Abstract: Pigeons that had been trained with a food reward both to peck at and to step on a horizontal plate were allowed to observe a conspecific demonstrator pecking at or stepping on the plate before a test in which the observers were not rewarded for either pecking or stepping. In experiment 1, the demonstrators were not rewarded while being observed. In spite of this, the observers provided evidence of imitation: those that had observed pecking made a greater proportion of pecking responses on test than observers of stepping. In experiment 2, each observer was exposed to a pecking or a stepping conspecific on two occasions. On one occasion, the demonstrator received a food reward for each demonstrated response (continuous reinforcement condition), and on the other the demonstrator's responses were rewarded only rarely (variable interval condition). The observers provided equally strong evidence of imitation in each of these conditions; on test, they made proportionally more of the observed response both when the demonstrators had been richly rewarded and when they had been rarely rewarded. These results show that pigeons engage in `blind' imitation, that is, their imitative behaviour is not always guided by observational learning about response outcomes.

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.

Abstract: 1. 1. The communication performance of 12 rhesus monkeys was investigated in a situation in which the rewards of both members of a pair of monkeys could not exceed chance levels unless the operator monkey responded to cues provided by the informant monkey which indicated the location of food. Each member of the pair was trained in both operator and informant roles in different phases of the experiment. Communication performance improved progressively to levels consistently above chance. However, communication learning appeared to be specific to the role in which the individual was trained, and when roles were reversed no evidence of transfer was obtained. Tests of foodsharing behaviour showed a substantial increase in the tendency to share food with the partner following communication training. This occurred however, only when the partner was the only social stimulus present; if another monkey was also present there was no evidence of preferential responses to the partner. In all phases of communication training, monkeys which were housed together performed more efficiently than did monkeys housed individually.2. 2. The acquisition of stimulus-producing responses was investigated by causing an opaque screen to remain in front of the informant unless the operator monkey pulled a vertical lever at the front of its restraining cage. Initially, operators responded immediately to the foodcarts, but with further testing there was a steady increase in the tendency to defer the response to the food-carts until the lever had been pulled, revealing the informant monkey.3. 3. Transfer of communication training was tested with new monkey informants, and with two inanimate stimuli, a mechanical puppet, and a stationary plaque. The latter two objects were placed behind the rewarded food-carts before each trial. There was clear evidence of positive transfer to each of these conditions, but marked differences among conditions were obtained. Performance with the monkeys averaged 76 per cent. correct, as compared with 62 and 40 per cent., with the puppet and the plaque, respectively.4. 4. To test the ability of trained operator monkeys to select the appropriate informant on the basis of behavioural cues, the communication situation was arranged so that two informant monkeys were present on all trials. However, on any trial only one of these informants could be rewarded, and the operator's rewards were contingent upon delivering food to this informant. Efficiency of discrimination began at approximately 45 per cent, (chance = 25 per cent. and improved progressively to levels above 75 per cent.

Abstract: Few studies of female mate choice have been carried out among free-ranging non-human primates. To qualify as female mate choice, behaviour by oestrous females must predict the occurrence or rate of potentially fertile copulations, in comparisons between heterosexual dyads. In this paper, data are presented to show three behaviour patterns that meet this criterion in free-ranging rhesus macaques, Macaca mulatta, at the island colony of Cayo Santiago: (1) selective cooperation with male sexual solicitations (hip-grasps), (2) restoration of proximity following attacks on females by intruding males, and (3) proximity maintenance (in one of two study groups). Oestrous females maintained proximity preferentially to lower ranking males, but this appeared to reflect differences in the tactics necessary to achieve copulations with males of different dominance ranks, rather than preference for lower ranking mates. Male-oestrous female dyads showed consistency over two consecutive mating seasons in which partner was responsible for proximity maintenance. Male dominance rank was positively correlated with copulatory rate with fertile females. However, in one study group, males to whom oestrous females maintained proximity more actively had higher copulatory rates with fertile females, independent of the effects of male dominance rank.

Abstract: The marginal value theorem predicts that when resources are clumped in space, a forager can maximize its rate of intake by deciding to leave a patch when its current feeding rate falls below the average for the habitat. A group version of the model predicts that when rate-maximizing group members share a patch, they should leave sooner, and each with less gain, than single animals exploiting the same patch. We tested these predictions in the laboratory by measuring patch departure decisions of spice finches, Lonchura punctulataexploiting food patches alone or in groups of three under two habitats that require different travel times. As predicted, group members left the patch sooner and with fewer seeds than single foragers. Unlike the model's assumptions, however, birds did not share the patch equally, and their exploitation curves could not be simply derived from those of single foragers. Grouping decreased the effect of travel time on patch exploitation. Moreover, within each group the bird expected to leave first delayed its departure although it collected fewer seeds than the others. This delayed departure could aim to maintain group membership. We noted an increased variability in seed number collected by group members compared with single foragers, which could be a cost of group foraging.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour