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Spagnoletti, N., Visalberghi, E., Verderane, M. P., Ottoni, E., Izar, P., & Fragaszy, D. (2012). Stone tool use in wild bearded capuchin monkeys, Cebus libidinosus. Is it a strategy to overcome food scarcity? Anim. Behav., 83(5), 1285–1294.
Abstract: To determine whether tool use varied in relation to food availability in bearded capuchin monkeys, we recorded anvil and stone hammer use in two sympatric wild groups, one of which was provisioned daily, and assessed climatic variables and availability of fruits, invertebrates and palm nuts. Capuchins used tools to crack open encased fruits, mostly palm nuts, throughout the year. Significant differences between wet and dry seasons were found in rainfall, abundance of invertebrates and palm nuts, but not in fruit abundance. Catulè nuts were more abundant in the dry season. We tested the predictions of the necessity hypothesis (according to which tool use is maintained by sustenance needs during resource scarcity) and of the opportunity hypothesis (according to which tool use is maintained by repeated exposure to appropriate ecological conditions, such as preferred food resources necessitating the use of tools). Our findings support only the opportunity hypothesis. The rate of tool use was not affected by provisioning, and the monthly rate of tool use was not correlated with the availability of fruits and invertebrates. Conversely, all capuchins cracked food items other than palm nuts (e.g. cashew nuts) when available, and adult males cracked nuts more in the dry season when catulè nuts (the most common and exploited nut) are especially abundant. Hence, in our field site capuchins use tools opportunistically.
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Hoffmann, G., Bentke, A., Rose-Meierhöfer, S., Berg, W., Mazetti, P., & Hardarson, G. H. (2012). Influence of an active stable system on the behavior and body condition of Icelandic horses. animal, 6(10), 1684–1693.
Abstract: Horses are often stabled in individual boxes, a method that does not meet their natural needs and may cause psychical and
musculoskeletal diseases. This problem is particularly evident in Iceland, where horses often spend the long winter periods in cramped
boxes. The aim of this study was to analyze the suitability of a group housing system in Iceland, but the results are also applicable to
horses of other regions. Eight Icelandic horses were observed in an active stable system, and their behavior and time budget were
recorded. Movement and lying behavior were studied with ALT (Activity, Lying, Temperature detection) pedometers. The effect of an
automatic concentrate feeding station (CFS) on the horses’ behavior was examined. In the first period of investigation, the horses
were fed concentrates manually, and in the second period, they were fed with the CFS. Additional behavioral observations and a
determination of social hierarchy occurred directly or by video surveillance. The physical condition of the horses was recorded by body
weight (BW) measurement and body condition scoring (BCS). The results showed a significant increase between the first and second
trial periods in both the activity (P,0.001) and the lying time (P50.003) of the horses with use of the CFS. However, there was no
significant change in BW during the first period without the CFS (P50.884) or during the second period with the CFS (P50.540).
The BCS of the horses was constant at a very good level during both trial periods, and the horses showed a low level of aggression, a
firm social hierarchy and behavioral synchronization. This study concludes that group housing according to the active stable principle is
a welfare-friendly option for keeping horses and is a suitable alternative to conventional individual boxes.
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Thornton Alex, & Lukas Dieter. (2012). Individual variation in cognitive performance: developmental and evolutionary perspectives. Philos Trans R Soc Lond B Biol Sci, 367(1603), 2773–2783.
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Proops, L., & McComb, K. (2012). Cross-modal individual recognition in domestic horses (Equus caballus) extends to familiar humans. Proceedings of the Royal Society B: Biological Sciences, 279(1741), 3131–3138.
Abstract: It has recently been shown that some non-human animals can cross-modally recognize members of their own taxon. What is unclear is just how plastic this recognition system can be. In this study, we investigate whether an animal, the domestic horse, is capable of spontaneous cross-modal recognition of individuals from a morphologically very different species. We also provide the first insights into how cross-modal identity information is processed by examining whether there are hemispheric biases in this important social skill. In our preferential looking paradigm, subjects were presented with two people and playbacks of their voices to determine whether they were able to match the voice with the person. When presented with familiar handlers subjects could match the specific familiar person with the correct familiar voice. Horses were significantly better at performing the matching task when the congruent person was standing on their right, indicating marked hemispheric specialization (left hemisphere bias) in this ability. These results are the first to demonstrate that cross-modal recognition in animals can extend to individuals from phylogenetically very distant species. They also indicate that processes governed by the left hemisphere are central to the cross-modal matching of visual and auditory information from familiar individuals in a naturalistic setting.
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Benson-Amram, S., & Holekamp, K. E. (2012). Innovative problem solving by wild spotted hyenas. Proc R Soc B, 279, 4087–4095.
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von Rohr, C. R., Koski, S. E., Burkart, J. M., Caws, C., Fraser, O. N., Ziltener, A., et al. (2012). Impartial Third-Party Interventions in Captive Chimpanzees: A Reflection of Community Concern. PLoS ONE, 7(3), e32494 EP -.
Abstract: <p>Because conflicts among social group members are inevitable, their management is crucial for group stability. The rarest and most interesting form of conflict management is policing, i.e., <italic>impartial interventions by bystanders</italic>, which is of considerable interest due to its potentially moral nature. Here, we provide descriptive and quantitative data on policing in captive chimpanzees. First, we report on a high rate of policing in one captive group characterized by recently introduced females and a rank reversal between two males. We explored the influence of various factors on the occurrence of policing. The results show that only the alpha and beta males acted as arbitrators using manifold tactics to control conflicts, and that their interventions strongly depended on conflict complexity. Secondly, we compared the policing patterns in three other captive chimpanzee groups. We found that although rare, policing was more prevalent at times of increased social instability, both high-ranking males and females performed policing, and conflicts of all sex-dyad combinations were policed. These results suggest that the primary function of policing is to increase group stability. It may thus reflect prosocial behaviour based upon “community concern.” However, policing remains a rare behaviour and more data are needed to test the generality of this hypothesis.</p>
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Sueur, C., Deneubourg, J. - L., & Petit, O. (2012). From Social Network (Centralized vs. Decentralized) to Collective Decision-Making (Unshared vs. Shared Consensus). PLoS ONE, 7(2), e32566 EP -.
Abstract: <p>Relationships we have with our friends, family, or colleagues influence our personal decisions, as well as decisions we make together with others. As in human beings, despotism and egalitarian societies seem to also exist in animals. While studies have shown that social networks constrain many phenomena from amoebae to primates, we still do not know how consensus emerges from the properties of social networks in many biological systems. We created artificial social networks that represent the continuum from centralized to decentralized organization and used an agent-based model to make predictions about the patterns of consensus and collective movements we observed according to the social network. These theoretical results showed that different social networks and especially contrasted ones – star network vs. equal network – led to totally different patterns. Our model showed that, by moving from a centralized network to a decentralized one, the central individual seemed to lose its leadership in the collective movement's decisions. We, therefore, showed a link between the type of social network and the resulting consensus. By comparing our theoretical data with data on five groups of primates, we confirmed that this relationship between social network and consensus also appears to exist in animal societies.</p>
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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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Meagher, R. K., & Mason, G. J. (2012). Environmental Enrichment Reduces Signs of Boredom in Caged Mink. PLoS ONE, 7(11), e49180.
Abstract: <p>Animals housed in impoverished cages are often labelled ‘bored’. They have also been called ‘apathetic’ or ‘depressed’, particularly when profoundly inactive. However, these terms are rarely operationally defined and validated. As a negative state caused by under-stimulation, boredom should increase interest in stimuli of all kinds. Apathy (lack of interest), by contrast, should manifest as decreased interest in all stimuli, while anhedonia (loss of pleasure, a depressive symptom) should specifically decrease interest in normally rewarding stimuli. We tested the hypotheses that mink, a model carnivore, experience more boredom, depression-like apathy, or anhedonia in non-enriched (NE) cages than in complex, enriched (E) cages. We exposed 29 subjects (13 E, 16 NE) to ten stimuli categorized <italic>a priori</italic> as aversive (e.g. air puffs), rewarding (e.g. evoking chasing) or ambiguous/neutral (e.g. candles). Interest in stimuli was assessed via latencies to contact, contact durations, and durations oriented to stimuli. NE mink contacted all stimuli faster (P = 0.003) than E mink, and spent longer oriented to/in contact with them, albeit only significantly so for ambiguous ones (treatment*type P<0.013). With stimulus category removed from statistical models, interest in all stimuli was consistently higher among NE mink (P<0.0001 for all measures). NE mink also consumed more food rewards (P = 0.037). Finally, we investigated whether lying down while awake and stereotypic behaviour (both increased by NE housing) predicted these responses. Lying awake positively co-varied with certain measures of increased exploration. In contrast, stereotypic ‘scrabbling’ or locomotion (e.g. pacing) did not. Overall, NE mink showed no evidence of apathy or depression, but instead a heightened investigation of diverse stimuli consistent with boredom. This state was potentially indicated by spending much time lying still but awake (although this result requires replication). Boredom can thus be operationalized and assessed empirically in non-human animals. It can also be reduced by environmental enrichment.</p>
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