The Susa family is the most historically significant gorilla group in Rwanda — possibly in the world. Named after the Susa River on the slopes of Mount Karisimbi, this was one of the original groups studied by Dian Fossey at her Karisoke Research Centre from the late 1960s onward. Fossey’s observations of the Susa family, combined with her work with other groups, produced the foundational scientific understanding of mountain gorilla social behaviour, ecology, and conservation needs that underpins everything known about the species today. The families that visitors trek in Rwanda and Uganda in 2026 — all of them — exist in recoverable numbers partly because of what Fossey documented about Susa and its contemporaries.
The Family Split — Susa A and Karisimbi
The original Susa family grew to be one of the largest gorilla groups ever recorded — at peak size, the family had over forty members. Large groups create the social conditions for splitting: subordinate silverbacks develop relationships with subsets of females, competition for rank intensifies, and eventually a portion of the group separates to form an independent family. The Susa split occurred around 2007–2010, producing two successor groups: Susa A, which retained most of the original membership and the Susa name, and the Karisimbi family, which took the name of the volcano on whose slopes it ranges. Both groups are habituated for trekking and both are assigned on standard Rwanda gorilla permits.
Susa A — What to Expect
Susa A is a large, multi-silverback family that ranges on the high slopes of Mount Karisimbi. The family dynamic during encounters reflects its complexity — multiple adult males of different ranks, a large number of females and juveniles, and the social interactions between them that a single-silverback family simply cannot provide. The encounter with Susa A is one of the most layered in Rwanda. It is also one of the most demanding to reach: Susa A consistently involves the longest average trek times in the park, often four to five hours return, at altitudes that test visitors who are not conditioned for high-altitude hiking.
Trek Details
Trek time: 3 to 5 hours return. Altitude: 3,000–3,700 metres. Difficulty: very challenging — the most demanding regular trek in Volcanoes National Park. The terrain above the bamboo zone on Karisimbi involves steep, root-covered slopes in dense Hagenia forest with occasional open rocky sections at higher elevation. This trek requires genuine physical preparation: cardiovascular fitness, appropriate high-altitude layering, good boots with ankle support, and the honesty to tell the ranger coordinator at the briefing if you are not in the condition the trek requires.
Conservation Legacy
Visiting the Susa family carries a particular weight for visitors who know the history. The individuals in the group today are the descendants of animals that Fossey named, documented, and protected at considerable personal cost. The habituation that makes your encounter possible was built across decades of daily contact by Karisoke researchers who walked the same slopes you will walk tomorrow. That continuity — from the Susa River group of the 1960s to the family you will find at 3,500 metres in the morning — is the living result of the conservation model Fossey helped establish.