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Malavasi, R., & Huber, L. (2016). Evidence of heterospecific referential communication from domestic horses (Equus caballus) to humans. Anim. Cogn., 19(5), 899–909.
Abstract: Referential communication occurs when a sender elaborates its gestures to direct the attention of a recipient to its role in pursuit of the desired goal, e.g. by pointing or showing an object, thereby informing the recipient what it wants. If the gesture is successful, the sender and the recipient focus their attention simultaneously on a third entity, the target. Here we investigated the ability of domestic horses (Equus caballus) to communicate referentially with a human observer about the location of a desired target, a bucket of food out of reach. In order to test six operational criteria of referential communication, we manipulated the recipient’s (experimenter) attentional state in four experimental conditions: frontally oriented, backward oriented, walking away from the arena and frontally oriented with other helpers present in the arena. The rate of gaze alternation was higher in the frontally oriented condition than in all the others. The horses appeared to use both indicative (pointing) and non-indicative (nods and shakes) head gestures in the relevant test conditions. Horses also elaborated their communication by switching from a visual to a tactile signal and demonstrated perseverance in their communication. The results of the tests revealed that horses used referential gestures to manipulate the attention of a human recipient so to obtain an unreachable resource. These are the first such findings in an ungulate species.
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Taubert, J., Weldon, K. B., & Parr, L. A. (2016). Robust representations of individual faces in chimpanzees (Pan troglodytes) but not monkeys (Macaca mulatta). Anim. Cogn., , 1–9.
Abstract: Being able to recognize the faces of our friends and family members no matter where we see them represents a substantial challenge for the visual system because the retinal image of a face can be degraded by both changes in the person (age, expression, pose, hairstyle, etc.) and changes in the viewing conditions (direction and degree of illumination). Yet most of us are able to recognize familiar people effortlessly. A popular theory for how face recognition is achieved has argued that the brain stabilizes facial appearance by building average representations that enhance diagnostic features that reliably vary between people while diluting features that vary between instances of the same person. This explains why people find it easier to recognize average images of people, created by averaging multiple images of the same person together, than single instances (i.e. photographs). Although this theory is gathering momentum in the psychological and computer sciences, there is no evidence of whether this mechanism represents a unique specialization for individual recognition in humans. Here we tested two species, chimpanzees (Pan troglodytes) and rhesus monkeys (Macaca mulatta), to determine whether average images of different familiar individuals were easier to discriminate than photographs of familiar individuals. Using a two-alternative forced-choice, match-to-sample procedure, we report a behaviour response profile that suggests chimpanzees encode the faces of conspecifics differently than rhesus monkeys and in a manner similar to humans.
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Ringhofer, M., & Yamamoto, S. (2016). Domestic horses send signals to humans when they face with an unsolvable task. Anim. Cogn., , 1–9.
Abstract: Some domestic animals are thought to be skilled at social communication with humans due to the process of domestication. Horses, being in close relationship with humans, similar to dogs, might be skilled at communication with humans. Previous studies have indicated that they are sensitive to bodily signals and the attentional state of humans; however, there are few studies that investigate communication with humans and responses to the knowledge state of humans. Our first question was whether and how horses send signals to their potentially helpful but ignorant caretakers in a problem-solving situation where a food item was hidden in a bucket that was accessible only to the caretakers. We then examined whether horses alter their behaviours on the basis of the caretakers’ knowledge of where the food was hidden. We found that horses communicated to their caretakers using visual and tactile signals. The signalling behaviour of the horses significantly increased in conditions where the caretakers had not seen the hiding of the food. These results suggest that horses alter their communicative behaviour towards humans in accordance with humans’ knowledge state.
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Sommer, V., Lowe, A., & Dietrich, T. (2016). Not eating like a pig: European wild boar wash their food. Anim. Cogn., 19(1), 245–249.
Abstract: Carrying food to water and either dunking or manipulating it before consumption has been observed in various taxa including birds, racoons and primates. Some animals seem to be simply moistening their food. However, true washing aims to remove unpleasant surface substrates such as grit and sand and requires a distinction between items that do and do not need cleaning as well as deliberate transportation of food to a water source. We provide the first evidence for food washing in suids, based on an incidental observation with follow-up experiments on European wild boar (Sus scrofa) kept at Basel Zoo, Switzerland. Here, all adult pigs and some juveniles of a newly formed group carried apple halves soiled with sand to the edge of a creek running through their enclosure where they put the fruits in the water and pushed them to and fro with their snouts before eating. Clean apple halves were never washed. This indicates that pigs can discriminate between soiled and unsoiled foods and that they are able to delay gratification for long enough to transport and wash the items. However, we were unable to ascertain to which degree individual and/or social learning brought this behaviour about.
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Cinková, I., & Policht, R. (2016). Sex and species recognition by wild male southern white rhinoceros using contact pant calls. Anim. Cogn., 19(2), 375–386.
Abstract: Recognition of information from acoustic signals is crucial in many animals, and individuals are under selection pressure to discriminate between the signals of conspecifics and heterospecifics or males and females. Here, we first report that rhinos use information encoded in their calls to assess conspecifics and individuals of closely related species. The southern (Ceratotherium simum) and critically endangered northern (C. cottoni) white rhinos are the most social out of all the rhinoceros species and use a contact call pant. We found that southern white rhino pant calls provide reliable information about the caller’s sex, age class and social situation. Playback experiments on wild territorial southern white rhinoceros males revealed that they responded more strongly to the pant calls of conspecific females compared to the calls of other territorial males. This suggests that pant calls are more important form of communication between males and females than between territorial males. Territorial southern males also discriminated between female and territorial male calls of northern species and reacted more intensively to the calls of northern than southern males. This might be caused by a novelty effect since both species naturally live in allopatry. We conclude that white rhinos can directly benefit from assessing individuals at long distances using vocal cues especially because their eyesight is poor. Pant calls thus likely play a significant role in their social relationships and spatial organization. In addition, better understanding of vocal communication in white rhinos might be helpful in conservation management particularly because of their low reproduction in captivity.
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Ward, A., & Webster, M. (2016). Sociality: The Behaviour of Group-Living Animals.
Abstract: Covers the aspects of social behaviour of animals in comprehensive form Provides a clear overview to up-to-date empirical and theoretical research on social animal behaviour
Discusses collective animal behaviour, social networks and animal personality in detail
The last decade has seen a surge of interest among biologists in a range of social animal phenomena, including collective behaviour and social networks. In ‘Animal Social Behaviour’, authors Ashley Ward and Michael Webster integrate the most up-to-date empirical and theoretical research to provide a new synthesis of the field, which is aimed at fellow researchers and postgraduate students on the topic. ​
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Smolla, M., Alem, S., Chittka, L., & Shultz, S. (2016). Copy-when-uncertain: bumblebees rely on social information when rewards are highly variable. Biol. Lett., 12(6).
Abstract: To understand the relative benefits of social and personal information use in foraging decisions, we developed an agent-based model of social learning that predicts social information should be more adaptive where resources are highly variable and personal information where resources vary little. We tested our predictions with bumblebees and found that foragers relied more on social information when resources were variable than when they were not. We then investigated whether socially salient cues are used preferentially over non-social ones in variable environments. Although bees clearly used social cues in highly variable environments, under the same conditions they did not use non-social cues. These results suggest that bumblebees use a 'copy-when-uncertain' strategy.
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Bailey, D. (2016). Dominance Hierarchies in Horses: Comparing and Contrasting Different Methods for Assessing Hierarchies. Ursidae: The Undergraduate Research Journal at the University of Northern Colorado, 5(3).
Abstract: Understanding animal social structures is imperative when it comes to the care, housing and handling of large herd animals. Knowing how hierarchies are structured, along with environmental and physiological aspects that may affect them, will allow owners and breeders to house and care for their animals. The aim of my study was to better understand two methods used to assess dominance hierarchies in horses, Equus caballus, and to predict which method would be more useful for owners housing domestic horses. I designed an experiment where I compared a structured method, the paired feeding test, with behavioral observations from the horses’ natural setting. I hypothesized that the structured method would not conclude the same dominance hierarchy as the natural observations. I also hypothesized that traits of the horses, such as size or age, would correlate with the hierarchy ranking within a herd. A herd of six individual horses from a small ranch east of Platteville, Colorado was used to test the two methods. I found that the two methods measured different hierarchies. The paired feeding test showed no correlations to any of the physical measurements, as well as did not provide a hierarchy that was similar to the natural dominance observations of the horses. Natural observations established a more linear hierarchy and had significant correlations with weight and overall body size. The results indicate that the paired feeding test may not be a valid method for establishing dominance hierarchies within domestic horses housed in a small range.
I recommend use of natural observations over paired feeding tests for ranchers, breeders or owners trying to understand the dominance hierarchies among their herds.
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Suter, S. M., Giordano, M., Nietlispach, S., Apollonio, M., & Passilongo, D. (2016). Non-invasive acoustic detection of wolves. Bioacoustics, .
Abstract: Monitoring wolves (Canis lupus) is a difficult and often expensive task due to high mobility,pack dynamic, shyness and nocturnal activity of this species. Wolves communicate acoustically trough howling, within pack and with packs of the neighbourhood. A wolf howl is a low frequency vocalization that can be transmitted over long distances and thus be used
for monitoring tasks. Animated howling survey is a current method to monitor wolves indifferent areas all over the world. Animated howling, however, may be invasive to residential wolf packs and could create possible negative reactions from local human population. Here we show that it is possible to detect wolves by recording spontaneous howling events. We measured the sound pressure level of wolf howls on captive individuals and we further found that simulated howling may be recorded and clearly identified up to a distance of 3 km. We finally conducted non-invasive acoustic detection of wolves in a free ranging population. The use of passive sound recorders may provide a powerful non-invasive tool for future wolf monitoring and thus help to established sustainable management plans for this species.
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Chapron, G., & Treves, A. (2016). Blood does not buy goodwill: allowing culling increases poaching of a large carnivore. Proc. R. Soc. Lond. B, 283(1830).
Abstract: Quantifying environmental crime and the effectiveness of policy interventions is difficult because perpetrators typically conceal evidence. To prevent illegal uses of natural resources, such as poaching endangered species, governments have advocated granting policy flexibility to local authorities by liberalizing culling or hunting of large carnivores. We present the first quantitative evaluation of the hypothesis that liberalizing culling will reduce poaching and improve population status of an endangered carnivore. We show that allowing wolf (Canis lupus) culling was substantially more likely to increase poaching than reduce it. Replicated, quasi-experimental changes in wolf policies in Wisconsin and Michigan, USA, revealed that a repeated policy signal to allow state culling triggered repeated slowdowns in wolf population growth, irrespective of the policy implementation measured as the number of wolves killed. The most likely explanation for these slowdowns was poaching and alternative explanations found no support. When the government kills a protected species, the perceived value of each individual of that species may decline; so liberalizing wolf culling may have sent a negative message about the value of wolves or acceptability of poaching. Our results suggest that granting management flexibility for endangered species to address illegal behaviour may instead promote such behaviour.
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