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How we protect critically endangered Grauer’s gorillas in the Congo Basin

In addition to our more than 55+ years of daily monitoring and protection of endangered mountain gorillas in Rwanda, the Fossey Fund has also engaged in daily protection of the critically endangered Grauer’s gorillas in the Democratic Republic of the Congo (DRC) for the past 24 years. This vital work takes place in an area of community-managed forests that we helped establish – the Nkuba Conservation Area (NCA) – which has received official recognition from the Congolese government.

Our daily tracking of Grauer’s gorillas is very different from our process in Rwanda, where we know each gorilla individually. The gorillas we follow in the DRC are not habituated to the presence of humans, so we follow them a day behind. We use their night nests, food remains, trampled vegetation, fecal droppings, and other signs to gather general information on their movements and activities. Additional tools such as remote cameras – also known as camera traps – help us collect even more data about the gorillas and other crucial species in the forest, such as chimpanzees, leopards and elephants.

In addition, the forest where these gorillas range is extremely remote and large – requiring our dedicated trackers to hike for days to reach them and camp for two weeks at a time, carrying the supplies they need while traversing difficult and sometimes treacherous terrain. 

Despite these challenges, our teams have now delineated five distinct Grauer’s groups in NCA that we can track regularly, reports Raymond Tokunda, our gorilla program manager in the DRC. We estimate the size of each group from counting their nest sites. The size and location of each nest can also provide key clues about the age of the gorilla who made it. Yet, we do not know the individual gorillas themselves. 

We also collect data on the travel and range of each group. On average, these groups cover about 2.1 kilometers of forest each day, with home ranges of about 20 square kilometers in any given month. Their annual home ranges are considerably larger than the ranges of the mountain gorillas, a result of differences in their feeding ecology. Grauer’s gorillas rely more on fruits than mountain gorillas do, which requires them to travel farther.

Remarkably, our tracking shows that the Grauer’s gorillas are returning to areas they had previously avoided, indicating that our protection efforts have reduced threats, such as snares and human activities, in this area.

Here’s a look at the five main Grauer’s groups we follow. Their names originally reflected the areas in which they were found, but some have now been given additional names, as noted below. 

Mbobi (Bansamba) group

The tracking of this group began in 2013, when our teams set up camp at the Bansamba river bank. This family of gorillas has 15 to 18 nests, so the group size is at least that big. They range in the Bansamba river watershed area, near the tributary of another river.

The name “Mbobi” was given to the group in honor of a member of the traditional landowner family as well as a local hill. It also refers to a type of tropical tree that grows here and which helps provide a good habitat for this gorilla group to forage. 

Grauer’s gorilla nest

Membe group

Tracking of the Membe family began in 2014. This group usually has 10-13 nests and is named after its range in the area of Membe mountain, located on a bank of the Kyassa River.

Odakifa (Modiedie) group

We began tracking this group in 2017. It normally has 26-32 nests and also ranges around several rivers, including a slowly flowing one called “Modiedie.” Our trackers have given this group the additional name “Odakifa,” which means positive behavior and acceptance.

Idumba (Temps-Present1) group

The tracking of this group began in 2020, after it was clarified as being distinct from the Bansamba group. At present, this gorilla family has 8 to 12 nests. Its living space is located north of the Bansamba sector, on the bank of Kyassa River. The traditional landowners of the area have given this group the nickname “Idumba,” which means “determination.”

Inamahasa (Temps-Present2) group

In June 2021, another group of gorillas with 6 to 9 nests was discovered in the same area as the Idumba group. However, this family has a wider range, which extends to another sector, bordering the Inamahasa River. 

In addition to following these groups of Grauer’s gorillas, we also collect data on other animals and plants in the forest, as well as information on human activities. We’ve  documented that our presence in the NCA helps protect all the crucial biodiversity of this important forest, which is located in the Congo Basin, one of our planet’s last and best remaining natural defenses against climate change.

Want to learn more about our work in the DRC, including our award-winning trackers?  Click through to these stories: 

Heroes in the forests of Congo: Fossey gorilla trackers receive Disney Conservation award

Press Release: Our work in DR Congo expands by 50%