Briard, L., Dorn, C., & Petit, O. (2015). Personality and Affinities Play a Key Role in the Organisation of Collective Movements in a Group of Domestic Horses. Ethology, 121(9), 888–902.
Abstract: Understanding how groups of individuals with different motives come to daily decisions about the exploitation of their environment is a key question in animal behaviour. While interindividual differences are often seen only as a threat to group cohesion, growing evidence shows that they may to some extent facilitate effective collective action. Recent studies suggest that personality differences influence how individuals are attracted to conspecifics and affect their behaviour as an initiator or a follower. However, most of the existing studies are limited to a few taxa, mainly social fish and arthropods. Horses are social herbivores that live in long-lasting groups and show identifiable personality differences between individuals. We studied a group of 38 individuals living in a 30-ha hilly pasture. Over 200 h, we sought to identify how far individual differences such as personality and affinity distribution affect the dynamic of their collective movements. First, we report that individuals distribute their relationships according to similar personality and hierarchical rank. This is the first study that demonstrates a positive assortment between unrelated individuals according to personality in a mammal species. Second, we measured individual propensity to initiate and found that bold individuals initiated more often than shy individuals. However, their success in terms of number of followers and joining duration did not depend on their individual characteristics. Moreover, joining process is influenced by social network, with preferred partners following each other and bolder individuals being located more often at the front of the movement. Our results illustrate the importance of taking into account interindividual behavioural differences in studies of social behaviours.
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Meriggi, A., Dagradi, V., Dondina, O., Perversi, M., Milanesi, P., Lombardini, M., et al. (2014). Short-term responses of wolf feeding habits to changes of wild and domestic ungulate abundance in Northern Italy. Ethology Ecology & Evolution, 27(4), 389–411.
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Clucas, B., Marzluff, J. M., Mackovjak, D., & Palmquist, I. (2013). Do American Crows Pay Attention to Human Gaze and Facial Expressions? Ethology, 119(4), 296–302.
Abstract: Interactions between species can lead to the evolution of interspecific communication. Non-verbal communication by humans, both intentional and unintentional, can be interpreted by other species. We tested whether American crows (Corvus brachyrhynchos) were sensitive to human facial features under field conditions by comparing flight initiation distances and urgency of escape behavior to human approaches varying in eye contact and facial expression. We first examined whether crows distinguish between an approaching human who is directly gazing at them and a human approaching them with an averted gaze. In a second experiment, we tested whether crows differentiate a smiling from scowling human approaching them with direct or averted gaze. In the first experiment, we found that crows fled sooner and more urgently when humans were directly gazing at them. Similarly, in the second experiment, crows responded sooner to a direct vs. averted gaze; however, they did not react differently to varying human facial expressions. We suggest that crows use human gaze as a reliable visual cue compared with facial expressions when making decisions about responding to approaching humans. This is the first study to show that a wild corvid species changes its behavior based on human gaze, possibly representing an adaptation to living in human-dominated urban areas and suggesting crows might perceive human intention by this visual cue.
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Dochtermann, N. A., & Jenkins, S. H. (2011). Multivariate Methods and Small Sample Sizes. Ethology, 117(2), 95–101.
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Huang, S. - P., Yang, S. - Y., & Hsu, Y. (2011). Persistence of Winner and Loser Effects Depends on the Behaviour Measured. Ethology, 117(2), 171–180.
Abstract: Abstract Recent contest experience can influence an individual’s behaviour in subsequent contests. When the probability of winning a subsequent contest is used to quantify experience effects, a loser effect usually lasts longer than a winner effect. This conclusion, however, may be caused by this probability understating the persistence of the influence of a winning experience on contest decisions. Using Kryptolebias marmoratus, a mangrove killifish, as the study organism, we investigated whether different conclusions about the relative persistence of winning and losing experiences would be reached when different aspects of contest behaviour (probability of initiating attacks, probability of winning non-escalated and escalated contests, escalation rate and contest duration) were measured. The results indicated that the apparent persistence of the effect of winning or losing experiences varied with the behaviour studied. When the likelihood to initiate attacks was used, no winner effect was detected while the loser effect lasted for <1 d. When escalation rate was used, the winner effect lasted for 2–4 d, while the loser effect lasted for 1–2 d. When the probability of winning non-escalated contests was used, the winner effect was detectable for <1 d, while the loser effect lasted for 2–4 d. And, when contest duration was used, the winner effect was detectable for 2–4 d, but no loser effect was detectable. These results show that (1) the probability of winning a subsequent contest understated the persistence of the influence of a winning experience on the fish’s contest decisions, (2) the measures most effective at detecting winner effects are different from those most effective at detecting loser effects and (3) in K. marmoratus, both effects can be detected 2 d after the completion of experience training but both dissipate in 4 d.
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Mersmann, D., Tomasello, M., Call, J., Kaminski, J., & Taborsky, M. (2011). Simple Mechanisms Can Explain Social Learning in Domestic Dogs (Canis familiaris). Ethology, 117(8), 675–690.
Abstract: Abstract Recent studies have suggested that domestic dogs (Canis familiaris) engage in highly complex forms of social learning. Here, we critically assess the potential mechanisms underlying social learning in dogs using two problem-solving tasks. In a classical detour task, the test dogs benefited from observing a demonstrator walking around a fence to obtain a reward. However, even inexperienced dogs did not show a preference for passing the fence at the same end as the demonstrator. Furthermore, dogs did not need to observe a complete demonstration by a human demonstrator to pass the task. Instead, they were just as successful in solving the problem after seeing a partial demonstration by an object passing by at the end of the fence. In contrast to earlier findings, our results suggest that stimulus enhancement (or affordance learning) might be a powerful social learning mechanism used by dogs to solve such detour problems. In the second task, we examined whether naïve dogs copy actions to solve an instrumental problem. After controlling for stimulus enhancement and other forms of social influence (e.g. social facilitation and observational conditioning), we found that dogs’ problem solving was not influenced by witnessing a skilful demonstrator (either an unknown human, a conspecific or the dog’s owner). Together, these results add to evidence suggesting that social learning may often be explained by relatively simple (but powerful) mechanisms.
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Baragli, P., Paoletti, E., Vitale, V., & Sighieri, C. (2011). Looking in the correct location for a hidden object: brief note about the memory of donkeys (Equus asinus). Ethology Ecology & Evolution, 23(2), 187–192.
Abstract: In recent years, considerable literature has been published on cognition in horses; however, much less is known about the cognitive abilities of domestic donkey (Equus asinus). This study aimed to expand our knowledge of donkey cognition by assessing their short-term memory capacity. We employed a detour problem combined with the classic delayed-response task, which has been extensively used to compare working memory duration in a variety of different species. A two-point choice apparatus was used to investigate location recall and search behaviour for a food target, after a short delay following its disappearance. Four donkeys completed the task with a 10 sec delay, while four others were tested with a 30 sec delay. Overall, each group performed above chance level on the test, showing that subjects had successfully encoded, maintained, and retrieved the existence and location of the target despite the loss of visual contact.
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Bamford, A. J., Monadjem, A., & Hardy, I. C. W. (2010). Associations of Avian Facial Flushing and Skin Colouration with Agonistic Interaction Outcomes. Ethology, , no-no.
Abstract: Abstract Facial flushing, a colour change caused by variation of blood flow through highly vascularized skin, has been observed in taxonomically diverse bird species but the function of the behaviour has not been assessed. Lappet-faced vultures, Aegypius tracheliotos, have unfeathered heads that can rapidly flush from pink to dark red, and this has been hypothesized to indicate contest ability in vulture gatherings. We show that adults with flushed heads won most interactions against those with pale heads. A previously unnoticed colour variation of the throat, visible only when the head is flushed, was also related to the outcome of interactions: blue-throated adults participated in, and won, more interactions than red-throated adults. We suggest that the non-fixed groups of which lappet-faced vulture populations consist promote the evolution of signals of dominance that can be adjusted extremely rapidly.
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Collier, T. C., Blumstein, D. T., Girod, L., & Taylor, C. E. (2010). Is Alarm Calling Risky? Marmots Avoid Calling from Risky Places. Ethology, , no-no.
Abstract: Abstract Alarm calling is common in many species. A prevalent assumption is that calling puts the vocalizing individual at increased risk of predation. If calling is indeed costly, we need special explanations for its evolution and maintenance. In some, but not all species, callers vocalize away from safety and thus may be exposed to an increased risk of predation. However, for species that emit bouts with one or a few calls, it is often difficult to identify the caller and find the precise location where a call was produced. We analyzed the spatial dynamics of yellow-bellied marmot (Marmota flaviventris) alarm calling using an acoustic localization system to determine the location from where calls were emitted. Marmots almost always called from positions close to the safety of their burrows, and, if they produced more than one alarm call, tended to end their calling bouts closer to safety than they started them. These results suggest that for this species, potential increased predation risk from alarm calling is greatly mitigated and indeed calling may have limited predation costs.
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Martín, J., López, P., Bonati, B., & Csermely, D. (2010). Lateralization When Monitoring Predators in the Wild: A Left Eye Control in the Common Wall Lizard (Podarcis muralis). Ethology, , no-no.
Abstract: Abstract Lateralization is the function specialization between left and right brain hemispheres. It is now ascertained in ectotherms too, where bias in eye use for different tasks, i.e., visual lateralization, is widespread. The lateral eye position on the head of ectotherm animals, in fact, allows them to observe left/right stimuli independently and allows lateralized individuals to carry out left and right perceived tasks at the same time. A recent study conducted on common wall lizards, Podarcis muralis, showed that lizards predominantly monitor a predator with the left eye while escaping. However, this work was conducted in a controlled laboratory setting owing to the difficulty of carrying out lateralization experiments under natural conditions. Nevertheless, field studies could provide important information to support what was previously found in the laboratory and demonstrate that these traits occur in nature. In this study, we conducted a field study on the antipredatory behavior of P. muralis lizards. We simulated predatory attacks on lizards in their natural environment. We found no lateralization in the measure of eye used by the lizard to monitor the predator before escaping from it, but the eye used was probably determined by the relative position of the lizard and the predator just before the attack. This first eye used did not affect escape decisions; lizards chose to escape toward the nearest refuge irrespective of whether it was located to the lizard’s left or right side. However, once they had escaped to a refuge, lizards had a left eye–mediated bias to monitor the predator when first emerging from the refuge, and this bias was likely independent of other environmental variables. Hence, these field findings support a left eye–mediated observation of the predator in P. muralis lizards, which confirms previous findings in this and other species.
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