VTrans Amphibian Road-Crossing Modeling

Statewide, VT

21,405 MI
of Roads and
Railroads Modeled
1,596 MI
of Potential

Identifying Amphibian Road-Crossing Hotspots

The State of Vermont is home to a wide array of amphibians, including rare or uncommon species such as the Jefferson, blue-spotted, and four-toed salamanders. Many amphibian species make seasonal movements between their breeding habitat in wetlands and upland overwintering habitats. When roads lie between these two habitats, amphibian mortality can be high as they attempt to traverse these crossings, which can have devastating impacts to local amphibian populations. Some of these road-crossing “hotspots” have been identified, but many have not.

In order to gain a more comprehensive understanding of these “hotspots”, VTrans tasked MJ with assisting them in modeling areas across the state where relatively large numbers of amphibians are likely to cross the roadway. To accomplish this task, MJ teamed with the University of Vermont (UVM) Spatial Analysis Lab and herpetologist Jim Andrews to adapt and improve a prior pilot study model. The MJ team developed a GIS-based model that combines wetland/upland, land cover, forest types, topography, and other landscape features to identify the most likely amphibian crossing “hotspots”, statewide. VTrans and designers can now use this data to identify areas where amphibians may be impacted and where mitigation measures, such as building amphibian crossing structures, may be warranted. These types of structures will assist in reducing amphibian mortality.