Wildlife Fencing Escape Ramp Monitoring: Preliminary Results for Mule Deer in Southwest Colorado

Animal-vehicle collisions have negative impacts to human safety and wildlife populations and are therefore a topic of great concern to transportation and wildlife managers. Beyond risks of injury or death, animal-vehicle collisions can result in high economic costs from property damage and loss of wildlife recreation opportunities. A key mitigation measure includes use of wildlife fencing. However, fencing can also create a physical barrier that traps wildlife in right-of-way areas near the road and it blocks wildlife linkages across the landscape; thus it has the potential to increase animal-vehicle collisions and hinder wildlife movement. To allow escape for wildlife, earthen ramps are often constructed from inside of the right-of-way with a gradual slope to the height of the wildlife fence, which creates a sharp drop outside the fence allowing wildlife to jump to safety. The authors provide preliminary results for a monitoring effort that will eventually have 2 years of data. From August 2012 – April 2013, they monitored 11 escape ramps embedded within a 5-mile stretch of wildlife fencing along Highway 550, north of Ridgway, Colorado. The authors focused on quantifying successful escape ramp usage by mule deer as a function of escape ramp design using motion-activated infra-red video cameras. Ramp characteristics important in determining escape success included jump height, slope, and whether a horizontal bar was present. Ramp visits had strong seasonality with greatest use in fall and early spring. The authors also report on the use of these ramps by other wildlife species. In addition to a better understanding of the seasonality in ramp use over the remainder of the study, the authors plan to assess whether road or landscape characteristics help explain ramp use.