A Brief Review of the Scientific Literature on Elk, Roads, & Traffic

Outside of wilderness areas, road networks are a ubiquitous feature of most landscapes inhabited by elk (Cervus elaphus). Roads have obvious utility: they facilitate basic transportation, commerce, recreation, land and facility management, firefighting, etc. However, roads also potentially have effects on ecosystems and the organisms that inhabit them (Forman et al. 1997, Coffin 2007). These effects commonly vary with season; road type, location, and construction; time-of-day; type and/or level of use; and species of organisms potentially affected. Fahrig and Rytwinski (2009) recently summarized nearly 80 studies that quantified the effects of roads and traffic on the abundance of 130 species of wildlife. In the studies they reviewed, the ratio of negative to positive effects of roads on the abundance of wildlife was 5:1. Across species groups, road effects on large mammals were predominantly negative. Others have also broadly reviewed the influences of roads on ecosystems and species based on published research (Forman and Alexander 1998, Spellerberg 1998); these authors also concluded that roads and traffic often mediate complex effects and impacts, despite their utility.

Dating back to the 1970s, a substantial number of published scientific papers have specifically explored and quantified the influences of roads and traffic on elk, in part because of the importance of elk-centered recreation in the Pacific Northwest and Intermountain West (Bolon 1994). In this paper, I review many of these published reports. Research on the effects of roads and traffic on elk and elk management have focused on 3 broad, yet inter-related ways roads may potentially affect elk: 1) physiologic and energetic effects, 2) effects on distribution and habitat use, and 3) effects on vulnerability to mortality and, potentially, population dynamics. See also Gaines et al. (2003), Rowland et al. (2004), and Gagnon and Dodd (2007) for other reviews of the influence of roads on elk behavior.