- - Road Ecology


Road ecology “explores and addresses the relationship between the natural environment and the road system” (Forman et al. 2003).

Roads form a dense network across the United States and southern Canada, and extend in some instances far into northern Canada. Their number continues to grow. At the same time, more and more two-lane highways are being replaced with multi-lane superhighways.

Roads and traffic have a negative, and often severe, impact on many ecosystems (e.g., Jaeger 2012). Landscapes and wildlife habitat are fragmented. Waterways and wetlands are disrupted. Wildlife are killed directly in vast numbers in collisions with vehicles. Roads act as conduits for invasive species. Large areas are mined for aggregate to use in road construction. Salt and other chemicals are spread on roadways as de-icers. Chemicals are used to kill vegetation along road right-of-ways. 


In some jurisdictions (e.g., in some European countries) attempts have been made for several decades to permit large mammals to safely cross highways, including the construction of many wildlife passages over and under roadways.

In Canada attention to this problem has lagged far behind. Highways are typically not designed and constructed to accommodate the safe passage of large mammals. However, there have been a few exceptions in recent years. Wildlife overpasses have been constructed at key localities along the Trans-Canada Highway through Banff National Park, Alberta. Fencing is used to funnel wildlife to the crossings. Monitoring indicates that the passages are being utilized by a wide variety of animals and that collisions with cars and trucks have been substantially reduced.  An overpass and fencing have recently been completed over the newly expanded Highway 69 in Ontario south of Sudbury. This is believed to be the first wildlife overpass in Canada east of the Rocky Mountains.

Wildlife overpass on Highway 69 south of Sudbury, Ontario

Wildlife overpass on Trans Canada Highway, Banff Alberta

More commonly, large wildlife underpasses are being incorporated into the design of new highways. The recently opened Highway 50 between Gatineau and La Chute, Quebec includes several such structures, as does the new four-lane Trans-Canada Highway in New Brunswick.

Wildlife underpass on Trans-Canada Highway south of Perth-Andover, New Brunswick

Wildlife fencing and one-way escape gate along Trans-Canada Highway, New Brunswick

Unfortunately on most Canadian highways little effort has been made to address the issue of large mammals, except to post signs warning of increased danger where crossing by moose, deer or elk are common.


A staggering number of amphibians and reptiles are killed each year on Canadian roads (e.g. Ontario Road Ecology Group 2010; Jochimsen et al. 2004; Clevenger et al. 2001, Ashley and Robinson 1996, Fahrig et al. 1995).

To address such problems it is now becoming more common to see fencing and small underpasses being utilized in specific areas (e.g., wetlands) to keep amphibians and reptiles off of roadways.

Signs are also posted to alert drivers of areas where large numbers of amphibians and reptiles may be crossing.

These examples of wildlife passages, fencing and signage indicate the potential for mitigating some of the effects of roads on wildlife, while making roads safer for drivers. However, it is important that such structures be incorporated in all new highways and in all new expansion or up-grade projects (Fahrig and Rytwinski 2009).

There is also an urgent need for scientific studies to quantify the effects of roads and road networks on ecosystems. As discussed by van der Ree et al. (2011), few such studies have been carried out, although there are many studies that examine the effects on individual species.


Road construction utilizes vast quantities of aggregates which are mined in open pit quarries. These quarries cause serious environmental damage. Yet they are often located within sensitive ecosystems, causing loss of habitat, and damage to waterways, wetlands and aquifers. In many cases they have destroyed prime farmland.

There have been many controversial proposals for aggregate quarries in recent years. For example, a mega quarry, which would have been the largest in Canada, was proposed on Class 1 farmland of the Niagara Escarpment, a designated UNESCO World Biosphere Reserve. Only a massive Stop the Mega Quarry campaign by concerned citizens succeeded in halting the project. Unfortunately, there are numerous other quarry proposals for the region [link www.pitsense.ca].



The following steps are needed to help mitigate the damage of roads to ecosystems and wildlife.

  1. Reduce the number of roads and vehicles.

  2. Designate roadless areas. These areas should be as large as possible.

  3. Design road networks to avoid the most sensitive ecological features, and reduce ecosystem fragmentation, damage to waterways and wetlands, and roadkill.

  4. Incorporate wildlife crossings (overpasses and/or underpasses) and appropriate fencing in all road construction, upgrade and maintenance projects.

  5. Identify key “hotspots” for wildlife crossing existing roads and implement mitigation measures.

  6. Reduced speed limits, especially at night.

  7. Install signage to alert drivers in areas where animals are most active.

  8. Prohibit aggregate mining in sensitive natural areas and on prime farmland.

  9. Increase aggregate recycling.

  10. Conduct scientific studies to quantify the effects of roads and road networks on ecosystems.

  11. Conduct scientific studies on the efficiency of various mitigation measures.

  12. Educate the public on road ecology issues.


Ashley, P. E. and J. T. Robinson.  1996.  Road mortality of amphibians, reptiles and other wildlife on the Long Point Causeway, Lake Erie, Ontario.  Canadian Field Naturalist 110: 403-412.

Clevenger, A. P., M. McIvor, D. McIvor, B. Chruszcz, and K. Gunson.  2001.  Tiger salamander, Ambystoma tigrinum, movements and mortality on the Trans-Canada Highway in southwestern Alberta.  The Canadian Field-Naturalist 115: 199-204.

Fahrig, L. and T. Rytwinski, 2009. Effects of roads on animal abundance: an empirical review and synthesis. Ecology and Society 14 (1): 21.

Fahrig, L., J.H. Pedlar, S.E. Pope, P.D. Taylor, and J.F. Wegner. 1995. Effects of road traffic on amphibian density. Biological Conservation 73: 177-182

Forman, R. T. T., D. Sperling, J. A. Bissonette, A. P. Clevenger, C. D. Cutshall, V. H. Dale, L. Fahrig, R. France, C. R. Goldman, K. Heanue, J. A. Jones, F. J. Swanson, T. Turrentine, and T. C. Winter. 2003. Road ecology: science and solutions. Island Press, Washington, D.C., USA. 481 p.

Jaeger, J.A. 2012. Road ecology. The Birkshire Encyclopedia of Sustainability: Ecosystem Management and Sustainability, p. 344-350.

Jochimsen, D.M., C.R. Peterson, K.M. Andrews, and J. W. Gibbons. 2004. A literature review of the effects of roads on amphibians and reptiles and the measures used to minimize those effects. Idaho Fish and Game Department, USDA Forest Service. 78 p.

Ontario Road Ecology Group. 2010. A guide to road ecology in Ontario. Toronto Zoo, Scarborough, Ontario.

van der Ree, R., J. A. G. Jaeger, E. A. van der Grift, and A.P. Clevenger. 2011. Effects of roads and traffic on wildlife populations and landscape function: road ecology is moving towards larger scales. Ecology and Society 16 (1): 48.