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Rendall, D. (1999). Review of Machiavellian Intelligence II: Extensions and Evaluations. Ethology, 105(2), 178–182.
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Carson, K., & Wood-Gush, D. G. M. (1983). Equine behaviour: II. A review of the literature on feeding, eliminative and resting behaviour. Appl. Animal. Ethol., 10(3), 179–190.
Abstract: The literature on the feeding, eliminative and resting behaviour of horses has been reviewed to collate the information available on these subjects. The grazing and eliminative behaviour patterns of domestic horses are unlike those of free-ranging Equidae. The reasons for this are not known, but it can cause wasted grazing of up to 90% of a field. Certain conditions, such as provision of supplementary hay and lack of available herbage, can cause these behaviour patterns to change, although it is not known how to manipulate the grazing behaviour of horses to prevent deterioration of the pasture. Grazing behaviour is influenced by many variables and is more complex than the feeding behaviour of a stabled horse. Horses sleep for approximately 12% of the day and show 4 different sleep/wakefulness states -- alert wakefulness, drowsiness, slow-wave sleep and paradoxical sleep. Horses are able to maintain slow-wave sleep while standing, but they need to lie down for paradoxical sleep to occur, rarely spending more than 30 consecutive minutes in lateral recumbency.
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Baragli, P., Paoletti, E., Vitale, V., & Sighieri, C. (2011). Looking in the correct location for a hidden object: brief note about the memory of donkeys (Equus asinus). Ethology Ecology & Evolution, 23(2), 187–192.
Abstract: In recent years, considerable literature has been published on cognition in horses; however, much less is known about the cognitive abilities of domestic donkey (Equus asinus). This study aimed to expand our knowledge of donkey cognition by assessing their short-term memory capacity. We employed a detour problem combined with the classic delayed-response task, which has been extensively used to compare working memory duration in a variety of different species. A two-point choice apparatus was used to investigate location recall and search behaviour for a food target, after a short delay following its disappearance. Four donkeys completed the task with a 10 sec delay, while four others were tested with a 30 sec delay. Overall, each group performed above chance level on the test, showing that subjects had successfully encoded, maintained, and retrieved the existence and location of the target despite the loss of visual contact.
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Baragli, P., Vitale, V., Paoletti, E., Sighieri, C., & Reddon, A. R. (2011). Detour behaviour in horses (Equus caballus). J. Ethol., 29(2), 227–234.
Abstract: The objective of this study was to investigate the ability of horses (Equus caballus) to detour around symmetric and asymmetric obstacles. Ten female Italian saddle horses were each used in three detour tasks. In the first task, the ability to detour around a symmetrical obstacle was evaluated; in the second and third tasks subjects were required to perform a detour around an asymmetrical obstacle with two different degrees of asymmetry. The direction chosen to move around the obstacle and time required to make the detour were recorded. The results suggest that horses have the spatial abilities required to perform detour tasks with both symmetric and asymmetric obstacles. The strategy used to perform the task varied between subjects. For five horses, lateralized behaviour was observed when detouring the obstacle; this was consistently in one direction (three on the left and two on the right). For these horses, no evidence of spatial learning or reasoning was found. The other five horses did not solve this task in a lateralized manner, and a trend towards decreasing lateralization was observed as asymmetry, and hence task difficulty, increased. These non-lateralized horses may have higher spatial reasoning abilities.
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Sakura O, & Matsuzawa T. (1991). Flexibility of wild chimpanzees nut-cracking behavior using stone hammers and anvils: an experimental analysis. Ethology, 87, 237.
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Vervaecke, H., Stevens, J., Vandemoortele, H., Sigurjönsdöttir, H., & De Vries, H. (2007). Aggression and dominance in matched groups of subadult Icelandic horses (Equus caballus). J. Ethol., 25(3), 239–248.
Abstract: Abstract We studied sex differences in the nature of aggression and dominance behaviour in two newly formed groups of 1-year-old Icelandic horses. One herd contained nine geldings, the other nine mares. The groups were matched with regard to dominance-determining traits such as age, weaning age, composition of native herd, social experience, genetic origin, body condition and maternal dominance status. High-ranking individuals of both sexes were more aggressive, high-ranking males were older, and high-ranking females had a better body condition. Frequencies of aggressions were similar in both groups. The mares reacted significantly more by showing submission upon an aggression rather than by not responding or by escalating the aggression. For the geldings, this difference was not observed due to a lower tendency to submit. A linear dominance hierarchy was found in both groups. David`s scores provided additional information regarding cardinal rank distances and were used to calculate steepness of hierarchies. The female hierarchy was somewhat steeper compared to the male hierarchy, suggesting somewhat lower despotism among males. This was mainly a consequence of the lower unidirectionality in male submission. Male contests occurred predominantly between dyads at top and mid positions, suggesting a low degree of acceptance of the hierarchy.
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Hemelrijk, C. K., & Hildenbrandt, H. (2008). Self-Organized Shape and Frontal Density of Fish Schools. Ethology, 114(3), 245–254.
Abstract: Abstract Models of swarming (based on avoidance, alignment and attraction) produce patterns of behaviour also seen in schools of fish. However, the significance of such similarities has been questioned, because some model assumptions are unrealistic [e.g. speed in most models is constant with random error, the perception is global and the size of the schools that have been studied is small (up to 128 individuals)]. This criticism also applies to our former model, in which we demonstrated the emergence of two patterns of spatial organization, i.e. oblong school form and high frontal density, which are supposed to function as protection against predators. In our new model we respond to this criticism by making the following improvements: individuals have a preferred ‘cruise speed’ from which they can deviate in order to avoid others or to catch up with them. Their range of perception is inversely related to density, with which we take into account that high density limits the perception of others that are further away. Swarm sizes range from 10 to 2000 individuals. The model is three-dimensional. Further, we show that the two spatial patterns (oblong shape and high frontal density) emerge by self-organization as a side-effect of coordination at two speeds (of two or four body lengths per second) for schools of sizes above 20. Our analysis of the model leads to the development of a new set of hypotheses. If empirical data confirm these hypotheses, then in a school of real fish these patterns may arise as a side-effect of their coordination in the same way as in the model.
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Mettke-Hofmann, C., Winkler, H., & Leisler, B. (2002). The Significance of Ecological Factors for Exploration and Neophobia in Parrots. Ethology, 108(3), 249–272.
Abstract: Exploratory behaviour plays an important role in most animals for gathering information about their environment. If it constitutes an adaptation to different environmental conditions exploratory behaviour should differ between species. This has been tested with several hypotheses. Sixty-one parrot species (Psittacidae) from eight tribes with different diets and habitat preferences were investigated in aviaries. Two tests were carried out. First, a novel object (wooden ring) in the familiar aviary was presented on two test days in the exploration test. Latencies until first contact with the object and the duration of exploration were recorded. Secondly, in the neophobia test, novel objects were placed beside the feeding dish and latencies until first food intake were recorded. The exploration and neophobia data were related to 12 (13) ecological variables using multiple regression analyses. Phylogenetic relationships were considered. Species that inhabit complex habitats, such as forest edges, or that feed on buds or species from islands showed the shortest latencies in the exploration test. In contrast, long latencies were related to a diet including a great amount of seeds and/or flowers. The longest duration of exploration occurred in species eating nuts or originating from islands, whereas short durations were related to feeding on seeds. Neophobia was positively related to a diet consisting of insects, and negatively to a diet of leaves. There was no relationship between measures of exploration and neophobia. Exploration and neophobia seem to be tightly related to the ecology of a species.
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Ellis, L. (1995). Dominance and reproductive success among nonhuman animals: A cross-species comparison. Ethol. a. Sociob., 16(4), 257–333.
Abstract: This paper updates and extends Dewsbury's (1982) review of the literature on dominance and reproductive success (RS). The findings from approximately 700 studies are included, over two thirds of which were unavailable to Dewsbury. In order to give a highly condensed and yet meaningful overview, the main findings are represented in four tables, one for male nonprimates, one for female nonprimates, one for male primates, and one for female primates. In the tables for males, findings are analyzed in terms of six different indicators of RS, and in the tables for females, in terms of eight RS indicators. Outside the primate order, evidence largely supported the hypothesis that high-ranking males enjoy greater RS than do subordinate males. For females, studies are more evenly divided between those supporting the hypothesis that high rank and RS are positively correlated and those indicating no significant rank-RS relationship. This may reflect both the lower saliency of hierarchical relationships among females, as well as the lower variability in RS among females, relative to males. Among primates, a complex picture has emerged, especially in the case of males. Much of the complexity appears due to the importance of age and seniority in affecting dominance rank. Also, in some primate species, female preferences for sex partners seem to have little to do with the male's dominance rank, at least at the time mating takes place. Nevertheless, the majority of studies suggest that high- to middle-ranking males have at least a slight lifetime reproductive advantage over the lowest ranking males.
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Houpt, K. A., Law, K., & Martinisi, V. (1978). Dominance hierarchies in domestic horses. Appl. Animal. Ethol., 4(3), 273–283.
Abstract: Dominance hierarchies were studied in 11 herds of domestic horses and ponies (Equus caballus). A paired feeding test was utilized to establish the dominance--subordination relationship between each pair of animals in a herd. Aggressive actions, threats, bites, kicks and chases were also recorded. In small herds linear hierarchies were formed, but in large herds triangular relationships were observed. Aggression was correlated with dominance rank. Body weight, but not age, appear to affect rank in the equine hierarchy. Juvenile horses were more likely to share feed with each other than were adult horses and were usually subordinate to adult horses. The daughters of a dominant mare were dominant within their own herds.
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