The magnitude of the US 93 North reconstruction project offers an unprecedented opportunity to evaluate to what extent these mitigation measures help improve safety through a reduction in wildlife-vehicle collisions and to what extent they maintain habitat connectivity for wildlife.

In addition, the landscape along US 93 North is heavily influenced by human use, in contrast to the more natural habitats along most of the other road sections that have large-scale wildlife mitigation in North America. Since roads with most wildlife-vehicle collisions are in rural areas influenced by human use, the results from the US 93 North project are expected to be of great interest to agencies throughout North America.

Data Collection

In 2002, prior to US 93 North’s reconstruction, data were collected and a final report on the preconstruction monitoring findings was published in 2007. While the preconstruction monitoring and research efforts are valuable on their own, their main purpose is to provide a reference for a before-after comparison with the post-construction data.

In 2010 MDT contracted with WTI-MSU to conduct the post-construction research evaluating the effectiveness of the mitigation measures. For this project, the CSKT act as a subcontractor to WTI-MSU. This post-construction evaluation will be completed in 2015.

The goals of the research are to investigate the “effectiveness” of the wildlife crossing structures and wildlife fencing and to identify best management practices and further research that may benefit future wildlife-vehicle collision reduction and wildlife crossing mitigation projects. Consistent with the direction provided by MDT, the project is centered on three main subjects:camera_picture

  • Improvement in human safety through a reduction in wildlife-vehicle collisions;
  • Maintaining habitat connectivity for wildlife through the use of the wildlife crossing structures; and
  • A cost-benefit analyses for the mitigation measures.

For a detailed description of data collection methods and the research plan, please see Huijser et al. 2009’s Proposal

Generally, data collection and monitoring methods include:

  • Collection of the number of animal-vehicle collisions through Montana Highway Patrol accident reports, MDT carcass removal reports, and Montana Fish, Wildlife, and Parks bear road mortality data
  • Digital motion-sensitive wildlife cameras (see picture) at the majority of crossing structures, ends of fences, and jump-outs
  • Sand tracking beds at jump-outs and selected crossing structures
  • Deer pellet group surveys to measure potential changes in the deer population size

Preliminary Results

Yearly reports for  201020112012, and 2013 describe in detail the results of post-construction wildlife-vehicle collision and wildlife crossing monitoring research. Here is a quick summary!

During 2010, 2011, and 2012, over 53,600 wildlife movements have been documented with use by over 30 species. The majority of movements is by white-tailed deer, mule deer, and domestic dogs and cats (Figure 1 and Table 1). Thousands of ‘other’ species have used the structures as well (Table 2). The estimate is reported as a minimum because not all 41 structures on US93N are monitored using wildlife cameras.

To see great pictures of wildlife using the structures, head to the Photo Gallery page!

Figure 1. Wildlife use of 27 wildlife crossing structures monitored in 2010, 2011, and 2012 (total 53,604)


Table 1. Wildlife use of 27 wildlife crossing structures monitored in 2010, 2011, and 2012 (total 53,604)

White-tailed deer 6,712 14,206 13,088
Mule deer 1,174 1,952 1,656
Domestic dog 1,130 2,362 1,147
Domestic cat 785 1,588 1,011
Other (unknown species) 1,660 2,358 2,214
Total 12,022 22,466 19,116

Table 2. Number and percentage of wildlife use in the “other” category in Figure 1 and Table 1

Coyote 356 263 164
Black bear 297 289 418
Raccoon 281 439 377
Bobcat 142 202 127
Birds 125 553 317
Red fox 95 250 247
Western striped skunk 86 124 142
Mountain lion 29 51 104
Rabbits and hares 26 55 38
American badger 20 9 13
Beaver 14 0 0
Grizzly bear 3 15 4
River otter 6 3 0
Elk 0 6 2
Long-tailed weasel 2 1 1
Yellow-bellied marmot 2 2 2
Common porcupine 1 0 2
Moose 1 0 2
Bear (unk species) 10 3 2
Canine (unk dog vs coyote) 73 0 0
Deer (unk species) 561 63 186
Other/Unknown 91 30 66
Total 2,221 2,358 2,214

Other Research on US93N

Research on the wildlife crossing structures has been completed by several graduate students .

Allen, Tiffany Dore Holland, “The Use of Wildlife Underpasses and the Barrier Effect of Wildlife Guards for Deer and Black Bear” (2011). Theses, Dissertation, Professional Papers.

Connolly-Newman, Hayley R., "Effect of Cover on Small Mammal Abundance and Movement Through Wildlife Underpasses" (2013). Theses, Dissertations, Professional Papers. Paper 350.

Fairbank, Elizabeth Rose, "Use and Effectiveness of Wildlife Crossing Structures with Short Sections of Wildlife Fencing" (2014). Theses, Dissertations, Professional Papers. Paper 4164.

Purdum, Jeremiah P., "Acceptance of Wildlife Crossing Structures on US Highway 93 Missoula,Montana" (2013). Theses, Dissertations, Professional Papers. Paper 47.


Student Art Contest


The People's Way Partnership conducted the Safe Passages for Wildlife poster contest to teach school-age children about the importance of wildlife crossing structures under and over highways for both human and wildlife safety.
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