Participatory monitoring reveals village-centered gradients of mammalian defaunation in central Africa

Abstract

Tropical areas are facing a bushmeat crisis involving the systematic over-exploitation of large-bodied mammals for both subsistence and commercial purposes. We hypothesize that because hunting generally originates from villages, it will create “halos of defaunation” where abundances of large mammals increase with distance away from villages. Whilst such patterns have been well characterized at the landscape scale, examining how defaunation halos vary between different villages has received considerably less attention. Forests immediately surrounding villages are of considerable importance to the people residing within them and the factors hypothesized to influence local defaunation halos (e.g. village size, hunting practices and access to local markets) may affect local livelihoods and the ecological integrity of nearby forests. To address this, we adopted a participatory approach to establish and monitor sixty transects across ten village-distance gradients (1-8 km) in Gabon. Trained paraecologists, recruited from local villages, walked each transect twice monthly to determine the encounter rates of medium and large mammals across the village distance gradient and monitored village-level bushmeat availability.We found that overall rates of mammal observation and estimated species richness were constant across the village-distance gradient, however the total number of individuals encountered and bushmeat biomass were lower close to villages – consistent with local depletion of wildlife. These general trends were underpinned by depleted mammal species diversity with increasing proximity to villages and a marked shift in mammal community composition: small, non-hunted species were encountered most frequently near villages, whereas large, hunted species were encountered most frequently away from villages. We found some evidence for inter-village variation in the strength and depth of defaunation halos, which may be driven in part by the village-level hunting intensity. Several of the key parameters identified in landscape-scale bushmeat studies did not detectably influence village-level defaunation (e.g. road or market distance). Despite the prevalence of bushmeat hunting in the region, the conservation value of forests immediately surrounding villages was demonstrated through the detection of large-bodied species of conservation concern (e.g. chimpanzee and gorilla) at a high proportion of survey locations.The compositional shifts in mammal communities detailed here will ultimately lead to the altered composition and diversity of forests around villages, with potential implications for human livelihoods, health and transmission of zoonotic disease. This research also demonstrates the effectiveness of engaging paraecologists to answer focused ecological questions - the first step in facilitating effective natural resource management by local communities.