Minimizing the biodiversity impact of Neotropical oil palm development JAMES J. GILROY 1 , GRAHAM W. PRESCOTT 2 , JOHANN S. CARDENAS 3 , PAMELA GONZ  ALEZ DEL PLIEGO CASTA ~ NE D A 4,5 , ANDR  ES S  ANCHEZ 3 , LUIS E. ROJAS-MURCIA 3 , CLAUDIA A. MEDINA URIBE 3 , TORBJØRN HAUGAASEN 1 andDAVID P. EDWARDS 5,6 1 Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences,  As, Norway, 2 Department of Zoology, University of Cambridge, Cambridge, UK, 3 Instituto de Investigaci on de Recursos Biol ogicos Alexander von Humboldt, Bogot a, Colombia, 4 School of Environmental Sciences, University of East Anglia, Norwich, UK, 5 Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK, 6 School of Marine & Tropical Biology, James Cook University, Cairns, Qld, Australia Abstract Oil palm agriculture is rapidly expanding in the Neotropics, at the expense of a range of natural and seminatural hab- itats. A key question is how this expansion should be managed to reduce negative impacts on biodiversity. Focusing on the Llanos of Colombia, a mixed grassland–forest system identified as a priority zone for future oil palm develop- ment, we survey communities of ants, dung beetles, birds and herpetofauna occurring in oil palm plantations and the other principal form of agriculture in the region – improved cattle pasture – together with those of surrounding natu- ral forests. We show that oil palm plantations have similar or higher species richness across all four taxonomic groups than improved pasture. For dung beetles, species richness in oil palm was equal to that of forest, whereas the other three taxa had highest species richness in forests. Hierarchical modelling of species occupancy probabilities indicated that oil palm plantations supported a higher proportion of species characteristic of forests than did cattle pastures. Across the bird community, occupancy probabilities within oil palm were positively influenced by increasing forest cover in a surrounding 250 m radius, whereas surrounding forest cover did not strongly influence the occurrence of other taxonomic groups in oil palm. Overall, our results suggest that the conversion of existing improved pastures to oil palm has limited negative impacts on biodiversity. As such, existing cattle pastures of the Colombian Llanos could offer a key opportunity to meet governmental targets for oil palm development without incurring significant biodi- versity costs. Our results also highlight the value of preserving remnant forests within these agricultural landscapes, protecting high biodiversity and exporting avian ‘spill-over’ effects into oil palm plantations. Keywords: agroecosystems, amphibians, ants, birds, community ecology, dung beetles, pastoral, reptiles, tropical savannah Received 16 March 2014; revised version received 30 June 2014 and accepted 3 July 2014 Introduction Oil palm cultivation is expanding rapidly in many parts of the tropics, despite the severe environmental costs incurred when plantations replace natural habitats (Fitzherbert et al., 2008; Koh & Wilcove, 2008; Danielsen et al., 2009). Demand for oil palm is set to increase, par- ticularly with the expanding market for biofuels (Slade et al., 2014). Although most research on environmental impacts has focussed on developments in Asia (Zhou & Thomson, 2009), oil palm expansion is gaining momen- tum in Africa and South America (Butler & Laurance, 2009; Sayer et al., 2012). In the Neotropics, few studies have directly assessed the impacts of oil palm expan- sion on biodiversity (Livingston et al., 2013), inhibiting evidence-based development policies. The economic and social benefits of oil palm develop- ment can be high (Rist et al., 2010; Lee et al., 2011), bringing strong incentives for governments to encour- age oil palm growth. The Colombian government, for example, have identified oil palm as a top priority for agricultural development, forming a mainstay of the country’s ambitious biofuel programme (MADR, 2006, 2008; Castiblanco et al., 2013). An important question is how the environmental impacts of such goals can be minimized. For biodiversity, the most promising option is for policymakers to promote oil palm development on existing agricultural lands, relieving pressure on remaining wilderness areas (Koh & Wilcove, 2008; Correspondence: Present address: James J. Gilroy, School of Envi- ronmental Science, University of East Anglia, UK, tel. +44 1603 592542, fax +44 1603 591327, e-mail: james.gilroy1@googlemail. com 1 © 2014 John Wiley & Sons Ltd Global Change Biology (2014), doi: 10.1111/gcb.12696 Global Change Biology