Reducing wildlife mortality on Interstate 90

Animal-vehicle collisions are a growing safety, socio-economic, and ecological concern as vehicle miles traveled and human encroachment into wildlife habitat increases throughout the United States. More than 1 million deer-vehicle collisions occur annually in the United States resulting in more than 200 fatalities, 29,000 injuries, and costing $1.1 billion in vehicle damage alone. Vehicle-related wildlife mortality can threaten some wildlife populations' long-term viability, which, in turn, can impact the ecological integrity of ecosystems. Transportation and natural resource agencies are searching for potential solutions to this ubiquitous "side effect" of transportation systems.

Numerous measures to reduce animal-vehicle collisions have been tried with varying degrees of success. The most promising method is wildlife fencing (with wildlife passages to reduce habitat fragmentation), which has been shown to reduce animal-vehicle collisions by 80-90%.

In partnership with the Western Transportation Institute (WTI) and the Montana Department of Transportation (MDT), CERI began a study to assess the amount and nature of roadkill on Interstate 90 over Bozeman Pass in 2000. Data on roadkill locations and species has been systematically collected since 2001. Between 2001 and 2005 at least 1,336 animals were killed; over half were deer, but at least 34 elk, 48 coyotes, 18 black bears, 18 red fox, and 8 mountain lions, were also killed.

Deer, elk and mountain lions are some of the many species killed on Interstate 90.

Using these roadkill data CERI convinced the Montana Department of Transportation to include a section of wildlife fencing in their plans to rebuild a bridge over the Montana Rail Link crossing near Bear Canyon. In 2004 CERI constructed a track bed to record the number of animals crossing underneath the bridge. Two years of data were collected from this trackbed. Remote cameras were placed in culverts to record animal movements. The bridge was replaced in 2006 and lengthened to provide more room for wildlife to cross under the highway. Fencing was then installed to direct animals underneath the Interstate through the bridge or through a pair of large culverts. The fencing was completed in the spring of 2007 and CERI began a monitoring project to determine the effectiveness of the fencing at reducing roadkill and increasing animal movement underneath the highway.

		By December 2010, CERI will have a better idea as to how effective the fence is. However, in the first 2 years of data collection, only one deer has been killed on the highway within the fenced area. There also appear to be more deer than before crossing through the railroad underpass and more bears than before passing through the culverts. CERI has also been working with the Bozeman Pass Working Group (BPWG) to address ways to protect and improve wildlife connectivity and human safety in the Bozeman Pass area. This group has helped secure conservation easements and land exchanges to protect wildlife habitat on both sides of the MRL bridge crossing site. CERI has given presentations to local audiences and has led field trips for university students, college students, highway professionals, and interested stakeholders.
Digging track bed to record animal movements