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28 <br /> In fragmented landscapes,habitat connectivity can be achieved through naturally occurring or created <br /> habitat corridors(Gilbert-Norton et al. 2010), defined as"patch[es] of habitat(often linear)that link two <br /> or more other natural habitat patches,providing habitat for animals as they disperse or migrate"(NCWRC <br /> 2012) (see Appendix B: Glossary for more detailed definition). Corridors can include crossing structures <br /> that enable wildlife to cross barriers such as roads,reducing wildlife collisions with vehicles(Bennett <br /> 1999). Corridors allow wildlife populations to move to meet daily and seasonal resource needs,to <br /> interbreed with other populations, and to colonize new or former habitat areas (such as after recovery <br /> from disturbance or disease)by increasing the potential for dispersal from one habitat patch to another <br /> (MRCS 2004,Hilty et al. 2006). Maintaining habitat connectivity reduces the susceptibility of wildlife <br /> populations and species to decline and local extinction that can occur through, for example,the <br /> deleterious effects of increased predation, disease, and natural catastrophes when there are no avenues for <br /> escape or recovery through movement of individuals between populations and habitat areas(Rudnick et <br /> al. 2012). <br /> THE IMPORTANCE OF WILDLIFE CROSSINGS <br /> Roads contribute to wildlife habitat fragmentation and can function as barriers to wildlife movement or <br /> sources of wildlife mortality from wildlife-vehicle collisions (WVC)(National Research Council 2005) <br /> (Figure 5). In the US,over one million vertebrates are killed each day due to WVC(Bissonette and <br /> Cramer 2008 in Ernest and Sutherland 2017). Human safety is also at issue,with more than 61,000 <br /> wildlife-related vehicle crashes recorded in North Carolina from 2011 to 2013,causing nearly 20 human <br /> fatalities, greater than 3,400 injuries, and more than$149 million in damages(Oliver 2014 in Ernest and <br /> Sutherland 2017). <br /> Pollution <br /> Barrier effects <br /> Traffic mortality <br /> Corridor/ <br /> Dispersal <br /> Corriclorl Habitat transformation <br /> Dispersal <br /> Predation <br /> Disturbancel <br /> /1.ldancel Road effect <br /> Edge effects zone <br /> Figure 5. Schematic showing the primary effects of roads on wildlife species and <br /> populations(reproduced from National Research Council 2005). <br /> Wildlife crossings,including underpasses, overpasses,and wildlife-friendly culverts, can facilitate <br /> wildlife movements and have been shown to reduce WVC (Clevenger et al. 2001 in Ernest and <br /> Sutherland 2017). Indeed,properly designed wildlife crossing structures installed or retrofitted at priority <br /> A Landscape Plan for Wildlife Habitat Connectivity 15 <br />