Terrestrial mammal responses to oil palm dominated landscapes in Colombia

The rapid expansion of oil palmcultivation in the Neotropics has generated great debatearound possible biodiversity impacts. Colombia, for example, is the largest producer of oil palmin the Americas, but the effects of oil palmcultivation on native fauna are poorly understood. Here, we compared how richness, abundance and composition of terrestrial mammal species differ between oil palmplantations and riparian forestin the Colombian Llanos region. Further, we determined the relationships and influence of landscape and habitat level variables on those metrics. We found that species richnessand composition differed significantly between riparian forestand oil palm, with site level richness inside oil palmplantations 47% lower, on average, than in riparian forest. Within plantations, mammalian species richnesswas strongly negatively correlated with cattle abundance, and positively correlated with the density of undergrowthvegetation. Forest structure characteristics appeared to have weak and similar effects on determining mammal species richnessand composition along riparian foreststrips. Composition at the landscape level was significantly influenced by cover type, percentage of remaining forest and the distance to the nearest town, whereas within oil palmsites, understoryvegetation, cattle relative abundance, and canopy cover had significant effects on community composition. Species specific abundance responses varied between land cover types, with oil palmhaving positive effects on mesopredators, insectivoresand grazers. Our findings suggest that increasing habitat complexity, avoiding cattle and retaining native riparian forestregardless of its structure inside oil palm-dominated landscapes would help support higher native mammal richness and abundance at both local and landscape scales.