Pichardo, M. (2000). Valsequillo biostratigraphy. III: Equid ecospecies in Paleoindian sites. Anthropol Anz, 58(3), 275–298.
Abstract: Greater precision in North American Pleistocene equid taxonomy makes it now possible to exploit the ubiquitous horse remains in Paleoindian sites as ecological index-fossils. The horses of Central Mexico and the Southern Plains can be sorted by tooth size alone, except for two rare large horses of the Southern Plains. The species endemic to these grasslands and south to Central Mexico are Equus pacificus (large), E. conversidens (small), E. francisci (smallest). The Southern Plains were also occupied by a specialized grazer E. excelsus (Burnet and Sandia caves) and E. occidentalis (Dry and Sandia caves). West of the Rocky Mountains E. occidentalis was dominant. East of the Mississippi River two woodland species are found: E. fraternus and E. littoralis.
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Cooper, J. J., McDonald, L., & Mills, D. S. (2000). The effect of increasing visual horizons on stereotypic weaving: implications for the social housing of stabled horses. Appl Anim Behav Sci, 69(1), 67–83.
Abstract: Stabled horses commonly perform stereotypic patterns of weaving, where the horse shifts its weight from side to side often swinging its head. Ten warm-blood types, of which five were known to reliably weave, were housed in similar 12x12 ft wooden loose boxes in a single stable block surrounding a courtyard. Each horse was exposed to each of five stable designs. These were: the conventional front top-half of the door open only with a view of the stable courtyard (F); front half-door open and a similar half-door open at the back of the stable with a view to the surrounding fields (FB); back open only (B); front and one-side panel open with a view into the adjacent stable (FS); and front, back and both sides open (All4). During observation days, horses were brought in from the field at 0830 h, fed concentrate at 0930 h, fed haylage at 1005 h and turned out at 1600 h. Behaviour was recorded from 0900 to 1040 h, 1200 to 1300 h and 1500 to 1600 h. Weaving was most common prior to feeding in the morning and prior to putting out to pasture in the afternoon. There was a significant effect of stable design on weaving, with less weaving in the FS and All4 designs than the F treatment. There was also a significant effect of stable design on repetitive nodding, though in this case, FB, B, FS and All4 designs each reduced nodding compared with the F treatment. The effect of stable design can be explained in a number of ways. Firstly, it could be the novelty of the environmental change, though there was no evidence in this study of an increase in stereotypy with prolonged exposure to the new stable designs. Secondly, opening windows may increase opportunities for environmental interaction, and the expression of new activities may compete with stereotypic behaviour for the horse's time. Thirdly, the open windows may allow expression of specific activities such as environmental monitoring or social interaction that are denied by the conventional stable.
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Weeks, J. W., Crowell-Davis, S. L., Caudle, A. B., & Heusner, G. L. (2000). Aggression and social spacing in light horse (Equus caballus) mares and foals. Appl. Anim. Behav. Sci., 68(4), 319–337.
Abstract: Aggression and social spacing were studied in 14 light horse mares and their foals living at pasture. Focal samples were collected on each mare-foal dyad for 6 to 10.5 h from 2 months of foal age until weaning at approximately 4 months of age. Observations on foals continued until approximately 6 months of age for 7.5 to 10.5 h per foal. Every 2 min the identities of all individuals within 5 m were recorded. All occurrences of agonistic behavior, and the participants, were recorded during the focal samples. In addition, during feeding of supplemental grain, all occurrences of agonistic behavior by all subjects were recorded. Significant correlations were found between mare rank and the rank of foals both prior to and after weaning. Before weaning, the rank of the foal was significantly correlated with birth order. No significant correlation between birth order and foal rank was found for the post-weaning hierarchy. An animal's gender had no significant effect on foal rank or the choice of preferred associate. Both prior to and after weaning, foals associated preferentially with the foal of their dam's most preferred associate. In addition, significant positive correlations were found between rank of mares and foals and the rate at which they directed aggression to other herd members. (C) 2000 Elsevier Science B.V.
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Weiss, A., King, J. E., & Figueredo, A. J. (2000). The heritability of personality factors in chimpanzees (Pan troglodytes). Behav Genet, 30(3), 213–221.
Abstract: Human personality and behavior genetic studies have resulted in a growing consensus that five heritable factors account for most variance in human personality. Prior research showed that chimpanzee personality is composed of a dominance-related factor and five human-like factors--Surgency, Dependability, Emotional Stability, Agreeableness, and Openness. Genetic, shared zoo, and nonshared environmental variance components of the six factors were estimated by regressing squared phenotypic differences of all possible pairs of chimpanzees onto 1 – Rij, where Rij equals the degree of relationship and a variable indicating whether the pair was housed in the same zoo. Dominance showed significant narrow-sense heritability. Shared zoo effects accounted for only a negligible proportion of the variance for all factors.
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Mrabet, O., Es-Salah, Z., Telhiq, A., Aubert, A., Liege, S., Choulli, K., et al. (2000). Influence of gender and behavioural lateralisation on two exploratory models of anxiety in C3H mice. Behav Processes, 52(1), 35–42.
Abstract: Behavioural lateralisation, which has been postulated to be an individual personality trait, is related to the activity of various physiological systems including the immune system. As lateralisation has been related to anxiety, which is known to influence immune reactivity, it can be hypothesized that the relation between lateralisation and immune reactivity involves individual behavioural patterns as they appear in exploratory-based anxiety models. In order to answer this question, a behavioural investigation focussing on exploratory activity was undertaken in male and female C3H mice previously selected for their paw preference. The observations were performed using two generic paradigms: elevated plus-maze and open field. Exploratory behaviour in the open field, but not in the plus-maze, was influenced by the interactive effect of gender and behavioural lateralisation. A significant difference between male and female mice was found in left-pawed but not in right-pawed nor ambidextrous animals, left-pawed female mice displaying the less exploratory behaviours. These results provide a first evidence of inter-individual variations in exploratory behaviours involving interaction between gender and lateralisation.
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Cameron, E. Z., Linklater, W. L., Stafford, K. J., & Minot, E. O. (2000). Aging and improving reproductive success in horses: declining residual reproductive value or just older and wiser? Behav. Ecol. Sociobiol., 47(4), 243–249.
Abstract: In many mammalian species, female success in raising offspring improves as they age. The residual reproductive value hypothesis predicts that each individual offspring will be more valuable to the mother as she ages because there is less conflict between the current and potential future offspring. Therefore, as mothers age, their investment into individual offspring should increase. Empirical evidence for an influence of declining residual reproductive value on maternal investment is unconvincing. Older mothers may not invest more, but may be more successful due to greater experience, allowing them to target their investment more appropriately (targeted reproductive effort hypothesis). Most studies do not preclude either hypothesis. Mare age significantly influenced maternal investment in feral horses living on the North Island of New Zealand. Older mares, that were more successful at raising foals, were more protective for the first 20 days of life, but less diligent thereafter. Total maternal input by older mothers did not seem to be any greater, but was better targeted at the most critical period for foal survival and a similar pattern was observed in mares that had lost a foal in the previous year. In addition, older mothers were more likely to foal in consecutive years, supporting the hypothesis that they are investing less than younger mares in individual offspring. Therefore, older mothers seem to become more successful by targeting their investment better due to experience, not by investing more in their offspring.
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Le Pendu, Y., Guilhem, C., Briedermann, L., Maublanc, M. - L., & Gerard, J. - F. (2000). Interactions and associations between age and sex classes in mouflon sheep (Ovis gmelini) during winter. Behav. Process., 52(2-3), 97–107.
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Mercado E., Killebrew D.A., Pack A.A., Macha I.V.B., & Herman L.M. (2000). Generalization of 'same-different' classification abilities in bottlenosed dolphins. Behav. Process., 50, 79–94.
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McLean, I. G., Schmitt, N. T., Jarman, P. J., Duncan, C., & Wynne, C. D. L. (2000). Learning For Life: Training Marsupials To Recognise Introduced Predators. Behaviour, 137(10), 1361–1376.
Abstract: Raising endangered species in captivity for reintroduction necessarily results in animals that lack appropriate skills for coping with problems to be faced in the wild, such as predators. Using classical conditioning techniques involving linking fear of a live dog with the image of a fox, we demonstrate an adjusted fear response for two wallaby species (rufous bettongs Aepyprymnus rufescens, quokkas Setonix brachyurus). No differences in response to the fox were found for wild-caught and captive-born bettongs, even though wild-caught subjects were likely to have encountered canids prior to capture. Attempts to condition a fear response by quokkas to an odour were unsuccessful. An attempt to induce fear of the stuffed fox by linking to fear of humans in quokkas was unsuccessful, but quokkas generalised from fear of the dog to fear of the fox, despite a delay of several weeks. Trained dogs offer a valuable and ethically acceptable mechanism for improving the ability of captive-reared (or sequestered) animals to recognise and cope with predators.
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Vervaecke, H., de Vries, H., & van Elsacker, L. (2000). The Pivotal Role Of Rank In Grooming And Support Behavior In A Captive Group Of Bonobos (Pan Paniscus). Behaviour, 137(11), 1463–1485.
Abstract: We investigated dyadic grooming relationships in a captive group of bonobos (Pan paniscus) and questioned what social function grooming fulfils in the 'market of services and favors'. Hereto we examined which of two theoretical models – grooming for support (Seyfarth, 1977, 1980) or grooming according to the similarity principle (de Waal & Luttrell, 1986) – best accounted for the observed grooming distribution. Similarity in traits did not correlate with increased grooming or close proximity among the individuals. Therefore, the similarity hypothesis was rejected. Seyfarth's model of rank-related grooming was largely confirmed. The animals distributed their grooming according to the rank of the receivers. We found an exchange between grooming and receipt of support. There was more grooming up than down the hierarchy. However, not all predictions about rank-related competition over grooming were confirmed. We found that dyadic grooming reciprocity indeed increased with decreasing rank distance. Yet, there was no increase of grooming within the dyad with decreasing rank distance and high ranking individuals were not competed over at the highest rates. The observed correlation between grooming and support received represents an important fit with Seyfarth's prediction, but does not allow for conclusions about underlying causal processes. Other causal explanations, besides the 'groom to receive support' hypothesis, that could explain a similar correlation are discussed.
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