Lone Silverback Drama Continues for Inshuti

The lone silverback drama involving Inshuti and his group has continued on through the end of this week, reports the Fossey Fund’s Karisoke Research Center field staff. The dominant silverback truly cannot catch a break from the lone males ranging in the forest tenaciously seeking out females to steal. Yesterday, Karisoke researcher Winnie Eckardt, PhD. and research assistant Samedi Muyco witnessed an interaction that lasted from early morning to late afternoon and had the females of the group shaking with fear. This particular interaction involved Giraneza, an impressive lone silverback who split from Pablo’s group four years ago when he was just 13 years old.

But Giraneza wasn’t the only lone silverback threatening Inshuti’s group on Thursday. Also on the trail was Tuyizere, the lone male who has been making frequent appearances in the Karisoke-monitored groups throughout the last several months. When the field team arrived, Tuyizere was interacting with the group, but was quickly deterred by the team’s presence and lingered about 100 meters from the rest of the gorillas for the duration of the afternoon. Giraneza more than made up for Tuyizere’s reluctance with a constant onslaught of displays toward the group leader. The mammoth Inshuti responded with intimidating displays of his own and charged Giraneza multiple times throughout the data collection period.

Young female Nyandwe “was very interested in going with Giraneza” said Eckardt. "She was frequently looking at the lone silverback. Inshuti had the hardest time to move her up and away” from the intruder. Eckardt reported that the group leader was working hard to move his females higher up the mountain for most of the day, but Nyandwe took her time and was noticeably lagging behind. Eckardt observed one instance where Nyandwe was keeping an eye on both males. When she saw that Inshuti had moved higher up with the rest of the group, she started making her move towards Giraneza. But, Inshuti caught her and moved quickly back down to guard his female. Nyandwe feigned disinterest in the lone silverback and followed Inshuti back up to the group. And it wasn’t only Nyandwe that had an eye for Giraneza. Female Taraja was also very interested in going with him, but with her young offspring still in tow, she likely reasoned it wasn’t a good idea to attempt to transfer at this time.

Field Data Coordinator John Ndayambaje reported that Inshuti’s group was peaceful this afternoon and no lone silverbacks were found on their trail. Hopefully this will mark an end to the incessant intruders and Inshuti will have time to heal from his wounds.

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Injured Silverback Inshuti in Stable Condition - Fossey Fund Blog Post

Karisoke researcher Winnie Eckardt, Ph.D., accompanied the team assembled to assess the condition of injured dominant silverback Inshuti this morning. Eckardt reported that “although his injuries are indeed severe, the group leader appears to be toughing it out -- in typical Inshuti style” and a medical intervention was not necessary. She added “overall, the group appears to be exhausted from the incident and was traveling slowly, stopping frequently to rest.” With Inshuti injured, adult female Shangaza took the initiative to lead the group away from the one lone silverback who was still on the trail of the group.

Inshuti grooming himself.

Karisoke trackers were able to successfully identify this remaining lone silverback as 21-year-old Turatsinze -- the same male that participated in an interaction with Titus group last November in an attempt to acquire female Ubufatanye (Fat). Turatsinze has been a lone silverback since 2006 when he dispersed from Pablo group on Oct. 18 of that year. It appears that he has traveled solo long enough -- and is anxious to start his own group.

And Inshuti is all too familiar with Turatsinze’s struggle. Interestingly, Inshuti is one of the few lone silverbacks observed by the Karisoke Research Center to build a group “from the ground up,” gradually acquiring one female after another. Eckardt reflects that he was “incredibly tenacious and tough. He wasn’t going to give up until he had formed his own group.” It appears that same strength and tenacity has served him well in keeping his group together.

Inshuti was observed directing “neigh vocalizations” towards female Taraja three times this morning. This could provide some insight as to what lured the lone silverbacks to his group. Over the last week, Inshuti was seen copulating with the female, which could indicate that she may be able to conceive again. Inshuti’s “neigh vocalizations” could have been an attempt to strengthen the bond between the pair, and deter her from leaving his group to accompany the lone silverback.

Inshuti was feeding very little today and his condition must be monitored closely throughout the next several days by Karisoke field staff. MGVP veterinarians will visit the group again Tuesday to ensure that he is recovering smoothly. As for Turatsinze -- the lone silverback was 700 meters from the group when the team left this afternoon and moving in the opposite direction. Trackers will continue to search for the missing lone silverback for identification purposes.


Jessica Burbridge, Field Communications Officer

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Silverback Leader Inshuti Attacked by Two Lone Silverbacks

Silverback Inshuti

Two lone silverbacks joined forces and attacked 24-year-old dominant silverback Inshuti today, reports Fossey Fund Field Data Coordinator John Ndayambaje. Inshuti sustained three large bite wounds on his head and one on his neck. Veterinarians Dr. Dawn Zimmerman and Dr. Jean-Felix Kinani (of the Mountain Gorilla Veterinary Project), along with a team of Karisoke trackers, will trek to the group tomorrow to assess the damage and potentially carry out a medical intervention. Karisoke researcher Winnie Eckardt, PhD., will join the team to collect behavioral data and fecal samples for her ongoing study on stress in the mountain gorillas.


Ndayambaje reported that the interaction began in the Tamu area between Mount Visoke and Mount Karisimbi at 11:24 a.m. and lasted almost 2-1/2 hours, until the pair of silverbacks retreated from the group at 1:49 p.m. The unidentified silverbacks displayed 19 times throughout the first half of the interaction, pushing Inshuti and his group to travel over 1.5 kilometers through the forest, in an attempt to get away from the intruders. Inshuti displayed three times before the physical interaction began, when he sustained the bite wounds.

With the absence of any other males in the group to help Inshuti, the three females, Shangaza, Taraja and Nyandwi, participated in the interaction in defense of their infants and injured leader. The two infants remained on their mother’s backs throughout the entire interaction -- which the field staff found particularly interesting because, at almost 3 years old, both offspring are at an age that they would not normally need to travel on their mothers' backs. Females Shangaza and Taraja reportedly charged the two silverbacks twice. On the first occasion, they charged both silverbacks jointly, causing the males to turn and retreat. Next, they charged only one of the silverbacks, at which point, the other male charged the females, who then retreated. During this time, Inshuti attempted to display, but was too weak to chest beat and was only able to display with hooting vocalizations. Inshuti group trackers report that the pair of silverbacks are 350 meters away from the group at this time. Inshuti is said to be in critical condition and appears to be in quite a lot of pain.

Although the attackers are not yet officially identified, the field staff believes these two silverbacks could possibly be 15-year-old Gushimira and 14-year-old Twihangane, the gorillas that dispersed from Pablo group on August 16. However, there are currently six lone silverbacks that are monitored by the Karisoke Research Center in this area and realistically, the aggressors could be any of them. Along with the medical intervention team for Inshuti, another team of trackers will enter the forest tomorrow morning to track the silverbacks and attempt to identify the individuals.

Gorilla Program Manager Veronica Vecellio says that “this is not the first time that Inshuti has been involved in such an aggressive interaction -- he suffered serious wounds from both Beetsme and Pablo (late silverbacks) in the past. He is a strong individual and he will likely bounce back from this.”
Our Karisoke staff is, of course, enormously concerned and hopes that Inshuti will recover from these injuries. Without Inshuti, this group would be in disarray, with the two infants of the group in an extremely vulnerable position.

An account of tomorrow’s observations and possible medical intervention will be reported promptly.

Jessica Burbridge, Field Communications Officer

A Most Persistent Solitary Silverback

The Fossey Fund’s Karisoke™ Research Center routinely monitors nine groups of mountain gorillas. Ranging in the same area are six well-known solitary silverbacks that make appearances from time to time when they are searching out social groups in hopes of attracting females. By the end of 2011, Karisoke researchers had recorded 82 encounters with a lone silverback, 54 of which were active interactions with a social group. These interactions happened under a variety of different scenarios and lasted anywhere from mere seconds to an entire day, to weeks on end. While these silverbacks are frequently alone, they are almost always on the trail of another group, biding their time to make a move.

The behavior of the lone silverback

Solitary silverbacks spend several years - and sometimes their entire adult life - traveling alone. The young males are born and raised in the safety of a gorilla group, but as they grow into adults and the characteristic silver hair begins to show on their back, the desire to become dominant can cause them to strike out on their own. The silverback will then begin a lonely quest that may last for years, peppered with dramatic interactionss. Throughout that time, the lone silverback will periodically pursue a social group, usually with his eye on a specific female he would like to acquire. Displaying and vocalizing dramatically, he can push the group’s dominant silverback to react aggressively, sometimes resulting in violence or injury. More frequently however, the field staff observes "auditory interactions" between social groups and the lone silverbacks. This occurs when the lone silverback announces his presence with intimidating chest beats and hooting vocalizations, to which the silverbacks within the group will respond accordingly. Sometimes the interaction will end there, if the group is successful in discouraging the outsider.

Will persistence pay off?

Without a doubt, the most tenacious of these six lone silverbacks has been Gwiza, whom Karisoke trackers encountered 31 times in 2011. Gwiza left Shinda’s group in April 2004 when he was 16 years old. During the past eight years he has been observed traveling alone. Interestingly enough, since the death of dominant silverback Shinda and the subsequent group split, Gwiza’s interaction frequency has increased dramatically. The lone silverback routinely targets Ugenda’s and Ntambara’s groups (the two groups that resulted from thebreakup of Shinda's group). It seems that, despite his decision to live and travel alone, silverback Gwiza still does not want to stray too far from his origins....

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