Bamboo is an important food for many animals, including mountain gorillas living in the Virunga Volcanoes mountains, especially the fresh shoots that grow seasonally from April to May and October to November. Since bamboo grows abundantly at the lower altitude of Volcanoes National Park, many gorilla groups come down to the bamboo zone when there are fresh shoots to eat. This also means groups are closer to each other than usual, which often leads to interesting interactions.
Group interactions: peaceful or not
The nature of these encounters varies, with some being peaceful while others are aggressive and may even involve physical fights. There are many factors involved, such as how familiar the groups are with each other and whether reproductive females are present.
Here are some examples from the current bamboo season:
Calmness among former group mates
In October and November, Titus and Segasira groups met twice in the bamboo zone. These groups used to be one until they split in 2022, so the gorillas know each other well. This made their meetings calm, with little tension. The silverbacks, like Segasira, displayed using only postures, while younger gorillas spent the time playing.
A special moment happened when Ishimwe from Titus group, shared a long gaze with his mother, Taraja, who is now in Segasira’s group. Even though they live in different groups, it seems they recognize each other. Also, Macibiri, an 8-year-old female from Titus group, proved to be a favorite among Segasira’s group during this meeting, and even carried some of their infants on her back, a sign that she is known and trusted.
Chasing and herding
Encounters among other groups were less calm. For example, Dushishoze’s group had three interactions, two with Matsiko’s group and one with Susa’s group. In the first two, the silverbacks of Dushishoze chased Matsiko, the only silverback in his group. Matsiko avoided fighting, likely because his group recently had a newborn and didn’t want to risk any injury to the infant or his group.
The encounter with Susa’s group was more intense. Seven silverbacks were involved, and there was even an attempt by female Turimaso to leave Susa’s group and join Dushishoze. Her dominant silverback quickly stopped her by herding her back to his group.
And biting unwelcome silverbacks
Solitary silverbacks also create challenges and were involved in several interactions this bamboo season. These lone males often take big risks trying to interact with groups and attract females. For example, Segasira’s group faced a lone silverback, Imbuto (a well-known male of the area), who boldly entered the group. Segasira and his group charged at him, and Segasira bit him to drive him away. Imbuto left with minor wounds but will likely avoid this group for now. Segasira’s protective behavior was likely more intense because of the presence of young infants in his group.
Another solitary male approached Hirwa’s group. The twin silverbacks there (Gato and Gakuru) gave a long chase trying to move the rival male away to a safe distance from the group.
Bamboo season is a fascinating time for observing gorilla behavior. This year, despite many interactions, no major changes happened among the groups. As the bamboo shoot season winds down, the gorillas will soon return to higher altitudes, creating more space between groups.
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 20 years and shares her deep knowledge and insights about their lives.
