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Wolff, A., & Hausberger, M. (1994). Behaviour of foals before weaning may have some genetic basis. Ethology, 96(1), 1–10.
Abstract: In this preliminary study on foal behaviour, 13 French saddlebred foals (2-3 mo old) and their dams were observed on pasture. The most important findings are the interindividual quantitative differences in foal behaviour patterns as well as in the amount of mainly foal-initiated time spent at given distances from their mares. Interindividual differences seem in part due to a sire effect
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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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McComb, K., & Clutton-Brock, T. (1994). Is mate choice copying or aggregation responsible for skewed distributions of females on leks? Proc Biol Sci, 255(1342), 13–19.
Abstract: In several lek-breeding populations of birds and mammals, females arriving on leks tend to join males that already have females in their territories. This might occur either because females have an evolved preference for mating with males that are attractive to other females, or because they join groups of other females to obtain greater safety from predation or dangerous harassment by males. We have previously used controlled experiments to show that oestrous fallow deer females join males with established harems because they are attracted to female groups rather than to the males themselves. Here we demonstrate that the preference for males with females over males without females is specific to oestrous females and weak or absent in anoestrous ones, and that it is not associated with a preference for mating with males that have previously been seen to mate with other females. Furthermore, oestrous females given the choice between males that do not already have females with them show no significant preference for antlered over deantlered males or for older males over younger ones. We conclude that female attraction to other females on the lek is likely to be an adaptation to avoiding harassment in mixed-sex herds. In this situation, a male's ability to maintain the cohesion of his harem may be the principal cause of variation in mating success between males.
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Araba, B. D., & Crowell-Davis, S. L. (1994). Dominance relationships and aggression of foals (Equus caballus). Appl. Anim. Behav. Sci., 41(1-2), 1–25.
Abstract: Studied a herd of 15 Belgian brood-mares and 10 foals. Specific aspects of social structure studied were dominance-subordinance relationships, preferred associates, social spacing, aggression rates, the frequency of aggressions administered down the dominance hierarchy, and interactive play bouts. The rank order of the foals, both before and after weaning, was positively correlated with the rank order of their dams. There was also a significant relationship between a foal's rank and its total aggression or aggression rate per subordinate post-weaning. Higher ranking foals had higher rates of aggression. Over 80% of threats were directed down the dominance hierachy. The play-rank order of the foals, scored by the number of times foal left a play bout, was not significantly correlated with the rank order as scored by agonistic interactions. -from Authors
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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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FitzGibbon, C. D. (1994). The costs and benefits of predator inspection behaviour in Thomson's gazelles. Behav. Ecol. Sociobiol., 34(2), 139–148.
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Noë, R., & Hammerstein, P. (1994). Biological markets: supply and demand determine the effect of partner choice in cooperation, mutualism and mating. Behav. Ecol. Sociobiol., 35(1), 1–11.
Abstract: The formation of collaborating pairs by individuals belonging to two different classes occurs in the contexts of reproduction and intea-specific cooperation as well as of inter-specific mutualism. There is potential for partner choice and for competition for access to preferred partners in all three contexts. These selective forces have long been recognised as important in sexual selection, but their impact is not yet appreciated in cooperative and mutualistic systems. The formation of partnerships between members of different classes has much in common with the conclusion of trade agreements in human markets with two classes of traders, like producers and consumers, or employers and employees. Similar game-theoretical models can be used to predict the behaviour of rational traders in human markets and the evolutionarily stable strategies used in biological markets. We present a formal model in which the influence of the market mechanism on selection is made explicit. We restrict ourselves to biological markets in which: (1) Individuals do not compete over access to partners in an agonistic manner, but rather by outcompeting each other in those aspects that are preferred by the choosing party. (2) The commodity the partner has to offer cannot be obtained by the use of force, but requires the consent of the partner. These two restrictions ensure a dominant role for partner choice in the formation of partnerships. In a biological market model the decision to cooperate is based on the comparison between the offers of several potential partners, rather than on the behaviour of a single potential partner, as is implicitly assumed in currently accepted models of cooperation. In our example the members of one class A offer a commodity of fixed value in exchange for a commodity of variable value supplied by the other class, B. We show that when the B-class outnumbers the A-class sufficiently and the cost for the A-class to sample the offers of the B-class are low, the choosiness of the A-class will lead to selection for the supply of high value commodities by the B-class (Fig. 3a). Under the same market conditions, but with a high sampling cost this may still be the evolutionariy stable outcome, but another pair of strategies proves to be stable too: relaxed choosiness of class A coupled with low value commodities supplied by class B (Fig. 3b). We give a number of examples of mating, cooperative and mutualistic markets that resemble the low sampling cost situation depicted in Fig. 3a.
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Walter, B., & Trillmich, F. (1994). Female aggression and male peace-keeping in a cichlid fish harem: conflict between and within the sexes in Lamprologus ocellatus. Behav. Ecol. Sociobiol., 34(2), 105–112.
Abstract: Conflicts of interest within and between the sexes are important processes leading to variability in mating systems. The behavioral interactions mediating conflict are little documented. We studied pairs and harems of the snail-shell inhabiting cichlid fish Lamprologus ocellatus in the laboratory. Due to their larger size, males controlled the resource that limited breeding: snail shells. Males were able to choose among females ready to spawn. Females were only accepted if they produced a clutch within a few days of settling. When several females attempted to settle simultaneously the larger female settled first. Females were least aggressive when guarding eggs. Secondary females were more likely to settle when the primary female was guarding eggs. In established harems females continued to be aggressive against each other. The male intervened in about 80% of female aggressive interactions. Male intervention activity correlated with the frequency of aggression among the females in his harem. The male usually attacked the aggressor and chased her back to her own snail shell. When a male was removed from his harem, aggression between females increased immediately and usually the secondary female was expelled by the primary female within a few days. Time to harem break-up was shorter the more mobile the primary females' young were and did not correlate with the size difference between harem females. Male L. ocellatus interfere actively in female conflict and keep the harem together against female interests. Female conflict presumably relates to the cost of sharing male parental investment and to the potential of predation by another female's large juveniles on a female's own small juveniles.
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Feh, C.., BOLDSUKH, T., & TOURENQ, C. (1994). Are family groups in equids a response to cooperative hunting by predators? The case of Mongolian Kulans (Equus hemionus luteus Matschie). Rev Ecol (Terre Vie), 49, 11–20.
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Huber W,. (1994). Dokumentation der fünf bekannten Lebendaufnahmen vom Quagga,Equus quagga quagga Gmelin, 1788 (Mammalia, Perissodactyla, Equidae). Spixiana 17, , 193–199.
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