Causes, mechanisms, and consequences of contest competition among female mountain gorillas in Rwanda

Cyril Grueter, A.M. Robbins, D. Abavandimwe, V. Vecellio, F. Ndagijimana, S. Ortmann, T.S. Stoinski, M.M. Robbins

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    9 Citations (Scopus)

    Abstract

    © 2015 The Author.Socioecological models predict that contest competition will arise when high quality foods can be usurped or monopolized, leading to more favorable energy balances and higher reproductive success for high-ranking females. Gorillas are interesting species for studying such predictions due to the variety of ecological conditions that they experience in different locations. Using data from 23 female mountain gorillas in 3 social groups in the Virunga Massif, we examined food characteristics that may influence contest competition (food site residence times [FSRT]), proximate mechanisms of such competition (aggression and avoidance), and potential consequences of competition (rank-related differences in energy intake rates, travel expenditures, and activity budgets). The average FSRT of each female was significantly correlated with dominance rank, which suggests that high-ranking females may have greater access to foods that are easier to usurp (as predicted with contest competition). High-ranking females were significantly more aggressive than low-ranking females, and both aggression and avoidance were significantly higher while feeding than during other activities. Contrary to predictions for contest competition, however, rank was not significantly correlated with energy intake rates nor with the proportion of time spent traveling versus feeding. Thus, we did not find any energetic benefits to explain why high-ranking females had significantly higher reproductive success in earlier studies. We propose several alternative explanations and discuss the potential complications of assessing contest competition in species with weak dominance relationships.
    Original languageEnglish
    Pages (from-to)766-776
    JournalBehavioral Ecology
    Volume27
    Issue number3
    DOIs
    Publication statusPublished - 2015

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    contest competition
    Rwanda
    Gorilla
    mountains
    ranking
    mountain
    food
    aggression
    reproductive success
    residence time
    energy intake
    prediction
    food quality
    activity pattern
    travel
    energy balance
    energy
    expenditure
    energetics

    Cite this

    Grueter, C., Robbins, A. M., Abavandimwe, D., Vecellio, V., Ndagijimana, F., Ortmann, S., ... Robbins, M. M. (2015). Causes, mechanisms, and consequences of contest competition among female mountain gorillas in Rwanda. Behavioral Ecology, 27(3), 766-776. https://doi.org/10.1093/beheco/arv212
    Grueter, Cyril ; Robbins, A.M. ; Abavandimwe, D. ; Vecellio, V. ; Ndagijimana, F. ; Ortmann, S. ; Stoinski, T.S. ; Robbins, M.M. / Causes, mechanisms, and consequences of contest competition among female mountain gorillas in Rwanda. In: Behavioral Ecology. 2015 ; Vol. 27, No. 3. pp. 766-776.
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    abstract = "{\circledC} 2015 The Author.Socioecological models predict that contest competition will arise when high quality foods can be usurped or monopolized, leading to more favorable energy balances and higher reproductive success for high-ranking females. Gorillas are interesting species for studying such predictions due to the variety of ecological conditions that they experience in different locations. Using data from 23 female mountain gorillas in 3 social groups in the Virunga Massif, we examined food characteristics that may influence contest competition (food site residence times [FSRT]), proximate mechanisms of such competition (aggression and avoidance), and potential consequences of competition (rank-related differences in energy intake rates, travel expenditures, and activity budgets). The average FSRT of each female was significantly correlated with dominance rank, which suggests that high-ranking females may have greater access to foods that are easier to usurp (as predicted with contest competition). High-ranking females were significantly more aggressive than low-ranking females, and both aggression and avoidance were significantly higher while feeding than during other activities. Contrary to predictions for contest competition, however, rank was not significantly correlated with energy intake rates nor with the proportion of time spent traveling versus feeding. Thus, we did not find any energetic benefits to explain why high-ranking females had significantly higher reproductive success in earlier studies. We propose several alternative explanations and discuss the potential complications of assessing contest competition in species with weak dominance relationships.",
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    Grueter, C, Robbins, AM, Abavandimwe, D, Vecellio, V, Ndagijimana, F, Ortmann, S, Stoinski, TS & Robbins, MM 2015, 'Causes, mechanisms, and consequences of contest competition among female mountain gorillas in Rwanda' Behavioral Ecology, vol. 27, no. 3, pp. 766-776. https://doi.org/10.1093/beheco/arv212

    Causes, mechanisms, and consequences of contest competition among female mountain gorillas in Rwanda. / Grueter, Cyril; Robbins, A.M.; Abavandimwe, D.; Vecellio, V.; Ndagijimana, F.; Ortmann, S.; Stoinski, T.S.; Robbins, M.M.

    In: Behavioral Ecology, Vol. 27, No. 3, 2015, p. 766-776.

    Research output: Contribution to journalArticle

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    T1 - Causes, mechanisms, and consequences of contest competition among female mountain gorillas in Rwanda

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    AU - Robbins, A.M.

    AU - Abavandimwe, D.

    AU - Vecellio, V.

    AU - Ndagijimana, F.

    AU - Ortmann, S.

    AU - Stoinski, T.S.

    AU - Robbins, M.M.

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    AB - © 2015 The Author.Socioecological models predict that contest competition will arise when high quality foods can be usurped or monopolized, leading to more favorable energy balances and higher reproductive success for high-ranking females. Gorillas are interesting species for studying such predictions due to the variety of ecological conditions that they experience in different locations. Using data from 23 female mountain gorillas in 3 social groups in the Virunga Massif, we examined food characteristics that may influence contest competition (food site residence times [FSRT]), proximate mechanisms of such competition (aggression and avoidance), and potential consequences of competition (rank-related differences in energy intake rates, travel expenditures, and activity budgets). The average FSRT of each female was significantly correlated with dominance rank, which suggests that high-ranking females may have greater access to foods that are easier to usurp (as predicted with contest competition). High-ranking females were significantly more aggressive than low-ranking females, and both aggression and avoidance were significantly higher while feeding than during other activities. Contrary to predictions for contest competition, however, rank was not significantly correlated with energy intake rates nor with the proportion of time spent traveling versus feeding. Thus, we did not find any energetic benefits to explain why high-ranking females had significantly higher reproductive success in earlier studies. We propose several alternative explanations and discuss the potential complications of assessing contest competition in species with weak dominance relationships.

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    ER -