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Which male gorilla is in charge?

With an amazing five silverbacks, the dynamics between the males in the Kwitonda group are always exciting.

One of the mountain gorilla groups that the Fossey Fund studies in Rwanda’s Volcanoes National Park contains five adult males – silverbacks – who are in various stages of working out their dominance hierarchy. Normally, there is only one dominant silverback in a group, and if there are other adult males, they will have a clear rank below him. Having five adult males in a group is a relatively rare occurrence, although the record is held by Shinda’s group back in 2003 with eight silverbacks.

The Kwitonda group is currently composed of 18 individuals, though it once had 40 members before splitting in 2021. The oldest male, at age 29, is Akarevuro, followed by Karibu (age 18), Cyusa (age 14), Kataza (age 13) and Kungahara (age 12). There is kinship among them, with Karibu and Cyusa being brothers. Both are also the uncles of Kataza.

So far, the top spots are clear: Akarevuro is the dominant – first-ranking male – and Karibu is the second ranking. But the remaining three males are still working out their ranks and often challenge each other as they compete for the third, fourth and fifth positions. These competitions are interesting to observe and offer unique insight into the social structure of gorilla groups, as they also involve the females and various alliances that may form among the males.

Cyusa exhibits some behaviors, such as claiming the location of the younger males (what we call a displacement – a classic display of dominance) of the younger males, which suggest he holds the third-ranking position. Cyusa, though older, is only just starting to show the silver hair on his back, and he’s also quite a calm gorilla who often ventures away on his own or is on the periphery of the group. Yet, when he is with the family, the younger males seem to grant him his third-ranking position.

Kataza, who is the fourth-ranking male, often challenges Cyusa as well as the two other subordinate males. His back has not yet started to turn silver, but unlike his uncles, Karibu and Cyusa, he is lively and daring. Kataza often challenges Kungahara, the fifth-ranking male. Kataza seems to take pleasure in these confrontations, searching for Kungahara, who is often busy feeding or resting. 

Kataza’s boldness is fueled by the support of the dominant male Akarevuro, who does not intervene when Kataza shows off. Kataza even copulates with females while Akarevuro is nearby, facing no interference. 

“Kataza is quite a tactful male,” says Jean de Dieu Nsanzineza, Fossey Fund data and operations coordinator.  “His behavior makes him a troublemaker toward other subordinate males, while at the same time also wins him the dominant male’s favors.”

Kungahara is the fifth-ranking and youngest adult male in the family but seems to have a body size that is already bigger than the two males ranking just above him. Since larger males are more likely to achieve dominance, it will be interesting to see if his size ends up working in his favor.  Kungahara’s mother, Mugeni, is known for her strong and successful offspring. Her older son, Marambo, leads a family of 21 individuals, and son Urwego leads a family of seven. Kungahara seems to have inherited his bloodline’s good genes and promises to become a successful male as he reaches his peak of development. Mother Mugeni has also been observed nursing her infants for a longer time than usual, another factor that may contribute to the vigor that runs in the family line.

“Having this number of young adult males affects the overall group dynamics significantly; in particular we see more short-term splitting of the group than when there is only one or two males,” explains Didier Abavandimwe, Fossey Fund research officer. “We hope that the youngest silverbacks will learn from Akarevuro’s leadership and opt for collaboration rather than competition, to ensure this group’s stability.”