Distribution of a Community of Mammals in Relation to Roads and Other Human Disturbances in Gabon, Central Africa

Abstract

We present the first community-level study of the associations of both roads and other human disturbances with the distribution of mammals in Gabon (central Africa). Our study site was in an oil concession within a littoral mosaic landscape. We conducted surveys along 199 line transects and installed camera traps on 99 of these transects to document mammal presence and abundance. We used generalized linear mixed-effect models to document associations between variables related to the ecosystem (land cover, topography, and hydrology), roads (coating, width of rights of way, condition, type of vehicle used on the road, traffic level, affiliation of users, and general type of road), and other human disturbances (urbanization, agriculture, hunting, logging, gathering, and industrial activities) and the abundance or presence of 17 species or groups of mammals including elephant (Loxodonta cyclotis), buffalo (Syncerus caffer), sitatunga (Tragelaphus spekei), red river hog (Potamochoerus porcus), smaller ungulates, gorilla (Gorilla gorilla), chimpanzee (Pan troglodytes), side-striped jackal (Canis adustus), carnivores, monkeys, and large rodents. Some types of roads and other human disturbances were negatively associated with the abundance or presence of elephants, buffalos, gorillas, sitatungas, some monkeys, and duikers. The pattern of associations of mammals with roads and other human disturbances was diverse and included positive associations with road presence (red river hog, some monkeys, and duikers), agriculture (sitatunga, small carnivores, and large rodents) and industrial activities (sitatunga, red river hog, red duikers, and side-striped jackal). Our results suggest that the community of mammals we studied was mostly affected by hunting, agriculture, and urbanization, which are facilitated by road presence. We recommend increased regulation of agriculture, hunting, and road building in the area.Distribución de una Comunidad de Mamíferos en Relación a Carreteras y Otras Perturbaciones Humanas en Gabón, Africa CentralResumenPresentamos el primer estudio a nivel de comunidad de la relación entre carreteras y otras perturbaciones humanas con la distribución de mamíferos en Gabón (África central). Nuestro sitio de estudio está dentro de una concesión petrolera en un paisaje litoral heterogéneo. Realizamos muestreos a lo largo de 199 transectos lineales e instalamos cámaras trampa en 99 de ellos para documentar la presencia y abundancia de mamíferos. Utilizamos modelos lineales generalizados con efectos mixtos para documentar las asociaciones entre variables relacionadas con el ecosistema (cobertura de suelo, topografía e hidrología), carreteras (tipo de revestimiento, ancho de derecho de vía, condición, tipo de vehículos que utilizan la carretera, nivel de tráfico, afiliación de los usuarios y el tipo general de carretera) y otras perturbaciones humanas (urbanización, agricultura, caza, tala, recolecta y actividades industriales) y la abundancia o presencia de 17 especies o grupos de mamíferos incluyendo e...

Antipoaching standards in onshore hydrocarbon concessions drawn from a Central African case study

“…With the similarly observed increase in logging and charcoal production, as well as agricultural deforestation at our site (Eyenbiang Ndong 2011), we believe the decreasing poaching trend resulted from game becoming rare or overhunted close to the local town, thus poaching drifted outside the concessions. This pattern is consistent with the results of landscape-scale monitoring of mammals in the area (Vanthomme et al 2013). This reinforces the need to couple antipoaching efforts with regular monitoring of the mammals targeted by hunters to understand observed trends.…”

“…Despite these measures, poaching, consumption, and trade of bushmeat occur in their oil concession, and large-mammal products are regularly observed in markets and restaurants in the nearest town. Preferred means of poaching at the study site are wire snaring and gun hunting for small mammals, as well as for African forest elephants (Loxodonta cyclotis) and buffalos (Syncerus caffer nanus), although they are fully protected in Gabon (Vanthomme et al 2013). Wire snares are illegal across Africa because they indiscriminately kill or disable animals of all sizes (Becker et al 2013), but in Gabon, snaring is commonly justified to protect plantations that are also frequently the base for gun-hunting trips.…”

“…Small and large game poaching increased with distance from town, meaning poachers were willing or obliged to travel several kilometers to hunt. This is probably because target species avoid road edges and areas under direct human influence in the study area (Vanthomme et al 2013).…”

Effects of Road Density and Pattern on the Conservation of Species and Biodiversity

“…Another emerging issue is that roads bring humans more readily into contact with wildlife. Three studies demonstrated that as road networks develop and increase accessibility of the landscape, the opportunities for hunting also increased [93][94][95]. Essentially, road networks increased the proportion of the landscape that could be accessed by humans and in so doing decreased the amount of available wildlife refuge [93].…”

“…Three studies demonstrated that as road networks develop and increase accessibility of the landscape, the opportunities for hunting also increased [93][94][95]. Essentially, road networks increased the proportion of the landscape that could be accessed by humans and in so doing decreased the amount of available wildlife refuge [93]. For example, a notable increase in the bushmeat trade is threatening the population persistence of game species [95].…”