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Fritz, J., Bisenberger, A., & Kotrschal, K. (2000). Stimulus enhancement in greylag geese: socially mediated learning of an operant task. Animal Behaviour, 59(6), 1119–1125.
Abstract: We recently observed the spreading of a novel tradition in a flock of semiferal greylag geese, Anser anser: an increasing number of individuals began to bite and chew the stems of butterbur, Petasites hybridus. Because this behaviour spread particularly fast within families, social learning seemed to be involved. We therefore designed an experiment with hand-reared goslings, which were socially imprinted on humans, to investigate whether and how the observation of an experienced tutor affects the acquisition of a novel skill. Goslings had to open the gliding lid of a box to get at a food reward. To each of seven hand-reared observers a human tutor demonstrated where and how to open the lid, whereas seven controls remained untutored. All observers learned to perform the task but only one of the controls succeeded. The observers explored more often at the position shown by the tutor than elsewhere and seemingly learned by trial and error. In contrast, control birds explored primarily at positions that did not allow them to open the box. These results indicate that in greylag goslings the observation of an experienced model facilitates the learning of an operant task. We conclude that stimulus enhancement followed by operant conditioning were the mechanisms involved, which may have accounted for the fast spread of the stem-chewing tradition between family members.
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McComb, K., Moss, C., Sayialel, S., & Baker, L. (2000). Unusually extensive networks of vocal recognition in African elephants. Anim Behav, 59.
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Baker, P. J., Funk, S. M., Harris, S., & White, P. C. L. (2000). Flexible spatial organization of urban foxes, Vulpes vulpes, before and during an outbreak of sarcoptic mange. Anim. Behav., 59(1), 127–146.
Abstract: The social and spatial organization of urban fox groups prior to and during an outbreak of sarcoptic mange was compared with predictions derived from the resource dispersion hypothesis (RDH). We investigated the availability of three key resources. Neither daytime rest sites nor breeding sites appeared to be limited in availability. The availability of food deliberately supplied by local householders was examined by questionnaire surveys. The daily and weekly amount of food supplied was greatly in excess of the minimum requirements of a pair of foxes, but was consistent between territories. The availability of this food source increased markedly as a result of more people feeding the foxes. In agreement with the RDH, group size prior to the outbreak of mange increased from 2.25 animals (N=4) to 6.57 animals (N=7). Before the outbreak of mange, two territories were divided. Increased scavenge availability on smaller territories may have promoted these changes. Excluding these spatial changes, territories were very stable between years. After the outbreak of mange, group size declined as a direct result of mange-induced mortality. Surviving animals increased their ranges only after neighbouring groups had died out. Ranges did not increase in size in response to a decline in food availability. Nor were the increases in range size associated with the relinquishment of parts of the existing territory. These postmange changes are contrary to the RDH. Three factors may have promoted these changes: the elimination of interstitial space, the forced dispersal of young or future division of the territory.
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Mendres, K. A., & de Waal, F. B. M. (2000). Capuchins do cooperate: the advantage of an intuitive task. Anim. Behav., 60(4), 523–529.
Abstract: We used a cooperative pulling task to examine proximate aspects of cooperation in captive brown capuchin monkeys, Cebus apella. Specifically, our goal was to determine whether capuchins can learn the contingency between their partner's participation in a task and its successful completion. We examined whether the monkeys visually monitored their partners and adjusted pulling behaviour according to their partner's presence. Results on five same-sex pairs of adults indicate that (1) elimination of visual contact between partners significantly decreased success, (2) subjects glanced at their partners significantly more in cooperative tests than in control tests in which no partner-assistance was needed, and (3) they pulled at significantly higher rates when their partner was present rather than absent. Therefore, in contrast to a previous report by Chalmeau et al. (1997, Animal Behaviour, 54, 1215-1225), cooperating capuchins do seem able to take the role of their partner into account. However, the type of task used may be an important factor affecting the level of coordination achieved. Copyright 2000 The Association for the Study of Animal Behaviour.
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de Waal, F. B. M. (2000). Attitudinal reciprocity in food sharing among brown capuchin monkeys. Anim. Behav., 60(2), 253–261.
Abstract: Capuchin monkeys (Cebus apella) share food even if separated by a mesh restraint. Pairs of capuchins were moved into a test chamber in which one of them received apple pieces for 20 min, and the other received carrot pieces for the next 20 min. Previous research had shown a correlation between the rate of food transfer in both directions across female-female dyads. The present study confirmed this result. Reciprocity across dyads can be explained, however, by symmetry in affiliative and tolerant tendencies between two individuals, provided these tendencies determine food sharing. The present study was designed to exclude this symmetry-based explanation by testing each pair (N=16) of adult females on six separate occasions. There existed a significant covariation across tests of sharing in both dyadic directions, a result unexplained by relationship symmetry. Moreover, control procedures (i.e. testing of a food possessor without a partner, or testing of two individuals with the same food or two different foods at the same time) indicated that behaviour during food trials is not fully explained by mutual attraction or aversion. The monkeys take the quality of their own and the partner's food into account, and possessors limit transfers of high-quality foods. Instead of a symmetry-based reciprocity explanation, a mediating role of memory is suggested, and a mirroring of social attitude between partners. Copyright 2000 The Association for the Study of Animal Behaviour.
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Linklater, W. L., & Cameron, E. Z. (2000). Tests for cooperative behaviour between stallions. Anim. Behav., 60(6), 731–743.
Abstract: Breeding groups with multiple stallions occur sympatrically with single-stallion breeding groups in feral horse, Equus caballus, populations. Mutualism and reciprocal altruism between stallions have been proposed to explain the origin and functioning of multistallion bands. However, empirical support for these hypotheses is contradictory and incomplete. Furthermore, there are no explicit tests of the predictions that each hypothesis makes about stallion behaviour and social structure. We compared nine multistallion and 18 single-stallion bands in the Kaimanawa Ranges, New Zealand. Compared with agonistic behaviours, affiliative behaviours were relatively unimportant in the relationships between stallions within bands. The number of stallions in the band did not have a positive influence on mare group size, stability, home range quality or reproductive success in bands. Furthermore, there was a positive relationship between aggression ('intolerance') by the dominant towards subordinate stallions and the subordinates' effort in mare group defence ('helping') but a negative relationship between helping effort by subordinates and their proximity to, and mating with, the bands' mares. Therefore, the predictions of the mutualism and reciprocal altruism hypotheses were not supported. Indeed, for some of the predictions we found the opposite outcomes to be true. Multistallion bands had significantly poorer reproductive success, and dominant stallions were less tolerant of subordinates that helped most and reduced their access to mares. Nevertheless, in all other respects Kaimanawa stallions in multistallion bands behaved like those described elsewhere. Thus, we reject cooperative hypotheses for multimale breeding groups in horses and discuss the mate parasitism and consort hypotheses as better alternatives. Copyright 2000 The Association for the Study of Animal Behaviour.
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Cameron EZ, L. W. L. (2000). Individual mares bias investment in sons and daughters in relation to their condition. Anim. Behav., 60(3), 359–367.
Abstract: The Trivers-Willard hypothesis (TWH) predicts that a mother will treat a son or daughter differently depending on her ability to invest and the impact of her investment on offspring reproductive success. Although many studies have investigated the hypothesis, few have definitively supported or refuted it because of confounding factors or an inappropriate level of analysis. We studied maternal investment in sons and daughters in feral horses, Equus caballus, which meet the assumptions of the TWH with a minimum of confounding variables. Population level analyses revealed no differences in maternal behaviour towards sons and daughters. When we incorporated mare condition, we found that sons were more costly to mares in good condition, whereas daughters were more costly to mares in poor condition, although no differences in maternal behaviour were found. However, since the TWH makes predictions about individual mothers, we examined investment by mares who reared both a son and a daughter in different years of the study. Mares in good condition invested more in their sons in terms of maternal care patterns, costs to maternal body condition and costs to future reproduction. Conversely, mares in poor condition invested more in daughters. Therefore, with an appropriate level of analysis in a species in which confounding variables are minimal, the predictions of the Trivers-Willard hypothesis are supported. Copyright 2000 The Association for the Study of Animal Behaviour.
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Goncalves, D. M., Oliveira, R. F., Korner, K., Poschadel, J. R., & Schlupp, I. (2000). Using video playbacks to study visual communication in a marine fish, Salaria pavo. Anim. Behav., 60(3), 351–357.
Abstract: Video playbacks have been successfully applied to the study of visual communication in several groups of animals. However, this technique is controversial as video monitors are designed with the human visual system in mind. Differences between the visual capabilities of humans and other animals will lead to perceptually different interpretations of video images. We simultaneously presented males and females of the peacock blenny, Salaria pavo, with a live conspecific male and an online video image of the same individual. Video images failed to elicit appropriate responses. Males were aggressive towards the live male but not towards video images of the same male. Similarly, females courted only the live male and spent more time near this stimulus. In contrast, females of the gynogenetic poecilid Poecilia formosa showed an equal preference for a live and video image of a P. mexicana male, suggesting a response to live animals as strong as to video images. We discuss differences between the species that may explain their opposite reaction to video images.
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Mottley, K., & Giraldeau, L. A. (2000). Experimental evidence that group foragers can converge on predicted producer-scrounger equilibria. Anim. Behav., 60(3), 341–350.
Abstract: When foraging together, animals are often observed to feed from food discoveries of others. The producer-scrounger (PS) game predicts how frequently this phenomenon of food parasitism should occur. The game assumes: (1) at any moment all individuals can unambiguously be categorized as either playing producer (searching for undiscovered food resources) or scrounger (searching for exploitation opportunities), and (2) the payoffs received from the scrounger tactic are negatively frequency dependent; a scrounger does better than a producer when the scrounger tactic is rare, but worse when it is common. No study to date has shown that the payoffs of producer and scrounger conform to the game's assumptions or that groups of foragers reach the predicted stable equilibrium frequency (SEF) of scrounger, whereby both tactics obtain the same payoff. The current study of three captive flocks of spice finches, Lonchura punctulata, provides the first test of the PS game using an apparatus in which both assumptions of the PS game are met. The payoffs to the scrounger, measured as feeding rate (seeds/s), were highly negatively frequency dependent on the frequency of scrounger. The feeding rate for scrounger declined linearly while the rate for producer either declined only slightly or not at all with increasing scrounger frequency. When given the opportunity to alternate between tactics, the birds changed their use of each, such that the group converged on the predicted SEF of scrounger after 5-8 days of testing. Individuals in this study, therefore, demonstrated sufficient plasticity in tactic use such that the flock foraged at the SEF of scrounger. Copyright 2000 The Association for the Study of Animal Behaviour.
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Reader, S. M., & Laland, K. N. (2000). Diffusion of foraging innovations in the guppy. Anim. Behav., 60(2), 175–180.
Abstract: The way in which novel learned behaviour patterns spread through animal populations remains poorly understood, despite extensive field research and the recognition that such processes play an important role in the behavioural development, social interactions and evolution of many animal species. We conducted a series of controlled diffusions of foraging information in replicate experimental populations of the guppy, Poecilia reticulata. We presented novel foraging tasks over 15 trials to mixed-sex groups, made up of food-deprived and nonfood-deprived adults (experiment 1) or small, young fish and old, large adults (experiment 2). In these diffusions, knowledge of a route to a feeder could spread through the group by subjects learning from others, discovering the route for themselves, or, most likely, by some combination of these social and asocial learning processes. We found a striking sex difference, with novel foraging information spreading at a significantly faster rate through subgroups of females than of males. Females both discovered the goal and learned the route more quickly than males. Food-deprived individuals were faster at completing the tasks over the 15 trials than nonfood-deprived guppies, and there was a significant interaction between sex and size, with a sex difference in adults but not young individuals. There was also an interaction between sex and hunger level, with food deprivation having a stronger effect on male than female performance. We suggest that information may diffuse in a similar nonrandom or 'directed' manner through many natural populations of animals. Copyright 2000 The Association for the Study of Animal Behaviour.
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