Chimps documented attacking and killing gorillas in the wild for the first time: study
Scientists have documented what appear to be the first-ever lethal chimpanzee attacks against gorillas, according to a new study.
Researchers at Osnabrück University and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, were shocked to observe the attacks firsthand in the wild in Loango National Park in Gabon.
The team was there to study and analyze the behavior of 45 chimpanzees as part of the Loango Chimpanzee Project. They are focusing on the chimps’ group composition, social relationships, interactions with neighboring groups, hunting behavior, tool use and communicative skills, the researchers said.
“Interactions between chimpanzees and gorillas have so far been considered as relatively relaxed,” said study co-author Simone Pika of the Institute of Cognitive Science, Comparative BioCognition, University of Osnabrück, 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.”
But that’s not what they saw on two 2019 research trips.
“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, Ph.D. student and first author of the study, 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.”
It went downhill from there. In two encounters, lasting 52 and 79 minutes, the chimps formed coalitions to attack the gorillas, the researchers’ statement said.
The conflict in February 2019 involved 18 chimpanzees and five gorillas — one silverback, three adult females and one infant, according to Science Alert — and lasted 52 minutes. The chimps came upon the gorillas while returning from an excursion into neighboring territories.
The second interaction, which took place in December 2019, involved 27 chimpanzees, some of them involved in the first incident. This time there were seven gorillas (one silverback, three adult females, one juvenile and two infants), and the encounter lasted 79 minutes. This time, the chimps found the gorillas at the start of a territory border patrol, Science Alert said.
“The two silverbacks of the two groups and the adult females defended themselves and their offspring,” the researchers’ statement said. “While both silverbacks and several adult females escaped, two gorilla infants were separated from their mothers and killed.”
In each confrontation the chimps separated an infant gorilla from its mother and killed it, and in the December fight the chimps ate the baby gorilla. The other gorillas escaped, and some chimps were injured, the researchers said in the study, published Monday in the journal Nature.
The researchers are now trying to sort out what might have caused the chimps to be so aggressive. It could have been that the chimps saw their fellow primates as prey, or were confronting them over territory, or that habitat degradation leading to decreased food sources could have pushed them over the edge, the researchers surmised.
“It could be that sharing of food resources by chimpanzees, gorillas and forest elephants in the Loango National Park results in increased competition and sometimes even in lethal interactions between the two great ape species,” study co-author Tobias Deschner posited.
