INTRODUCTION

The Trans-Canada Highway (TCH) is one of the most important transportation corridors in Canada, connecting the nation’s east and west. However, it has raised environmental concerns as the corridor bisects the Banff National Park (BNP), fragmenting the habitats of wildlife population and acting as a barrier to natural movements in the park (Ford et. al, 2009; Clevenger et. al, 1997). This kind of barrier causes biological isolation of species to some extent, leading to the disturbance of genetic flow. Further, the highway is a crucial factor that contributes to wildlife mortality. About half of the wildlife death can be due to highways as reported in 1996, making it more crucial to mitigate the impact of the TCH on wildlife (Jiling, 2014). The Banff Wildlife Crossing Project (BWCP) first commenced in 1978, before the term “nature-based solutions (NBS)” was even coined. Yet, this project carries the principles of what we know today as NBS, and thanks to the long-lasting nature of the project, it has provided us with many datapoints to analyze its effects as well as insights into how a long-term NBS project should be managed.

The scientific and conservation communities have been focusing on the environmental impact of the highways. In particular, they were concerned about the predicted growth in population and transportation demand in the Rocky Mountains, coupled with the highway expansion plan. For instance, the effects of the TCH on wildlife in Banff could reduce the wildlife population through increasing mortality and decreasing rate of genetic flow on both sides of the highway, meaning a genetic segregation is formed to some extent (Alexander & Waters, 2000). Therefore, the main objective of the project is to minimize these impacts by reducing the collision rate between wildlife and vehicles as well as ensuring the connectivity between the wildlife groups between two sides of the highway. Additionally, stakeholders had the aim of increasing transportation activities and at the same time making sure wildlife agencies and surrounding communities are more aware so that other similar situations in other parts of Canada or the world could benefit from the findings of BWCP.

Based on the above information, we have selected “Banff Wildlife Crossings Project: Integrating Science and Education in Restoring Population Connectivity Across Transportation Corridors” for our literature review. The paper was produced by multiple wildlife biology researchers in the Western Transportation Institute College of Engineering Montana State University. They discuss different types and designs of the crossing structure, noting that different animal species prefer one over another. An extensive review is given for the methodology as well, increasing the applicability of a wildlife crossing to other parts of the world.

Figure 1: Trans-Canada Highway study area, the mitigation phases and their stage of construction (source: Clevenger et. al, 2009)

OBJECTIVE

The BWCP mainly focuses on wildlife monitoring and analysis, providing a strong background for transportation communities and wildlife researchers based on the environmental and social benefits of the highway in Banff. Additionally, the project intends to share insights on wildlife crossing design features, requirements, and its effectiveness. Generally, the objectives of the project can be divided into four aspects as follows (Clevenger et. al, 2009):

• Partnership: Sustain and advance the international collaboration between public and private sectors in conservation science and the management of transportation systems within natural and working landscapes.
• Science: a) Conduct research on gene flow among grizzly and black bears utilizing wildlife crossings on TCH and model population viability; b) Continue monitoring and studying the use of wildlife crossings by various species; and c) Develop science-based guidelines for effective wildlife mitigation in transportation projects based on research findi
• Technology Transfer and Education: Disseminate research results through major international journals, books, and conferences focused on transportation and ecology. Enhance professional knowledge about reducing highway impacts on wildlife and fisheries through training programs.
• Community Awareness: Increase public understanding and awareness of the BWCP and its research outcomes to advocate for similar highway mitigations across the Yellowstone to Yukon bioregion and North America. This will be achieved through field trips, workshops, media outreach, and educational initiatives in schools, universities, and museums.

METHODOLOGY

The BWCP uses multiple data collection and evaluation methods to assess impact mitigation effects along the TCH. The main method includes using trackpads which are located at the crossing structures. These trackpads are made of a mixture of sand, silt, and clay, and they are visited every few days to record animal traces, allowing researchers to observe animals’ crossing frequencies. Additionally, the project installed remote cameras on the overpasses and later constructed underpasses. The cameras can not only improve species detection during extreme weather, but also provide valuable data on animal behavior, such as group size and crossing time, or similar information potentially missed by track pads.

For the population analysis, the project implements a non-invasive genetic sampling method to assess the benefits of the wildlife crossings, especially on black bear and grizzly bear populations. This method needs to collect hair samples from bears using iron netting placed across trackpads at crossing structures. The DNA analysis of these hair samples provides information on their species, gender, and genetic relatedness. This can help researchers determine the number of bears using the crossing, as well as gender and their relationship to the population. By analyzing these collected data, the BWCP gets a more comprehensive understanding of wildlife crossing structure usage and its effects on the environment.

CHALLENGES

After the crossings were completed in the 1980s, a long-term investigation was bound to happen as one of the earliest wildlife crossing projects in the world. However, some challenges arose during research as well as data analysis.

First, securing long-term funding was a major obstacle. While the initial funding (from 1996 to 2002) was provided entirely by Parks Canada, given its long-lasting nature, it was imperative that the project secured long-term funding. To achieve this, the project sought securing external funding, namely through partnerships. And in order to secure a stable partnership, they had to demonstrate the value of long-term monitoring. The BWCP was eventually completed through partnerships between Parks Canada, several private foundations, and the Western Transportation Institute.

Another challenge is balancing the trade-offs in the monitoring methods. For example, while trackpads are recommended for some species such as coyotes and grizzly bears because of higher probability of detection, it requires the researchers to sweep through the area, making the process labor-intensive. On the other hand, remote cameras were often used because of their cost- effectiveness and data quality, but limitations existed including theft and camera failure. Toward the end the project increased its reliance on cameras but continued to use trackpads as a backup for camera failures. Combining different monitoring methods to capitalize on the strengths of both methods while minimizing their weaknesses is essential.

Finally, the results from this study must be thoroughly discussed before being able to apply to other projects around the world. For example, the ecological context could greatly differ from place to place i.e., the success observed in Banff with species like elk, wolves, and bears, does not guarantee similar results in Singapore. The authors recommend that when applying the case study in Banff to other projects, we must conduct a detailed ecological assessment of the targeted area and adapt/adjust the management strategies.

OUTCOME AND BENEFITS

The literature discusses the effectiveness of using fences and crossing structures in reducing the negative effects of the TCH on wildlife. After 12 years of monitoring, it has been proven that these measures for reducing wildlife-vehicle collisions and promoting habitat connectivity are indeed meaningful. The project involved a variety of species, noting their individual adaptation times to the structures, and emphasizing the importance of continuous data collection. The result of this long-term monitoring showed different species are attracted to different kinds of crossing structures. For instance, the literature revealed that deer almost exclusively utilized overpasses while cougars preferred smaller underpasses. Details can be seen in Table 1.

Investigating the broader ecological effects of the mitigation strategies was another major objective for the project. Researchers conducted non-invasive genetic sampling to determine if the crossing structures can promote gene flow and support the long-term survivability of populations. This project has a rather strong emphasis on bears, analyzing hair samples collected from the crossings, hair traps, etc. The project also emphasizes the importance of lessons learned from Banff and how to apply them to other locations facing similar challenges. However, it also stresses that mitigation efforts must be adapted to local conditions, including species composition, traffic volume, and other factors on the site.

Table 1. Species use of paired overpasses and underpasses, 1997–2009 (source: Clevenger et. al, 2009)

DISCUSSION

The BWCP demonstrates the effectiveness of NBS. Specifically, it shows that wildlife crossings have a significant effect on the local ecosystems. The implementation of crossing structures drastically reduced wildlife mortality, restoring habitat connectivity and contributing to the long-term viability of wildlife populations. This indicates that species-specific considerations must be taken into account when producing effective mitigation strategies. This project has gained international recognition, serving as a exemplar for similar projects globally, proving that well- planned infrastructure development has the potential to be an NBS.

The project also emphasizes the importance of long-term data collection and analysis. Over 12 years of data collection made it possible to analyze long-term usage patterns that would have been missed otherwise i.e., with shorter monitoring periods. It also allowed researchers to track species-specific adaptation to the crossing structures. For example, while initial observations suggested certain species avoid using the crossings, the long-term data reveal that many species, especially carnivores like grizzly bears, require a longer period to adapt. This demonstrates that long-term monitoring and analysis are essential to avoid jumping to conclusions. Furthermore, the large dataset gathered over a long period of time provides information on species’ population trends, such as the steady increase in the use of the crossings by grizzly bears, which is not achievable with short-term studies. The continuous monitoring allowed researchers to keep track of the changes in the species distribution along the TCH. Animals captures on photograps are shown in Figure 2, 3 and 4.

Figure 2. Animal captured on camera using wildlife crossings (source: Clevenger et. al, 2009)

Figure 3. Animal captured on camera using wildlife crossings (source: Clevenger et. al, 2009)

Finally, the project helps us understand what is needed when designing and implementing similar mitigation strategies around the world. The finding that different species react to different types of crossing structures implies that understanding different species’ adaptation periods, design preferences, and the interplay between animal behavior and crossing structure use are crucial – transportation planners and conservationists can make better decisions for similar projects only after adjusting such factors for the local conditions. We can see that BWCP itself adapted to better suit the real-life conditions; while the project initially relied on trackpads, it discovered that cameras offered a more cost-effective method for detecting animal traces. This adaptation demonstrates the project's commitment to ongoing evaluation and the fine-tuning of its methodologies to ensure the accuracy and efficiency of data collection, indicating the importance of being flexible for other long-term projects.

Figure 4. Animal captured on camera using wildlife crossings (source: Clevenger et. al, 2009)

CONCLUSION

The literature concludes that the mitigation measures, i.e. wildlife crossing structures, have successfully reduced the mortality rate for the wildlife along the TCH, and improved the habitat connectivity along the corridor. In particular, the long-term monitoring data spanning over 12 years provides strong evidence for how effective those measures were. This shows the importance of long-term monitoring to understand species-specific behaviors such as adaptation periods, and constructing effective mitigation strategies with different designs. While broader application of the project's findings to other initiatives globally is recommended, at the same time the report emphasizes the need for context-specific adaptation and long-term commitment to address emerging challenges in road ecology and wildlife conservation.

REFERENCES

1. Alexander, S. M., Waters, N. M. (2000). The effects of highway transportation corridors on wildlife: a case study of Ban€ National Park, Transportation Research Part C, 8: 307-320.
2. Clevenger, A. (1997). Publications.ca. Retrieved from Research Links: https://publications.gc.ca/collections/Collection/R61-16-5-1E.pdf.
3. Clevenger, A. P., Ford, A. T., and Sawaya, M. A. (2009). Banff Wildlife Crossings Project: Integrating Science and Education in Restoring Population Connectivity Across Transportation Corridors. Parks Canada Agency.
4. Ford, A. T., Rettie, K., and Clevenger, A. P. (2009). Fostering ecosystem function through an international public–private partnership: a case study of wildlife mitigation measures along the Trans-Canada Highway in Banff National Park, Alberta, Canada, International Journal of Biodiversity Science & Management, 5:4, 181-189.
5. Jiling, W. (2014). Effectiveness of wildlife crossing structures on providing habitat connectivity for wild animals. University of British Columbia.

ABOUT AUTHORS

Haruhiko Yokota is a master's student in Rail and Urban Transport at the Technical University of Munich. His research focuses on the interrelations between transportation infrastructure and urban environments, employing a range of evaluation and analysis methods. He holds a B.A. from McGill University in Computer Science and Urban Systems.

Kaiyuan Meng is currently a M.Sc. student in Rail and Urban Transport at the Technical University Munich Asia. He finished his B.Sc. in Transportation, City Planning and Environmental Policies in 2024, which is a dual degree between University College Dublin (UCD), Ireland and Chang’an University (CHD), China.

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