects of dominance on reproductive performance appeared to be less related to food intake than to competitive and aggressive interactions, potentially resulting in higher levels of stress for subordinates.
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Povinelli DJ, Parks KA, & Novak MA. (1991). Do rhesus monkeys (Macaca mulatta) attribute knowledge and ignorance to others? J. Comp. Psychol., 105, 318.
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Klingel, H. (1991). Dix ans parmi les zèbres. Terre Sauvage, 48, 34–43.
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Scheidhacker, M., Bender, W., & Vaitl, P. (1991). Die Wirksamkeit des therapeutischen Reitens bei der Behandlung chronisch schizophrener Patienten. Nervenarzt, 62(5), 283–287.
Abstract: After describing horse-riding as a facility in managing mentally ill patients, a program for chronic schizophrenic in-patients is presented. Clinical experience with this program and also results of a controlled study are reported. The therapeutic value and slope for horse-riding are discussed in relation to different diagnoses.
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Schwarzenberger, F., Mostl, E., Bamberg, E., Pammer, J., & Schmehlik, O. (1991). Concentrations of progestagens and oestrogens in the faeces of pregnant Lipizzan, trotter and thoroughbred mares. J Reprod Fertil Suppl, 44, 489–499.
Abstract: Faecal samples were collected at weekly intervals from pregnant Lipizzan mares during Weeks 7-16 following mating and from Lipizzan, Trotter and Thoroughbred mares during the last 3 months of gestation. After parturition, samples were taken daily from the Thoroughbred mares for another 6 days. Non-pregnant mares served as controls. The concentrations of unconjugated oestrogens (Eg), 20 alpha-OH-progestagens (20 alpha-G) and 20 beta-OH-progestagens (20 beta-G) were measured by enzyme immunoassay. In the faeces of Lipizzan mares, immunoreactive progestagens were significantly (P less than 0.01) elevated above the levels in non-pregnant mares by Week 11, and Eg by Week 13 of pregnancy onwards. During the last 3 months of gestation, concentrations of Eg were significantly higher in Trotter mares than in Lipizzan and Thoroughbred mares. Concentrations of 20 alpha-G and 20 beta-G increased to maximal values in the last month of gestation. There was no significant difference among the 3 breeds with respect to 20 alpha-G but, during the 10 weeks before parturition, concentrations of 20 beta-G in the Lipizzan mares were significantly lower (P less than 0.05) than those in the Thoroughbred mares. They were also significantly lower than those of the Trotter mares during the last 4 weeks of gestation. After parturition, the concentrations of Eg and progestagens had declined to baseline values by Days 3 and 4 respectively. From these results we conclude that high concentrations of progestagens with 20 alpha- and 20 beta-hydroxyl groups are present in the faeces of pregnant mares, especially during the last month of gestation.
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Jablonska, E. M., Ziolkowska, S. M., Gill, J., Szykula, R., & Faff, J. (1991). Changes in some haematological and metabolic indices in young horses during the first year of jump-training. Equine Vet J, 23(4), 309–311.
Abstract: Effects of an 18 min exercise test, on three separate occasions during a one year jump-training programme, was studied in seven horses. Determinations were carried out on venous blood for packed cell volume, haemoglobin, total protein, lactate and pyruvate, glucose, free fatty acids, insulin, glucagon, blood gases, bicarbonate, pH, aldolase, aspartate aminotransferase and alanine amino-transferase. Exercise caused a slight increase in lactate and pyruvate, total protein, aldolase, alanine aminotransferase, pO2, bicarbonate and pH. Glucose, free fatty acids and pCO2 levels decreased. Training caused no significant difference in these changes. However, during the year, increases in lactate and decreases in pH (resting levels) were observed.
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Kirkpatrick, J. F., & Turner, J. W. (1991). Changes in herd stallions among feral horse bands and the absence of forced copulation and induced abortion. Behav. Ecol. Sociobiol., 29(3), 217–219.
Abstract: Forced copulation and induced abortion were investigated in a herd of feral horses inhabiting a coastal barrier island. Eight mares were diagnosed pregnant in August and October 1989 by means of urinary and fecal steroid metabolites, prior to documented changes in herd stallions. These mares were observed for harassment and forced copulation by the new stallions and for the presence of foals during the spring and summer of 1990. No incidents of harassment or attempts at forced copulation were witnessed and seven of the eight mares produced foals in 1990. These data indicate that forced copulation and induced abortion are not common events among all feral horse herds and suggest reinvestigation of this hypothesized phenomenon.
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Mal, M. E., Friend, T. H., Lay, D. C., Vogelsang, S. G., & Jenkins, O. C. (1991). Behavioral responses of mares to short-term confinement and social isolation. Appl. Anim. Behav. Sci., 31(1-2), 13–24.
Abstract: Thirty-six mares, blocked by age and temperament score, were assigned to one of three treatment groups: pasture (P); confinement stalls (C), allowing social contact; isolation stalls (ISS), allowing no contact with conspecifics. After 48 h on treatment, the mares were observed in situ for 1 h. Medium temperament and highly reactive ISS mares spent more time eating grain (P<0.01) and exhibited more grain-eating bouts (P<0.03) than P and C mares. Calm P mares had longer forage-eating bouts than C and ISS mares (P<0.02). During a 15 min open-field test in a 23 m x 23 m pen after 72 h on treatment, ISS mares traveled farther (P<0.005) than C and P mares, spent more total time trotting (P<0.01) than C and P mares, and exhibited a greater number of trotting bouts (P<0.01) than both C and P mares. Isolated mares spent less total time standing during the open-field test than C (P<0.05) and P (P<0.01) mares, but exhibited a greater number of standing bouts than C (P<0.05) and P (P<0.01) mares. Isolated mares also exhibited a greater number of total activity bouts (P<0.01) during the open-field test than both C and P mares; P mares also exhibited fewer activity bouts than C mares (P<0.1). Results indicate that mares kept in confined and isolated environments showed greater motivation for movement and performance of a greater number of activities than those maintained on pasture with conspecifics.
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