AUTHOR’S POSTPRINT Published version of this article at http://omicron.ch.tuiasi.ro/EEMJ/issues/vol11/vol11no6.htm Environmental Engineering and Management Journal, June 2012, Vol.11, No. 6: 1171-1178. The Link Between Roadkills Distribution And The Surrounding Landscape In Two Highways In Navarre, Spain Jordi Puig  , Arturo H. Ariño, Luis Sanz University of Navarra, Department of Zoology and Ecology, E-31080 Pamplona, Spain Abstract A research on wildlife road-kills, mostly medium-sized mammals, has been conducted for two years along two highways (namely A-15 and A-10) in the Euro Siberian area of northwest Navarre (Northern Spain) between the westernmost side of the Pyrenees and the Basque Mountains. The study intended to find out a link between their distribution and the structure of the landscape surrounding it. The roads were segmented into 100-m stretches, and inspected weekly for roadkill by research staff with the collaboration of the maintenance service of both freeways. The data of the 539 animals recorded and geolocated in the segments were analysed spatially and matched to the surrounding landscape and presence of crossing structures. Results showed that the spatial distribution of wild medium-sized mammal road-kills along these freeways was not random, and that the surrounding landscape and the potential permeability of these roads did affect the road-kill rates. Existence of permeable crossings and heterogeneous landscape units reduced roadkill, while homogeneous agricultural and human landscapes increased roadkill rates. Key words: highway, landscape, Pyrenees, road ecology, roadkill, wildlife Received: December, 2011; Revised final: May, 2012; Accepted: June, 2012  Author to whom all correspondence should be addressed: E-mail: jpbaguer@unav.es; Phone: +34 948 425 600 (Ext. 6496); Fax: +34 948 425 649 1. Introduction The “barrier effect” could be described as the resistance provided by a linear infrastructure against the wildlife moving through it (Baur and Baur, 1990; Clevenger et al., 2001; Conrey and Mills, 2001; Curatolo and Murphy, 1986; Klein, 1971; Mader, 1984; Oxley et al., 1974; Richardson et al., 1997; Swihart and Slade, 1984; Solheim et al., 1995, Wilkins, 1982). The “barrier effect” is due to several mechanisms. Firstly, a change in the movement patterns of terrestrial fauna (Beier, 1995; Cameron et al., 1995; Gibbs, 1998; Lovallo and Anderson, 1996; McLellan and Shackleton, 1988; Murphy and Curatolo, 1987; Trewhella and Harris, 1990) that can be measured by fencing, changes in habitats near roads, noise, vibrations and lighting. Secondly, the increase in roadkill (Aaris-Sorensen, 1995; Ashley and Robinson, 1996; Coulson, 1982; Davies et al., 1987; Drews, 1995; Fahrig et al., 1995; Groot-Bruinderink and Hazebroek, 1996; Hels and Buchwald, 2001; Lehnert and