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Hinz, K., Sennet, S., Maros, K., & Krueger, K. (2015). Waiting behaviour in front of a computerized feeding system in an active stable – Effects on heart rate, heart rate variability and sensory laterality in horses. In Current research in applied ethology [Aktuelle Arbeiten zur artgemäßen Tierhaltung. Darmstadt: KTBL-Schrift 510.
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Zhang, Y., Cao, Q. S., Rubenstein, D. I., Zang, S., Songer, M., Leimgruber, P., et al. (2015). Water Use Patterns of Sympatric Przewalski's Horse and Khulan: Interspecific Comparison Reveals Niche Differences. Plos One, 10(7), e0132094.
Abstract: Acquiring water is essential for all animals, but doing so is most challenging for desert-living animals. Recently Przewalski's horse has been reintroduced to the desert area in China where the last wild surviving member of the species was seen before it vanished from China in the1960s. Its reintroduction placed it within the range of a close evolutionary relative, the con-generic Khulan. Determining whether or not these two species experience competition and whether or not such competition was responsible for the extinction of Przewalski's horses in the wild over 50 years ago, requires identifying the fundamental and realized niches of both species. We remotely monitored the presence of both species at a variety of water points during the dry season in Kalamaili Nature Reserve, Xinjiang, China. Przewalski's horses drank twice per day mostly during daylight hours at low salinity water sources while Khulans drank mostly at night usually at high salinity water points or those far from human residences. Spatial and temporal differences in water use enables coexistence, but suggest that Przewalski's horses also restrict the actions of Khulan. Such differences in both the fundamental and realized niches were associated with differences in physiological tolerances for saline water and human activity as well as differences in aggression and dominance.
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Leadbeater, E. (2015). What evolves in the evolution of social learning? J Zool, 295(1), 4–11.
Abstract: Social learning is fundamental to social life across the animal kingdom, but we still know little about how natural selection has shaped social learning abilities on a proximate level. Sometimes, complex social learning phenomena can be entirely explained by Pavlovian processes that have little to do with the evolution of sociality. This implies that the ability to learn socially could be an exaptation, not an adaptation, to social life but not that social learning abilities have been left untouched by natural selection. I discuss new empirical evidence for associative learning in social information use, explain how natural selection might facilitate the associative learning process and discuss why such studies are changing the way that we think about social learning.
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Hintze, S., Smith, S., Patt, A., Bachmann, I., & Würbel, H. (2015). What eye wrinkles in horses tell us about their emotional state. In Proceedings of the 3. International Equine Science Meeting.
Abstract: Wrinkles above the eye ball are common in domestic horses but may differ in number and shape both between and within individuals. They are caused by contraction of the inner eye brow raiser, and some people working with horses call them “worry wrinkles”, considering them to reflect emotional states. However, as yet no study has formally investigated the relationship between eye wrinkles and emotional state in horses.
The aim of the present study was to induce states of different emotional valence and to assess whether positive emotional states would reduce the expression of eye wrinkles while negative emotional states would increase it. Sixteen horses were confronted in a balanced order with two presumably positively and two negatively valenced situations each. Positive situations included anticipation of a food reward (FA) and petting (P), negative situations included food competition (FC) and waving a plastic bag (PB). Each situation lasted for 60s (TRT) and was preceded by a 60s control phase (CON). Throughout CON and TRT pictures of the eyes were taken, and for each horse four pictures per situation (FA, P, FC, PB) and phase (CON and TRT) were randomly selected (n = 512) and scored in random order and blind to treatment for six outcome variables: overall impression (qualitative), number, angle and markedness of eye wrinkles, presence of eye white, and shape of eye lid.
Data were analysed separately for the right and left eye using linear mixed effects models (angle, number), generalised linear mixed models (eye white, markedness), and ordered logistic regression (qualitative, shape of eye lid), with “situation” (FA, P, FC, PB), “phase” (CON, TRT) and their two-way interaction as fixed effects.
Expression of eye wrinkles did not vary consistently across “situation” and “phase”. Independent of phase, eye white appeared less frequently during P than during FA (z=-3.15, p=0.009), FC (z=-2.94, p=0.02), and PB (z=4.17, p<0.001) in the left eye and during PB (z=4.10, p 0.001) in the right eye. Similarly, wrinkles were less marked during P compared to the other situations in the left eye (FA: z=3.15, p=0.009; FC: z=-2.94, p=0.017; PB: z=4.17, p<0.001) and compared to PB in the right eye (z=4.10, p=0.001), while no differences between situations occurred in number of wrinkles, overall impression and shape of eye lid for both eyes. Consistent with our hypothesis, P induced relaxation of the underlying muscle in the right eye resulting in a wider angle compared to its control phase (interaction situation*phase: F3,10=3.71, p=0.055; post-hoc comparison: z=-3.57, p=0.009), while FC induced muscle contraction, resulting in a sharper angle in the left eye (interaction situation*phase: F3,11=6.57, p=0.011; z=3.73, p=0.005).
We conclude that emotional valence may affect characteristics of eye winkle expression in horses which might therefore be a promising indicator of horses’ emotional states, but further research is needed to validate the relevant outcome variables.
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Roubová, V., Konecná, M., Smilauer, P., & Wallner, B. (2015). Whom to Groom and for What? Patterns of Grooming in Female Barbary Macaques (Macaca sylvanus). Plos One, 10(2), e0117298.
Abstract: Grooming is one of the most conspicuous social interactions among nonhuman primates. The selection of grooming partners can provide important clues about factors relevant for the distribution of grooming within a social group. We analyzed grooming behavior among 17 semi-free ranging female Barbary macaques (Macaca sylvanus). We tested whether grooming is related to kinship, rank and friendship. Furthermore, we tested whether grooming is reciprocated or exchanged for rank related benefits (i.e. lower aggression and increased tolerance whilst feeding). We found that in general grooming was reciprocally exchanged, directed up the hierarchy and at the same time affected by friendship and kinship. Grooming was more frequent among individuals with higher friendship values as well as amongst related individuals. We also divided our data set on the basis of rank difference and tested if different power asymmetries between individuals affected the tendency to exchange grooming for rank related benefits and grooming reciprocation. In support of our initial hypothesis our results show that the reciprocation of grooming was a significant predictor of grooming interactions between individuals of similar rank, but not between those individuals more distantly separated in the social hierarchy. However, we did not find any evidence for grooming being exchanged for rank related benefits in either data set. Our results, together with previously published studies, illustrate the behavioral flexibility of macaques. It is clear that multiple studies of the same species are necessary to gather the data required for the solid comparative studies needed to shed light on patterns of grooming behavior in primates.
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Kruger, K. (2015). Wie schlau sind Pferde? Soziales Lernen und innovative Anpassungen der Pferde. In Göttinger Pferdetage’15. Warendorf: FN Verlag.
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