The Madison Valley is situated in the Greater Yellowstone Ecosystem (GYE) and plays a key role in connecting this ecologically intact ecosystem to other intact areas of the Central Rockies, particularly the wildlands of central Idaho and the Selway-Bitterroot Ecosystem. US 287 and MT 87 were hypothesized to form a partial barrier for wildlife movement between protected lands around Yellowstone National Park, Hebgen Lake, and a large block of core wildlife habitat on public lands in the Gravelly, Snowcrest, and Centennial Mountains. These highways also bisect important winter range for ungulates. Traffic volumes are likely to increase incoming years, along with risk to motorists and impacts on wildlife. The overall objective of this project was to investigate the effect of the major highways in the Madison Valley on wildlife mortality and movement patterns. If data such as these are available in the early planning stages of highway projects, accommodation measures can be built into planned construction in a way that minimizes cost.
The study area, in the Madison Valley, Montana, covered approximately 90 miles along the US 287 corridor from Norris Hill to the junction of US 191, including the portion of MT 87 from the US 287 junction to Raynolds Pass on the Montana-Idaho border. Wildlife carcass data were systematically collected three times per week, year-round for two years and then analyzed to determine patterns in carcass locations and identify hotspots. Animal location and movement data were also collected year-round over the two-year period, and photo monitoring was used to qualitatively assess species movement at 11 existing culverts and bridges. Data were also incorporated from other sources including recent telemetry data from state and federal agencies. Research was conducted by WTI in partnership with the Craighead Institute.