Collision mortality is seasonally variable in areas where animal migrations cross traffic routes, a problem only expected to intensify as more people move to these areas. We completed the first of three years of post-construction monitoring of two wildlife underpasses installed south of the growing town of Jackson, Wyoming, USA to facilitate ungulate (and other wildlife) movement between summer and winter range. In the first post-construction migration season, we observed a reduction in ungulate collisions in the section where the underpasses and high fencing were installed, relative to sections of the same road to the North and South of the completed construction. Both underpasses were used by a variety of wildlife species, including the two migrating ungulates, Elk (Cervus canadensis) and Mule Deer (Odocoileus hemionus). We observed differences in the timing of underpass use by the most common species both across annual and daily cycles. We found evidence of directional movement corresponding to expected migration patterns for Elk, but not for Mule Deer, despite observing distinct patterns of seasonal activity. Camera monitoring at both ends of underpasses allowed us to calculate camera-specific detection probabilities, to estimate missed crossing events and apply adjustments to camera positioning.
Wildlife movement: connectivity, safety, across eco-tones