Rosie Gloyns

Producer, Mountain Gorilla



The formidable silverback Cantsbee has decided to share power

The world's largest mountain gorilla group has embraced power-sharing to secure its future.

Modern day politics might seem a long way from the forested slopes of the Virunga volcanoes in Rwanda.

But on these slopes the largest group of mountain gorillas in the world is now ruled by a coalition government.

The 46 strong group was featured in the BBC Two series Mountain Gorilla, and since filming the BBC team has been following the animals' progress via regular updates from the field.

The mighty 31-year-old silverback Cantsbee has led the group for 15 years and is one of the last gorillas known and named by the pioneer of mountain gorilla research Dian Fossey.

But it looks as if Cantsbee's time as a great leader could be coming to an end.

Start of an era

Cantsbee has been followed since the day he was born.

Dian Fossey believed Cantsbee's mother was a male, until the female gorilla gave birth. Upon seeing the tiny little baby, Fossey exclaimed, "can't be," which led to his name.

This scientific monitoring of mountain gorillas started with Dian Fossey but has continued for over 35 years.

It enables a fascinating window into their lives and also serves to protect mountain gorillas as a species.

The gorillas are visited every single day of the year by researchers and staff from the national parks.

The presence of these gorilla observers detracts poachers from operating within the gorillas' home ranges.

It also means that veterinary monitoring and intervention are possible, saving precious gorilla lives in a population that is very close to the edge.

Last survivors

Researchers estimate that there are approximately 680 mountain gorillas left in the world.

They live in two pockets of remaining habitat; the forests of Bwindi National Park in Uganda and the Virunga volcanoes that span the borders of Uganda, Rwanda and Democratic Republic of Congo.

Surrounding these two forest islands is one of the most densely populated areas in Africa and the mountain gorillas' habitat has shrunk fuelled by the growing demand for food by the ever increasing human population.

Cantsbee's constituents, the largest group of mountain gorillas in the world

These forests are now heavily protected and carefully managed but still gorillas fall victim to illegal snares and are susceptible to human diseases that can prove fatal to a species whose immunity to even the common cold has not developed.

Cantsbee and his group of 46 represent about 7% of the mountain gorillas left in the world.

Time to power share

Every male gorilla's ultimate aim is to lead a group of their own but the majority will never succeed.

Becoming a dominant silverback guarantees them access to females but the responsibility for defence of the group also rests on their considerable shoulders.

During the BBC's six month period of filming, Cantsbee led his group with great confidence.

PONOKA'S DISAPPEARANCE While it's all change for Cantsbee and the Virunga volcano population, the BBC has also received updates about the gorillas they filmed in Bwindi National Park where the other half of the surviving mountain gorillas reside. As part of the Mountain Gorilla series the BBC followed a young gorilla called Ponoka (above) who was making his way through the first year of life. The BBC captured his first birthday on camera - a milestone for any young gorilla when statistically they become more likely to survive into adulthood. Just weeks after his first birthday Ponoka's group interacted with their neighbouring group of gorillas. Researchers did not witness the interaction but they soon realised that Ponoka was no longer with his mother and the rest of his group. Two field assistants found that both Ponoka and his older brother had become confused during the interaction and had followed the other group. Ponoka was clearly distressed and was being carried by his older brother who is about four times his size. Field assistants returned the following day but Ponoka was no where to be seen. Teams searched the forest for several days but Ponoka has not been found.

He was supported by an especially large number of younger males; five silverbacks and a further eight blackbacks who were yet to grow their silver saddle of hair that develops at about 14 years of age.

Since the end of filming, and as Cantsbee has aged, he has relied more and more on these other males to ensure group cohesiveness and protection.

But until now his formidable strength has been enough of a deterrent to rival males.

One of the younger silverbacks, Gicurasi, is 15 years old. At the age of 31 Cantsbee is starting to look past his peak, whereas Gicurasi is in his prime.

Researchers have observed sexually active females showing attraction to the young silverback. At the beginning of the year the group split temporarily, and a few females opted to follow the younger silverback.

This subgroup, led by Gicurasi, always rejoined the main group after one day of independent travel but these group splits represent a first under Cantsbee's leadership.

Now it seems that the group has reached an equilibrium; Cantsbee had allowed Gicurasi access to receptive females, which previously would have been out of bounds. In return Cantsbee gets to keep the group together.

As researchers from the Dian Fossey Gorilla fund told the BBC, it could be that: "Cantsbee finds it convenient to allow sexual opportunities for the young male in order to ensure efficient collaboration in protecting the group."

It is unclear if this power sharing between the two silverbacks will work for any length of time - it could be the end of an era and Cantsbee's time as the leader of the largest group in the world may be drawing to a close.

For those that have followed him throughout his life it is hard not to feel sad seeing him enter his twilight years. But for now the coalition between the two males is an advantage for all group members.

They can make the most of the experience of the older leader and at the same time benefit from the strength and protection of the younger male.

It could be that the largest group of mountain gorillas in the world has found the best of both worlds.

Find out more about mountain gorillas by visiting the webpage of Mountain Gorilla, which was first broadcast on Sunday, 29 August 2010 on BBC Two.