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Boogert, N. J., Reader, S. M., & Laland, K. N. (2006). The relation between social rank, neophobia and individual learning in starlings. Anim. Behav., 72(6), 1229–1239.
Abstract: Researchers with diverse interests in topics ranging from the formation of dominance hierarchies and social intelligence to animal personalities have predicted specific, and often conflicting, relations between social rank, neophobia and learning ability. We investigated the relations between these variables in captive groups of wild-caught starlings, Sturnus vulgaris, adopting a multidimensional approach to social rank and neophobia. Both agonistic and competitive rank orders were determined for each group and we tested individuals in the absence of their groupmates for object neophobia, latency to feed in a novel environment and performance on an extractive foraging task. In each starling group, the fastest learners occupied the highest competitive ranks, supporting the hypothesis that cognitive ability is positively correlated with social dominance. Competitive rank orders, however, did not correlate significantly with agonistic rank orders. Situation-specific foraging neophobia was suggested: individuals showed consistency in their latencies to feed near a variety of novel objects, but no significant correlation was found between this measure of object neophobia and latency to feed in a novel environment. Starlings fastest to feed in the novel environment were fastest in solving the foraging task. We discuss the implications of these findings for researchers studying hierarchy formation in animal groups, social intelligence and animal personalities.
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Kenward, B., Rutz, C., Weir, A. A. S., & Kacelnik, A. (2006). Development of tool use in New Caledonian crows: inherited action patterns and social influences. Anim. Behav., 72(6), 1329–1343.
Abstract: New Caledonian crows, Corvus moneduloides, are the most advanced avian tool makers and tool users. We previously reported that captive-bred isolated New Caledonian crows spontaneously use twig tools and cut tools out of Pandanus spp. tree leaves, an activity possibly under cultural influence in the wild. However, what aspects of these behaviours are inherited and how they interact with individual and social experience remained unknown. To examine the interaction between inherited traits, individual learning and social transmission, we observed the ontogeny of twig tool use in hand-reared juveniles. Successful food retrieval was preceded by stereotyped object manipulation action patterns that resembled components of the mature behaviour, demonstrating that tool-oriented behaviours in this species are an evolved specialization. However, there was also an effect of social learning: juveniles that had received demonstrations of twig tool use by their human foster parent showed higher levels of handling and insertion of twigs than did their naive counterparts; a choice experiment showed that they preferred to handle objects that they had seen being manipulated by their human foster parent. Our observations are consistent with the hypothesis that individual learning, cultural transmission and creative problem solving all contribute to the acquisition of the tool-oriented behaviours in the wild, but inherited species-typical action patterns have a greater role than has been recognized.
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McElreath, R., & Strimling, P. (2006). How noisy information and individual asymmetries can make `personality' an adaptation: a simple model. Anim. Behav., 72(5), 1135–1139.
Abstract: Recent attention has been drawn to the existence of individual differences in correlated behaviour across contexts, animal `personality' (Gosling 2001, Psychological Bulletin, 127, 45-86) and behavioural syndromes (Sih et al. 2004b, Quarterly Review of Biology, 79, 241-277). The causes of these patterns of behaviour are subjects of debate. Here, we present a very simple model of how adaptively managing noisy information, combined with differences in individual state, can lead to evolutionarily stable differences in how individuals respond to environmental cues. When information is very noisy, behavioural syndromes are most likely, but as long as there is some error, some types of individuals display the same behaviour in all contexts. In extreme cases, very few individuals display flexible behaviour, and different stable behavioural types dominate the population.
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Mateo, J. M. (2006). The nature and representation of individual recognition odours in Belding's ground squirrels. Anim. Behav., 71(1), 141–154.
Abstract: In many taxonomic groups, odours provide cues to species identity, reproductive status, genetic relatedness and individual identity. These odour cues are often used to mark territories or other resources and to recognize individuals through direct or indirect olfactory investigation. Belding's ground squirrels, Spermophilus beldingi, frequently scent-mark their environment and they also investigate the scent glands of conspecifics, which suggests that odours play a modulating role in their social relationships. I conducted studies to determine what information is conveyed by various S. beldingi odours and whether this information is used by conspecifics for social recognition. Spermophilus beldingi produce a number of cues that are individually distinct, including odours from oral, dorsal, pedal and anal glands and from ears, but apparently not from urine, although it is unclear whether all of these odours are used for social recognition. This discrimination among odours of individuals does not require prior familiarity with the odour bearers. The volatile components of some odours are sufficient to permit individual discrimination, which may explain how animals appear to [`]recognize' each other from a short distance. Finally, S. beldingi incorporate multiple odours into their memories of conspecifics as perception of one odour of an individual generalizes to a second odour from it, suggesting a mental representation of familiar individuals. The production of multiple unique odours may facilitate accurate discrimination of conspecifics along several social dimensions, and some of these odours also vary with relatedness. Together, these results indicate a rich olfactory milieu mediating the social lives of S. beldingi.
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de Vries, H., Stevens, J. M. G., & Vervaecke, H. (2006). Measuring and testing the steepness of dominance hierarchies. Anim. Behav., 71(3), 585–592.
Abstract: In the analysis of social dominance in groups of animals, linearity has been used by many researchers as the main structural characteristic of a dominance hierarchy. In this paper we propose, alongside linearity, a quantitative measure for another property of a dominance hierarchy, namely its steepness. Steepness of a hierarchy is defined here as the absolute slope of the straight line fitted to the normalized David's scores (calculated on the basis of a dyadic dominance index corrected for chance) plotted against the subjects' ranks. This correction for chance is an improvement of an earlier proposal by de Vries (appendix 2 in de Vries, Animal Behaviour, 1998, 55, 827-843). In addition, we present a randomization procedure for determining the statistical significance of a hierarchy's steepness, which can be used to test the observed steepness against the steepness expected under the null hypothesis of random win chances for all pairs of individuals. Whereas linearity depends on the number of established binary dominance relationships and the degree of transitivity in these relationships, steepness measures the degree to which individuals differ from each other in winning dominance encounters. Linearity and steepness are complementary measures to characterize a dominance hierarchy.
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Poisbleau, M., Fritz, H., Valeix, M., Perroi, P. - Y., Dalloyau, S., & Lambrechts, M. M. (2006). Social dominance correlates and family status in wintering dark-bellied brent geese, Branta bernicla bernicla. Anim. Behav., 71(6), 1351–1358.
Abstract: In many gregarious species, including ducks and geese, being dominant provides more benefits than costs, because dominants have better access to resources essential for survival or reproduction. In geese, being in better body condition during migration towards the breeding grounds positively influences reproductive success. However, underlying proximate mechanisms linking prebreeding body condition on the wintering grounds to breeding success remain poorly understood. We investigated social dominance correlates and family status, in three consecutive winters, in a free-ranging, migrating, dark-bellied brent goose population. Families with juveniles dominated pairs, and pairs dominated singletons. Dominance rank did not increase with the number of juveniles per family. Males were dominant over females. Social dominance and reproductive status for a given winter were significantly correlated with body mass, body size and body condition during the previous winter, suggesting that body condition in winter also affects subsequent breeding success and hence also dominance. Levels of testosterone and triiodothyronine were not correlated with immediate or later dominance or reproductive status. We discuss the role of family status as a signal of social status in determining reproductive strategies.
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Pompilio, L., & Kacelnik, A. (2005). State-dependent learning and suboptimal choice: when starlings prefer long over short delays to food. Anim. Behav., 70(3), 571–578.
Abstract: Recent studies have used labels such as `work ethics', `sunk costs' and `state-dependent preferences' for apparent anomalies in animals' choices. They suggest that preference between options relates to the options' history, rather than depending exclusively on the expected payoffs. For instance, European starlings, Sturnus vulgaris, trained to obtain identical food rewards from two sources while in two levels of hunger preferred the food source previously associated with higher hunger, regardless of the birds' state at the time of testing. We extended this experimentally and theoretically by studying starlings choosing between sources that differed not only in history but also in the objective properties (delay until reward) of the payoffs they delivered. Two options (PF and H) were initially presented in single-option sessions when subjects were, respectively, prefed or hungry. While option PF offered a delay until reward of 10 s in all treatments, option H delivered delays of 10, 12.5, 15 and 17.5 s in four treatments. When training was completed, we tested preference between the options. When delays in both options were equal (10 s), the birds strongly preferred H. When delay in H was 17.5 s, the birds were indifferent, with intermediate results for intermediate treatments. Preference was not mediated by disrupted knowledge of the delays. Thus, preferences were driven by past state-dependent gains, rather than by the joint effect of the birds' state at the time of choice and knowledge of the absolute properties of each alternative, as assumed in state-dependent, path-independent models of optimal choice.
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Abeyesinghe, S. M., Nicol, C. J., Hartnell, S. J., & Wathes, C. M. (2005). Can domestic fowl, Gallus gallus domesticus, show self-control? Anim. Behav., 70(1), 1–11.
Abstract: An important aspect of cognition is whether animals live exclusively in the present or can anticipate the future. Defined as self-control, the ability to choose a large, remote reinforcer over a small, proximate reinforcer available at the same frequency has been examined in a number of species, often proving difficult to demonstrate. We investigated self-control for food in domestic fowl using a standard two-key operant task and an equivalent two-choice return maze (TCRM) task. When hens chose between a 2-s delay to a 3-s feed access (impulsive) and a 6-s delay to a 7-s feed access (self-control), they appeared unable to discriminate in the TCRM but were impulsive in the operant task. We explored reasons for not choosing self-control in the operant task, first by examining the relation between feed access time and actual feed intake. A second operant experiment examined whether failure to show self-control could be attributed to an inability to combine the delay and access (quantity) reward information associated with choices to reach overall predictions of value. New hens chose between a 2-s delay to a 3-s feed access (impulsive) and either a 22-s delay to a 22-s feed access (standard self-control) or a 6-s delay to a 22-s feed access (jackpot self-control). While hens were impulsive in the standard condition, they showed significant and pronounced self-control in the jackpot condition, eliminating the possibility of an absolute cognitive constraint. Impulsive behaviour can instead be explained by temporal discounting: perceived depreciation of reward value as a function of the uncertainty associated with delay. Implications for welfare are discussed.
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Nicol, C. J., & Badnell-Waters, A. J. (2005). Suckling behaviour in domestic foals and the development of abnormal oral behaviour. Anim. Behav., 70(1), 21–29.
Abstract: We investigated how the behaviour of domestic foals, Equus caballus, living at pasture with their dams was associated with foal gender, mare rank and the development of abnormal oral behaviour, both during the preweaning period, and over a period of up to 4 years postweaning. A population of 186 foals belonging to private owners and commercial studs was studied. The behaviour of male and female foals hardly differed, but mare rank affected patterns of foal social interaction and suckling behaviour, with foals of subordinate mares involved in more affiliative interactions. These foals also spent more time in perisuckling activities such as teat nuzzling than foals of other mares. During the study, 18 foals developed abnormal oral behaviour before weaning and 42 foals developed abnormal oral behaviour after weaning. The development of abnormal oral behaviour was associated with suckling behaviour in a variety of ways. Foals that had already developed abnormal oral behaviour at the time of the preweaning observations were involved in more suckling terminations within bouts than normal foals or foals that developed future abnormal behaviour, and pushing the udder with the muzzle was most frequent in these foals. Foals that had no current abnormal oral behaviour, but that would develop this in the future, spent more time suckling and twice as much time teat nuzzling as other foals. The results add to the growing evidence of associations between digestive function and abnormal oral behaviour in horses.
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Earley, R. L., Druen, M., & Alan Dugatkin, L. (2005). Watching fights does not alter a bystander's response towards naive conspecifics in male green swordtail fish, Xiphophorus helleri. Anim. Behav., 69(5), 1139–1145.
Abstract: Bystanders are capable of extracting cues from signalling interactions between others and appear to use information gained via eavesdropping when confronted with the watched individuals. A question that has gained little attention is whether observing fights affects bystander behaviour outside the context of interacting with the watched individuals. Our aim was to determine whether watching fights elicits general changes in bystander aggression levels in Xiphophorus helleri. We manipulated the bystanders' ability to witness encounters using clear, one-way-mirror and opaque partitions. After watching (or not watching) an initial contest, the bystanders were pitted against naive conspecifics instead of the animals they had seen fight. Observing fights did not alter the bystanders' propensity to initiate aggression, escalate, or win against naive individuals, indicating that bystanders do not experience general changes in aggressive behaviour after watching a fight. Earlier work in this species, however, has shown that bystanders respond in predictable ways to individuals they have witnessed winning or losing a fight. Taken together, these data support the notion that bystanders consistently modify their behaviour towards previously watched winners or losers in response to information gained via eavesdropping. We discuss our results in light of some recent work on the behavioural and endocrinological responses triggered by watching fights and suggest that comparative approaches to understanding networking phenomena may be productive.
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