Wildlife Crossings: Key to Highway Safety in Banff National Park
When the 82-kilometer section of the Trans-Canada Highway that runs through the Rocky Mountains in Banff National Park was built in the early 1950s, it wasn't expected to be the significant artery it is today. But as park visitation increased, traffic volume surged—and so did highway-related wildlife mortality.
Wildlife Crossings Key to Highway Safety in Banff (C) Joel Sartore
In 1978, Public Works Canada proposed twinning the section of the highway that runs from the park's east gate to the Banff townsite to improve the safety of motorists and animals. The twinning ultimately extended to Castle Junction by 1997 and the British Columbia border by 2014. Along with the twinning came an interesting engineering opportunity through Parks Canada—the construction of wildlife crossings to decrease vehicle collisions and restore critical migration routes that the highway had blocked. Banff's first two wildlife overpasses were built in 1996 for $1.5 million each. A series of underpasses followed, tunneling beneath the highway to provide a safe alternative.
Combined with fencing to keep the animals off the road, the structures have reduced animal-vehicle collisions in the area by more than 80% and more than 96% for elk and deer alone. The overpasses look like any other highway bridge to passing motorists: solid concrete arching over the highway. But catch a glimpse of the top, and it's clear they cater to a different crowd—the forest stretches from one side to the other, uninterrupted by the highway below. Fencing along the sides ensures the fauna stays out of harm's way.
Long-term research and monitoring of the structures—which started in 1996 and is ongoing—shows that more than 12 species—including deer, lynx, coyotes, wolves, wolverines, and bears—use the crossings, even changing their behavior to do so.
Elk were the first large species to use the crossings, testing them out while they were still under construction.
Monitoring also shows that different species have different preferences: grizzly bears, deer, moose, and elk favor the open air of the overpasses, while cougars and black bears prefer the cozy coverage the tunnels provide.
The crossings also help maintain genetic diversity in wildlife populations, reconnecting the habitat on either side of the highway and allowing the different groups of the same species to interact.
Banff's Wildlife Crossings Project, which includes bridges and tunnels enabling wildlife to cross the highway safely, has inspired scientists worldwide to incorporate highway mitigation projects in their countries.
Wildlife Crossing in Banff National Park (C) Wikimedia Commons
Why Do Animals Cross the Highway?
Animals need to cross the highway to search for companionship, mates, food, shelter, and, in some cases, to escape predators.
Do highway fencing and wildlife crossing structures prove effective?
It took some cautious species, such as grizzly bears, up to five years to utilize wildlife crossing structures; however, most species are now taking advantage of these crossings to safely navigate the Trans-Canada Highway (TCH). Since the implementation of fencing and crossing structures, the number of wildlife-vehicle collisions has decreased by over 80%.
Do Animals Prefer Underpasses or Overpasses?
Wildlife utilizes both underpasses and overpasses; however, different species exhibit specific preferences when given a choice. Grizzly bears, wolves, elk, moose, and deer tend to prefer crossing structures that are high, wide, and short. In contrast, black bears and cougars typically favor long, low, and narrow underpasses.
Does Human Use of Wildlife Crossings Affect How Animals Use Them?
Yes. When people use crossings, animals tend to use them less. Human use of overpasses is prohibited in Banff National Park.
How Do Small Animals Get Across the Highway?
Small and medium-sized animals, such as snowshoe hares, pine marten, fishers, porcupines, squirrels, and voles, have different requirements for movement across the TCH. Pine martens, snowshoe hares, and red squirrels used drainage culverts more often when traffic volumes were high, while coyotes used them less.
What Is the Greatest Threat to Healthy Wildlife Populations?
Roadkill has a swift and direct impact on wildlife populations, noticeable within one or two generations of the species involved. Conversely, the effects of complete obstacles like highways that inhibit animal crossings might take several generations to manifest in a population. For example, in the case of grizzly bear populations, understanding the implications of barrier effects could take as long as 50 years, which might lead to considerable repercussions for genetic diversity and the overall health of the population.
How Do We Know Where to Put Future Wildlife Crossings?
Over the years, information about where different species are most likely to cross the highway has been collected using:
Radio telemetry monitoring
Animal tracks in the snow
Wildlife observations
Roadkill hot spots
Wildlife movement models were built using mapping software to predict the most likely locations for wildlife travel across the TCH based on topography and habitat data for five species (black and grizzly bears, wolves, elk, and moose). Locations for future wildlife crossing structures were then identified.
Due to increased traffic, concerns regarding motorist safety, and wildlife deaths related to highways, an upgrade of the Trans-Canada Highway's 82 km stretch in Banff National Park started in 1981 to expand from two lanes to a four-lane divided highway. Completed in January 2014, this project includes 38 wildlife underpasses and six overpasses extending from the east entrance of Banff National Park to the Yoho National Park border, along with one underpass located in Yoho National Park.
The installation of highway fencing in Banff National Park has led to a reduction of over 80% in wildlife-vehicle collisions, with reductions exceeding 96% specifically for elk and deer. Wildlife crossings are specifically built to connect essential habitats and facilitate the safe transportation of animals across busy roadways.
Banff National Park features the highest number and a diverse range of wildlife crossing structures in the entire world. It also hosts the longest continuous monitoring program and boasts the largest dataset concerning wildlife mitigation globally.
As of 2012, wildlife crossings have recorded the passage of eleven species of large mammals over 150,000 times since 1996. These species include grizzly and black bears, wolves, coyotes, cougars, moose, elk, deer, bighorn sheep, and more recently, both wolverines and lynxes.
Animals often take time to adapt to utilizing wildlife crossings after they are built. For more cautious species like grizzly bears and wolves, it may take as long as five years before they feel comfortable using the newly constructed crossings. Elk were the earliest large species to start using the crossings, even while they were still being constructed!
Studies indicate that grizzly bears, elk, moose, and deer favor wildlife crossings that are elevated, spacious, and short in distance, which includes overpasses. Conversely, black bears and cougars appear to prefer crossings that are elongated, low, and narrow.
Research utilizing DNA is investigating how wildlife crossings benefit animals like bears and wolverines. DNA hair samples are obtained by placing barbed wire at crossings or at strategically selected "hair-snagging sites" within the broader landscape.
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