Lethal coalitionary attacks of chimpanzees (Pan troglodytes troglodytes) on gorillas (Gorilla gorilla gorilla) in the wild

Lara M Southern,Tobias Deschner,Simone Pika

doi:10.1038/s41598-021-93829-x

Lara M Southern, Tobias Deschner + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-93829-x

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Abstract

Intraspecies violence, including lethal interactions, is a relatively common phenomenon in mammals. Contrarily, interspecies violence has mainly been investigated in the context of predation and received most research attention in carnivores. Here, we provide the first information of two lethal coalitionary attacks of chimpanzees (Pan troglodytes troglodytes) on another hominid species, western lowland gorillas (Gorilla gorilla gorilla), that occur sympatrically in the Loango National Park in Gabon. In both events, the chimpanzees significantly outnumbered the gorillas and victims were infant gorillas. We discuss these observations in light of the two most widely accepted theoretical explanations for interspecific lethal violence, predation and competition, and combinations of the two-intraguild predation and interspecific killing. Given these events meet conditions proposed to trigger coalitional killing of neighbours in chimpanzees, we also discuss them in light of chimpanzees’ intraspecific interactions and territorial nature. Our findings may spur further research into the complexity of interspecies interactions. In addition, they may aid in combining field data from extant models with the Pliocene hominid fossil record to better understand behavioural adaptations and interspecific killing in the hominin lineage.

Highlights

Intraspecies violence, including lethal interactions, is a relatively common phenomenon in mammals
Concerning our closest living relatives, the great apes, intraspecific killing has frequently been reported across multiple chimpanzee (Pan troglodytes) communities e.g.,5–7 and gorilla (Gorilla gorilla)[8,9,10] groups
Chimpanzees travel to the periphery of the territory to search for signs of members of other communities or may even make deep incursions into neighbouring communities involving lethal coalitionary a ttacks[13,14,15]. The latter has been associated with fission–fusion social systems and has spurred considerable research attention, suggesting functional parallels and evolutionary continuities between chimpanzee violence and lethal intergroup raiding in humans[6,16,17]

Summary

Introduction

Intraspecies violence, including lethal interactions, is a relatively common phenomenon in mammals. The majority of killings involve intercommunity rather than intracommunity attacks, and most often are made by coalitions of males during territorial boundary p atrols[5,13] During these patrols, chimpanzees travel to the periphery of the territory to search for signs of members of other communities or may even make deep incursions into neighbouring communities involving lethal coalitionary a ttacks[13,14,15]. Chimpanzees travel to the periphery of the territory to search for signs of members of other communities or may even make deep incursions into neighbouring communities involving lethal coalitionary a ttacks[13,14,15] The latter has been associated with fission–fusion social systems and has spurred considerable research attention, suggesting functional parallels and evolutionary continuities between chimpanzee violence and lethal intergroup raiding in humans[6,16,17]. On western lowland gorillas (Gorilla gorilla gorilla) suggested that groups may show high levels of territoriality and actively defend core regions of their home ranges against n eighbours[26]

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