Banff National Park of Canada
Trans-Canada Highway Twinning
Banff Crossings Project Report, 2002
FREQUENTLY ASKED QUESTIONS
Is the Trans-Canada Highway fencing effective in reducing wildlife-vehicle collisions?
Highway mitigation, (structures designed to minimize the impact of the road) consisting of fencing and wildlife crossing structures, has been highly effective in reducing wildlife-vehicle collisions. The mitigation measures have resulted in more than an 80% reduction in all wildlife road-kills, and more than 95% reduction in road-kills for ungulate species.
How do we know what wildlife are using the crossing structures?
We are able to see what wildlife use the crossing structures by checking raked track pads within the structures every 2-3 days. We check the passages year-round. Animals leave their tracks on the track pads and we identify the species, the number of individuals, and their direction of travel.
Are the crossing structures working?
It depends on your criteria, whether you are referring to one species in particular, or the park ecosystem. Judging the success of mitigation measures needs to take into account both the goal of reducing road-kills (fencing) and the barrier effects of highways (wildlife passages). From our five years of monitoring we can safely say the crossing structures are working from a multi-species perspective as we have documented use by all animals from marten, to grizzly bears. If we also want to determine if these measures are maintaining the biological fitness of the animals, long-term co-lateral research studies will have to be carried out.
What do wildlife prefer& an underpass or an overpass?
Results from our research indicate that all wildlife needs cannot be entirely met by one simple crossing structure type. All wildlife in Banff were documented using underpasses and overpasses alike; however, for each species some designs seem more suitable than others. Wildlife underpasses are generally exposed, restricted, and often narrow environments. Cougars and other wildlife that need cover tend to prefer underpasses. Deer and elk, which typically live in open habitats, appear to prefer structures like the overpasses or open-span bridge underpasses, that are more open, i.e., wide, high and have lots of light.
How long and often do you need to monitor wildlife movements at crossing structures?
Our 5-year study spanned a time when wolves in the Bow Valley ranged from nearly locally extinct, to 17 individuals divided between two, year-round resident packs, the Bow Valley and Fairholme packs. Wolf behavior towards the wildlife crossing structures also varied from nearly complete avoidance by one seasonally-occcurring pack (Cascade), to multiple passages per day at any given underpass by the Fairholme pack. The wildlife underpasses adjacent to and east of Banff were not used in the winter for the six years the Cascade pack visited the Bow Valley.
The appearance of a group of resident wolves that adapted quickly to the same wildlife underpasses the Cascade pack shunned in winter, underscores the need for long-term monitoring, in conjunction with co-lateral wildlife studies to properly assess the conservation value of wildlife crossing structures. Small sampling windows, typical of six month, one- or two-year monitoring programs are too brief, can provide erroneous results and do not adequately sample the range of variability in species wildlife crossing structure use patterns, in landscapes with complex wildlife-human land use interactions.
Is animal use changing over time?
Yes. As species' population numbers change over time, the species' use changes. Phase 1 & 2 saw an eightfold, increase in wolf use with the addition of the Fairholme pack in the park. On the contrary, cougar use decreased as cougar numbers declined in the vicinity of the townsite. Also animals take some time to adapt to new structures in the landscape; overpass use increased for grizzly bears, cougars, and wolves throughout the five years of monitoring. This is why long-term monitoring is essential to understand the changing dynamics of crossing structure use.
Do predators sit and wait at the entrances to the wildlife crossing structures for their prey?
Most passage studies record no evidence of predation in or around passages. We only found one instance where a cougar appeared to have preyed on an elk at an underpass near the Banff townsite. Animals probably tend to avoid the road corridor after passage due to high traffic volumes and noise disturbance.
What is a greater threat to maintaining healthy wildlife populations – barrier effects (not getting across the road)? or road mortality (getting killed on the road)?
Roads impact wildlife primarily by road-kill and limiting movements across them. Both impacts do not impact wildlife populations equally. Road-kill has an immediate and direct effect on a population, easily seen in 1-2 generation's time. On the other hand, complete barrier effects (no animals moving across) can take several generations to develop within a population. Barrier effects on a grizzly population may take as long as 50 years to measure due to their long generation time.
How will we know where to put the wildlife crossing structures in the future?
Many studies in Banff have been working towards answering this question during the last five years. Previous TCH improvement projects had little time to collect valuable information on where the most important wildlife crossing locations are on the TCH. Numerous research projects have collected this "animal tracking" information by way of 1) radio telemetry monitoring of bears, wolves and cougars, 2) snow tracking, 3) observations, and 4) where animals do not successfully cross the highway (road-kills). Wildlife movement models have been developed in a Geographic Information System to predict the likely locations for wildlife travel across the TCH and the animal tracking information above has been used to measure how accurate the models are in their predictions. The results indicate that the models are very accurate and therefore they are being used to map future wildlife crossing structure locations on the TCH.
For more information see Chapter 6
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