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Krueger, K., Gruentjens, T., & Hempel, E. (2023). Wolf contact in horses at permanent pasture in Germany. Plos One, 18(8), e0289767.
Abstract: Wolves returned to Germany in 2000, leading to fear in German horse owners that their horses could be in danger of wolf attacks or panic-like escapes from pastures when sighting wolves. However, reports from southern European countries indicate that wolf predation on horses diminishes with increasing presence of wildlife. Therefore, we conducted a long-term, filed observation between January 2015 and July 2022 on 13 non breeding riding horses, mares and geldings, kept permanently on two pastures within the range of wildlife and a stable wolf pack with annual offspring. Wildlife cameras at the fences of the pastures made 984 times recordings of wolves and 3151 times recordings of wildlife in and around the pastures. Between 1 January 2022 and 23 March 2022 we observed two stable horse groups. Pasture 1 was grazed by five horses of mixed breed, four mares and one gelding, with the median age of 8 years (min. = 6y, max. = 29y). Pasture 2 was grazed by eight heavy warmbloods and draught horses, three mares and five geldings, with the median age of 16 years (min. = 13y, max. = 22y). During this period no wolf was recorded at pasture 2, but wild boar several times, whereas at pasture 1, wolves were recorded 89 times, and for the wildlife mostly hare. Wolves may have avoided pasture 2 because of the presence of wild boar or because the large group of older, heavy breed horses may have formed a stable, protective group. The latter needs to be confirmed in a follow-up field observation, which records anti-predator behavior and welfare indicators in horses. In conclusion, wolves did not attack the mature horses on pastures with plenty of wildlife and the horses did not respond to the presence of wolves with visible signs of reduced welfare or panic. This indicates that wolves may prefer to prey on easily accessible wildlife around and at horse pastures and that Central European horses become accustom to the presence of non-hunting wolves.
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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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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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Karenina, K., Giljov, A., Baranov, V., Osipova, L., Krasnova, V., & Malashichev, Y. (2010). Visual Laterality of Calf–Mother Interactions in Wild Whales. PLoS ONE, 5(11), e13787.
Abstract: Background
Behavioral laterality is known for a variety of vertebrate and invertebrate animals. Laterality in social interactions has been described for a wide range of species including humans. Although evidence and theoretical predictions indicate that in social species the degree of population level laterality is greater than in solitary ones, the origin of these unilateral biases is not fully understood. It is especially poorly studied in the wild animals. Little is known about the role, which laterality in social interactions plays in natural populations. A number of brain characteristics make cetaceans most suitable for investigation of lateralization in social contacts. Methodology/Principal Findings Observations were made on wild beluga whales (Delphinapterus leucas) in the greatest breeding aggregation in the White Sea. Here we show that young calves (in 29 individually identified and in over a hundred of individually not recognized mother-calf pairs) swim and rest significantly longer on a mother's right side. Further observations along with the data from other cetaceans indicate that found laterality is a result of the calves' preference to observe their mothers with the left eye, i.e., to analyze the information on a socially significant object in the right brain hemisphere. Conclusions/Significance Data from our and previous work on cetacean laterality suggest that basic brain lateralizations are expressed in the same way in cetaceans and other vertebrates. While the information on social partners and novel objects is analyzed in the right brain hemisphere, the control of feeding behavior is performed by the left brain hemisphere. Continuous unilateral visual contacts of calves to mothers with the left eye may influence social development of the young by activation of the contralateral (right) brain hemisphere, indicating a possible mechanism on how behavioral lateralization may influence species life and welfare. This hypothesis is supported by evidence from other vertebrates. |
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Broekhuis, F., Madsen, E. K., Keiwua, K., & Macdonald, D. W. (2019). Using GPS collars to investigate the frequency and behavioural outcomes of intraspecific interactions among carnivores: A case study of male cheetahs in the Maasai Mara, Kenya. Plos One, 14(4), e0213910.
Abstract: Intraspecific interactions between individuals or groups of individuals of the same species are an important component of population dynamics. Interactions can be static, such as spatial overlap, or dynamic based on the interactions of movements, and can be mediated through communication, such as the deployment of scent marks. Interactions and their behavioural outcomes can be difficult to determine, especially for species that live at low densities. With the use of GPS collars we quantify both static and dynamic interactions between male cheetahs (Acinonyx jubatus) and the behavioural outcomes. The 99% home-ranges of males overlapped significantly while there was little overlap of the 50% home-ranges. Despite this overlap, male cheetahs rarely came into close proximity of one another, possibly because presence was communicated through frequent visits to marking posts. The minimum distance between individuals in a dyad ranged from 89m to 196m but the average proximity between individuals ranged from 17,145 ± 6,865m to 26,367 ± 11,288m. Possible interactions took place more frequently at night than by day and occurred mostly in the 50% home-range of one individual of a dyad or where cores of both individuals overlapped. After a possible encounter male cheetahs stayed in close proximity to each other for up to 6 hours, which could be the result of a territory defence strategy or the presence of a receptive female. We believe that one of the encounters between a singleton and a 5-male coalition resulted in the death of the singleton. Our results give new insights into cheetah interactions, which could help our understanding of ecological processes such as disease transmission.
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Fureix, C., Jego, P., Henry, S., Lansade, L., & Hausberger, M. (2012). Towards an Ethological Animal Model of Depression? A Study on Horses. PLoS ONE, 7(6), e39280 EP -.
Abstract: <sec><title>Background</title><p>Recent reviews question current animal models of depression and emphasise the need for ethological models of mood disorders based on animals living under natural conditions. Domestic horses encounter chronic stress, including potential stress at work, which can induce behavioural disorders (<italic>e.g.</italic> “apathy”). Our pioneering study evaluated the potential of domestic horses in their usual environment to become an ethological model of depression by testing this models’ face validity (<italic>i.e.</italic> behavioural similarity with descriptions of human depressive states).</p></sec><sec><title>Methodology/Principal Findings</title><p>We observed the spontaneous behaviour of 59 working horses in their home environment, focusing on immobility bouts of apparent unresponsiveness when horses displayed an atypical posture (termed <italic>withdrawn</italic> hereafter), evaluated their responsiveness to their environment and their anxiety levels, and analysed cortisol levels. Twenty-four percent of the horses presented the withdrawn posture, also characterized by gaze, head and ears fixity, a profile that suggests a spontaneous expression of “behavioural despair”. When compared with control “non-withdrawn” horses from the same stable, withdrawn horses appeared more indifferent to environmental stimuli in their home environment but reacted more emotionally in more challenging situations. They exhibited lower plasma cortisol levels. Withdrawn horses all belonged to the same breed and females were over-represented.</p></sec><sec><title>Conclusions/Significance</title><p>Horse might be a useful potential candidate for an animal model of depression. Face validity of this model appeared good, and potential genetic input and high prevalence of these disorders in females add to the convergence. At a time when current animal models of depression are questioned and the need for novel models is expressed, this study suggests that novel models and biomarkers could emerge from ethological approaches in home environments.</p></sec>
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Proops, L., Rayner, J., Taylor, A. M., & McComb, K. (2013). The Responses of Young Domestic Horses to Human-Given Cues. PLoS ONE, 8(6), e67000 EP -.
Abstract: <p>It has been suggested that the process of domestication, at least in some species, has led to an innate predisposition to be skilled at reading human communicative and attentional cues. Adult domestic horses (<italic>Equus caballus</italic>) are highly sensitive to subtle bodily cues when determining if a person is attending to them but they are less adept at using human communicative cues in object choice tasks. Here we provide the first study into the ontogeny of such skills in order to gain insights into the mechanisms underlying these abilities. Compared with adult horses, youngsters under the age of three could use body orientation but not more subtle cues such as head movement and open/closed eyes to correctly choose an attentive person to approach for food. Across two object choice experiments, the performance of young horses was comparable to that of adult horses – subjects were able to correctly choose a rewarded bucket using marker placement, pointing and touching cues but could not use body orientation, gaze, elbow pointing or tapping cues. Taken together these results do not support the theory that horses possess an innate predisposition to be particularly skilled at using human cues. Horses' ability to determine whether humans are attending to them using subtle body cues appears to require significant experience to fully develop and their perhaps less remarkable use of limited cues in object choice tasks, although present at a much earlier age, is likely to reflect a more general learning ability related to stimulus enhancement rather than a specific ‘human-reading’ skill.</p>
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Roth, L. S. V., Balkenius, A., & Kelber, A. (2008). The Absolute Threshold of Colour Vision in the Horse. PLoS ONE, 3(11), e3711 EP -.
Abstract: <p>Arrhythmic mammals are active both during day and night if they are allowed. The arrhythmic horses are in possession of one of the largest terrestrial animal eyes and the purpose of this study is to reveal whether their eye is sensitive enough to see colours at night. During the day horses are known to have dichromatic colour vision. To disclose whether they can discriminate colours in dim light a behavioural dual choice experiment was performed. We started the training and testing at daylight intensities and the horses continued to choose correctly at a high frequency down to light intensities corresponding to moonlight. One Shetland pony mare, was able to discriminate colours at 0.08 cd/m2, while a half blood gelding, still discriminated colours at 0.02 cd/m2. For comparison, the colour vision limit for several human subjects tested in the very same experiment was also 0.02 cd/m2. Hence, the threshold of colour vision for the horse that performed best was similar to that of the humans. The behavioural results are in line with calculations of the sensitivity of cone vision where the horse eye and human eye again are similar. The advantage of the large eye of the horse lies not in colour vision at night, but probably instead in achromatic tasks where presumably signal summation enhances sensitivity.</p>
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Collins, G. H., Petersen, S. L., Carr, C. A., & Pielstick, L. (2014). Testing VHF/GPS Collar Design and Safety in the Study of Free-Roaming Horses. Plos One, 9(9), e103189.
Abstract: Effective and safe monitoring techniques are needed by U.S. land managers to understand free-roaming horse behavior and habitat use and to aid in making informed management decisions. Global positioning system (GPS) and very high frequency (VHF) radio collars can be used to provide high spatial and temporal resolution information for detecting free-roaming horse movement. GPS and VHF collars are a common tool used in wildlife management, but have rarely been used for free-roaming horse research and monitoring in the United States. The purpose of this study was to evaluate the design, safety, and detachment device on GPS/VHF collars used to collect free-roaming horse location and movement data. Between 2009 and 2010, 28 domestic and feral horses were marked with commercial and custom designed VHF/GPS collars. Individual horses were evaluated for damage caused by the collar placement, and following initial observations, collar design was modified to reduce the potential for injury. After collar modifications, which included the addition of collar length adjustments to both sides of the collar allowing for better alignment of collar and neck shapes, adding foam padding to the custom collars to replicate the commercial collar foam padding, and repositioning the detachment device to reduce wear along the jowl, we observed little to no evidence of collar wear on horses. Neither custom-built nor commercial collars caused injury to study horses, however, most of the custom-built collars failed to collect data. During the evaluation of collar detachment devices, we had an 89% success rate of collar devices detaching correctly. This study showed that free-roaming horses can be safely marked with GPS and/or VHF collars with minimal risk of injury, and that these collars can be a useful tool for monitoring horses without creating a risk to horse health and wellness.
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Dwan, K., Altman, D. G., Arnaiz, J. A., Bloom, J., Chan, A. - W., Cronin, E., et al. (2008). Systematic Review of the Empirical Evidence of Study Publication Bias and Outcome Reporting Bias. Plos One, 3(8), e3081.
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.
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