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Penzhorn, B. L., & Novellie, P. A. (1991). Some behavioural traits of Cape mountain zebras and their implications for the management of asmall conservation area. Appl. Anim. Behav. Sci., 29(1-4), 293–299.
Abstract: The social organisation of mountain zebras (Equus zebra zebra) consists of breeding herds (1 male, 2.4 females (range 1–5) and their offspring) which remain stable over many years, and bachelor groups. Foals leave their maternal herds of their own accord. In a free-ranging population the behaviour of the foals in leaving the herd is probably an adequate mechanism to prevent inbreeding, but inbreeding may occur in confined populations. Individual recognition by means of stripe pattern allows a check to be kept.
Seasonal movement of mountain zebras is associated with a relative change in diet quality (as indicated by crude protein contents of preferred food plants and of faeces) between summer and winter habitats. Any conservation area should be large and varied enough to include both summer and winter habitats. Mountain zebras favour taller grass than most antelope species, harvesting their food at 50–150 mm from the ground. The existence of large populations of antelope could, therefore, be detrimental to zebras.
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Penzhorn, B. L., & Novellie, P. A. (1991). Some behavioural traits of Cape mountain zebras (Equus zebra zebra) and their implications for the management of a small conservation area. Appl. Anim. Behav. Sci., 29(1-4), 293–299.
Abstract: The social organisation of mountain zebras (Equus zebra zebra) consists of breeding herds (1 male, 2.4 females (range 1-5) and their offspring) which remain stable over many years, and bachelor groups. Foals leave their maternal herds of their own accord. In a free-ranging population the behaviour of the foals in leaving the herd is probably an adequate mechanism to prevent inbreeding, but inbreeding may occur in confined populations. Individual recognition by means of stripe pattern allows a check to be kept. Seasonal movement of mountain zebras is associated with a relative change in diet quality (as indicated by crude protein contents of preferred food plants and of faeces) between summer and winter habitats. Any conservation area should be large and varied enough to include both summer and winter habitats. Mountain zebras favour taller grass than most antelope species, harvesting their food at 50-150 mm from the ground. The existence of large populations of antelope could, therefore, be detrimental to zebras.
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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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Dugatkin, L., & Alfieri, M. (1991). Tit-For-Tat in guppies (Poecilia reticulata): the relative nature of cooperation and defection during predator inspection. Evol. Ecol., 5(3), 300–309.
Abstract: Summary The introduction of game-theoretical thinking into evolutionary biology has laid the groundwork for a heuristic view of animal behaviour in which individuals employ “strategies” – rules that instruct them how to behave in a given circumstance to maximize relative fitness. Axelrod and Hamilton (1981) found that a strategy called Tit-For-Tat (TFT) is one robust cooperative solution to the iterated Prisoner's Dilemma game. There exists, however, little empirical evidence that animals employ TFT. Predator inspection in fish provides one ecological context in which to examine the use of the TFT strategy.
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Dugatkin, L. A., & Alfieri, M. (1991). Guppies and the TIT FOR TAT strategy: preference based on past interaction. Behav. Ecol. Sociobiol., 28(4), 243–246.
Abstract: The evolution of cooperation requires either (a) nonrandom interactions, such that cooperators preferentially interact with other cooperators, or (b) conditional behaviors, such that individuals act cooperatively primarily towards other cooperators. Although these conditions can be met without assuming sophisticated animal cognition, they are more likely to be met if animals can remember individuals with whom they have interacted, associate past interactions with these individuals, and base future behavior on this information. Here we show that guppies (Poecilia reticulata), in the context of predator inspection behavior, can identify and remember (for at least 4 h) the “more cooperative” among two conspecifics and subsequently choose to be near these individuals in future encounters.
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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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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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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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Klingel, H. (1991). Dix ans parmi les zèbres. Terre Sauvage, 48, 34–43.
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Klingel, H. (1991). Tausend Zebras im Computer. Das Tier, 10, 8–16.
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