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Observations of severe and lethal coalitionary attacks in wild mountain gorillas

In humans and chimpanzees, most intraspecific killing occurs during coalitionary intergroup conflict. In the closely related genus Gorilla, such behavior has not been described. We report three cases of multi-male, multi-female wild mountain gorilla (G. beringei) groups attacking extra-group males....

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Autores principales: Rosenbaum, Stacy, Vecellio, Veronica, Stoinski, Tara
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5111119/
https://www.ncbi.nlm.nih.gov/pubmed/27849056
http://dx.doi.org/10.1038/srep37018
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author Rosenbaum, Stacy
Vecellio, Veronica
Stoinski, Tara
author_facet Rosenbaum, Stacy
Vecellio, Veronica
Stoinski, Tara
author_sort Rosenbaum, Stacy
collection PubMed
description In humans and chimpanzees, most intraspecific killing occurs during coalitionary intergroup conflict. In the closely related genus Gorilla, such behavior has not been described. We report three cases of multi-male, multi-female wild mountain gorilla (G. beringei) groups attacking extra-group males. The behavior was strikingly similar to reports in chimpanzees, but was never observed in gorillas until after a demographic transition left ~25% of the population living in large social groups with multiple (3+) males. Resource competition is generally considered a motivator of great apes’ (including humans) violent intergroup conflict, but mountain gorillas are non-territorial herbivores with low feeding competition. While adult male gorillas have a defensible resource (i.e. females) and nursing/pregnant females are likely motivated to drive off potentially infanticidal intruders, the participation of others (e.g. juveniles, sub-adults, cycling females) is harder to explain. We speculate that the potential for severe group disruption when current alpha males are severely injured or killed may provide sufficient motivation when the costs to participants are low. These observations suggest that the gorilla population’s recent increase in multi-male groups facilitated the emergence of such behavior, and indicates social structure is a key predictor of coalitionary aggression even in the absence of meaningful resource stress.
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spelling pubmed-51111192016-11-23 Observations of severe and lethal coalitionary attacks in wild mountain gorillas Rosenbaum, Stacy Vecellio, Veronica Stoinski, Tara Sci Rep Article In humans and chimpanzees, most intraspecific killing occurs during coalitionary intergroup conflict. In the closely related genus Gorilla, such behavior has not been described. We report three cases of multi-male, multi-female wild mountain gorilla (G. beringei) groups attacking extra-group males. The behavior was strikingly similar to reports in chimpanzees, but was never observed in gorillas until after a demographic transition left ~25% of the population living in large social groups with multiple (3+) males. Resource competition is generally considered a motivator of great apes’ (including humans) violent intergroup conflict, but mountain gorillas are non-territorial herbivores with low feeding competition. While adult male gorillas have a defensible resource (i.e. females) and nursing/pregnant females are likely motivated to drive off potentially infanticidal intruders, the participation of others (e.g. juveniles, sub-adults, cycling females) is harder to explain. We speculate that the potential for severe group disruption when current alpha males are severely injured or killed may provide sufficient motivation when the costs to participants are low. These observations suggest that the gorilla population’s recent increase in multi-male groups facilitated the emergence of such behavior, and indicates social structure is a key predictor of coalitionary aggression even in the absence of meaningful resource stress. Nature Publishing Group 2016-11-16 /pmc/articles/PMC5111119/ /pubmed/27849056 http://dx.doi.org/10.1038/srep37018 Text en Copyright © 2016, The Author(s) http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Article
Rosenbaum, Stacy
Vecellio, Veronica
Stoinski, Tara
Observations of severe and lethal coalitionary attacks in wild mountain gorillas
title Observations of severe and lethal coalitionary attacks in wild mountain gorillas
title_full Observations of severe and lethal coalitionary attacks in wild mountain gorillas
title_fullStr Observations of severe and lethal coalitionary attacks in wild mountain gorillas
title_full_unstemmed Observations of severe and lethal coalitionary attacks in wild mountain gorillas
title_short Observations of severe and lethal coalitionary attacks in wild mountain gorillas
title_sort observations of severe and lethal coalitionary attacks in wild mountain gorillas
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5111119/
https://www.ncbi.nlm.nih.gov/pubmed/27849056
http://dx.doi.org/10.1038/srep37018
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