Vermont’s new Terrestrial Passage Screening Tool ranks all the bridges and culverts on the state system with respect to facilitating wildlife movement. The tool relies on statewide omniscape modeling and includes scores for landscape context, site-level conditions, and structure characteristics. This tool is the most recent step in a long series of efforts that Vermont has undertaken to better understand the interaction of roads and wildlife and fits into a larger state conservation design.
The Vermont Conservation Design is a database and mapping tool for identifying Vermont's lands and waters that support important ecosystems, natural communities, habitats, and species. (It helps coordinate conservation implementation among state agencies and conservation partners, including both the work of NGOs as well as in municipal land use planning. That design incorporates a comprehensive view of connected habitat not only for far ranging mammals but also for climate migration of all manner of species. It includes an understanding of diversity in the physical landscape with riparian connections and wildlife road crossings (based on models of structural connectivity showing potential over-the-road locations). The design is currently being updated to include LIDAR-derived land cover data to better map connecting lands and will feature the TPST to expand the understanding of the importance of transportation infrastructure that facilitates under the road movement.
Habitat connectivity has a different look in the eastern U.S. context than it does in other places around the world. Here there aren’t large herds of ungulates that migrate across roads and most eastern species feel more secure in close forests than in wide-open-places. Furthermore, the landscape context of privately owned land with frequent sideroads and driveways has significant implications for fencing that would increase the efficacy of overpasses. The TPST enables VT transportation and wildlife officials to better prioritize structures that facilitate under the road movement and is an essential element in our overall conservation design.