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Krause Hoare, Hemelrijk, & Rubenstein. (2000). Leadership in fish shoals. Fish Fish, 1, 82–89.
Abstract: Leadership is not an inherent quality of animal groups that show directional locomotion. However, there are other factors that may be responsible for the occurrence of leadership in fish shoals, such as individual differences in nutritional state between group members. It appears that front fish have a strong influence on directional shoal movements and that individuals that occupy such positions are often characterised by larger body lengths and lower nutritional state. Potential interactions between the two factors and their importance for positioning within shoals need further attention. Initiation of directional movement in stationary shoals and position preferences in mobile shoals need to be addressed separately because they are potentially subject to different constraints. Individuals that initiate a swimming direction may not necessarily be capable of the sustained high swimming performance required to keep the front position or have the motivation to do so, for that matter. More empirical and theoretical work is necessary to look at the factors controlling positioning behaviour within shoals, as well as overall shoal shape and structure. Tracking of marked individuals whose positioning behaviour is monitored over extended time periods of hours or days would be useful. There is an indication that shoal positions are rotated by individuals according to their nutritional needs, with hungry fish occupying front positions only for as long as necessary to regain their nutritional balance. This suggests that shoal members effectively take turns at being leaders. There is a need for three-dimensional recordings of shoaling behaviour using high-speed video systems that allow a detailed analysis of information transfer in shoals of different size. The relationship between leadership and shoal size might provide an interesting field for future research. Most studies to date have been restricted to shoals of small and medium size and more information on larger shoals would be useful.
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Vervaecke, H., de Vries, H., & van Elsacker, L. (2000). Dominance and its Behavioral Measures in a Captive Group of Bonobos (Pan paniscus). Int. J. Primatol., 21(1), 47–68.
Abstract: We investigated the existence of a social dominance hierarchy in the captive group of six adult bonobos at the Planckendael Zoo. We quantified the pattern of dyadic exchange of a number of behaviors to examine to what extent each behavior fits a linear rank order model. Following de Waal (1989), we distinguish three types of dominance: agonistic dominance, competitive ability and formal dominance. Fleeing upon aggression is a good measure of agonistic dominance. The agonistic dominance hierarchy in the study group shows significant and strong linearity. The rank order was: 1. female (22 yr), 2. female (15 yr)., 3. male (23 yr.), 4. female (15 yr.), 5. male (9 yr.), 6. male (10 yr.). As in the wild, the females occupy high ranks. There is prominent but nonexclusive female agonistic dominance. Teeth-baring does not fulfil the criteria of a formal submission signal. Peering is a request for tolerance of proximity. Since its direction within dyads is consistent with that of fleeing interactions, it is a useful additional measure to determine agonistic ranks in bonobos. In competitive situations, the females acquire more food than other group members do. The rank obtained from access to food resources differs from the agonistic rank due to female intrasexual social tolerance, expressed in food sharing. We typify the dominance styles in the group as female intrasexual tolerance and male challenging of rank differences. The agonistic rank order correlates significantly with age and has a strong predictive value for other social behaviors.
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Miller, R. M. (2000). The revolution in horsemanship. J Am Vet Med Assoc, 216(8), 1232–1233.
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Madigan, J. E., & Whittemore, J. (2000). The role of the equine practitioner in disasters. J Am Vet Med Assoc, 216(8), 1238–1239.
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McCutcheon, L. J., & Geor, R. J. (2000). Influence of training on sweating responses during submaximal exercise in horses. J Appl Physiol, 89(6), 2463–2471.
Abstract: Sweating responses were examined in five horses during a standardized exercise test (SET) in hot conditions (32-34 degrees C, 45-55% relative humidity) during 8 wk of exercise training (5 days/wk) in moderate conditions (19-21 degrees C, 45-55% relative humidity). SETs consisting of 7 km at 50% maximal O(2) consumption, determined 1 wk before training day (TD) 0, were completed on a treadmill set at a 6 degrees incline on TD0, 14, 28, 42, and 56. Mean maximal O(2) consumption, measured 2 days before each SET, increased 19% [TD0 to 42: 135 +/- 5 (SE) to 161 +/- 4 ml. kg(-1). min(-1)]. Peak sweating rate (SR) during exercise increased on TD14, 28, 42, and 56 compared with TD0, whereas SRs and sweat losses in recovery decreased by TD28. By TD56, end-exercise rectal and pulmonary artery temperature decreased by 0.9 +/- 0.1 and 1.2 +/- 0.1 degrees C, respectively, and mean change in body mass during the SET decreased by 23% (TD0: 10.1 +/- 0.9; TD56: 7.7 +/- 0.3 kg). Sweat Na(+) concentration during exercise decreased, whereas sweat K(+) concentration increased, and values for Cl(-) concentration in sweat were unchanged. Moderate-intensity training in cool conditions resulted in a 1.6-fold increase in sweating sensitivity evident by 4 wk and a 0.7 +/- 0.1 degrees C decrease in sweating threshold after 8 wk during exercise in hot, dry conditions. Altered sweating responses contributed to improved heat dissipation during exercise and a lower end-exercise core temperature. Despite higher SRs for a given core temperature during exercise, decreases in recovery SRs result in an overall reduction in sweat fluid losses but no change in total sweat ion losses after training.
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Parr, L. A., Winslow, J. T., Hopkins, W. D., & de Waal, F. B. (2000). Recognizing facial cues: individual discrimination by chimpanzees (Pan troglodytes) and rhesus monkeys (Macaca mulatta). J Comp Psychol, 114(1), 47–60.
Abstract: Faces are one of the most salient classes of stimuli involved in social communication. Three experiments compared face-recognition abilities in chimpanzees (Pan troglodytes) and rhesus monkeys (Macaca mulatta). In the face-matching task, the chimpanzees matched identical photographs of conspecifics' faces on Trial 1, and the rhesus monkeys did the same after 4 generalization trials. In the individual-recognition task, the chimpanzees matched 2 different photographs of the same individual after 2 trials, and the rhesus monkeys generalized in fewer than 6 trials. The feature-masking task showed that the eyes were the most important cue for individual recognition. Thus, chimpanzees and rhesus monkeys are able to use facial cues to discriminate unfamiliar conspecifics. Although the rhesus monkeys required many trials to learn the tasks, this is not evidence that faces are not as important social stimuli for them as for the chimpanzees.
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Rendall, D., Cheney, D. L., & Seyfarth, R. M. (2000). Proximate factors mediating “contact” calls in adult female baboons (Papio cynocephalus ursinus) and their infants. J Comp Psychol, 114(1), 36–46.
Abstract: “Contact” calls are widespread in social mammals and birds, but the proximate factors that motivate call production and mediate their contact function remain poorly specified. Field study of chacma baboons (Papio cynocephalus ursinus) revealed that contact barks in adult females were motivated by separation both from the group at large and from their dependent infants. A variety of social and ecological factors affect the probability of separation from either one or both. Results of simultaneous observations and a playback experiment indicate that the contact function of calling between mothers and infants was mediated by occasional maternal retrieval rather than coordinated call exchange. Mothers recognized the contact barks of their own infants and often were strongly motivated to locate them. However, mothers did not produce contact barks in reply unless they themselves were at risk of becoming separated from the group.
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Merl, S., Scherzer, S., Palme, R., & Möstl, E. (2000). Pain causes increased concentrations of glucocorticoid metabolites in horse feces. J Equine Vet Sci, 20(9), 586–590.
Abstract: The concentration of 11,17-dioxoandrostanes (11,17-DOA), a group of cortisol metabolites, was measured using enzyme immunoassay in fecal samples of horses experiencing painful episodes. One group of horses consisted of 10 stallions castrated (samples were collected daily for 10 days); the other group was made up of 29 horses which were brought to an animal hospital because of signs of colic (samples were collected twice daily for six days). Before castration, median concentrations of 10.5 nmol/kg feces were measured. On days 1 and 2 after castration, median 11,17-DOA values increased up to 26.2 and 50.0 nmol/kg feces, respectively, and decreased thereafter to levels lower than at the beginning of the sampling period. High variations were measured between individual cases of colic. In animals with colic, all horses excreted more than 33 nmol 11,17-DOA/kg feces for various periods. The highest concentration measured was 885 nmol/kg feces. One animal out of the 29 colic horses did not show any clinical signs of pain upon arrival in the hospital. The 11,17-DOA values were below 17 nmol/kg feces in all those samples. From this data we conclude, that the concentration of 11,17-DOA in feces is a parameter for painful situations that have occurred one or two days earlier.
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Miyashita, Y., Nakajima, S., & Imada, H. (2000). Differential outcome effect in the horse. J Exp Anal Behav, 74(2), 245–253.
Abstract: hree horses were trained with a discrimination task in which the color (blue or yellow) of a center panel signaled the correct (left or right) response (lever press). Reinforcing outcomes for the two correct color-position combinations (blue-left and yellow-right) were varied across phases. Discrimination performance was better when the combinations were differentially reinforced by two types of food (chopped carrot pieces and a solid food pellet) than when the combinations were randomly reinforced by these outcomes or when there was a common reinforcer for each of the correct combinations. However, the discrimination performance established by the differential outcome procedure was still 80% to 90% correct, and an analysis of two-trial sequences revealed that the stimulus color of the preceding trial interfered with discrimination performance on a given trial. Our demonstration of the differential outcome effect in the horse and its further analysis might contribute to more efficient control of equine behavior in the laboratory as well as in horse sports.
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Zentall, T. R., Kaiser, D. H., Clement, T. S., Weaver, J. E., & Campbell, G. (2000). Presence/absence-sample matching by pigeons: divergent retention functions may result from the similarity of behavior during the absence sample and the retention interval. J Exp Psychol Anim Behav Process, 26(3), 294–304.
Abstract: Divergent choose-absence retention functions typically found in pigeons following presence/absence-sample matching have been attributed to the development of a single-code/default coding strategy. However, such effects may result from adventitious differential responding to the samples. In Experiment 1, retention functions were divergent only when differential sample responding could serve as the basis for comparison choice. In Experiment 2, when pecking did not occur during the retention interval, a choose-absence bias was found, but when pecking occurred during the retention interval, a choose-presence bias resulted. In Experiment 3, positive transfer was found when a stimulus associated with the absence of pecking replaced the absence sample but not when a stimulus associated with pecking replaced the presence sample. Thus, presence/absence-sample matching may not encourage the development of a single-code/default coding strategy in pigeons.
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