In the first observed incident of its kind, a group of chimpanzees killing gorillas and even devouring an infant was observed in the forests of Gabon. The attack was unprovoked and chimps and gorillas have earlier been observed co-existing peacefully.
Researchers are stunned at the aggressive behavior of the group and said more studies were needed to determine the cause of this deviance from normal primate behavior.
The lethal encounter between the two species was observed in Gabon’s Loango National Park. The scientists released their observations in Nature, which was published this week.
The first confrontation was observed in December 2019. A group of over 2 dozen chimps attacked a family of 5 gorillas. The gorillas were forced to abandon an infant which was killed.
Lara Southern, the lead author of the study said that they had at first mistaken the incident to be a normal encounter between two warring groups of chimpanzees. But the sound of chest beatings alerted them that one of the groups involved in the fight was a small group of gorillas. Another incident of chimpanzees killing gorillas was observed in February 2019 when an infant was killed and devoured almost entirely by just one adult female chimpanzee.
These two encounters are the first recorded incidents of chimpanzees killing gorillas. Researchers from the Max Planck Institute For Evolutionary Anthropology and the Osnabruck University, Germany, said that these species normally do not attack each other though they are fiercely aggressive and territorial.
Most fights in the animal kingdom usually take place between members of the same species. Cognitive biologist Simone Pika says that gorillas and chimpanzees have thus far been observed to be relatively relaxed in their interactions.
They have been previously observed peacefully foraging from the same tree. They have even been observed interacting playfully in the forests of Congo.
Predation And Competition Suspected To Be Reason Behind Chimpanzees Killing Gorillas
Researchers are at a loss to determine the cause of such aggressive behavior and said that more studies are needed to conclude.
Some researchers suggested that their unusual behavior could be linked to a scarcity of food and a decline in productivity in the forests aggravated by climate change.
Primatologist Tobias Deschner said that their observation was the first record evidence of chimpanzees killing gorillas. It is evident that the occurrence of a large number of chimps can trigger a lethal reaction towards gorillas. The most likely explanation say scientists was competition for food and space, both at a premium as forests around the world are cut down for human use.
Gorillas as a species are genetically distant from chimpanzees and humans. They are believed to have evolved separately from a common ancestor around 8 million years ago.
Gorillas live in unified social groups consisting of one or even more male adults, females, and their infants.
Chimpanzees range across central and eastern Africa and their interaction can be marked even sympathetic in some areas.
In both incidents of chimpanzees killing gorillas, the gorillas were outnumbered by a large group of chimpanzees. The second attack took place only when the silverback abandoned the group. While the victims in both the events were infant gorillas, it was only during the second incident that the infant was consumed by the chimpanzees.
One explanation is that the incidents of chimpanzees killing gorillas was a specific case of hunting with the infant gorillas being targeted as prey. The other explanation is that these two events were examples of interspecific competition between the gorillas and chimpanzees. While earlier observations have been observed to be peaceful, the encounters took place during periods when food was scarce and competition fierce.