The Washington State Department of Transportation and partner agencies have devoted a great deal of time and money to the Snoqualmie Pass East Project – a major widening and enhancement project on Interstate-90 within the Cascade Mountains. This projects includes the construction of dozens of wildlife crossing structures (WCS), including two wildlife overpasses (one constructed and one planned), designed to achieve full ecological connectivity in a sensitive environment that supports movements of many species from cougar and elk to wolverine and fisher. The project area is flanked by U.S. Forest Service land and several access roads supporting ample outdoor recreation which can lead to human encroachment on WCS. While only a few long-term studies within the WCS interface have investigated the effects of human presence on wildlife use of structures, the evidence is clear: human disturbance has the chance, and is even likely, to disturb wildlife activity, altering their natural behavior and potentially sabotaging the major investments made to increase habitat connectivity. This presentation will review the relevant literature related to human disturbance of wildlife, both within and away from the WCS interface, and discuss why it is recommended that efforts be taken to limit, or entirely eliminate, unpermitted human use of structures designed to convey wildlife movement.
Mitigation / restoration
wildlife crossing structures