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Dugatkin, L. A., & Wilson, D. S. (1994). Choice experiments and cognition: a reply to Lamprecht & Hofer. Anim. Behav., 47(6), 1459–1461.
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Dumont, B., Boissy, A., Achard, C., Sibbald, A. M., & Erhard, H. W. (2005). Consistency of animal order in spontaneous group movements allows the measurement of leadership in a group of grazing heifers. Appl. Anim. Behav. Sci., 95(1-2), 55–66.
Abstract: The term `leadership' has been used in several different senses, resulting in very different ways of identifying leaders and apparently inconsistent conclusions on how leadership is determined in herbivores. We therefore propose the following definitions: (i) a leader is the individual that is consistently the one who initiates long-distance, spontaneous group movements toward a new feeding site and (ii) long-distance spontaneous group movements are movements which happen when an animal changes activity and location and is immediately followed by a similar change in activity and location by other members of the group. Using these definitions, we tested for consistency of movement order across time and situation within a group of fifteen 2-year-old heifers. We found that the same individual was recorded as the very first animal in 48% of movements toward a new feeding site and could therefore be identified as the `leader'. We also showed that movement order when the animals entered an experimental plot, or progressed slowly through the field during a grazing bout, did not produce the same result. This method, which enables us to identify leaders in groups of animals at pasture, should improve our knowledge of how leadership is determined in grazing herbivores.
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Dunbar, R. I., & Dunbar, E. P. (1976). Contrasts in social structure among black-and-white colobus monkey groups. Anim. Behav., 24(1), 84–92.
Abstract: Three types of Colobus guereza groups may be distinguished on the bases of size and composition, namely small one-male groups, large, one-male groups and multi-male groups. The social structure of each type of group is described in terms of the distribution of non-agonistic interactions, the frequency and distribution of agonistic behaviour and the organization of the roles of vigilance, territorial defence and leadership. A number of differences are found between the group types which appear to be related to the differences in group size and composition. It is suggested that these group types represent stages in the life-cycle of colobus groups, and that such an interpretation may help to resolve some of the conflicting reports in the literature.
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Duncan, I. J. H. (1995). D.G.M. Wood-Gush Memorial Lecture: An applied ethologist looks at the question “Why?”. Appl. Anim. Behav. Sci., 44(2-4), 205–217.
Abstract: The question “Why does an animal behave as it does?” can be answered in terms of ontogeny, function, phylogeny and causation. The achievements of applied ethology relative to those four approaches are reviewed, gaps in our knowledge are identified and predictions for fruitful avenues of future research are made. Ontogenic studies have been useful in the past and it is suggested that studies of the effects of early experience on the sexual behaviour of animals used in artificial breeding schemes might pay dividends. It is proposed that functional studies should be approached cautiously. More information is required on the process of domestication in order to increase the chances of success in the trend to farm exotic species. Studies on causation are likely to continue to be the mainstay of applied ethological research. It is suggested that within this category, studies on states of suffering, motivation and cognition are urgently required to answer the most pressing questions on animal welfare.
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Duncan, I. J. H., & Petherick, J. C. (1989). Proceeding (Paper presented at the Winter Meeting of the Society for Veterinary Ethology, London, Great Britain, 30 November 1988)Cognition: The implications for animal welfare. Appl. Anim. Behav. Sci., 24(1), 81–1010.
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Duncan, P., & Vigne, N. (1979). The effect of group size in horses on the rate of attacks by blood-sucking flies. Anim. Behav., 27(Part 2), 623–625.
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Earley, R. L., Druen, M., & Alan Dugatkin, L. (2005). Watching fights does not alter a bystander's response towards naive conspecifics in male green swordtail fish, Xiphophorus helleri. Anim. Behav., 69(5), 1139–1145.
Abstract: Bystanders are capable of extracting cues from signalling interactions between others and appear to use information gained via eavesdropping when confronted with the watched individuals. A question that has gained little attention is whether observing fights affects bystander behaviour outside the context of interacting with the watched individuals. Our aim was to determine whether watching fights elicits general changes in bystander aggression levels in Xiphophorus helleri. We manipulated the bystanders' ability to witness encounters using clear, one-way-mirror and opaque partitions. After watching (or not watching) an initial contest, the bystanders were pitted against naive conspecifics instead of the animals they had seen fight. Observing fights did not alter the bystanders' propensity to initiate aggression, escalate, or win against naive individuals, indicating that bystanders do not experience general changes in aggressive behaviour after watching a fight. Earlier work in this species, however, has shown that bystanders respond in predictable ways to individuals they have witnessed winning or losing a fight. Taken together, these data support the notion that bystanders consistently modify their behaviour towards previously watched winners or losers in response to information gained via eavesdropping. We discuss our results in light of some recent work on the behavioural and endocrinological responses triggered by watching fights and suggest that comparative approaches to understanding networking phenomena may be productive.
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Eccles, T. R., & Shackleton, D. M. (1986). Correlates and consequences of social status in female bighorn sheep. Anim. Behav., 34(5), 1392–1401.
Abstract: Dominance-subordinance relationships among a captive group of adule bighorn sheep (Ovis canadensis californiana) were studied from May 1977 to December 1978. Social interactions between females were brief in duration and infrequent. Although a dominance hierarchy was evident among the females, it was not linear. Horn length and body weight were not consistently correlated with social status. The highest ranking females were the most aggressive individuals, initiating more agonistic interactions than subordinates. Females with high social status did not have higher quality diets, lower activity costs, or higher productivity than low ranking females.
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Edouard, N., Fleurance, G., Dumont, B., Baumont, R., & Duncan, P. (2009). Does sward height affect feeding patch choice and voluntary intake in horses? Appl. Anim. Behav. Sci., 119(3-4), 219–228.
Abstract: The numbers of horses grazing at pasture are increasing in developed countries, so a proper understanding of their feeding selectivity and of the tactics they use for extracting nutrients from swards is essential for the management of horses and grasslands. Resource acquisition in herbivores can be optimised through the modulation of their intake and patch selection, both being strongly dependent on the characteristics of swards. However, the principles by which horses adjust their grazing behaviour in response to variations in sward features are not completely understood. The aim of this study was to determine whether the behaviour of horses conforms to optimal foraging models. We hypothesized that, faced with binary choices between vegetative swards of a good and similar quality at three different heights, horses would select the taller sward, i.e. that allowing a higher reward in terms of dry matter intake rate. Three groups of three 2-year-old saddle horses were grazed on a semi-natural pasture that was managed to produce three contrasting sward heights at 6, 11 and 17 cm, in a Latin-square design. The instantaneous intake rate was determined from bite rate measured at pasture on the three sward heights, and bite mass estimated from measurements using swards offered indoors in experimental trays. Daily dry matter intake was estimated individually by total faecal collection and an estimation of digestibility from faecal nitrogen. Short-term (first 30 min) and daily preferences were assessed from the time spent grazing each sward offered in pair-wise tests at pasture. The results show that daily voluntary intake (an average of 21 g DM kg LW-1 day-1) and total grazing time (an average of 14 h day-1) were independent of sward height and of the choice of patches offered. In choice situations, the animals spent more time grazing on the taller sward, both during the first 30 min and at the daily scale. These results show that horses choose between vegetative patches of a good and similar quality according to the predictions from optimal foraging models, and select the one that they can ingest faster. Further research will now have to explore how the horses will adapt their feeding behaviour when they face a trade-off between sward height and quality.
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Ellard, M. - E., & Crowell-Davis, S. L. (1989). Evaluating equine dominance in draft mares. Appl. Anim. Behav. Sci., 24(1), 55–75.
Abstract: The social hierarchy of a herd of 12 draft mares was assessed using agonism in the field, paired-feeding tests and a group-feeding test. Results from the paired-feeding test correlated significantly, but imperfectly, with those from the field. Differential motivation among subjects for the feed and disruption of ambiguous relationships among mares reduced the reliability of the paired-feeding test as a measure of social dominance. Results from the group-feeding test did not correlate significantly with the field hierarchy and only a few mares ever ate from the bucket. Height, weight and age each correlated significantly with rank; a mare's tendency to remain alone did not. Total aggressive scores during the paired-feeding test correlated with rank. However, a high-ranking mare was no more aggressive to each of her subordinates than was a low-ranking mare. Rather, all mares aggressed more against individuals close in rank to themselves and with preferred field associates. In the field, mares associated most with other mares of similar rank.
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