In August 2011, three male gorillas who had been members of
Pablo’s group, the largest gorilla group the Dian Fossey Gorilla Fund
International monitors (named after a legendary silverback), left the group
together: Gushimira and Twihangane, two young 14-year-old silverbacks, and
Irakoze, who at age 11 is a year shy of silverback status. The three males
formed a bachelor group, which according to Gorilla Program Coordinator
Veronica Vecellio “is a rare event and has been witnessed by Fossey Fund staff
only one time prior to this.” Vecellio also notes that this bachelor group was
especially unusual, as the three gorillas are not biologically related. “The
only thing Gushimira, Irakoze and Twihangane had in common at the time was
their age.”
However, shortly after the bachelor group formed the
trackers were unable to locate their trail. In November 2011, Irakoze made a
brief reappearance in Pablo’s group before disappearing yet again from both the
group and the trackers’ sight. Despite the unusual nature of the non-familial
bachelor group, considering that the three gorillas are at an adventurous age
and had originally left on their own as a group, Fossey Fund staff assumed that
they were still together and that the split occurred under normal
circumstances. So when Gushimira was located on Feb. 20 this year for the first
time since 2011, with a modest group of his own consisting of all three of the
females from Ugenda’s group -- Kanama, Inziza, and Kurudi -- it was clear that
the bachelor group was no longer together, which came as a great surprise.
On April 26, the mystery surrounding the disappearing
bachelor group deepened, when trackers spotted Twihangane alone for the first
time since he left with the bachelor group in late 2011. Twihangane was seen in
an area that was once frequented by Pablo’s group and unusually near Musilikale’s
group, a recent splinter from Pablo’s group, who were also lingering around
their former group’s area. Twihangane, now 16, is the son of Mahane, the
dominant female in Pablo’s group who recently transferred to Musilikale’s
smaller subgroup. Twihangane’s mother’s presence in the Musilikale group might
explain his proximity to them upon his return.
Gushimira with females Gushimira with females
As the gorilla community in Volcanoes National Park is very
close-knit, we are not surprised at Twihangane reappearance, but it suggests
more questions than answers. It is unclear why the bachelor group broke up and
why Twihangane is still alone and what his intentions are for revisiting the
area where his former group ranges. Additionally, we are still wondering where
Irakoze has been all this time.
Cants bee, the oldest gorilla we now monitor, has been the
dominant silverback in Pablo’s group for close to 19 years. In his old age, we
have started to see other silverbacks in the group attempt to assert their
dominance and take his place as top-ranking gorilla. According to Vercelli,
“There have been occasions in the past where solo silverbacks have come into a
group and attempted to establish dominance, particularly if the group was
undergoing dominance shifts due to the old age or death of a dominant
silverback.” Though Irakoze is still missing, we cannot exclude the possibility
that he or Twihangane might reappear in Pablo’s group at the right time and
attempt to take the dominant role, despite their long absences.
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