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

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lara M. Southern ◽  
Tobias Deschner ◽  
Simone Pika
Keyword(s):  
Pan Troglodytes ◽  
Gorilla Gorilla ◽  
Interspecies Interactions ◽  
Intraspecific Interactions ◽  
Gorilla Gorilla Gorilla ◽  
Research Attention ◽  
Lethal Violence ◽  
Pan Troglodytes Troglodytes ◽  
In The Wild ◽  
Interspecific Killing

AbstractIntraspecies 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.

Colour preferences in relation to diet in chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla), and mandrills (Mandrillus sphinx)

2021 ◽  
Author(s):  
M. Carmen Hernández ◽  
Sandra González-Campos ◽  
Isabel Barja
Keyword(s):  
Color Vision ◽  
Pan Troglodytes ◽  
Gorilla Gorilla ◽  
Black And White ◽  
Mandrillus Sphinx ◽  
In The Wild ◽  
Sampling Intervals ◽  
Colour Preferences ◽  
Two Phases ◽  
Zero Group

Although trichromatic color vision has been extensively studied as it grants significant advantages for Old World primates, it is unknown which selective pressures were behind trait’s evolution. The leading hypothesis would be that colour vision arose as a foraging adaptation because it allowed individuals to spot food more efficiently. To test this, we exposed three chimpanzees (Pan troglodytes), five gorillas (Gorilla gorilla) and three mandrills (Mandrillus sphinx) to colour cardboard plates to assess if colours related to diet were the most preferred. Experimental setting was divided in two phases. During the first one, animals were provided with colour cardboard plates of only one colour per data collection session. The order of colour presentation was randomly determined: white, black, yellow, green and red. In phase two, primates were simultaneously provided with cardboard plates of all colours. Behavioural interactions with plates were measured using a one-zero group focal sampling (10 s sampling intervals and 20 m observation periods). Results showed that when animals were exposed to only one colour at a time, they exhibited different colour preferences depending on the species considered. Chimpanzees preferred red and yellow, the colours linked to fruits, while gorillas selected red and white. Mandrills exhibited fewer differences between colours preference, being red the most selected. Furthermore, when all colours were simultaneously provided, individuals chose colours related to diet over black and white. Although there were clear individual differences, our results support that trichromatic color vision is an advantage in detecting and selecting red items. In the wild, it could be important in the detection of reddish fruits and leaves.

Sign in / Sign up

Export Citation Format

Share Document