Musilikale’s group, with its 23 gorillas, is one of the largest mountain gorilla groups monitored daily by the Dian Fossey Gorilla Fund in Rwanda. The group is also a prime example of a multi-male, multi-female composition, where social dynamics are shaped by individual personalities, competition for females, and the strong leadership of the dominant silverback, Musilikale.
Musilikale’s dominant status has always been undisputed, but this summer we noticed that he’s been taking steps to reinforce his position by frequently displacing other males, especially the younger subordinate silverbacks in the group, Icumbi and Turakomeje.
Displacement is a typical dominant behavior in gorillas used to establish or reinforce hierarchy. A dominant gorilla will approach another and take its feeding or resting spot. This can also happen during movement, where the dominant gorilla overtakes another while walking in a line, a behavior referred to as “passing.” Researchers regularly record these occurrences to understand the dominance hierarchy within the group. These behaviors are usually rare in Musilikale’s group but have recently become frequent, always ending in Musilikale’s favor.
These increased tensions and excitement are likely due to several females in the group being reproductively receptive or close to giving birth. So Musilikale’s normally clear leadership is sometimes being challenged by the younger males, who provoke him by approaching females and attempting to mate.
Three brothers interacting
A unique aspect of this group is the presence of three brothers, from the same mother. These brothers are split into two units: Icumbi and Turakomeje, who share a strong bond with each other, and the youngest, Itorero, who is closer to Musilikale. Musilikale played a fatherly role to Itorero when the group was first formed and Itorero was very young, though we haven’t yet confirmed his paternal biology. Now 13 years old, Itorero is in a phase where he creates conflicts by showing off to females and displaying to his brothers, while feeling supported by his strong father. However, despite the soft spot Musilikale has for him, he has begun using disciplinary vocalizations, known as pig grunts, to calm Itorero.
Females and youngsters are involved too
The group’s nine adult females – who are at different reproductive stages – are clearly influencing the recently increasing male competition as well. They stay close to Musilikale during resting periods, highlighting his role as the central figure, surrounded by the entire group. At the same time, the subordinate males position themselves in order to catch females’ attention.
The group also includes 10 youngsters, five of whom are infants. Some of the young females like Urungano and Umwiza are starting to show interest in the males, especially Itorero, even mating with him, as he is central in the group.
It’s hard to predict which female will give birth next, but it’s certain that we will soon celebrate more than one new arrival in this growing gorilla family.
Fun facts
Urungano, thought originally to be a male, has become the most-targeted and interested in male attention. This behavior led us to reconsider Urungano’s gender.
Brothers Icumbi and Turakomeje are very large in size. They inherited this characteristic from their matrilineal family. Musilikale’s group includes some of the largest males known.
The group formed via a separation from the large and historic Pablo group in 2013, initiated by Musilikale. He was followed by other gorillas, most of whom are still part of the group. Interestingly, many females have also joined the group, possibly attracted by the large size of the males, which guarantees strong protection.
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.
