By Ebong Lionel. Edited by Shuimo Trust

The Cross River gorilla (Gorilla gorilla diehli) is the northern and western-most gorilla subspecies and is restricted to the hilly rain-forest region along the Nigeria-Cameroon border, which forms the headwaters of the Cross River. It is one of the species of great apes that have often been associated closely with humans. The Cross River Gorillas is separated by about 300 km (190 mi) from the nearest population of western lowland gorillas (Gorilla gorilla gorilla), and by around 250 km (160 mi) from the gorilla population in the Ebo Forest of Cameroon. Estimates from 2014 suggest that fewer than 250 mature Cross River gorillas are remaining in the wild, making them the world’s rarest great ape. 

In Cameroon, the Lebialem Highlands in the Western Highlands of Cameroon stands as a major range area of this endangered species. This landscape encompasses the Tofala Hill Wildlife Sanctuary (THWS), which is located between longitudes 598006m and 609830m and latitudes 615778m and 634006m. It is a major host of the CRG in Cameroon’s Western Highlands. The Sanctuary has a surface area of over 8000ha. The area is characterized by an undulated landscape from Bechati (200m) in the lower altitudes to Fossimondi (1800m) in the higher altitudes, with a chain of peaks notably the Tofala Hill (866m).

Conservation Status and Threats to the CRG 

IUCN classifies Gorilla gorilla diehli as Critically Endangered C2a (i) since the total population of mature individuals is estimated to be less than 250. As a result of illegal hunting and habitat loss from agriculture, logging and road construction, there is a strong probability that documented declines in the size of the population (Thalmann et al. 2011) may continue. In the Tofala Hills Wildlife Sanctuary, the CRG population is believed to be improving, based on the encountered signs and activities.

What is ERuDeF doing to conserve this rare species? 

In 2007, a survey was conducted in 5 villages with the aim of assessing taboos against hunting and eating this endangered species. In the Lebialem division of Cameroon, 86% of the population were in favour of the conservation of this species, seeing them as important morphological counterparts to humans which, in the case of their dying out, would cause the demise of their human totemic counterparts (Etiendem et al., 2011). One reason for the decline of cross-river gorillas was believed to be the decline of adhering to these totemic practices among younger people in the 18 to 25-year age range. Regardless, this taboo is still in place and it still strongly discourages the hunting of the cross River Gorilla. These totemic traditions are believed to be critical to the species’ continued survival and well-being. 

One of ERuDeF’s initiatives that have contributed to the long-term community-based conservation management of CRG and other species in the THWS is the Community Rangers Programme. This initiative has promoted the development of projects that have recruited and trained disengaged hunters to serve as Community Rangers in the conservation of the Cross River Gorillas, Nigeria Cameroon Chimpanzees (NCC) and other species found in this Protected Area of the Tropical Rainforest zone. 

Through financial assistance from the ACF, Thin Green Line and the Arcus Foundation, the Environment and Rural Development Foundation is gradually pushing biodiversity conservation to a sustainable end, with focal species being the CRG and NCC. Thanks to the Community Rangers training courses, ERuDeF have recorded a great deal of data on its habitat preference and topography, climate, Cross River gorilla’s wide range behaviour, diet, its grouping patterns. These data were all assessed and confirmed from indirect evidence, such as feeding trails, nests, and faeces, as key gorilla distribution factors. Also, CRs through their patrols have equally recorded lots of threats either directly from hunting, or indirectly from the destruction of their habitats. “Even amid the Anglophone crisis, we are braving the odd to save the last population of the cross river gorilla and other species in the Lebialem Highlands through the Community Rangers Support “, Louis Nkembi, President/CEO of ERuDeF is quoted as saying.  

Community Rangers encounter hunting threats in THWS

One of the greatest threats to the Cross River Gorilla and other species in the THWS is the high hunting pressure. Hunting in this protected area is done with guns and by trapping. Biomonitoring in the THWS has proven that the area has a high degree of hunting evidenced by pictures and videos of hunters with guns and other hunting equipment. “Hunting is in the decline since we started patrols in the Tofala Hill Wildlife Sanctuary. Some of us community rangers were even hunters before being recruited as community rangers” Nkemkejou Andreas, lead community ranger is quoted as saying. 

Gorilla Signs

Cross River gorillas have certain nesting behaviours (i.e. mean nest group size, style of the nest, location of the nest, and nest reuse patterns) that depend on things such as their current habitat, climate, food source availability and risk of attack or vulnerability. According to research done on the Cross River gorillas living in the Tofala Hills Wildlife Sanctuary, there is a high correlation between whether a nest is constructed on the ground or in a tree and the season. From April up until November, Cross River gorillas are more likely to build their nests within a tree, and from November on, they are more likely to build them on the ground. Also, as supported by Sunderland-Groves et al., (2009), it was found that more nests built at night were built on the ground as opposed to those in trees. Community rangers working in the Tofala Hills Wildlife Sanctuary have encountered gorilla signs in their daily patrols,

The Cross River gorilla’s diet consists largely of fruit, herbaceous vegetation, liana, and tree bark. Much like their nesting habits, what they eat is contingent on the season. Observations of the gorilla indicate that it seems to prefer fruit, but will settle for other sources of nutrition during the dry season of about 4–5 months in northern regions (Ferris S., 2005).

As asserted by Richard A, Gorillas and other primates are only a small part of the larger ecosystem and thus, they rely on many aspects of their habitat for survival. Also because of their body size, they cannot adapt to new environments and they have a rather slow reproductive rate. Even though there is somewhat limited research on Cross River gorillas, there is enough to conclude that these animals are currently able to sustain survival. 

Cross River Gorilla ecology

The Cross River gorilla, like many other gorilla subspecies, prefers a dense forest habitat that is uninhabited by humans. Due to the Cross River gorilla body’s size, they require large and diverse areas of the forest to meet their habitat requirements. Similar to most endangered primates, their natural habitat exists where humans are often occupying and using natural resources. Forests that are inhabited by the Cross River gorilla vary in altitude from approximately 100 to 2,037 meters (etiendem et al., 2013). They usually prefer to feed on fruits and fresh leaves. They can be identified directly or through their signs.

Consequences of the disappearance of the Cross River Gorilla 

Just like other primates that have a frugivorous diet that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts, and seeds, Cross River gorillas are important seed dispersers, playing a critical role in forest regeneration in their fragile ecosystem. Since they travel over long distances, they disperse seeds far from the mother tree, adding to the diversity of the forest flora. Their extinction will halt this ecological build-up. 

This role of seed dispersal is also critical for human survival, as humans are privileged to have a tree species that can be of value in a place where it never existed. Humans will have to depend on their local naturally endowed tree species without the presence of the CRG to disperse seeds.

Equally, gorillas like all wild animals play an important role in their environment in ensuring the natural balance in the food chain. Without these large-scale grazers’ presence and role in their habitats, and in eating lots of vegetation, the natural food chain would be disrupted. 

Gorillas play a key role in maintaining the biodiversity of their forest homes not only by spreading the seeds of the trees they eat, but also open up gaps in the trees as they move around, letting in light and helping sun-loving plants grow. Their presence in a particular habitat favours the well-being of other smaller species like squirrels that rely on their food remains. 

While immensely appreciating the efforts and support of the African Conservation Foundation, Thin Green Line and the Arcus Foundation, for their support in sustaining the conservation of the Cross River Gorilla in the THWS, ERuDeF is calling on all conservation stakeholders and partners to build synergy and develop initiatives that will help foster the conservation of the CRG and its habitat across its range and especially in the THWS and the Lebialem Highlands as a whole; the species major endemic zone. The time is now. Have a say