Witter, M. S., & Swaddle, J. P. (1994). Fluctuating Asymmetries, Competition and Dominance. Proc. Roy. Soc. Lond. B Biol. Sci., 256(1347), 299–303.
Abstract: Levels of fluctuating asymmetry (FA) in the primary feathers of European starlings, Sturnus vulgaris, have been shown to be sensitive to nutritional and energetic stress. Furthermore, between-individual variation in plumage FA has been found to be related to social dominance, even without social interactions during feather growth, with dominant birds exhibiting the highest levels of FA. Here we examine whether the relation between dominance and FA differs when birds are housed in social groups, under different degrees of competition for food, during moult. We reason that dominants should derive a greater benefit from their social status as competition for food increases. Our results support this proposition. The relation between dominance and FA differed significantly according to the degree of competition for food. However, in no cases did the dominants exhibit lower levels of FA than subdominants. When competition for food was low, dominants had higher levels of FA than subdominants. When competition for food was high, there was no systematic relation between dominance and FA. These results suggest that dominants may only derive a net benefit from their social status, under the circumstances of our experiment, during severe conditions of competition.
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Bauer, I. E., McMorrow, J. Y.,, & D. W. (1994). The Historic Ranges of Three Equid Species in North-East Africa: A Quantitative Comparison of Environmental Tolerances. J Biogeogr, 21(2), 169–182.
Abstract: The historic ranges of three equid species native to north-east Africa are analysed with respect to annual rainfall, several temperature parameters and a satellite-derived multispectral index of primary productivity. Equus africanus Fitzinger, Equus grevyi Oustalet and Equus burchelli Gray used to largely replace each other, geographically, with narrow zones of range overlap occurring between E. africanus and E. grevyi in the Awash valley, and between E. grevyi and E. burchelli in southern Ethiopia and northern Kenya. The three species are shown to succeed each other along an environmental gradient. The position of each species on this gradient and the resulting location and extent of its range are discussed. Competitive exclusion, specific adaptations and historic events are likely determinants of equid distribution. In the area of sympatry between E. grevyi and E. burchelli, mixed habitat characters as well as environmental fluctuations seem to prevent either species from excluding the other. Different social organizations of E. grevyi and E. burchelli and the resulting migratory patterns may be adaptations to the environment in their allopatric ranges; in their sympatric range they could alleviate competition.
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Burger, J., & Gochfeld. (1994). Vigilance in African mammals: differences among mothers, other females, and males. Behaviour, 131(3-4), 153–169.
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Kuckelkorn, B. (1994). Assessment of pregnancy in Kiang mares (Equus hemionus holdereri ) using estrogen determination in feces. Theriogenology, 42(1), 37–42.
Abstract: Analysis of fecal estrogens was used to diagnose pregnancy in 6 Kiang mares (Equus hemionus holdereri ) that were kept at Tierpark Berlin. Three extraction methods were compared and were followed by an established RIA for total estrogen. Extraction of desiccated feces with chloroform/n-hexane and KOH, with and without enzyme hydrolysis showed better results than extraction with diethylether without hydrolysis. Pregnancy was confirmed by observation of foaling in 2 mares that showed estrogen concentrations between 800 and 1800 ng/g and in 1 mare that showed widely fluctuating values between 500 and 1300 ng/g of feces. Two mares with estrogen concentrations below 500 ng/g were not seen to foal. The method using chloroform/n-hexane and KOH without enzyme hydrolysis seems practical for non-invasive evaluation of the endocrine status in this endangered Equidae species.
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Sappington, B. F., & Goldman, L. (1994). Discrimination learning and concept formation in the Arabian horse. J. Anim Sci., 72(12), 3080–3087.
Abstract: Discrimination learning and concept formation abilities were investigated in four mature Arabian horses. A series of two-choice discrimination problems were presented on stimulus panels that could open to allow access to food bowls. Selection of the correct stimulus resulted in food reinforcement, and an incorrect choice was not rewarded. The positions of the correct and incorrect stimuli were varied randomly during each test session, and the criterion for learning each problem was 85% correct for two consecutive sessions of 30 or 40 trials. Testing progressed through six discrimination problems. The first four were simple pattern discriminations, but the last two incorporated several different triangles as correct stimuli and thus involved the concept of triangularity. Two of the subjects successfully completed only simple pattern discriminations, one showed evidence of learning in the first concept problem, and one completed all six tests, including the two concept formation problems. The results demonstrate complex pattern discrimination ability in horses, and suggest that they may also have the ability to form and use concepts in problem solving.
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Mal, M. E., McCall, C. A., Cummins, K. A., & Newland, M. C. (1994). Influence of preweaning handling methods on post-weaning learning ability and manageability of foals. Appl. Anim. Behav. Sci., 40(3-4), 187–195.
Abstract: Twenty-three foals were used to determine if different amounts of handling between birth and weaning affected their later learning ability and manageability. Foals were assigned to one of three treatments: non-handled (NH) foals were not handled except for necessary maintenance procedures; intermediately handled (IH) foals were handled daily in two 10-min sessions for 7 days after birth and then not handled except for necessary maintenance procedures; extensively handled (EH) foals were handled daily for 7 days as were IH foals and then handled for 10 min once weekly until weaning. Foals were weaned at 120 +/- 10 days of age. On days 1, 3, and 15 after weaning, foals were subjected to a one-trial learning test. The learning test consisted of placing the foal in a familiar pen with an 1.5 X .6-m apparatus containing 40 15 X 15-cm compartments. Number of visits to the apparatus and compartment visited were recorded for 5 min. A small amount of concentrate feed then was placed in a target compartment, and visits were recorded for an additional 5 min. On day 16 after weaning, foals were subjected to a manageability test in which flight distance from an unfamiliar handler and reaction to a novel stimulus were recorded. Split-plot analysis of variance revealed no treatment differences in performance on the learning test (P > .05). Foal performance on the test was greater on day 15 than on day 1 or day 3 (P < .01). Analysis of variance indicated handling treatment had no effect (P > .05) on foal performance during the manageability test. Results indicate that this preweaning handling regimen has no effect on foal learning ability or manageability as measured by these procedures.
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Frey, G., & Hildenbrandt, E. (1994). Einführung in die Trainingslehre 1. Grundlagen. Schorndorf: Hofmann.
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(1994). Winter horse care. Journal of Equine Veterinary Science, 14(2), 115–117.
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Moehlman, P. D. (1994). Behavior and Ecology of Feral Asses (2nd edition). Ph.D. thesis, , Univ. of Wisconsin, Madison.
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Boesch, C. (1994). Cooperative hunting in wild chimpanzees. Anim. Behav., 48(3), 653–667.
Abstract: A model for the evolution of cooperation shows that two conditions are necessary for cooperation to be stable: a hunting success rate that is low for single hunters and increases with group size, and a social mechanism limiting access to meat by non-hunters. Testing this model on TaI chimpanzees, Pan troglodytes, showed that (1) it pays for individuals to hunt in groups of three or four rather than alone or in pairs, and (2) cooperation is stable because hunters gain more at these group sizes than cheaters, owing to a meat-sharing pattern in which hunting, dominance and age, in that order, determine how much an individual gets. In addition, hunters provide cheaters (about 45% of the meat eaters) with the surplus they produce during the hunts. Thus, cooperation in Tai male chimpanzees is an evolutionarily stable strategy, and its success allows cheating to be an evolutionarily stable strategy for Tai female chimpanzees. In Gombe chimpanzees, cooperation is not stable, first, because hunting success is very high for single hunters, and second, because no social mechanism exists that limits access to meat by non-hunters. The analysis showed that some assumptions made when discussing cooperation in other social hunters might be wrong. This might downgrade our general perception of the importance of cooperation as an evolutionary cause of sociality.
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