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Brunner, D., Kacelnik, A., & Gibbon, J. (1992). Optimal foraging and timing processes in the starling, Sturnus vulgaris: effect of inter-capture interval. Anim. Behav., 44(4), 597–613.
Abstract: Laboratory experiments with starlings, Sturnus vulgaris, were conducted to investigate the interaction between timing and cost-benefit considerations. The design simulated an environment in which food was distributed in patches. Patches contained a random number of food items (N=0-4) separated by a fixed inter-capture interval or fixed interval. All patches ended with sudden depletion. The time elapsed since the last prey capture was the only way to detect the depletion of the patch. Once the patch was depleted a new patch could be reached by travelling between two perches. Three measures of timing were taken: (1) rate of working for food as function of `waiting' time in a patch, (2) the time of the last response in a patch or `giving-in' time, and (3) the time at which travel was initiated or `moving-on' time. The fixed interval that characterized patches was varied between conditions. The mean time of the peak in working rate was consistently centred around the fixed interval, while the other two measures of timing kept a roughly linear relation to the fixed interval, with slope greater than one. In accordance with Scalar Expectancy Theory, variability in the three forms of timing was proportional to the magnitude of the fixed interval. The birds seemed to take account of this increase in variability as shown by the mean value of their giving-up criterion. These results imply that information-processing constraints are important for modelling behavioural optimality.
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Caraco, T., Kacelnik, A., Mesnick, N., & Smulewitz, M. (1992). Short-term rate maximization when rewards and delays covary. Anim. Behav., 44(Part 3), 441–447.
Abstract: In nature foragers must exploit resources that vary randomly in both the energy acquired per item (reward) and the time required to pursue, capture and process an item (delay). Furthermore, rewards and delays associated with particular resources may often covary significantly. An analytical model asks how variance-covariance levels for rewards and delays could influence choice of resources when lack of information or cognitive limitation implies that a consumer attempts to maximize its short-term rate of energy gain. Both greater expected reward and reduced expected delay clearly should enhance preference for a resource. The model predicts that increased delay variance and reduced reward-delay covariance should increase a forager's preference for a resource. A forager should be risk-averse towards reward variance when the reward-delay covariance is positive, but should become risk-prone towards reward variance when the reward-delay covariance is negative.
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Kacelnik, A., & Todd, I. A. (1992). Psychological mechanisms and the Marginal Value Theorem: effect of variability in travel time on patch exploitation. Anim. Behav., 43(2), 313–322.
Abstract: The Marginal Value Theorem (MVT) describes the behaviour that maximizes the ratio of expected gain over expected foraging time in a patchy environment. When travel time is variable, the MVT rationale and its predictions are sensitive only to the mean travel time and not to the spread or skew of the distribution. Two mechanistic arguments contradict these predictions. First, tests of the MVT have previously shown that there is a disproportionate influence of the last travel time, and second, psychological models of information processing suggest that memory for time intervals is strongly dependent on the scatter of the distribution experienced. These mechanistic concepts, combined with Jensen's inequality, suggest that patch exploitation should decrease as the scatter of the travel distribution increases. In a Skinner box experiment with pigeons, Columba livia, the problem was examined by simulating three environments with identical patches and the same mean travel time, but different travel time variability. Patch exploitation decreased with increasing variance in travel time. The results are used to argue in favour of the inclusion of realistic psychological properties as constraints in functional models of behaviour. Although both the MVT and the mechanistic models account for some features of the results, none of them can explain all the findings.
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Smith-Funk, E. D., & Crowell-Davis, S. L. (1992). Maternal behavior of draft mares (Equus caballus) with mule foals (Equus asinus x Equus caballus). Appl. Anim. Behav. Sci., 33(2-3), 93–119.
Abstract: Draft mares and their mule foals were observed from the day of birth to Week 17 of each foal's life. The rate of nursing was recorded and the duration of nursing activity to the nearest second. The rate at which foals engaged in nursing activity varied at each age. The duration of nursing bouts varied slightly as the foals matured. Aggression was recorded during both nursing and non-nursing activity for both the mares and foals. Maternal aggression was highest during nursing activity, especially during the pre-nurse nuzzling period. Maternal aggression increased as the foals matured. Mother-directed foal aggression was primarily in response to maternal aggression. Spatial relationships between each focal dyad were recorded when the foals were upright, not nursing and when they were recumbent. Spatial relationships differed based on the foal's state. The activity in which the mare engaged while her foal was recumbent was recorded. The movements of the mares were also recorded during foal recumbency. Mares approached or maintained their distance from their recumbent foal more than they left their recumbent foal in all weeks of the study, except Week 2.
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Povinelli DJ, Nelson KE, & Boysen ST. (1992). Comprehension of role reversal in chimpanzees: evidence of empathy? Anim. Behav., 43, 633.
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Aureli, F., Cossolino, R., Cordischi, C., & Scucchi, S. (1992). Kin-oriented redirection among Japanese macaques: an expression of a revenge system? Anim. Behav., 44(2), 283–291.
Abstract: The ability to recognize the close associates of other group members may permit the display of redirected aggression against the relatives of the former aggressor. However, the dominance structure and the kin-based alliance system of macaque society are expected not to favour the occurrence of this kin-oriented redirection. Nevertheless, within 1 h of being the victim of an attack, Japanese macaques, Macaca fuscata, were more likely to attack the former aggressor's kin than without such a conflict. The conditions under which the victim redirected against the former aggressor's kin were investigated. This kin-oriented redirection did not occur preferentially either after conflicts between individuals with unstable and/or uncertain dominance relationships or after conflicts with individuals that were unlikely to intervene in favour of their kin. Victims redirected against individuals that were younger than the former aggressor and often subordinate to the victim. They also redirected in an opportunistic way by joining polyadic interactions against the former aggressor's kin. The possibility that this kin-oriented redirection may have a long-term function in changing the aggressive attitude of the aggressor towards the victim is also discussed. In addition, the victim's kin also displayed a form of kin-oriented redirection. They were more likely to attack the kin of an individual after it had attacked their own kin.
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Manson, J. H. (1992). Measuring female mate choice in Cayo Santiago rhesus macaques. Anim. Behav., 44, 405–416.
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.
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Lamprecht, J. (1992). Variable Leadership in Bar-Headed Geese (Anser Indicus) : an Analysis of Pair and Family Departures. Behaviour, 122(1-2), 105–119.
Abstract: This paper reports quantitative leadership differences in semi-captive bar-headed geese (Anser indicus) at different times of the year, and in different types of groups. Leading is defined here as causing the departure or determining the direction of movement of the whole group. No permanent and exclusive leader of a pair or family group was found, rather relative leading frequencies of male, female and young showed a definite shifting pattern. Females led more often than their mates prior to breeding, and on nest pauses during the incubation period, but less often in summer, autumn and early winter. In families there was no difference between the frequencies of male and female leading. Family females led relatively more often than those of pairs without offspring. This difference was related to the presence, not the number, of young. Goslings led the family about as often as the parents during the rearing period in early summer, less often in autumn, winter and next spring. Such differences and changes are to be expected where competence in particular tasks and dependence on partners vary between group members, and where different situations require different abilities. For the geese, the results can be related to the different options of group members and to the different benefits they derive from leaving (or 'staying put') or following (or waiting for the others) in different situations.
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Rutberg, A. T., & Keiper, R. R. (1993). Proximate causes of natal dispersal in feral ponies: some sex differences. Anim. Behav., 46(5), 969–975.
Abstract: Abstract. Fifteen years of data on natal dispersal age and the context of dispersal for the feral ponies of Assateague Island, Maryland are presented. Ninety-seven per cent of males and 81% of females dispersed from their natal groups by 5 years of age. For animals that left their natal group, average age of dispersal was 20[middle dot]8 months for males and 24[middle dot]6 months for females. Male dispersal age was strongly and significantly correlated with number of peers in the natal group, and males dispersing with peers were significantly older than males dispersing without peers, suggesting that males delayed dispersal when peers were available for interaction. Female dispersal age was not influenced by number of peers, but was correlated with age of first reproduction. Factors not influencing dispersal age in either sex were presence of a younger sibling, maternal band transfers, and maternal age and dominance rank. The relatively high frequency of females failing to disperse from their natal groups is puzzling in light of data showing diminished fecundity in non-dispersing pony mares.
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Chalmeau, R., & Gallo, A. (1993). Social constraints determine what is learned in the chimpanzee. Behav. Process., 28(3), 173–179.
Abstract: A group of six chimpanzees was placed in a social learning situation, without training. The learning task was an operant conditioning situation; that is, a subject had to pull two handles simultaneously to cause a piece of fruit to fall into the cage. Only three individuals acquired the operant behaviour. For the operant individuals, social influences on the expression of the learning task were then examined; the dominant chimpanzee during feeding had an inhibiting effect when close to the operant subjects. Depending on the subject, social factors may influence not only the specific expression of what is learnt, but also the nature of what is learnt. Chimpanzees appear to experience situations differently: they develop an individual problem-solving strategy according to their social relationships even if the experimental procedure is the same for all.
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