In unusual behavior, chimpanzees are killing gorillas in unprovoked attacks — rare encounters that are leaving scientists stumped, according to a new study.
For the first time, scientists observed two lethal encounters between the species at the Loango National Park in Gabon, and they documented their findings in the journal Nature published on Monday.
The first incident happened in December 2019, when more than two dozen chimpanzees attacked five gorillas. The fight left behind an infant gorilla who wasn’t able to survive.
“At first, we only noticed screams of chimpanzees and thought we were observing a typical encounter between individuals of neighboring chimpanzee communities,” said Lara M. Southern, the study’s lead author, in a statement. “But then, we heard chest beats, a display characteristic for gorillas, and realized that the chimpanzees had encountered a group of five gorillas.”
Another attack happened in February 2019, according to researchers, which also resulted in the death of an infant gorilla. This time, the infant “was almost entirely consumed by one adult chimpanzee female,” the study said.
The Osnabrück University and the Max Planck Institute for Evolutionary Anthropology researchers from Germany said the two species are typically not violent toward each other, despite sometimes being territorial and aggressive.
However, most of the fights that go on in their animal kingdom is between their own kind.
“Interactions between chimpanzees and gorillas have so far been considered as relatively relaxed,” said Simone Pika, a cognitive biologist, in a statement.
“We have regularly observed both species interacting peacefully in foraging trees. Our colleagues from Congo even witnessed playful interactions between the two great ape species.”
The researchers say they need to conduct more studies to determine why these fights occurred. Some hypothesize that the behavior could stem from competition for food or the decline in the rainforest’s productivity due to climate change, according to the statement.
“Our observations provide the first evidence that the presence of chimpanzees can have a lethal impact on gorillas. We now want to investigate the factors triggering these surprisingly aggressive interactions,” said Tobias Deschner, a primatologist, in a statement.
Story cited here.