in a 20-mile stretch of Interstate15 south of its confluence with Interstate 70 led to the establishment of a mitigation strategy focused on mule deer. The strategy focused on two major objectives: 1) decrease wildlife-vehicle crashes and 2) maintain and improve landscape permeability that facilitates wildlife movement across the highway. The mitigation put in place involved the construction of exclusion fencing, right-of-way escape ramps, and two underpasses designed primarily for large-mammal passage. In this study, we assessed the effectiveness of the mitigation measures in reducing mule deer mortality and evaluated the success of the new underpasses in allowing wildlife to cross the road safely. In this poster, we compare the pre- and post-construction levels of road mortality. We also report observed problems with the mitigation structures as well as the solutions we used to solve them. We used remotely sensed cameras to record deer passage through the new underpasses during the Fall 2004 and Spring 2005 migrations and compare results with a 20-year old ‘control’ structure. Early results showed a sporadic and lower use of the new underpasses. We suspect that the novel presence of the new crossing structures, coupled with historic learned-behavioral migration patterns, may be responsible for these early results. The number of animals that used the new structures, however, leaves optimistic expectations for increased use in the future. We will test the prediction of increased use during the Fall 2005 and Spring 2006 migrations. In this poster, we also address the use of bait to encourage passage, and report on the occurrence of startle behavior in response to heavy traffic, suggesting that it may be fruitful to explore the effects of noise and the visual barriers to encourage underpass passage by wildlife.

Several indirect effects of roads on wildlife communities have been reported such as habitat quality alteration, loss in landscape connectivity, and barrier effects (Forman et al., 2003; Jaeger et al., 2005). An effect zone of up to 100m on either side of the road has been described as causing measurable impacts on ecological communities (Underhill and Anglod, 2000).

Roads can impact small mammal communities by: 1) creating an edge with different habitat characteristics (Garland and Bradley, 1984; Tyser and Worley, 1992); 2) promoting the introduction of exotic species (Getz et al., 1978; Vermeulen and Opdam, 1995; Underhill and Anglod, 2000); 3) increasing stress and reducing survival (Benedict and Billeter, 2004) through disturbance and contamination (Jefferies and French, 1972; Williamson and Evans, 1972; Quarles et al., 1974); 4) blocking movement thus causing genetic barriers and home range rearrangements (Oxley et al., 1974; Garland and Bradley, 1984; Mader, 1984; Swihart and Slade, 1984; Merriam et al., 1989; Gerlach and Musolf, 2000); and finally 5) causing direct road mortality (Wilkins and Schmidly, 1980; Ashley and Robinson, 1996; Mallick et al., 1998).

While the main focus of studies on the impact of roads on small mammals has been on road barrier effects, less attention has been given to the effect of roads on density and diversity of local communities.

Further analysis on the effect of roads on natural habitats is needed. Our objective was to assess and compare density estimators and diversity of small mammal communities in areas influenced by roads with areas having no road influence.