Abstract:Roads have detrimental impacts on wildlife populations around the world. Specifically, roads pose direct and indirect threats to wildlife by limiting dispersal movements or through vehicle-related mortality. The rate of wildlife mortality varies both in time and space depending on the landscape composition and the type and use of road infrastructure. The objective of this study was to investigate spatiotemporal variation of vertebrate mortality in a 4 km segment of the 34 national road, adjacent to Carara National Park, Costa Rica. We conducted 81 roadkill surveys by car and bicycle from June 2010 to May 2011, georeferenced the locations of the kills and identified them to the lowest possible taxonomic level. We recorded a total of 4 709 road-killed animals of at least 58 species of vertebrates during the whole study. Amphibians accounted for 93.5 % of all the vertebrate losses and showed strong spatiotemporal variation of mass mortality events. Reptiles, especially snakes, were the second most affected taxon followed by mammals and birds. Relative mortality per day in the 4 km segment was 125.4 amphibians, 4.6 reptiles, 2.7 mammals, 1 bird and 0.46 undetermined. Road proximity to the border of the park, traffic volumes and lack of enforcement of speed limits may influence the high rate of roadkills found. We suggest the reinforcement of speed limits, wildlife crossing signage and the retrofitting of the existing culverts as under passes for animals to minimize vertebrate mortality at the road adjacent to Carara National Park. Rev. Biol. Trop. 65 (4): 1261-1276. Epub 2017 December 01.Key words: amphibian mass-kill, animal-vehicle collisions, conservation areas, extinction threat, tropical forest.Road networks are human extensions that facilitate transportation and economic development. However, the construction and the use of roads generate a broad range of negative effects, including habitat loss, fragmentation, the emissions of chemicals and noise pollution (reviews in Forman et al., 2003;Coffin, 2007;Van der Ree, Smith, & Grilo, 2015). Furthermore, roads may limit or preclude animal dispersal (e.g. Mader, Schell, & Kornacker, 1990;Clarke, White, & Harris, 1998;Develey & Stouffer 2001;Colchero et al., 2010;Long, Diefenbach, Wallingford, & Rosenberry, 2010) and induce mortality through vehicle-animal collisions (reviews in Forman & Alexander, 1998;Forman et al., 2003;Coffin, 2007;Van der Ree et al., 2015).Although the road-automobile system is a relatively recent source of wildlife mortality, it accounts for millions of roadkills every year in different latitudes, and may well exceed natural mortality rates in certain populations (Forman & Alexander, 1998 (Bissonette, 2002) and 80 million birds (Erickson, Johnson, & Young Jr., 2005) in the United States. These numbers illustrate the magnitude of this human induced phenomenon.The frequency at which animals of different taxonomic groups are reported to be killed on roads varies greatly. After reviewing several early roadkill studies conducted during the ...