For more than 30 years, a group of researchers in collaboration with the Uganda Wildlife Authority, conducted a study on the social behaviors of chimpanzees, focusing particularly on their social structures. The chimpanzees studied were located in Ngogo within Kibale National Park in western Uganda.

In general, chimpanzees exhibit hostile intergroup relations across most or all of their geographic range, characterized by aggressive encounters between members of neighboring communities during foraging and patrols, where individuals from one community search for neighbors near territorial boundaries.

Attacks, which can sometimes be fatal, involve coalitions of adult males, targeting individuals across all age and sex classes. However, the risk of lethal intergroup coalitionary aggression is highest for adult males and infants, while it is lowest for sexually swollen females. The research indicates that this lethal aggression is driven by territorial disputes, as chimpanzees are highly territorial, as well as struggles for leadership, which extend to competition for sexual partners.

Dr. Margret Kobusigye, affiliated with the Department of Environmental Management at Makerere University and a participant in the research, states that the study examined chimpanzee behavior on a daily basis, from morning to dusk.

It revealed that the first breakup in Ngogo, a community known for having the largest number of chimpanzees in the world, occurred in 2015 due to a flu outbreak that resulted in the deaths of nearly 25 chimpanzees. This event significantly impacted the once large family, leading to some chimpanzees migrating west while others remained in the central area.

Over time, without the entire community reuniting, the chimpanzees established separate territories, including central and western regions. When a few individuals attempted to cross into another territory, they were killed, predominantly the males.

Due to the philopatric nature of male chimpanzees, which indicates that they do not migrate between communities, the research revealed that over the years, it became apparent that only females were crossing between groups, while some males remained stationary. This observation suggested that the alpha males had successfully established their territories, with Jackson claiming the central area and Younger taking control of the western region.

Younger’s attempt to venture into the Central region in search of food resulted in a confrontation that led to fatalities, thereby confirming the definitive separation of the previously united Ngogo family, which had comprised over 200 individuals, now divided into the Ngogo and Kanyawara groups.

https://www.researchgate.net/publication/7344277_Lethal_intergroup_aggression_by_chimpanzees_in_Kibale_National_Park_Uganda
 

The Chief Warden of Kibale Conservation Area, John Justine Tibesigwa, stated that following the widespread dissemination of these scientific findings, which have been referred to as a Chimpanzee Civil War and have gone viral, both local and international media, along with tourists, flocked to Kibale National Park, eager to witness the chimpanzee conflict. However, this was not the case, and instead, the opportunity was utilized to educate visitors about the social lives of chimpanzees, which bear striking similarities to human social structures, given that the two species share approximately 95% to 98.8% Deoxyribonucleic Acid (DNA).