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Silverback Kuryama’s Body Identified; a Formidable Legacy

Sept. 18, 2012

Silverback Kuryama’s Body Identified; a Formidable Legacy

The iconic silverback Kuryama was last seen by the Dian Fossey Gorilla Fund field staff on June 18, 2011, after he had separated from his group. This turned out to be the last time we would see him alive. His body has now been definitively identified.

Kuryama in January 2011Just a couple of months after the last sighting, Kuryama group trackers were following the group, now led by silverback Kirahure, when the gorillas passed by something large on the forest floor. When the trackers went to investigate they discovered the body of a silverback lying on the edge of a patch of smashed vegetation. Although the body was too far decomposed to be certain, based on its location and estimated age they tentatively identified it as Kuryama’s remains. The Mountain Gorilla Veterinary Project performed a post-mortem exam and sent a tissue sample to the Max Planck Institute for DNA analysis. Now, a little more than a year after the body was found, we have received the results from the Institute. Indeed, the silverback was Kuryama, and we can at last mark the end of his formidable legacy with scientific certainty.

Kuryama grew up in Beetsme’s group, led by his father, the famous silverback Titus. After reaching maturity, Kuryama rose to become the second-ranking silverback in Beetsme’s group, subordinate only to Titus. But in 2004, Kuryama and Titus began a struggle for dominance that would not resolve for almost three years. Karisoke Research Center Director Felix Ndagijimana, who did his master’s research on the gradual splitting of Beetsme’s group, says that the conflict between the two silverbacks was unusually subtle and they rarely fought. He believes this was related mostly to the calm, confident personality that they shared.

Kuryama's group in 2012As the dominance succession progressed, Beetsme’s group began to split into temporary subgroups, one led by Titus and the other by Kuryama. In addition, three silverbacks left Beetsme’s group entirely. One of the silverbacks, Ubwigenge, was never seen again, but Rano reappeared after a year. The third silverback, Bwenge, went on to form his own group, which is currently monitored by the Fossey Fund.

Kirahure and Vuba were the two youngest silverbacks in Beetsme’s group. They stayed with the group throughout the dominance shift, but usually remained on the periphery. On the occasions when the group ranged in subgroups, Vuba and Kirahure would often follow Kuryama. When Beetsme’s group split permanently in 2007, Kuryama left with some of its females as well as Vuba and Kirahure, while other females and a silverback chose to remain with Titus. For several years, Kuryama presided over his family as the dominant silverback.

The data technician for Kuryama’s group, Telsephore Nsengiyumva, who had also followed Beetsme’s group before the split, says that Kuryama was characterized by his calm and peaceful nature. While other silverbacks might become aggressive or display if trackers accidentally surprised them in the forest, the trackers never had such concerns about Kuryama. Ndagijimana says, “Kuryama was a very tolerant silverback. He may have learned or inherited some of that from his father, Titus, who was known to be an easygoing, great leader. He had this way of leading the group by example, not by aggression or force.”

Kirahure and KuryamaUnder his leadership, Kuryama’s group was very successful. The group’s range expanded and they gained more females. At one time, every female in the group had an infant, a sign of the group’s reproductive success. Ndagijimana believes Kuryama group’s success may be attributed to the silverback’s style of leadership. Nsengiyumva recalls that the females in the group always liked to be near Kuryama, and when there were conflicts between Kuryama and Vuba, Kirahure always supported Kuryama.

Unfortunately, Kuryama’s leadership was not to last. Just a few years after Kuryama split from Beetsme’s group, something began to change. Fossey Fund field staff noticed the changes during the bamboo shoot season of 2010. It was a particularly good season for bamboo shoots — there were many available — and the group was ranging in the bamboo zone, in the lower altitudes of the park. Around this time, the female Mahirwe came into estrus. Kuryama seemed to be Mahirwe’s favorite silverback in the group, but she copulated with Kirahure and Vuba as well. The three silverbacks began to fight over her. Usually Mahirwe and a silverback would try to copulate out of sight, but the other two silverbacks could hear their copulation vocalizations and would immediately arrive on the scene and begin fighting. Even Mahirwe was covered in wounds during this time. Two other females in the group were receptive as well, but Mahirwe caused the most conflict among the males.

Kirahure and MahirweThe group stayed together for some time after that bamboo season, but the dynamic was different now. Kuryama, Kirahure, and Vuba came into conflict more often. The females began to divide between those that liked to stay near Kirahure and those that liked to stay near Kuryama. Then, in May 2011, Kuryama’s group engaged in a long interaction with Isabukuru’s group. When trackers arrived, Kuryama had a deep wound on his back, and was behind the group. Kirahure and Vuba were now at the forefront of the interaction, protecting the group from Isabukuru and the second ranking silverback from his group, Kubaha.

Kuryama had been significantly weakened by the wounds he sustained in the interaction with Isabukuru’s group. Over the next few days, he gradually began trailing behind his group, with the distance between the silverback and the group increasing over time. Ndagijimana says he believes that Kuryama may have been trying to protect the group from further interactions with Isabukuru, even as he struggled to keep up, pointing out that silverbacks will sometimes take a position behind the group in order to protect them. Eventually, however, Kuryama’s ties with the group were severed. In June, field staff observed an auditory interaction between Kuryama and his former group, during which Kuryama hooted and Vuba hooted and chestbeat. Kuryama was last seen on June 18 by Isabukuru’s trackers. He was out of the park, feeding. His body would not be recovered until Aug. 2012.

Although Kuryama’s reign as dominant silverback in his group was short-lived, his legacy lives on in the Virunga mountains and in the body of scientific knowledge about mountain gorillas. Felix Ndagijimana presented a poster about Kuryama’s split from his father Titus’ group called “Dominance Shift Between Two Father and Son Silverbacks in a Virunga Mountain Gorilla Group” at the International Primatological Society Conference in Uganda in 2006. The split was also the subject of the 2008 documentary Titus: The Gorilla King. The group which bears Kuryama’s name still roams the forests of Volcanoes National Park today, with Kirahure as its leader. And Kuryama himself still has contributions to make. His skeleton was recently catalogued by the Mountain Gorilla Skeletal Project, which aims to help build capacity in Rwanda for skeletal preservation and to produce ongoing research on the skeletons that will support mountain gorilla conservation and develop our understanding of their evolutionary biology.

For all of the trackers and field staff who came to know Kuryama over the years, the confirmation of his death brings closure. Gorilla Program Manager Veronica Vecellio explains, “Kuryama died at the age of 25 as a solitary silverback. In view of the successful years that preceded this sad event, nobody would ever have predicted such a premature end. We were able to follow him for weeks when he was travelling alone, but when we suddenly lost his traces we kept our hopes alive that somehow he was recovering from the injuries and one day we would see him again.” Unfortunately, we now know that Kuryama indeed passed away. Sad though it is that this special silverback is no longer ranging in the forest, when one reflects on his life, we can truly say he contributed much to the mountain gorilla population of Volcanoes National Park and to the scientists and conservationists who continue to learn from him.