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Bräuer, J., Call, J., & Tomasello, M. (2008). Chimpanzees do not take into account what others can hear in a competitive situation. Anim. Cogn., 11(1), 1435–9448.
Abstract: Chimpanzees (Pan troglodytes) know what others can and cannot see in a competitive situation. Does this reflect a general understanding the perceptions of others` In a study by Hare et al. (2000) pairs of chimpanzees competed over two pieces of food. Subordinate individuals preferred to approach food that was behind a barrier that the dominant could not see, suggesting that chimpanzees can take the visual perspective of others. We extended this paradigm to the auditory modality to investigate whether chimpanzees are sensitive to whether a competitor can hear food rewards being hidden. Results suggested that the chimpanzees did not take what the competitor had heard into account, despite being able to locate the hiding place themselves by the noise.
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Virányi, Z., Range, F., & Huber, L. (2008). Attentiveness toward others and social learning in domestic dogs. In L. S. Röska-hardy, & E. Neumann-held (Eds.), Learning from Animals?: Examining the Nature of Human Uniqueness (pp. 141–154). New York, NY: Psychology Press.
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Smith, B. R., & Blumstein, D. T. (2008). Fitness consequences of personality: a meta-analysis. Behav. Ecol., 19(2), 448–455.
Abstract: The study of nonhuman personality capitalizes on the fact that individuals of many species behave in predictable, variable, and quantifiable ways. Although a few empirical studies have examined the ultimate consequences of personality differences, there has been no synthesis of results. We conducted a formal meta-analysis of published studies reporting fitness consequences of single personality dimensions to identify general trends across species. We found bolder individuals had increased reproductive success, particularly in males, but incurred a survival cost, thus, supporting the hypothesis that variation in boldness was maintained due to a “trade-off” in fitness consequences across contexts. Potential mechanisms maintaining variation in exploration and aggression are not as clear. Exploration had a positive effect only on survival, whereas aggression had a positive effect on both reproductive success and, not significantly, on survival. Such results would suggest that selection is driving populations to become more explorative and aggressive. However, limitations in meta-analytic techniques preclude us from testing for the effects of fluctuating environmental conditions or other forms of selection on these dimensions. Results do, however, provide evidence for general relationships between personality and fitness, and we provide a framework for future studies to follow in the hopes of spurring more in-depth, long-term research into the evolutionary mechanisms maintaining variation in personality dimensions and overall behavioral syndromes. We conclude with a discussion on how understanding and managing personality traits may play a key role in the captive breeding and recovery programs of endangered species.
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Christensen, J. W., Malmkvist, J., Nielsen, B. L., & Keeling, L. J. (2008). Effects of a calm companion on fear reactions in naive test horses. Equine Vet J, 40(1), 46–50.
Abstract: REASON FOR PERFORMING STUDY: In fear-eliciting situations, horses tend to show flight reactions that can be dangerous for both horse and man. Finding appropriate methods for reducing fearfulness in horses has important practical implications. OBJECTIVES: To investigate whether the presence of a calm companion horse influences fear reactions in naive subject horses. HYPOTHESES: The presence of a habituated (calm) companion horse in a fear-eliciting situation can reduce fear reactions in naive subject horses, compared to subject horses with a nonhabituated companion (control). METHODS: Minimally handled (n = 36), 2-year-old stallions were used, 18 as subjects and 18 as companions. Companion horses (n = 9) were habituated to an otherwise frightening, standardised test stimulus (calm companions), whereas the rest (n = 9) of the companion horses remained nonhabituated (control companions). During the test, unique pairs of companion and subject horses were exposed to the test stimulus while heart rate and behavioural responses were registered. Subsequently, subject horses were exposed to the stimulus on their own (post test). RESULTS: Subject horses, paired with a calm companion horse, showed less fear-related behaviour and lower heart rate responses compared to subject horses with control companions. Results from the post test suggest that the difference between treatment groups remained in the subsequent absence of companion horses. CONCLUSIONS AND POTENTIAL RELEVANCE: It appears possible to reduce fear reactions in young, naive horses by allowing them to interact with a calm companion horse in fear-eliciting situations.
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Scheiber, I. B. R., WeiB, B. M., Hirschenhauser, K., Wascher, C. A. F., Nedelcu, J. T., & Kotrschal, K. (2008). Does 'Relationship Intelligence' Make Big Brains in Birds? Open Biol J, 1, 6–8 (3).
Abstract: Lately, Emery et al. developed a bird-specific modification of the *social brain hypothesis*, termed *relationship intelligence hypothesis*. Although the idea may be valuable, we doubt that it is supported by sufficient evidence and critically discuss some of the arguments raised by the authors in favour of their new idea.
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Siniscalchi, M., Quaranta, A., & Rogers, L. J. (2008). Hemispheric specialization in dogs for processing different acoustic stimuli. PloS ONE, 3, e3349.
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Hemelrijk, C. K., Wantia, J.,, & Isler, K. (2008). Female Dominance over Males in Primates: Self-Organisation and Sexual Dimorphism. PLoS ONE, 3(7), e2678.
Abstract: The processes that underlie the formation of the dominance hierarchy in a group are since long under debate. Models of self-organisation suggest that dominance hierarchies develop by the self-reinforcing effects of winning and losing fights (the so-called winner-loser effect), but according to ‘the prior attribute hypothesis’, dominance hierarchies develop from pre-existing individual differences, such as in body mass. In the present paper, we investigate the relevance of each of these two theories for the degree of female dominance over males. We investigate this in a correlative study in which we compare female dominance between groups of 22 species throughout the primate order. In our study female dominance may range from 0 (no female dominance) to 1 (complete female dominance). As regards ‘the prior attribute hypothesis’, we expected a negative correlation between female dominance over males and species-specific sexual dimorphism in body mass. However, to our surprise we found none (we use the method of independent contrasts). Instead, we confirm the self-organisation hypothesis: our model based on the winner-loser effect predicts that female dominance over males increases with the percentage of males in the group. We confirm this pattern at several levels in empirical data (among groups of a single species and between species of the same genus and of different ones). Since the winner-loser effect has been shown to work in many taxa including humans, these results may have broad implications.3
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Roth II, T. C., Cox, J. G., & Lima, S. L. (2008). The Use and Transfer of Information About Predation Risk in Flocks of Wintering Finches. Ethology, 114(12), 1218–1226.
Abstract: ABSTRACT
Several studies in behavior have focused in some way on how groups of prey gather and use information about predation risk. Although asymmetries in information about risk exist among members of real groups, we know little about how such uneven information might affect individual or group antipredator decisions. Hence, we studied the use and transfer of information about the risk of predation in small flocks of wintering birds. House finches (Carpodacus mexicanus; 28 groups of three) were held in large enclosures divided into safe and risky patches. We controlled the information about risk available to each individual by conducting attacks with a model hawk that was visible to only a single (informed) bird. Repeated attacks on a single individual did not reduce the amount of feeding by other birds in that patch, although the time to resume feeding after observing a response to an attack event was somewhat longer than after a no attack event. These results suggest that informed individuals impart some information to naive (uninformed) birds, but this effect was not strong. In fact, the frequent return of informed individuals to feeders after observing uninformed individuals feed suggests that finches relied more on public information regarding safety than their own personal information in deciding when to feed. Group patch choice appeared to be based on a majority-rules decision, although an effect of dominance status was apparent. Our results suggest that subordinate flock members may exert a large influence over group decision-making by acting as spatial 'anchors'.
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Blumstein, D. T., Barrow, L., & Luterra, M. (2008). Olfactory Predator Discrimination in Yellow-Bellied Marmots. Ethology, 114(11), 1135–1143.
Abstract: The mechanism underlying olfactory predator identification may be relatively experience-independent, or it may rely on specific experience with predators. A mechanism by which prey might identify novel predators relies on the inevitable creation of sulfurous metabolites that are then excreted in the urine of carnivorous mammals. We tested whether free-living, yellow-bellied marmots (Marmota flaviventris) and mid-sized herbivores that fall prey to a variety of carnivorous mammals could discriminate herbivore (elk-Cervus elephas) urine from predator (red fox-Vulpes vulpes, coyote-Canis latrans, mountain lion-Felis concolor, wolf-Canis lupus) urine, a novel herbivore (moose-Alces alces), and a distilled water control. We further asked how specific this assessment was by testing whether marmots responded differently to predators representing different levels of risk and to familiar vs. unfamiliar predators. We found that marmots responded more to urine from coyotes (a familiar predator on adults), mountain lions (a potentially unfamiliar predator that could kill adults) and wolves (a locally extinct predator that could kill adults) than to elk urine (a non-predator). Red fox (a predator that poses a risk only to recently emerged marmot pups) urine elicited a less substantial (but not significantly so) response than coyote urine. Marmots can identify predators, even novel ones, using olfactory cues, suggesting that experience with a specific predator is not required to identify potential threats.
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Fernando Colmenares, & Fernando Silveira. (2008). Post-Conflict Non-Aggressive Behaviours may be neither Friendly nor Conciliatory – Conflict Management of Male Hamadryas Baboons.114(11), 1101–1112.
Abstract: The relational model of conflict resolution predicts that after an aggressive conflict there should be a motivational shift from aggression to attraction. Most tests of the reconciliation hypothesis assume, however, that all non-aggressive post-conflict behaviours between former opponents are motivationally homogeneous and qualify as friendly reunions. In fact, although the hypothesis predicts an increased occurrence of friendly contacts after conflicts, in practice, however, post-conflict reunions often include a mixture of contact and non-contact behaviours. Most reconciliation studies either (often) assume a conciliatory function for post-conflict reunions or (less often) test functional predictions. Finally, the valuable relationships hypothesis predicts that conciliatory rates should be relatively higher between friends and allies than between non-friends/allies. In this paper, we use data on non-aggressive interactions following conflicts between adult male hamadryas baboons that are neither friends nor allies to assess the implications of all these important but largely overlooked issues. The analyses of the rate and temporal relation of non-contact greeting (NCTG) to anxiety-related behaviours and side-directed aggression as well as of the behaviours used during non-aggressive interactions with male and female third-parties suggest that the NCTG used by males after conflicts were neither motivationally friendly nor functionally conciliatory. We point out that the gestures exchanged during these post-conflict NCTG can be interpreted as formalized signals of equal status and that the rate and form of the greetings used by male opponents are indicative of high relationship insecurity and incompatibility respectively. We conclude that although male hamadryas' post-conflict NCTG are not conciliatory they may serve to assess their opponents' attitude and to negotiate the restoring of their pre-conflict levels of peaceful but non-amicable co-existence.
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