Climate change may be behind chimp attacks, say scientists

Chimpanzees have been observed attacking and killing gorillas in the wild for the first time and scientists suggested climate change could be partly to blame.

The attacks in Gabon in central Africa were believed to have been sparked by competition for food.

Relations between chimpanzees and gorillas are traditionally relaxed and they have been recorded peacefully foraging, and even having playful encounters.

But researchers witnessed two brutal and fatal mass fights as they were studying chimpanzees in the Loango National Park.

On the first occasion, with researchers 30m away, a group of 27 chimpanzees launched an attack on five gorillas. The western lowland gorillas tried to defend themselves and injured several chimpanzees.

Four adult gorillas – two silverbacks and two females – escaped but an infant was killed.

In the second battle more than two dozen chimpanzees attacked seven gorillas, again killing an infant, which was then eaten.

Researchers from Osnabruck University and the Max Planck Institute for Evolutionary Anthropology in Germany published their report in Nature. They said fruit in Gabon’s forests was not as widespread as in the past, suggesting climate change could be a factor.

But they said more research was needed to establish the cause of the outbreak of violence among the apes.

Describing the first attack Lara M. Southern, author of the study, said: ‘‘At first, we only noticed screams of chimpanzees and thought we were observing a typical encounter between individuals of neighbouring communities. But then we heard chest beats, a display characteristic for gorillas, and realised that the chimpanzees had encountered a group of five gorillas.’’

During the fights the chimpanzees used their larger numbers, breaking into smaller groups and separating the gorillas from each other.

Their behaviour showed ‘‘functional parallels and evolutionary continuities between chimpanzee violence and lethal intergroup raiding in humans,’’ the study said.