The Afi Mountain Wildlife Sanctuary in Cross River State in southern Nigeria covers 104 km² (40 sq mi).^[1] The wildlife sanctuary was founded in 2000 to provide refuge for endangered animal species, including the Cross River gorilla, the Nigeria-Cameroon chimpanzee, the drill and the gray-necked rockfowl.

Afi is managed by the Cross River State Forestry Commission/Ministry of Climate Change and Forestry. Although the steep mountainous slopes of the sanctuary have largely protected the forest from logging, it is frequently damaged by dry-season bush fires that are set to clear land for farming or to catch game. Open areas created by fire are quickly colonized by herb species which form an important staple food for gorillas. The largest African wintering ground of the European swallow is in the western part of the sanctuary, where an estimated 20 million of these birds roost during the winter. The Sanctuary is surrounded by 16 communities with a total population of approximately 27,000 people.^[2]

Wildlife sanctuaries play a crucial role in preserving biodiversity and represent significant ecotourism potential, making them prominent sites for effective management and conservation efforts.^[3][4] These sanctuaries provide a habitat for a majority of the remaining flora and fauna species, particularly mammalian herbivores. However, human activities are causing increasing degradation of wildlife sanctuaries. Anthropogenic activities like game exploitation, logging, farming, and urbanization in the vicinity of protected areas pose significant challenges to wildlife conservation, particularly in West Africa.^[5][6] Consequently, numerous species have become rare, and their population numbers and habitats have seen significant declines in the past century.^[7] Human activities, both legal and illegal, can lead to the extinction of fauna species, particularly mammalian herbivores, and the loss of herbivores can disrupt ecosystems, often negatively affecting other species and ecosystem services.^[8] Both the environment and anthropogenic effects pose threats to the populations of large and small mammals. Human activities, especially illegal ones, have disrupted the ecological balance in protected areas, affecting various fauna species within these ecosystems.^[9] This disruption has significantly increased the rate of mammal extinction, impacting more than one-fifth of all global mammal species.^[10] Despite their important ecosystem services, fauna species continue to be endangered by human-induced activities.^[11] Habitat destruction and degradation stand out as major factors contributing to the extinction and decline of mammalian herbivores.^[12] Mammalian herbivores encompass mammals of various body sizes, both small and large, adapted to consuming plant materials and playing a fundamental role in rangeland dynamics. They are categorized into grazers, primarily feeding on grasses and forbs, and browsers, primarily feeding on woody vegetation.^[13] These herbivores inhabit diverse terrestrial ecosystems across the globe.^[8][14]

Protected areas hold ecological significance for both large and small mammals, influencing the extent of vegetation degradation and improvement.^[4] Human activities have significantly impacted the biosphere by altering original vegetation cover, replacing it with either different flora or artificial structures. On a global scale, one of the most ecologically significant anthropogenic impacts on mammalian herbivores is habitat loss. Herbivores are often utilized as indicator species, especially in the dynamics of land use and land cover.

This sanctuary is a biodiversity hotspot within the mountainous and relatively rugged rainforest area at the border of Southeastern Nigeria and Southwestern Cameroon. In May 2000, the Cross River State Government established this sanctuary with the primary goal of safeguarding endemic and endangered wildlife species, with a particular focus on the Cross River gorilla (Gorilla gorilla diehli), Nigerian-Cameroon chimpanzee (Pan troglodytes eliotii), and drill (Mandrillus leucophaeus). Surrounding this protected area are sixteen human communities, which include Katabang, Buanchor, Olum, Enyi, Kakwagom, Esekwe, Ebok-Ebuawa, Asuben, Bitiah, Kakubok, Ndemachang, Katchie, Ebbaken, Okubuchi, Nkanyia, and Njua-Kaku.^[15]

The entire region falls within a broad annual rainfall zone, receiving an average of 3,000 mm to 3,800 mm of rainfall, with variations increasing from lowland to uphill areas.^[16] The rainy season typically spans from March to September, while the dry season extends from October to March. The mean temperature across Afi Mountain is approximately 22.2 °C, but it rises to 27.4 °C in the lowland areas. The protected region is primarily situated in the tropical high forest vegetation zone and is rich in various tree species, including Pterocarpus osun, Albizia zygia, Parkia bicolor, Pycnanthus angolensis, Irvingia gabonensis, and Monodora myristica.^[17][18] Additionally, the Afi Mountain Wildlife Sanctuary (AMWS) is home to notable wildlife species such as the red river hog (Potamochoerus porcus),^[15] bushbuck (Tragelaphus scriptus), Shelley’s eagle owl (Bubo Shelleyi), African piculet (Sasia africana), migrating European barn swallows (Hirundo rustica), and the bare-necked rock fowl (Picarthertes oreas).

The white-throated monkey or White-throated guenon, (Cercopithecus erythrogaster), ranks among the planet's severely endangered primates.^[19] Despite being safeguarded by Nigeria's Endangered Species Decree No. 11 of 1985, it receives conservation and protection exclusively within national parks, game reserves, and wildlife sanctuaries.^[20] Notably, there is no existing record of prior surveys focusing on this monkey in the Afi Mountain Wildlife Sanctuary, despite its potential for ecotourism. Habitat disturbance triggered by deforestation is a primary concern, resulting in a reduction in the population of various animal species due to either mortality or migration to more stable habitats. Another significant challenge is indiscriminate hunting, contributing to the population decline of numerous animal species within any given habitat.^[21] Hence, it faces a considerable threat.^[22]

The white-throated monkey possesses distinctive white fur on its chest and throat, providing a stark contrast to the dark hue of the rest of its fur. Typically, its coat is a dark olive-brown or blackish shade and features a white rump patch. Its facial area is devoid of fur, displaying dark skin, and notable white beard and moustache features. Its tail is lengthy and often culminates in a tuft of white fur. This monkey species primarily inhabits the tropical rainforests of Central and West Africa, including various forest types like primary and secondary forests. Their activity is mainly diurnal and arboreal, spending a significant portion of their time in trees. Their dietary preferences encompass fruits, leaves, seeds, insects, and sporadically, small animals. These monkeys exhibit exceptional climbing skills and agility in jumping. Their social structure involves group living, ranging from small clusters to larger troops, typically led by a dominant male. Conservation-wise, the monkey holds a status of "Least Concern" on the IUCN Red List of Threatened Species.^[19] However, akin to numerous primate species, they encounter threats such as habitat degradation due to deforestation, hunting for bushmeat, and illegal wildlife trade. Similar to many primates, the white-throated monkey serves a crucial role in its ecosystem by aiding in seed dispersal, promoting the growth and regeneration of plants and trees within the forest.

The Cross River gorilla (Gorilla gorilla diehli), a specific type within the western gorilla (Gorilla gorilla) family, is primarily situated in adjacent forest sections along the borders of South-Southern Nigeria and South-Western Cameroon. This region is acknowledged as a biodiversity hotspot, notable for its abundance of species and endemism.^[23] Regrettably, this subspecies stands as one of the most critically endangered primates in Africa.^[24][25] In fact, it has been recognized as one of the planet's 25 most endangered primates.^[26] With human expansion encroaching on their habitats, the Cross River gorilla faces a swift decline in habitat, posing a serious threat to its population. The Cross River gorilla, chimpanzee (Pan troglodytes vellorosus), and drill (Mandrillus leucophaeus) are among the primates protected by the Endangered Species Decree 11 of 1985, yet they face the threat of being hunted for bushmeat and other purposes.^[27] The critical challenge to the survival of this subspecies lies in the absence of a comprehensive conservation strategy essential for its protection. Effectively conserving wild animal species necessitates accurate and reliable information regarding their population numbers, age distribution, sex ratio, productivity rates, distribution, daily routines, and seasonal movements.^[28] Obtaining precise population estimates is crucial for wildlife population management.^[29] Reliable knowledge of the status and trends of animal populations, gathered through inventories and socio-ecological studies, is a fundamental requirement for successful wildlife conservation programs.^[30][31] Therefore, understanding the number of individuals within the subspecies, their distribution, and abundance is a vital component of ecological studies focusing on gorillas and their habitat, particularly within the forested corridor spanning the Afi Mountains and Mbe Mountains. The Mbe Mountains host the nearest subpopulations of Cross River gorillas, making it a top priority for the AMWS partnership to safeguard the forested corridor connecting these areas. This protection is crucial to prevent the permanent isolation of gorillas and other mammals in the Afi Mountains, facilitating the development of specific conservation strategies and policies to advance gorilla conservation in both the Afi and Mbe Mountains. Estimating the population of Cross River gorillas is essential for assessing the habitat's suitability. Gorillas, much like the majority of primates, serve as valuable indicator species.^[32] Their presence and abundance within various ecosystems offer insights into hunting pressure, disease prevalence, and resource availability, aiding in conservation efforts.

The Nigeria mona monkey (Cercopithecus mona) is categorized as "Least Concern," and it is exclusive to Nigeria and Cameroon.^[33] These monkeys are of small to medium size and usually dwell in groups of up to 35.^[34] There is limited comprehensive data on the population of this species, relying mostly on rough approximations. The primary threat to the survival of mona monkeys is considered to be poaching for the bush meat trade, although habitat loss also poses a significant risk. The Cross River rainforest is now identified as a top priority area for conservation, particularly for the mona monkey, according to a recent IUCN action plan.^[33] Hence, evaluating the population status of the mona monkey is crucial to ensure effective protection of the species in its natural habitat. The Nigeria mona monkey is a matter of serious concern for various stakeholders^[33] due to Nigeria being home to the last significant population of mona monkeys in both Africa and globally.^[35] Despite being a subject of interest among primate communities, there is limited comprehensive information available about this species.^[36]

In Nigeria, a significant challenge in wildlife conservation stems from the escalating rate of habitat degradation or alteration caused by human actions.^[37] The extensive destruction and inadequate management of Nigeria's forest ecosystems are evident and have been exacerbated by ecological crises and climate change, resulting in diminished soil fertility and a notable decline in overall biological productivity.^[38] There is a report concerning loss of about 34% of the original wildlife habitat in Nigeria.^[39] Consequently, this has impacted wildlife resources within these ecological systems, leaving only fragmented populations of wildlife resources within designated protected areas such as wildlife sanctuaries, game reserves, and national parks.

A wildlife sanctuary, often situated within a protected area, serves as a natural haven where specific species receive complete protection. The Afi Mountain Wildlife Sanctuary is a notable illustration, and was designated from the Afi River Forest Reserve primarily to safeguard various primate species, including the Cross River gorilla, chimpanzee, drill monkey, and the mona monkey. The Afi Mountains encompass remnants of the original rainforests in the Southern Nigeria eco-zone, representing a crucial hope for preserving the region's remaining biological diversity over the long term. This sanctuary boasts a diverse collection of flora and fauna species. Moreover, it stands as a prominent site contributing to the achievement of the nation's tourism objectives, featuring appealing tourist attractions for potential visitors in Southern Nigeria. Recognized within the internationally acclaimed Gulf of Guinea biodiversity hotspot, the sanctuary holds significant importance.^[40][36] This region is considered a crucial stronghold for a substantial portion of pristine tropical forest in Nigeria, displaying the highest diversity among protected forests in West Africa.^[41] Additionally, it ranks among the locations renowned for their high primate species diversity in Nigeria.

The burgeoning growth of human populations comes at the cost of wildlife populations, particularly larger animals. Widespread devastation of wildlife and their habitats has resulted in a decline in wildlife populations, particularly primates. This decline predates the establishment of settled agriculture and animal husbandry. Primates, the closest relatives of humans in the entire living world, inhabit tropical forests and savanna woodlands within the tropics. While they are widespread, they are no longer secure due to intense human-induced impacts such as poaching, uncontrolled collection of non-timber forest products, unsustainable agricultural practices, logging of wild trees for timber, and indiscriminate bush burning.^[42] The expanding human populations encroaching into forest habitats and clearing forests for agriculture are the primary reasons for forest loss.^[43] Given that primates are most diverse in tropical forests, the loss of these forests is seen as the most significant threat to their survival.^[44]

It indicates that there are approximately 625 distinct primate species and subspecies, with almost all being endangered.^[45] Similar to other large mammals, primates are relatively easy to survey because they are conspicuous and face significant hunting pressure,^[46] making them valuable indicator species. In this context, a thriving primate population can serve as a reliable indicator of the overall health of a rainforest ecosystem.^[47][48] Threats resulting from forest loss, leading to wildlife decline, encompass forest fragmentation, primate crop raiding, and hunting of primates for medicinal purposes, as pets, and for food, adversely impacting the ability of primates to survive in the near future.

In order to secure the lives of animals on the mountain, community protection patrols were put in place. Local hunters were encouraged to use from trapping instead of shooting. An education and sensitization program was organized in the 16 villages surrounding the mountain, which brought the members of communities together for the first time as a common interest group. While hunting has been kept under control in the surrounding communities through proper awareness, the sanctuary holds a partnership with individuals to enable continuous protection of its forest and wildlife.^[49]

Afi is covered by an estimated 100 km² of lowland and sub-montane forest with rocky peaks rising to altitudes of 1,300m. Although the steep mountainous slopes of the sanctuary have largely protected it from logging the forest is frequently damaged by dry-season bush fires set to clear new farms or to flush game.^[50]

The Afi Mountain Ranch provides accommodation for tourists in cabins. The ranch has a walkway through the forest canopy, 25 metres above the ground.^[50][49]

• UNESCO World Heritage Sites in Nigeria

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6°20′N 9°00′E / 6.333°N 9.000°E / 6.333; 9.000