February 13, 2012
Inshuti's Group Splits After Lone Silverbacks Attack
A gorilla leader who until very recently had a promising future has met a serious setback, at least for now, after attacks by three lone silverbacks in a multiday interaction and has lost control of two of his three females. Dominant silverback Inshuti was attacked by the lone silverbacks Tuyizere and Turatsinze in late January and is still recovering from his wounds. Two of his females dispersed to eventually join Giraneza, a third lone silverback, while another female and her infant who disappeared for several days have just returned.
Inshuti, an unusually large silverback, succeeded in forming his own group in 2007 during a period when the three historic gorilla groups that had been monitored by the Karisoke™ Research Center for many years were splitting into nine groups. Born in 1988 into Group 5 (a group that was observed and named by Dian Fossey), he had followed silverback Shinda when Group 5 fissioned in 1993. He began attempting to acquire females for himself as early as 2003 but left to travel alone until more opportunities opened up in 2007, mostly from TItus's group, when the leader Titus was getting too old to retain his sexually active females. In that year, females Taraja and Shangaza transferred to him from Titus’s group and Ruhaka came from Bwenge’s group but soon left. In 2009 an additional arrival, Tayina, joined him from Titus’s group and stayed until she died last May. Inshuti’s latest conquests were Umwana from Titus’s group a year ago (though she left for parts unknown in October) and Nyandwi from Pablo’s group last August. The tenacious Inshuti’s success in starting his own group from scratch is unusual among males who travel alone.
The group seemed to stabilize last year, with two of the three remaining females raising infants. Then, on Jan. 27, Tuyizere and Turatsinze attacked Inshuti, inflicting large bite wounds on his head and neck, despite support from Nyandwi and especially Shangaza and Taraja, who, with their infants clinging to their backs, charged the intruders more than once during the 2 ½-hour-long interaction.
Karisoke staff were concerned about Inshuti’s condition, though he seemed to be “toughing it out – in typical Inshuti style,” according to researcher Winnie Eckardt, Ph.D., who studies stress in mountain gorillas. The day after the interaction, the group appeared to be exhausted and traveled slowly, with Shangaza taking the initiative to lead them away from Turatsinze, who was still following them. Veterinarians from the Mountain Gorilla Veterinary Project (MGVP) have visited Inshuti periodically since the interaction.
As Tuyizere and Turatsinze continued to make advances despite having to flee Inshuti’s defensive charges, another lone silverback saw his opportunity: Giraneza, an impressive silverback who had split from Pablo’s group four years before at age 13. Inshuti responded with multiple charges and managed to deter Nyandwi and Taraja from slipping away with the newcomer that day.
Following the interaction with Giraneza, the Karisoke field staff lost track of Inshuti’s group for five days, despite the efforts of two ranger patrols supported by the anti-poaching team. Finally, Inshuti was located on Feb. 8 — alone and weak, moving slowly but feeding well, at the bottom of Bikereri hill. Just one kilometer away up the hill, Giraneza and Nyandwi could be seen together, along with Turatsinze, who was with Taraja and her infant Akarusho. The trackers observed a “big fight” between the two formerly lone silverbacks, after which Taraja moved to Giraneza while Akarusho moved off alone for the end of the day. A third (unidentified) lone silverback was heard displaying 400 meters away. The anti-poaching team began to search for female Shangaza and her infant Ngwino and were especially concerned about the infant. To add to the drama, trackers removed two fresh snares from a site very close to Giraneza and the females.
The next day, the infant Akarusho joined Inshuti, in good shape though obviously distressed after spending a night alone. He cried when he saw Inshuti and stayed close to him all day. Inshuti continued to move and feed abundantly, but Field Operation Coordinator Jean Damascene Hategekimana (“Fundi”) said there was a smell from Inshuti’s wound, which is not a good sign. The veterinarians visited Inshuti the next day supported by Fundi and the trackers, and found that the wound did not look too bad; Dr. Jean Felix Kinani (MGVP) reassured the field staff, saying "he will still need some days to regain all his strength but he will eventually be fine." Infant Akarusho was fine, always with his father, with whom he shared a night nest. Female Shangaza and infant Ngwino finally rejoined Inshuti on Feb. 10. They are fine and healthy.
“This is very good news, as Inshuti has restablished his group even if it is smaller that the original one,” says Karisoke’s Gorilla Program Manager Veronica Vecellio.
Karisoke’s field team now has to monitor a tenth group of research gorillas every day, Giraneza’s. They are hiring temporary staff and rotating the trackers, a stretch but necessary. So far, Giraneza’s group is doing well, adjusting easily to their new routine.
“We were present at the presumed end of a gorilla group and formation of a new one,” said Vecellio. “This has not occurred among the gorillas observed by Karisoke since 2007-8. But all can still change! It is clearly a situation to monitor attentively, while avoiding any further stress to the gorillas.”
UPDATE: A dedicated field team has been established to monitor Giraneza's new group, which is in a transitional stage, according to Gorilla Program Manager Veronica Vecellio, as the silverback displays and struts to consolidate his dominance over the females. Inshuti went missing for three days in the third week of February, but has been located again, still travelling with 31-year-old female Shangaza and her offspring Ngwino as well as the infant Akarusho.
Compiled from reports by Gorilla Program Coordinator Veronica Vecellio and Jessica Burbridge, Field Communications Officer.