Abstract: Growing evidence shows a variety of sensorial and motor asymmetries in social and non-social interactions in various species, indicating a lateralized processing of information by the brain. Using digital video cameras on tripods and drones, this study investigated lateralization in frequency and duration of social behavior patterns, in affiliative, agonistic, and resting contexts, in a feral population of horses (Equus ferus caballus) in Northern Portugal, consisting of 37 individuals organized in eight harem groups. Affiliative interactions (including grooming) were more often performed, and lasted longer, when recipients were positioned to the right side. In recumbent resting (animals lying down) episodes on the left side lasted longer. Our results of an affiliative behavior having a right side tendency, provide partial support to the valence-specific hypothesis of Ahern and Schwartz (1979) – left hemisphere dominance for positive affect, affiliative behaviors. Longer recumbent resting episodes on the left side may be due to synchronization. However, in both instances it is discussed how lateralization may be context dependent. Investigating the position asymmetries of social behaviors in feral equids will contribute to a better understanding of differential lateralization and hemispheric specialization from the ecological and evolutionary perspectives.

Abstract: Evidence suggests that behavioural affective reactions to sweet and bitter substances are homologous in humans, nonhuman primates, and rodents. The sweet taste of sucrose elicits facial responses that include rhythmic tongue protrusions whereas the bitter taste of quinine elicits facial responses that include gapes, featuring an opening of the mouth and protrusion of the tongue. The present study using the horse (Equus caballus) was undertaken for three reasons: (1) there is debate about the presence of a sweet receptor gene in the horse, (2) there is a need to expand the examination of facial reactions to taste in lineages other than the closely related lineages of rodents and primates, and (3) the horse provides an opportunity to test the hypothesis that some social signals derive from movements related to taste reaction. The horses were given oral infusions of either sucrose or quinine and their behaviour was examined using frame-by-frame video analysis. Control groups were exposed received water or syringe insertion only. Amongst the many responses made to the infusions, the distinctive response to sucrose was a bob coupled with a slight tongue protrusion and forward movement of the ears; the distinctive response to quinine was a head extension and mouth gape accompanied by a large tongue protrusion and backward movement of the ears. Sucrose Bobs and Quinine Gapes are discussed with respect to: (1) the relevance of facial reactions to both sucrose and quinine to taste receptors in horses, (2) the similarity of features of taste expression in horses to those documented in rodents and primates, and (3) the dissimilarity between facial reactions to taste and other social signals displayed by horses.

Abstract: Background The increased use of meta-analysis in systematic reviews of healthcare interventions has highlighted several types of bias that can arise during the completion of a randomised controlled trial. Study publication bias has been recognised as a potential threat to the validity of meta-analysis and can make the readily available evidence unreliable for decision making. Until recently, outcome reporting bias has received less attention. Methodology/Principal Findings We review and summarise the evidence from a series of cohort studies that have assessed study publication bias and outcome reporting bias in randomised controlled trials. Sixteen studies were eligible of which only two followed the cohort all the way through from protocol approval to information regarding publication of outcomes. Eleven of the studies investigated study publication bias and five investigated outcome reporting bias. Three studies have found that statistically significant outcomes had a higher odds of being fully reported compared to non-significant outcomes (range of odds ratios: 2.2 to 4.7). In comparing trial publications to protocols, we found that 40-62% of studies had at least one primary outcome that was changed, introduced, or omitted. We decided not to undertake meta-analysis due to the differences between studies. Conclusions Recent work provides direct empirical evidence for the existence of study publication bias and outcome reporting bias. There is strong evidence of an association between significant results and publication; studies that report positive or significant results are more likely to be published and outcomes that are statistically significant have higher odds of being fully reported. Publications have been found to be inconsistent with their protocols. Researchers need to be aware of the problems of both types of bias and efforts should be concentrated on improving the reporting of trials.

Abstract: In recent years, Przewalski’s horses have been increasingly kept in semi-reserves. However,there areonly few studies ontheir behaviour and their ability to adaptto management interventions.In the main part of my dissertation, I focus on investigatingthe animals’ behaviour in different semi-reserves with varyinghabitats and living spaces. In addition, I investigate the horses’ behaviour during various management interventionsand analysetheensuing changes instress levels. Another aspect of my dissertation is the studyof social behaviour inPrzewalski’s horses. I investigate theparameters that should be used to demonstrate social bonds between individualsandassess whichdata provide the most meaningful results.In the commentary tochapter 1,several studies investigatingsocial bonds in horsesare discussed. Comparing the various studies, it is strikingthat no homogeneous analyses orevaluation criteria exist. While some authors only considersocial grooming, others include data onthe spatial proximity of the individuals in their evaluations, and various definitionsof proximity can also be found in the literature. Additionally, someauthors use friendly approaches between individuals asa furtherparameter wheninvestigating the social bonds.Continuing with this theme, in chapter 2I investigate the social behaviour of the horses and compare various analysis methods. I show that proactive behaviour, such as friendly approaches, is a good alternative to spatial proximity when investigating social bonds between group members, andis also useful for expanding the often very small data sets of mutual grooming in horses. Comparing Przewalski’s horses with wild living horses, I found no significant differences in the social behavior and the frequency of social interactions, regardlessof group size, group composition, habitat, and individual parameters such as age and gender.Inchapter 3,I investigate the behaviour of a Przewalski’s horse group when exploring a new area of their enclosure. Their behaviour changed, showing less resting and more feeding. Furthermore, the animals maintained greater distances from each other, and the alpha male, instead of herding the group from behind, led the group around the new area and walked in front of the other group members. Moreover, he showed a substantial increase in stress level during the first day.A general comparison of the behaviour of the Przewalski’s horses in different semi-reserves is provided in chapter 4. In it, the habitat choice of the animals and their reactions to various management interventions are investigated. It is shown that Przewalski’s horses prefer open grassland to dense woods, although keeping Przewalski’s horses in a pine forest does not influence the animals’ stress level. In contrast to habitat, food range, and changes in the group composition, which do not appear to change stress levels, individual factors, such as the hierarchy, influence the glucocorticoid level of the animals significantly. The largest increases in stress hormones were demonstrated when the horses were temporarily confined in smaller areas.The importance of the available space is also discussed in chapter 5, where it is shown that horses show less aggressive behaviour when more space is provided. In contrast, the husbandry system does not influence the animals’ aggression, but the way of feeding can additionally reduce agonistic behaviour, for example if food is offered ad libitum.In summary, the results of this study provide indications for the optimization of keeping Przewalski’s horses in semi-reserves. The animals can adapt themselves to the environment and thrive in habitats which do not correspond to their original steppe-like home. Nevertheless, the semi-reserves should provide sufficient grassland, as the horses prefer this type of habitat. General speaking, any types of habitat can only offer a suitable living space if the food range is sufficient for the number of horses. Otherwise, and especially during could winter months, supplementary feeding is necessary according to the body condition of the animals. This is particularly important for older, weakened, or very young animals, which are still adapting to life in the semi-reserve. Without sufficient food, stress hormones can increase and negatively influence the well-being of the horses. The same is true for management interventions: restricting the animals to small enclosures, for example, can adversely affect the horses’ well-being and should be only done if absolutely necessary. Targetedbehaviour observations allow the animals that have a special meaning for the group to be identified, and these should not be taken out of the group unless it is unavoidable, as young and unexperienced horses orientate themselves on those animals. This is especially true for the alpha male in a bachelor group, as these groups are often composed of young horses and the alpha-male provides the necessary stability and experience. Social bonds between individuals can be investigated by observing friendly and proactive behaviour, and social grooming and friendly approaches yield suitable data for such analysis.