Two of the gorilla families that the Dian Fossey Gorilla Fund monitors and protects every day are engaged in some interesting behaviors, as they have been interacting regularly – and peacefully – in the forest. Interactions between gorilla groups can be tense and even involve the transfer of some members between groups. But that hasn’t been the case with recent meetings between these two families, called Titus group and Segasira group.
Since March, our field teams have been observing these two groups encountering each other in the forest each month, witnessing some interesting behaviors and a remarkably relaxed atmosphere, as dominant silverback Segasira, who left Titus’ group in June 2022 to form his own group, still maintains strong connections with his former family.
The young gorillas play
A young female – 7-year-old Macibiri of Titus group – often steals the spotlight during these gatherings, especially when she interacts with her peers from the other group. When the groups are close together, Macibiri rushes to play with Ukwiyunga and Umutware, who are 8 and 7 years old, and other young gorillas from Segasira group also often join them. We even witnessed a female from Segasira group grooming Macibiri, indicating a deep bond between them.
The males display
While the youngsters are playing, the groups’ adult males maintain a protective stance. They show no signs of stress or aggression, unlike encounters we can see among adult males in other groups. Silverback Segasira may engage in display behaviors with silverback Urwibutso from Titus group. They are actually brothers and it seems like the brotherly connection plays a role in these displays – they appear to be showing off, rather than engaging in any real conflict. And after initial exchange of displays, they then calm down and even rest in close proximity. Meanwhile silverback Pato, the leader from Titus group, keeps his distance.
Other relatives have unique behaviors
We’ve also observed an interesting situation among a mother-son pair – Taraja and Ishimwe. They now live in Segasira and Titus groups respectively but meet each other during these interactions. Ishimwe actually once lived with the Segasira females, when they were in a different group altogether. Now when they meet during these interactions, he seems to keep a distance from his mother. It’s possible this may be because mother Taraja gave birth to a new infant in February. Or, he might be afraid of silverback Segasira, which could explain why he separated from his mother in the first place.
Another observation we’ve made during these encounters is that the females with very young infants don’t seem bothered by the presence of the other group, displaying remarkable calmness and trust. We have learned that familiarity among gorillas plays a pivotal role in determining their interactions, extending beyond their immediate families, which helps us understand this situation. When gorillas know each other, peaceful encounters among groups are more likely.
“I was surprised by how peaceful the event was,” says Joyce Uwineza, one of our new field research assistants, who witnessed a recent interaction.
“I expected aggression, but was amazed to see gorillas mingling peacefully, playing. Even silverbacks Segasira and Urwibutso regarded each other calmly.”
“The sight of females holding very young babies near each other was heartwarming,” she adds. “Especially since one of them had just given birth the day before. This is a vulnerable time, but the gorillas appeared relaxed.”
Gorilla group encounter trends
As gorilla researchers, we closely monitor group encounters. They offer invaluable insights into gorilla social dynamics and their remarkable adaptability, although they can also be challenging for the gorillas, resulting in conflicts, transfers or negative outcomes.
The mountain gorillas live in a limited area of forest, and their population is on the rise due to daily, intensive protection. This has led to more frequent interactions between groups and it appears that gorillas are adjusting their movements based on neighboring groups.
We’ve observed that newly formed groups that arise from group splits tend to maintain close proximity to familiar neighbors, resulting in more relaxed and predictable encounters. However, when they encounter a less familiar group or a solitary male, the situation can escalate rapidly and become highly stressful.
This article is part of a series presented by the Fossey Fund’s gorilla program Senior Advisor Veronica Vecellio, focusing on the mountain gorillas the Fossey Fund protects and studies every day in Rwanda. Veronica has worked with these gorilla families for nearly 20 years and shares her deep knowledge and insights about their lives.