Banff National Park of Canada

Park Management

Trans-Canada Highway Twinning

The Banff Wildlife Crossings Project Report, 2002

RESEARCH

WILDLIFE MORTALITY ON ROADS

What Animals Are Dying On The Roads?

We summarized the large mammal road-kills from 1981 to 2001 in our study area.

• 4051 large mammals were killed on highways. This included 188 large carnivores (black bears, grizzly bears, wolves, cougars) - black bears and wolves were killed in the largest proportions. A total of 3863 ungulates (deer, elk, big-horn sheep, and moose) were killed - deer and elk road-kills occurred in the largest numbers.
   
• The Trans-Canada Highway (TCH) in the province of Alberta, i.e. east of Banff National Park, and the TCH phase 1 and 2 sections (before they were mitigated) in Banff had the two highest road-kill rates for ungulates and carnivores.

What are the Characteristics of Wildlife-Vehicle Collisions?

Wildlife-vehicle collisions occurred more often during dark and dusk compared to when it was light. Accidents with wildlife also occurred more often on weekends than weekdays. Wildlife-vehicle collisions occurred more frequently in the fall, compared to spring or winter.

Passenger vehicles were involved in 86% of the wildlife-vehicle collisions on the highway. However when the number of passenger and large vehicles (e.g., motor homes, buses and large trucks) traveling on highways was taken into account, a higher proportion of accidents were caused by larger vehicles.

Motor vehicle accidents of all types can vary in their severity to passengers (no injury, injury, or death). A motorist is less likely to be injured in a wildlife-vehicle collision, than other types of accidents. Motorists were less likely to become injured when driving in slush, snow or ice conditions compared to dry conditions. And motorists were more likely to become injured when driving a passenger vehicle than driving a large vehicle.

What are the Characteristics of Small Animal Road-kills?

River otter killed on the highway
© Tony Clevenger

We wanted to know what characteristics are associated with small animals, coyote-sized and smaller, getting killed on the highway. We surveyed roads varying in traffic volume, configuration and adjacent landscape features for small animal road-kills between 1997-2000.

Kill rates were remarkably low compared to the amount of roads surveyed - much lower than previous studies in other study areas, surveying shorter road sections for shorter periods. Our low road-kill rates do not imply that the roads have little effect on small animal populations in the Bow Valley, as local animal populations may have already decreased from decades of cumulative road-kill impacts.

This may be explained by a higher number of bird individuals, than small mammal individuals within the TCH corridor. We suspect that the disturbance generated from a highway of such magnitude as the TCH may deter small animal movements onto or across the roadway.

We found that road-kills occurred in hotspots or were clustered along roads. Road-kills were less likely to occur on raised sections of road, but road-kills tended to occur close to vegetative cover, and far from wildlife passages or culverts. This suggests that when culverts are a certain distance apart there may be a greater tendency for animals to cross above the road. When culverts are close together, they are more likely to be used for safe passage.

Small mammal and bird road-kill rates were consistently higher on the low volume Bow Valley Parkway than on the high-speed, high volume TCH. Our findings show how two distinct road types can have different effects on small animal mortality and their distribution.

For more information see Chapter 4 in Final Report

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