Roads can greatly impact wildlife. Roads have been shown to directly or indirectly lead to habitat loss and fragmentation, poaching, over-trapping, snag reduction, negative edge effects (including increased noxious weed infiltration), movement barriers, displacement or avoidance, harassment or disturbance at specific use sites, and chronic negative interactions with humans (Wisdom et al. 2000). While hundreds of articles have documented how roads influence wildlife, no significant study has examined if and how road removal reverses these impacts.

In order to identify the best locations for wildlife road removal research, I conducted a literature review of wildlife research conducted in areas that have had extensive road removal. Where baseline data has been collected, replicate studies could be conducted to remove roads and determine how wildlife respond to road removal. After searching Wildlands CPR’s road database along with other databases such as Wildlife Ecology Worldwide, I created a spreadsheet that identified what research has been conducted on Forest Service lands where extensive road removal has occurred. I combined information on state and federal lands where road removal programs exist, the respective average miles removed per year, and what research has been done that addresses the effects of wildland roads on terrestrial wildlife. This review does not address aquatic research trends. Upon review of the data and literature, several key trends emerged. This paper highlights these trends and provides recommendations for future research sites and topics.

Research Trends:

By species:

Research on wildland roads and wildlife has been clustered predominately in the Western states of the U.S. with a few studies in the Northern Great Lakes region. Most studies were on the impacts of roads on threatened or endangered predators or game species. In the Northern Great Lakes region, several studies found that high road densities reduced wolf populations. There were a number of studies that found that roads reduced grizzly bear security in Yellowstone National Park, Wyoming, and the Flathead National Forest, Montana. Deer and elk habitat was found to be influenced by roads in Montana, California, Oregon, Washington and Colorado.

By Forest Service region:

Data gathered on roads decommissioned within the nine regions of the Forest Service during the period of 1995-2000 (Schaffer 2003) indicate that Regions I (Northern), III (Southwestern), and VI ( Pacific Northwest) had the highest average of combined system and non-system decommissioned roads per year. A closer look at the research, however, shows that the three regions vary greatly in terms of how many significant wildlife studies have been performed. For example, within Region III ( Arizona and New Mexico), only two road-related terrestrial wildlife research studies were identified on Forest Service lands. In both, researcher F.G. Van Dyke looked at the effects of roads on mountain lions. In Regions I ( Montana, Idaho and North Dakota) and VI ( Oregon and Washington), however, significant amounts of research have been conducted. Research on wildlife habitat and roads within Region I was conducted predominately in Montana. Grizzly bears are the primary research subject (four studies), followed by black bears, wolverine and elk.

Recommendations

While hundreds of studies have been conducted on the impact of roads on wildlife, road removal is occurring on a large scale in only a few areas. The areas that have had the most removed roads and have existing wildlife research have the greatest potential for future research. With the intent of building upon a baseline of road research and a large number of removed roads, the following are recommendations for immediate terrestrial research sites and subjects:

Forest Service Regions I and VI

These two regions contain the most miles of removed roads as well as the most extensive research conducted regarding roads and their effects on watersheds and terrestrial and aquatic species. Below are three key examples where existing data could be utilized as part of new research on road removal.

Montana: The Flathead National Forest has been the site of extensive studies on the black bear and grizzly bear. The University of Montana is also currently examining the impact of road removal on fish habitat restoration. With almost 400 miles of road removed in the Flathead, a study examining if road removal is securing grizzly bear habitat is needed.

Idaho: Several research projects on the impact of roads and elk have been conducted in Idaho. Most studies found improved elk security and increased hunter success following road closures. No study has examined if road removal has similar effects.

Oregon: While this state hosts the most studies regarding aquatic species, significant terrestrial wildlife studies have come out of the Starkey Experimental Station as well. Elk studies have also been conducted in the Coastal range. With baseline data collected, studies on deer and elk could be conducted where roads have been removed.

Conclusion

Although road removal is becoming an increasingly popular method of restoration, at this point there is little scientific research that addresses the impacts on terrestrial species and their habitats. Many questions, such as the influence of road removal on dispersal and migration of elk, grizzly bear and bighorn sheep have yet to be answered. There is, however, significant research addressing the impacts of roads on any number of species, from salamanders to moose and bald eagles. When this information is compiled with U.S. public land entities that have employed road removal as a restoration tool, the possibilities for future research sites and topics are clearly evident. Existing research from Montana, Idaho and Oregon can provide helpful and important baseline data from which further research can be conducted and remaining questions addressed. There is, however, potential for road removal research wherever baseline studies have been conducted or where there are active road removal programs.

Literature Cited

Schaffer, R. 2003. National Forest Service Road Decommissioning: an attempt to read through the numbers.. Available online at: http://www.wildlandscpr.org/WCPRpdfs/FSDecom.pdf [1].

Wisdom, M.J., R.S. Holthausen, B.C. Wales, C.D. Hargis, V.A. Saab, D.C. Lee, W.J. Hann, T.D. Rich, M.M. Rowland, W.J. Murphy, and M.R. Eames. 2000. Source habitats for terrestrial vertebrates of focus in the interior Columbia basin: broad-scale trends and management implications. Volume 1 – Overview. Gen. Tech. Rep. PNW-GTR-485. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. Available at: http://www.fs.fed.us/pnw/pubs/gtr485/gtr485v1.pdf [2].

—Ariel is a graduate student in the Environmental Studies Department of the University of Montana.