The Afi Mountain Wildlife Sanctuary (AMWS) occupies approximately 100 km² in the north-western area of the Afi River Forest Reserve in the northern part of Nigeria's Cross River State. The forest reserve was created in 1930, while the wildlife sanctuary was gazetted in 2000 with the particular aim of protecting a sub-population of Cross River gorillas (Gorilla gorilla diehli), currently considered to number 25-30 individuals. AMWS includes the main massif of Afi Mountain, a rugged hill range with five main peaks (the highest of them reaches 1,318 m) separated by deep valleys, and an extensive lowland area to the west of the mountain (Oates 2009). Rivers form on either side of these valleys and flow east or west down to the lowlands through valleys that separate each main ridge (McFarland 2007). These rivers provide the main water source for the 16 surrounding communities. The climate of Afi Mountain Wildlife Sanctuary is highly seasonal, with marked dry and rainy seasons. Substantial rain falls between May and October with the heaviest rainfall in July and September. November through March is the dry season with very little or no rainfall.

The Afi forest is located within Nigeria's largest remaining block of rain forest that straddles the border between south-western Cameroon and south-eastern Nigeria and that forms the heart of a globally significant biodiversity hotspot with high species richness and high levels of taxonomic endemism (Oates et al. 2004). Afi is particularly notable for its fauna of endangered primates (Cross River gorilla, Nigeria-Cameroon chimpanzee, and drill) and is also an important site for biome-restricted birds.

On 14 July 2012, a series of severe landslides ravaged several portions of the central and southern axis of Afi Mountain Wildlife Sanctuary, eroding vegetation along mountain valleys and slopes, destroying many illegal farms and watersheds as well as polluting sources of drinking water and killing some wildlife. Large patches of land slid away in different locations, leaving these portions of the sanctuary bare and open to erosion. It is estimated that there could have been as many as 50 simultaneous landslides on the same fateful day.

The cause of these landslides is unknown. Local people have linked it with the wrath of the gods, but the presence of large numbers of illegal farms within the sanctuary and the unusually high rainfall experienced within the month of July are likely the causes. There are at least 600 illegal farms in the wildlife sanctuary (Morgan et al. 2011), mostly cocoa and banana farms, in both the lowland areas and the steep slopes of the mountains. A recent study revealed that the deforestation rate is very high in the Afi Mountain Wildlife Sanctuary and that the annual deforestation rate doubled from 0.37% in 1998-2000 to 0.64% in 2000-2010 (Okeke 2013).

At the same time rainfall patterns have become increasingly unpredictable and erratic; rainfall in July 2012 was unusually high (more than 1,200 mm), and twice that of the previous month (June) and that of August same year. In the period from 1998 to 2000, the mean annual rainfall ranged from 3,420 to 3,650 mm (McFarland 2007), whereas in the period from 2010 to 2012 it ranged from 2,890 to 3,895 mm.

The impact of landslides cannot be over-emphasized and their effects have been felt by both the surrounding communities and the wildlife community in the sanctuary. A number of buildings in 5 communities, as well as 3 major bridges, were totally destroyed. Watersheds along the valleys were totally eroded resulting in acute scarcity in the surrounding communities. Sources of drinking water were severely polluted while others were mud-filled and silted. Carcasses of wildlife species, mostly duikers, porcupines, snakes and hyraxes were found, and some sections of the sanctuary became inaccessible for months. No ape carcasses were found immediately after the landslides and it is believed that no apes were killed directly, although maps of the distribution of ape nests within the sanctuary indicate that they may have been temporarily displaced towards the southern boundary of the sanctuary, and further towards the edges of the sanctuary where there are more farms. On 26 September 2012, during routine anti-poaching patrols, bones of two gorillas were discovered in a hunting shed on the southern edge of the sanctuary.

It is recommended that alternative sources of drinking water be provided to all the affected communities including ranger posts and base camps. All illegal farms should be eradicated and further encroachment discouraged.

Emmanuel Sampson Bassey and Francis Okeke

WCS acknowledges the support of the US Fish and Wildlife Service, the US Forest Service, North Carolina Zoo, the Kolmården Fundraising Foundation, Great Apes Survival Partnership (GRASP), Berggorilla & Regenwald Direkthilfe and Columbus Zoo for their financial and technical support. We are grateful to Pandrillus for providing the rainfall data and to the Cross River Forestry Commission for their collaboration.

References

McFarland, K. L. (2007): Ecology of Cross River Gorillas (Gorilla gorilla diehli) on Afi Mountain, Cross RiverState, Nigeria. Ph.D. Thesis, City University of New York Graduate Center, New York

Morgan, B. J. et al. (2011): Regional Action Plan for the Conservation of the Nigeria-Cameroon Chimpanzee (Pan troglodytes ellioti). IUCN/SSC Primate Specialist Group and Zoological Society of San Diego, CA, USA

Oates, J. F. (2009): Biodiversity of the Afi Forest Complex, Cross River State Nigeria: A Desk study

Oates, J. F. et al. (2004): Africa's Gulf of Guinea Forest Biodiversity Patterns and Conservation Priorities. Advances in Applied Conservation International, Washington D.C.

Okeke, O. F. (2013): Land Cover Change Analysis in Afi-Mbe-Okwangwo Landscape Cross River State Nigeria. Unpublished Report to Wildlife Conservation Society