GORILLAS

Listed as Critically Endangered by the International Union for Conservation of Nature (IUCN) since 2016, the Grauer's gorilla has suffered an alarming decline in population over the past few decades. A major study conducted by Plumptre et al. (2021) estimated a decline of nearly 58% in the population over a twenty-year period, mainly due to hunting for their meat, exacerbated by ongoing armed conflict since 1996. More recently, there has been an alarming explosion of habitat loss linked to uncontrolled exploitation of natural resources. The decline has continued in areas without effective protection mechanisms.

The main remaining strongholds of the Grauer's gorilla population are located in Kahuzi-Biega National Park and the neighboring forests of Oku, which together are thought to be home to 56% of the remaining global population, estimated at around 6,800 individuals! These sites are now the highest priority for the conservation of this subspecies, (Plumptre et al., 2021).

The population is estimated at approximately 1,571 individuals in KBNP (without counting the Lulingu area, unsurveyed) and 2,244 individuals in the Oku community forests. Including an estimate for the Lulingu area, the PNKB and Oku are home to up to 77% of the Grauer's gorilla population. In the Nkuba Conservation Area, which lies next to Oku, the gorilla population is between 100 and 2200 individuals, and appears to be stable since 2013 (van der Hoek et al., 2024).

For more than 20 years, WCS has supported the conservation of KBNP and its great apes, gradually extending coverage to previously restricted areas as the ICCN strengthens its operations. WCS has also been involved in the Oku forests since 2010, which have no official protection status despite considerable community support for their conservation.

The ecology and behaviour of Grauer’s gorillas is relatively well documented (Williamson & Butynski, 2013). Their groups are led by a dominant silverback male, accompanied by several adult females and their offspring. Females may change groups several times during their lifetime. The species has a varied diet consisting of leaves, stems, fruits, and sometimes termites or mushrooms. Despite their physical strength, these great apes are generally peaceful in nature, preferring to avoid confrontation.

A long and meticulous process called "habituation" involves gradually accustoming the gorillas to human presence without altering their natural behavior. This allows observers to study and discover the fascinating life and behavior of these primates. The habituation and tourism strictly follow IUCN Best practice Guidelines (McFie & Williamson 2013; Waters et al. 2023a;b).

In Kahuzi-Biega National Park, and more specifically in the highland sector (around Tshivanga), a team of experienced trackers is in daily contact with ten gorilla families, two of which are considered fully habituated to human presence. This situation not only promotes scientific research but also the development of ecotourism, in accordance with conservation rules.