Clutton-Brock, T. H., Green, D., Hiraiwa-Hasegawa, M., & Albon, S. D. (1988). Passing the buck: resource defence, lek breeding and mate choice in fallow deer. Behav. Ecol. Sociobiol., 23, 281–296.
Abstract: lsquoLekrsquo breeding systems, where males defend small, clustered mating territories, are thought to occur where the distribution of females is heavily clumped but males are unable to defend resources used by females. In this paper, we describe a breeding system in fallow deer where males are able to defend resources used by females but the most successful bucks instead defend small territories on a traditional mating ground; where the lek is sited in an area not heavily used by females at other times of year and is visited primarily by females in or close to oestrus; and where mating success on the lek is related to territory position and to male phenotype but not to the resources available on different lek territories. Comparisons with other ungulates suggest that lek breeding species fall into two groups: those where leks are regularly visited by herds of females many of which are not in oestrus and those, like fallow deer, where leks are visited primarily by oestrous females. In the latter species, it is unlikely that females visit the lek for ecological reasons.
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Hunte, W., & Horrocks, J. A. (1987). Kin and non-kin interventions in the aggressive disputes of vervet monkeys. Behav. Ecol. Sociobiol., 20, 257–263.
Abstract: Interventions in aggressive disputes were investigated in a free-living troop of vervets (Cercopithecus aethiops sabaeus) in Barbados. Interventions on behalf of kin were more frequent than on behalf of non-kin. Both types of interventions were more likely when the intervening animal outranked the opponent; presumably because retaliation probability, and hence cost of intervening, is low against low ranking opponents. The number of interventions given on behalf of both kin and non-kin increased with the number of disputes in which they were involved. In contrast to kin interventions, the number of interventions given on behalf of non-kin was correlated with that received by non-kin, suggesting that reciprocation is a necessary component of non-kin interventions. Non-kin interventions were more likely when the recipient outranked the opponent, presumably because reciprocation probability is high. Pairs of non-kin form structured reciprocal relationships based on the proportion of interventions allocated to each other, and most non-kin interventions flowed through these relationships. Males intervened on behalf of non-kin more frequently than did females. The implications of the results for the evolution of kin and reciprocal altruism were discussed.
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Leonard, M. L., Horn, A. G., & Eden, S. F. (1988). Parent-offspring aggression in moorhens. Behav. Ecol. Sociobiol., 23, 265–270.
Abstract: The purpose of this study was to explain parental aggression to offspring in the moorhen (Gallinula chloropus). Males and females did not feed different subsets of chicks. In addition, there was a positive correlation between feeding rates of each parent to a particular chick and the number of attacks (tousles) directed to that chick, contrary to what was expected if aggression served to divide the brood. In moorhens, large chicks outcompeted small chicks for parental feedings. However, adults were more aggressive to large chicks and as a result small chicks spent significantly more time closer to parents and received more feedings than large chicks. In 84% of broods every chick was attacked at least once, although large chicks were attacked more often than small chicks. The behaviour of chicks changed immediately after an attack (Table 2). Before an attack chicks were <1 m from the parents while after an attack they were >1 m. The apparent effect of parental aggression in moorhens is to reduce demands by chicks for feedings. Aggression appears to reduce sibling competition and to encourage chick independence.
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