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Schwartz, L. P., Silberberg, A., Casey, A. H., Kearns, D. N., & Slotnick, B. (2017). Does a rat release a soaked conspecific due to empathy? Anim. Cogn., 20(2), 299–308.
Abstract: In Experiment 1, rats choosing in an E maze preferred to release a rat standing in a pool of water to dry ground over a rat already standing on dry ground. Five additional experiments showed that the choosing rat's preference for releasing the wet rat was maintained by two separable outcomes: (1) the social contact offered by the released rat and (2) the reinforcing value of proximity to a pool of water. These results call into question Sato et al.'s (Anim Cogn 18:1039-1047, 2015) claim to have demonstrated that a rat's releasing of a wet rat to dry ground is empathically motivated.
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Schuetz, A., Farmer, K., & Krueger, K. (2017). Social learning across species: horses (Equus caballus) learn from humans by observation. Anim. Cogn., 20(3), 567–573.
Abstract: This study examines whether horses can learn by observing humans, given that they identify individual humans and orientate on the focus of human attention. We tested 24 horses aged between 3 and 12. Twelve horses were tested on whether they would learn to open a feeding apparatus by observing a familiar person. The other 12 were controls and received exactly the same experimental procedure, but without a demonstration of how to operate the apparatus. More horses from the group with demonstration (8/12) reached the learning criterion of opening the feeder twenty times consecutively than horses from the control group (2/12), and younger horses seemed to reach the criterion more quickly. Horses not reaching the learning criteria approached the human experimenters more often than those that did. The results demonstrate that horses learn socially across species, in this case from humans.
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Schneider, G., & Krueger, K. (2012). Third-party interventions keep social partners from exchanging affiliative interactions with others. Anim. Behav., 83(2), 377–387.
Abstract: Third-party interventions are defined as the interruption of dyadic interactions by third animals through direct physical contact, interposing or threats. Previous studies focused on the analysis of interventions against agonistic encounters. However, there have been no evaluations of interventions against affiliative behaviours, particularly in relation to the intervening animal�s social relationships and its social and spatial position. Horses, Equus caballus, are an interesting model species, as interventions against affiliative interactions occur more frequently than against agonistic interactions. In this study, 64 feral horses displayed 67 interventions in affiliative interactions and eight interventions in agonistic interactions within the observation period. We analysed the interventions in affiliative encounters, and found that it was mainly higher-ranking females that intervened in the affiliative interactions of group mates in the stable horse harems. The intervening animals took an active part in affiliative and agonistic encounters within the group, but did not occupy particular social roles or spatial positions. They intervened in affiliative interactions in which group mates with which they had social bonds interacted with other members of the group. They targeted the nonbonded animal and approached the one with which they were socially bonded. We suggest some species use third-party interventions in affiliative interactions to prevent competition for preferred social interaction partners from escalating into more costly agonistic encounters.
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Schnabel, C. L., Babasyan, S., Freer, H., & Wagner, B. (2017). Quantification of equine immunoglobulin A in serum and secretions by a fluorescent bead-based assay. Veterinary Immunology and Immunopathology, 188, 12–20.
Abstract: Abstract Only few quantitative reports exist about the concentrations and induction of immunoglobulin A (IgA) in mucosal secretions of horses. Despite this, it is widely assumed that IgA is the predominant immunoglobulin on mucosal surfaces in the horse. Here, two new monoclonal antibodies (mAbs) against equine IgA, clones 84-1 and 161-1, were developed and characterized in detail. Both IgA mAbs specifically bound monomeric and dimeric equine IgA in different applications, such as Western blots and fluorescent bead-based assays. Cross-reactivity with other equine immunoglobulin isotypes was not observed. The new IgA mAb 84-1 was used in combination with the previously characterized anti-equine IgA mAb BVS2 for the development and validation of a fluorescent bead-based assay to quantify total IgA in equine serum and various secretions. The IgA assay's linear detection ranged from 64 pg/ml to 1000 ng/ml. For the quantification of IgA in serum or in secretions an IgA standard was purified from serum or nasal wash fluid (secretory IgA), respectively. The different standards were needed for accurate IgA quantification in the respective samples taking the different signal intensities of monomeric and dimeric IgA on the florescent bead-based assay into account. IgA was quantified by the bead-based assay established here in different equine samples of healthy adult individuals. In serum the median total IgA was 0.45 mg/ml for Thoroughbred horses (TB, n = 10) and 1.16 mg/ml in Icelandic horses (ICH, n = 12). In nasopharyngeal secretions of TB (n = 7) 0.13 mg/ml median total IgA was measured, and 0.25 mg/ml for ICH (n = 12). Saliva of ICH (n = 6) contained a median of 0.15 mg/ml, colostrum of Warmbloods (n = 8) a median of 1.89 mg/ml IgA. Compared to IgG1 and IgG4/7 quantified in the same samples, IgA appeared as the major immunoglobulin isotype in nasopharyngeal secretions and saliva while it is a minor isotype in serum and colostrum. The newly developed monoclonal antibodies against equine IgA and the resulting bead-based assay for quantification of total IgA can notably improve the evaluation of mucosal immunity in horses.
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Schino, G., & Aureli, F. (2016). Reciprocity in group-living animals: partner control versus partner choice. Biol Rev, 92(2), 665–672.
Abstract: ABSTRACT Reciprocity is probably the most debated of the evolutionary explanations for cooperation. Part of the confusion surrounding this debate stems from a failure to note that two different processes can result in reciprocity: partner control and partner choice. We suggest that the common observation that group-living animals direct their cooperative behaviours preferentially to those individuals from which they receive most cooperation is to be interpreted as the result of the sum of the two separate processes of partner control and partner choice. We review evidence that partner choice is the prevalent process in primates and propose explanations for this pattern. We make predictions that highlight the need for studies that separate the effects of partner control and partner choice in a broader variety of group-living taxa.
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Schanz, L., Krueger, K., & Hintze, S. (2019). Sex and Age Don't Matter, but Breed Type Does--Factors Influencing Eye Wrinkle Expression in Horses. Front. Vet. Sci., 6, 154.
Abstract: Identifying valid indicators to assess animals' emotional states is a critical objective of animal welfare science. In horses, eye wrinkles above the eyeball have been shown to be affected by pain and other emotional states. From other species we know that individual characteristics, e.g. age in humans, affect facial wrinkles, but it has not yet been investigated whether eye wrinkle expression in horses is systematically affected by such characteristics. Therefore, the aim of this study was to assess how age, sex, breed type, body condition and coat colour affect the expression and/or the assessment of eye wrinkles in horses. To this end, we adapted the eye wrinkle assessment scale from Hintze et al. (2016) and assessed eye wrinkle expression in pictures taken from the left and the right eye of 181 horses in a presumably neutral situation, using five outcome measures: a qualitative first impression reflecting how worried the horse is perceived by humans, the extent to which the brow is raised, the number of wrinkles, their markedness and the angle between a line through both corners of the eye and the topmost wrinkle. All measures could be assessed highly reliable with respect to intra- and inter-observer agreement. Breed type affected the width of the angle (F2, 114 = 8.20, p < 0.001), with thoroughbreds having the narrowest angle (M = 23.80, SD = 1.60), followed by warmbloods (M = 28.00, SD = 0.60), and coldbloods (M = 31.00, SD = 0.90). None of the other characteristics affected any of the outcome measures, and eye wrinkle expression did not differ between the left and the right eye area (all p-values > 0.05). In conclusion, horses' eye wrinkle expression and its assessment in neutral situations was not systematically affected by the investigated characteristics, except for 'breed type', which accounted for some variation in 'angle'; how much eye wrinkle expression is affected by emotion or perhaps mood needs further investigation and validation.
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Saunders, F. C., McElligott, A. G., Safi, K., & Hayden, T. J. (2005). Mating tactics of male feral goats (Capra hircus): risks and benefits. Acta Ethol, 8.
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Sato, S., Sako, S., & Maeda, A. (1991). Social licking patterns in cattle (<em>Bos taurus</em>): influence of environmental and social factors. Applied Animal Behaviour Science, 32(1), 3–12.
Abstract: To investigate the functions of social licking in cattle, four calves (one heifer and one steer in each of two herds), known to exhibit frequent social licking were observed continuously for 2 h before sunset for 13 days, using the focal animal sampling method. Calves were observed under various environmental conditions. Social licking significantly decreased on rainy days and tended to increase in a dirty barn and when food was restricted. Solicitation for social licking occurred not only from dominant animals of pairs but also from subordinates. Of the licking interactions, 31% occurred following solicitation, and these accounted for 39% of the total time spent licking. Following solicitation, 78% of social licking was oriented to the head and the neck regions that were inaccessible to self-licking animals. Unsolicited licking, however, was oriented not only to the head and the neck but also to the back and the rump regions, and these two latter regions were the major ones to receive licking. The effect of social relationships on social licking was investigated using least-squares analysis of variance. Social factors investigated were the difference of dominance values, the dominance-subordinance relationship, and kinship and familiarity; the sex of calves involved was also considered. Only familiarity had a significant effect on licking; exchanges of social licking increased with length of cohabitation. We suggest that social licking may have a cleaning effect, a tension-reducing effect and a bonding effect.
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Sato, S. (1984). Social licking pattern and its relationships to social dominance and live weight gain in weaned calves. Appl. Anim. Behav. Sci., 12(1), 25–32.
Abstract: Social licking patterns of heifer and steer herds were observed and recorded during periods of resting and intermittent feeding. The results revealed the following features: (1) heifers and steers had 15.0 and 15.2 social licking interactions per hour which lasted for 37.8 and 41.0 s on average, respectively. The average time an animal spent licking was about 25 s per hour; (2) all the animals in the herds were licked by others, but only 72.3% of the animals licked other animals; (3) the animals close in the social hierarchy tended to lick each other for a longer time than did remote animals; (4) the time receiving l licking and weight gain tended to be positively correlated. The observations suggest that (1) the motivation of giving licking may be individual-specific and may be influenced by genetic factors, while that of receiving licking appears to be general, and that (2) social licking may mean not only cleaning the skin and hair of a passive partner, but also leading it to psychological stability.
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Sasväri, L. (1985). Different Observational Learning Capacity in Juvenile and Adult Individuals of Congeneric Bird Species. Z. Tierpsychol., 69(4), 293–304.
Abstract: Abstract and Summary: Since the adaptive significance of social organization is emphasized diversely in both anti-predator behaviour and food searching of birds, measures and comparisons of observational learning capacity of various species are needed. Four different experimental situations were built up for juvenile and adult individuals of tits (Parus major, P. caeruleus, P. palustris) and thrushes (Turdus merula, T. philo-melos). The birds learn more easily from conspecifics and learn easily when they already know a previous problem solving situation. The capacity of observational learning of the adult great tits surpasses that of adult blue tits and marsh tits, and that of the adult blackbirds exceeds that of the adult songthrushes. The higher performance of the great tit and blackbird can be related to their greater hemispheric index. The differences in the learning capacity of the naive individuals of the three tit species and that of the two thrush species were not significant. It is suggested, that the higher observational learning of the great tit and blackbird is evolved through maturational processes and can be reflected by their greater adaptability. Zusammenfassung: Lernen durch Nachahmung wurde in vier verschiedenen Situationen mit jungen und alten Individuen von Meisen- (Parus major, P. caeruleus, P. palustris) und Drosselarten (Turdus merula, T. philomelos) untersucht. Die Vögel lernten besser von Artgenossen und lernten leicht, wenn sie vorher bereits eine Problemlösungssituation kannten. Die Lernfähigkeit (durch Nachahmung) alter Kohlmeisen übertraf die alter Blau- und Sumpfmeisen; die Lernfähigkeit alter Amseln übertraf die alter Singdrosseln. Die höhere Leistung der Kohlmeisen und Amseln hängt mit ihrem höheren Hemisphären-Index zusammen. Naive Individuen der Meisen- und Drosselarten zeigten keine signifikanten Unterschiede in ihrer Lernfähigkeit. Es ist anzunehmen, daß die höhere Lernfähigkeit der Kohlmeise und der Amsel im Laufe der Entwicklung durch Reifungsprozesse zustande kommt und sich in ihrer höheren Anpassungsfähig-keit widerspiegelt.
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