Many animal migration patterns are still intact in the greater Jackson area due to the large quantity of protected land. Large animals such as elk, mule deer, and pronghorn have separate winter and summer habitats and are moving in the spring and fall. Elk, moose, and other large animals also converge in the low-lying areas around Jackson during the winter months to escape deep snow at higher elevations. All of this movement increases the likelihood of wildlife-vehicle collisions on roads. Jackson and Teton County have recorded over 5,000 wildlife–vehicle collisions since 1990. As a result, the Western Transportation Institute (WTI) was tasked with completing a report to examine the feasibility of a wildlife-crossing master plan. In May 2018, the WTI and Teton County published the Teton County Wildlife Crossing Master Plan. The master plan studied and identified seven highway segments suitable for wildlife crossings and other vehicle-collision mitigation. These highways include U.S. Route 191 (US 191), US 26, US 89, US 26, Wyoming Highway 220 (WYO 22) and WYO 390.
Overview From 2010 to 2018, 43 animal species were recorded in Teton County's wildlife–vehicle collision database. Elk (327 collisions), moose (143), and mule deer (1,427) had the largest numbers of collisions in the Jackson area. The WTI examined crash and carcass data when it developed the Teton County Wildlife Crossing Master Plan. Although the data tends to reflect large- and medium-sized collisions, safety and conservation concerns extend beyond these documented encounters; ecological concerns extend to aquatic habitats and fish populations. Although traffic and animal-migration patterns vary by season, there is a constant presence of vehicular traffic and large mammals in and around Jackson. Each of the seven identified highways averages 10,000 vehicles per day, with volumes varying from 23,000 vehicles per day at peak season on one road to 1,500 vehicles per day on the lowest-volume stretch of highway.
Human safety and economic impact Vehicle collisions with large mammals can result in property damage, injury and death. The Wyoming Department of Transportation (WYDOT) estimates that there is a 79-percent chance of a driver's colliding with wildlife on Wyoming roads. WYDOT also estimates that these collisions result in $50 million in damage per year (vehicle damage and personal-injury costs). WYDOT estimates that the average animal collision in Wyoming will cost a driver $11,600. In a 2003 study by the Jackson Hole Wildlife Foundation, it was estimated that wildlife collisions in Teton County cost $1.2 million per year. More recently, the Jackson Hole Wildlife Foundation completed an economic impact assessment for 2016-2017 that found total economic loss from wildlife collisions to be $3,172,837 in Teton County. The Nature Conservancy (TNC) estimates that wildlife collisions cost Wyoming drivers $25 million in injury and property damage, and $24 million to taxpayers in lost wildlife productivity. TNC also estimates that Wyoming wildlife collision costs involving mule deer, elk and moose are $10,500, $25,319, and $37,873, respectively. A number of studies document the economic value of wildlife, including the major local economic drivers of tourism, recreation and hunting. Studies indicate that there are approximately 211 fatalities and 29,000 human injuries in the United States each year due to vehicle collisions with wildlife.
Biological conservation Wildlife is impacted by roads and traffic in five broad categories: loss of habitat, road mortality, barriers to wildlife movement, decreases in habitat quality, and the introduction of non-native species. These categories are used to estimate the impact of roads on biological conservation. In addition to deer, elk and moose, animals with high conservation value in the area include river otter, lynx, grizzly bear, and bison. According to Anthony Clevenger of the WTI, "generalizations about the conservation value of habitat corridors remain elusive because of the species-specific nature of the problem". Due to the complex nature of habitats in and around Jackson, the Teton County Wildlife Crossing Master Plan evaluates the biological conservation value of each roadway based on the migration patterns of large and medium-sized mammals most likely to encounter vehicle traffic on a specific route. The Jackson Hole Wildlife Foundation (JHWF) demonstrated the urgency of this problem by tracking moose-specific deaths due to vehicle collisions in the Jackson area. JHWF tracked 50 moose deaths due to collisions over a decade, and compared that to the estimated 70 moose that live near town. Their research indicates that this moose population could be at risk due to the frequency of collisions. JHWF believes that it "can save an average of 190 moose, 210 elk and 360 deer every 20 years" with the construction of wildlife crossings. In assessing biological conservation value, the concept of ecological permeability becomes an important element of the master plan. Ecological permeability has broad scientific consensus. Although vehicle–wildlife collisions are the most acute aspect of biological conservation with respect to wildlife overpasses, the ability for species to migrate and interact with the larger ecosystem is considered crucial for the health and maintenance of species and ecosystem. Research also demonstrates that facilitating permeability requires that wildlife crossings be species-specific; for example, ungulates prefer overpasses and carnivores prefer underpasses. The Teton County Master Plan takes these biological-conservation and permeability factors into account in its analysis and planning process.
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