Banff National Park of Canada
Trans-Canada Highway Twinning
The Banff Wildlife Crossings Project Report, 2002
ARE WE REDUCING WILDLIFE ROADKILL?
There is still a lot to be learned about effective fencing designs and solutions for keeping wildlife away from roads, and thus avoiding road-kill. The sheer measure of fence material laid out on the TCH, the varying fence designs, and accompanying assortment of adjoining gates makes the wildlife exclusion fence in Banff an ideal object of mitigation study.
Do Fences Reduce Road-kill?
We measured the performance of highway mitigation fencing to reduce wildlife-vehicle collisions along three, 4-lane sections (phase 1, 2 and 3A) of the Trans-Canada Highway (TCH) from 1981 to 1999.
When fencing was put up, wildlife mortalities were reduced effectively as ungulate-vehicle collisions declined by more than 95%. Vehicle collisions with all wildlife were reduced with fencing by more than 80%.
Fencing results were mixed for carnivores. Mortality was highest (64%) for all carnivores on unmitigated sections of highway, however 50% of black bears and 75% of cougar kills occurred on fenced mitigated sections. Black bears and cougars easily climb over the mitigation fence, and coyotes can access the right-of-way by going under the fence at numerous ground gaps.
The marked decrease in wildlife mortalities along Phase 1 and 2 of the TCH after fencing is convincing evidence that fencing can be effective highway mitigation.
Chart showing the number of road-kills for phase 1 and 2 highway segments for each year with respect to installation of wildlife fencing and average annual daily traffic volumes from 1981-1999.© Tony Clevenger
The effectiveness of fencing in reducing wildlife mortalities was supported by Royal Canadian Mounted Police motor vehicle accident data for the Banff (fenced) and Canmore (unfenced) sections of the TCH. Between 1995 and 1997, 63% of the motor vehicle accidents on the unmitigated Canmore section involved wildlife (more than half the accidents), while only 11% (1 in 10 accidents) of the accidents on the mitigated Banff section involved wildlife.
Chart showing the incidence of wildlife-caused motor vehicle accidents on two distinct sections of Trans-Canada Highway - Canmore (unfenced, unmitigated) and Banff (fenced, mitigated).
© Tony Clevenger
Unburied vs. Buried Fences - Which Works Better at Keeping Animals Off the Highway?
An effective wildlife fence is needed if highway mitigation measures are to be successful. The fence is one part of the two-part mitigation equation = fencing + wildlife crossing structures. Fencing keeps wildlife away from the roadway and leads animals to wildlife crossing structures, so they can pass safely under or above the highway. Fences need to be effective for the highway to be safe for motorists and road mortality minimized.
Using five years of data documenting the number of fence intrusions by wildlife onto the TCH, we looked at how effective the buried fence (phase 3A) was at reducing fence intrusions compared to the unburied, ungulate-proof fence (phase 1 and 2).
We found more intrusions on the unburied phase 1 and 2 fence section compared to the buried phase 3A fence section.
Chart showing the number of intrusions by animals on the phase 1 & 2, phase 3A and the Castle Junction sections of the Trans-Canada Highway from January 1997 to February 2002.
© Tony Clevenger
For more information see Chapter 5 in Final Report
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