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Boyd, L., & Bandi, N. (2002). Reintroduction of takhi, Equus ferus przewalskii, to Hustai National Park, Mongolia: time budget and synchrony of activity pre- and post-release. Appl. Anim. Behav. Sci., 78(2-4), 87–102.
Abstract: A harem of takhi (Equus ferus przewalskii) was observed during introduction to the Hustain Nuruu Steppe Reserve of Mongolia. The goals were to examine whether the harem exhibited significant behavioural synchrony, whether release had an effect on time budget, and what the implications might be regarding acclimatisation to the wild. Behaviours were scan sampled every 10 min between the hours of 06:00 and 22:00, twice before release, twice immediately after release, and twice 2 years after reintroduction. Time budgets were constructed from these data. Considerable behavioural synchrony was evidenced both before and after release. Crepuscular grazing and midday resting were typical, regardless of the date relative to release. Upon release, the amount of time spent moving doubled for all age classes. It is suggested that this increase resulted from exploration. The amount of time spent grazing and standing remained unchanged; the increased amount of time spent moving came at the expense of resting. Two years later, the horses still spent more time moving than when captive. Somewhat less time was spent grazing, although the difference was not significant. More time was spent resting in 1996 than immediately after release. These time budgets provide evidence of successful acclimatisation to the wild. Trekking between favoured sites could account for the persistent increase in time spent moving, with concomitantly less time needed to meet nutritional needs by grazing and more time available for resting. Housing captive takhi in large enclosures is evidently insufficient to permit the amount of movement exhibited by this wild harem. The time budget of the 1- and 2-year olds was more similar to that of adults than foals, indicating approaching adulthood. That 1- and 2-year olds were nursed, without loss of body condition by the dam, provided additional evidence that the takhi achieved excellent nutritional status in the wild.
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Boyd, L. E. (1991). The behaviour of Przewalski's horses and its importance to their management. Appl. Anim. Behav. Sci., 29(1-4), 301–318.
Abstract: Przewalski's horses (Equus przewalskii) are believed to be extinct in the wild; the current known population of 797 animals exists wholly in zoos. The Species Survival Commission of the International Union for Conservation of Nature and Natural Resources is proposing to reintroduce this endangered species into its former Mongogian habitat within the next decade. Knowledge of the behavior of harem-forming equids in general and of Przewalski's horses in particular, is of great importance to the captive propagation and eventual reintroduction of this species. Horses are rarely solitary by nature. Solitary captive animals are prone to pacing. Juvenile male feral horses (Equus caballus) form bachelor herds upon dispersal from their natal band. Zoos can set up bachelor herds as a way of managing surplus males. The older, more dominant feral horse bachelors are the first to acquire mares. Bachelors do not generally obtain females until they are 4 or 5 years of age. The first females acquired are usually 1- and 2-year-old fillies dispersing from their natal band. Because of the age differential, the stallions are generally dominant to their mares. Behavioral impotence may result if captive stallions are given a harem at too young an age, especially if the harem contains older, more dominant, females. Typical harem sizes in the wild are 3-5 mares. Captive stallions with too large a harem may become either apathetic or aggressive toward their mares. Wild horses spend 60-70% of their time foraging. Captive animals may quickly consume their limited amounts of food and develop vices out of boredom. Provision of hay ad libitum reduces the amount of pacing seen in captive animals, and virtually eliminates coprophagy.
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Boyd, L. E. (1988). Ontogeny of behavior in Przewalski horses. Appl. Anim. Behav. Sci., 21(1-2), 41–69.
Abstract: Twelve colts and 12 fillies were observed during their first 2 years of life. Data on the foal's nearest neighbor, distance to dam and stallion, and time budget were compiled by age. The birth of one foal was witnessed. During their first month of life, Przewalski foals were dependent on the dam. She provided most of their nourishment and foals spent 54% of their time within 1 m of her. The biggest change in behavior of foals occurred between Months 1 and 2. The amount of time spent resting and nursing declined, while the amount of time spent foraging increased sharply. Foals began to leave their mothers and interact with peers by 3 weeks of age, and at 2 months they were interacting with older herd members. By 5 months of age, the amount of time spent in most behaviors was identical to that of adults, except that vocalization rates and involvement in aggression were lower than for adults. Juveniles spent less time stand-resting than adults throughout their first year, but more time in recumbent rest. Foals spent far less time with their sire than with their dam. However, an orphaned foal spent more time with his sire than did mothered foals, indicating that the sire assumed part of the role of the missing dam.
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Boyd, L. E., Carbonaro, D. A., & Houpt, K. A. (1988). The 24-hour time budget of Przewalski horses. Appl. Anim. Behav. Sci., 21(1-2), 5–17.
Abstract: A herd of 8 Przewalski horses were observed on pasture in summer. Fifteen-minute focal animal samples were used to determine the time budget of the horses during the periods 00.00-04.00, 04.00-08.00, 08.00-12.00, 12.00-16.00, 16.00-20.00 and 20.00-24.00 h EDT. The behavioral states recorded were feeding (grazing and eating grain), nursing, drinking, standing, stand-resting, self-grooming, mutual grooming, locomoting, playing, and lying laterally and sternally. The average number of behavioral states occurring per hour, and the defecation, urination, aggression and vocalization rates were also determined. Overall, the horses spent 46.4 +/- 5.9% of their time feeding, 1.3 +/- 0.1% nursing, 0.5 +/- 0.1% drinking, 20.6 +/- 5.4% standing, 15.7 +/- 3.2% stand-resting, 1.7 +/- 0.2% self-grooming, 2.2 +/- 0.7% mutual grooming, 7.4 +/- 1.0% locomoting, 1.2 +/- 0.3% playing, 1.2 +/- 0.5% lying laterally and 4.1 +/- 3.0% lying sternally. The horses averaged 45.2 +/- 5.8 behavioral states per hour, and 0.2 +/- 0.0 defecations, 0.3 +/- 0.0 urinations, 1.5 +/- 0.3 aggressions and 0.7 +/- 0.1 vocalizations per hour. The horses spent the greatest amount of time foraging between 20.00 and 04.00 h, when the temperatures were lower. They spent 68.2 +/- 2.2% of their time between 20.00 and 24.00 h feeding, but only 31.2 +/- 2.1% of their time feeding between 08.00 and 12.00 h. Recumbent rest was most common between 00.00 and 04.00 h. As temperatures rose during the daylight hours, the horses spent more time drinking and standing, rather than grazing. Stand-resting was the most common form of rest during the day. The horses exhibited the greatest number of activities per hour from 08.00 to 20.00 h. While standing in close proximity to one another during these hours, the horses exhibited the highest number of aggressions per hour (1.9-2.4).
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Boyd, R., & Silk, J. B. (1983). A method for assigning cardinal dominance ranks. Anim. Behav., 31(1), 45–58.
Abstract: Dominance hierarchies are widely described in nature. Commonly, an individual's ordinal rank is used as a measure of its position in the hierarchy, and, therefore its priority of access to resources. This use of ordinal ranks has several related drawbacks: (1) it is difficult to assess the magnitude or the significance of the difference in degree of dominance between two individuals; (2) it is difficult to evaluate the significance of differences between dominance matrices based on different behaviours or on the same behaviour at different times, and (3) it is difficult to use parametric statistical techniques to relate dominance rank to other quantities of interest. In this paper we describe a method for assigning cardinal dominance indices that does not suffer from these drawbacks. This technique is based on the Bradley-Terry model from the method of paired comparisons. We show how this model can be reinterpreted in terms of dominance interactions. and we describe a simple iterative technique for computing cardinal ranks. We then describe how to evaluate (1) whether the rank differences between individuals are significant, and (2) whether differences in the cardinal hierarchies based on different behaviours or the same behaviour at different times are significant. We then show how to generalize the method to deal with behaviours that sometimes have ambiguous outcomes, or behaviours for which the rank difference between a pair of individuals affects the rate of interaction between them.
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Boysen, S. T., Bernston, G. G., Hannan, M. B., & Cacioppo, J. T. (1996). Quantity-based interference and symbolic representations in chimpanzees (Pan troglodytes). J Exp Psychol Anim Behav Process, 22(1), 76–86.
Abstract: Five chimpanzees with training in counting and numerical skills selected between 2 arrays of different amounts of candy or 2 Arabic numerals. A reversed reinforcement contingency was in effect, in which the selected array was removed and the subject received the nonselected candies (or the number of candies represented by the nonselected Arabic numeral). Animals were unable to maximize reward by selecting the smaller array when candies were used as array elements. When Arabic numerals were substituted for the candy arrays, all animals showed an immediate shift to a more optimal response strategy of selecting the smaller numeral, thereby receiving the larger reward. Results suggest that a response disposition to the high-incentive candy stimuli introduced a powerful interference effect on performance, which was effectively overridden by the use of symbolic representations.
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Boysen, S. T., & Berntson, G. G. (1995). Responses to quantity: perceptual versus cognitive mechanisms in chimpanzees (Pan troglodytes). J Exp Psychol Anim Behav Process, 21(1), 82–86.
Abstract: Two chimpanzees were trained to select among 2 different amounts of candy (1-6 items). The task was designed so that selection of either array by the active (selector) chimpanzee resulted in that array being given to the passive (observer) animal, with the remaining (nonselected) array going to the selector. Neither animal was able to select consistently the smaller array, which would reap the larger reward. Rather, both animals preferentially selected the larger array, thereby receiving the smaller number of reinforcers. When Arabic numerals were substituted for the food arrays, however, the selector animal evidenced more optimal performance, immediately selecting the smaller numeral and thus receiving the larger reward. These findings suggest that a basic predisposition to respond to the perceptual-motivational features of incentive stimuli can interfere with task performance and that this interference can be overridden when abstract symbols serve as choice stimuli.
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Bracke, M. B. M., Spruijt, B. M., Metz, J. H. M., & Schouten, W. G. P. (2002). Decision support system for overall welfare assessment in pregnant sows A: Model structure and weighting procedure. J. Anim Sci., 80(7), 1819–1834.
Abstract: The problem of how to objectively assess the overall welfare status of animals under farming conditions has contributed to an ongoing debate that has hampered actual decision making on animal welfare. For this reason we constructed a model based on the assumed hierarchical organization of the animals' needs for overall welfare assessment in the case of pregnant sows. This model is implemented in a computer-based decision support system that takes a description of a housing and management system as input and produces a welfare score as output. A formalized procedure was used to construct the model for welfare assessment in pregnant sows on the basis of available scientific knowledge. This SOWEL (from SOw WELfare) model contains 37 attributes that describe the welfare-relevant properties of housing and management systems. In the decision support system these attributes are linked to scientific statements and a list of needs to provide a scientific basis for welfare assessment. Weighting factors that represent the relative importance of the attributes are derived from the scientific statements about the various welfare performance criteria that have been measured by scientists. The welfare score is calculated as the weighted average score. All information in the decision support system is stored in tables in a relational database such that newly available knowledge and insights can be incorporated to refine the model. The model has been developed in line with several existing models but it differs from these models in that it is the first to provide a formalized procedure to explicate the reasoning steps involved in welfare assessment based on available scientific knowledge. N1 -
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Brandt, K. (2004). A Language of Their Own: An Interactionist Approach to Human-Horse Communication. Society and Animals, 12(4), 299–316.
Abstract: This paper explores the process of human-horse communication using ethnographic data of in-depth interviews and participant observation. Guided by symbolic interactionism, the paper argues that humans and horses co-create a language system by way of the body to facilitate the creation of shared meaning. This research challenges the privileged status of verbal language and suggests that non-verbal communication and language systems of the body have their own unique complexities. This investigation of humanhorse communication offers new possibilities to understand the subjective and intersubjective world of non-verbal language using beings-human and nonhuman alike.
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Brannon, E. M., Cantlon, J. F., & Terrace, H. S. (2006). The role of reference points in ordinal numerical comparisons by rhesus macaques (Macaca mulatta). J Exp Psychol Anim Behav Process, 32(2), 120–134.
Abstract: Two experiments examined ordinal numerical knowledge in rhesus macaques (Macaca mulatta). Experiment 1 replicated the finding (E. M. Brannon & H. S. Terrace, 2000) that monkeys trained to respond in descending numerical order (4-->3-->2-->1) did not generalize the descending rule to the novel values 5-9 in contrast to monkeys trained to respond in ascending order. Experiment 2 examined whether the failure to generalize a descending rule was due to the direction of the training sequence or to the specific values used in the training sequence. Results implicated 3 factors that characterize a monkey's numerical comparison process: Weber's law, knowledge of ordinal direction, and a comparison of each value in a test pair with the reference point established by the first value of the training sequence.
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