Human Activity and Forest Degradation Threaten Populations of the Nigeria–Cameroon Chimpanzee (Pan troglodytes ellioti) in Western Cameroon

Abstract

Increased human activities such as commodity-led deforestation, extension of agriculture, urbanization, and wildfires are major drivers of forest loss worldwide. In Cameroon, these activities cause a loss of suitable primate habitat and could ultimately threaten the survival of chimpanzees (Pan troglodytes). We derived independent estimates of the population size of the Endangered Nigeria–Cameroon chimpanzee (Pan troglodytes ellioti) in Kom-Wum Forest Reserve, Cameroon, and surrounding unprotected forest areas through 1) direct observations, 2) camera trapping, 3) distance sampling, 4) marked nest counts, and 5) standing crop nest counts. In addition, we georeferenced signs of chimpanzee and human activity along line transects. We used a generalized linear mixed model to predict the occurrence of chimpanzees in response to edge length (measured as the perimeter of core forest patches), core area of forest patches (measured as area of forest patches beyond an edge width of 100 m), habitat perforation (measured as the perimeter of nonforested landscape within core forest patches), patch size(measured as area of forest patches), and forest cover. Chimpanzee density estimates ranged from 0.1 (direct observation) to 0.9 (distance sampling) individuals km−2 depending on estimation method with a mean nest group size of 7 ± 5.4 (SD). The mean encounter rate for signs of chimpanzee activity was significantly higher in mature forests (2.3 signs km−1) than in secondary forests (0.3 signs km−1) and above 1000 m elevation (4.0 signs km−1) than below 1000 m (1.0 signs km−1). The mean encounter rate for signs of human activity was significantly higher in secondary (8.0 signs km−1) than in mature forests (0.9 signs km−1). Secondary forests, habitat perforation, and edge length had a significant negative effect on the occurrence of chimpanzee signs. Overall, human activity and forest degradation affected the number of observed chimpanzee signs negatively. Regular antipoaching patrols and reforestation programs in degraded areas could potentially reduce threats to populations of endangered species and may increase suitable habitat area.

Environmental and anthropogenic effects on the nesting patterns of Nigeria–Cameroon chimpanzees in North‐West Cameroon

“…The positive association between primary forest and nest locations reported in this and previous studies may also be due to the presence of a high density of large fleshy fruits trees (Balcomb et al, 2000; Chitayat et al, 2021; Potts et al, 2011), and low impact of human activities (Strindberg et al, 2018). Although secondary forests may provide important food resources for chimpanzees (Basabose, 2005), our results strongly suggest that chimpanzees rarely nest in this vegetation type because of poaching and harvesting of timber and non‐timber plant products (Fotang et al, 2021). Chimpanzees avoided low elevations areas in this study because these habitats are made up of rich soils suitable for farming, especially along the banks of three rivers that flow through the reserve (Chuo et al, 2017; Fotang et al, 2021; Kah, 2015).…”

“…Although the selection of tall trees for nesting by chimpanzees is related to the presence of chimpanzee predators such as leopard at some study sites (Hernandez‐Aguilar et al, 2013; Pruetz et al, 2008; Stewart & Pruetz, 2013), the preference for tall trees for nesting in KWFR may be also related to human activities such as poaching and harvesting of timber and non‐timber forest products (Fotang et al, 2021). In fact, chimpanzee predators such as leopard were not found in KWFR in the current and past surveys (Chuo et al, 2017; Doumbé, 2015).…”

“…Maps of (a) Cameroon and the study location Kom‐Wum Forest Reserve (KWFR) in North‐West Cameroon (redpoint), (b) map of KWFR including major villages with transects for surveys (1–23) and location of camera traps (Fotang et al, 2021)…”

Reaffirming the Loma Mountains National Park in Sierra Leone as a critical site for the conservation of West African chimpanzee (Pan troglodytes verus)

“…Furthermore, more sustainable and responsible agricultural management should be urgently implemented to avoid deforestation, as well as providing alternative revenue sources, other than agriculture, for communities inhabiting around the LMNP. The reinforcement of the aforementioned traditional taboos against chimpanzee meat consumption, along with the awareness of the risks associated with zoonotic transmission of diseases from bushmeat hunting and consumption (i.e., Ebola), may also reduce the threats for the species (Fotang et al, 2021; Heinicke et al, 2019). Eventually, to evaluate trends in the abundance of the LMNP chimpanzees, a regular assessment is advisable as it would provide up‐to‐date data that will inform on temporal and spatial population changes.…”

Effect of Anthropogenic Activities on the Population of Moor Macaques (Macaca maura) in South Sulawesi, Indonesia

“…We considered a habitat as suitable for macaques when forest cover was ≥50% per km 2 , because this is necessary for moor macaques to find shelter and food (Fotang et al, 2021). We considered primary, old and young secondary forest and agroforest (i.e., forest area composed of natural plant species growing among crops; Nekaris et al, 2017) as suitable forest types for moor macaques.…”