Scholarly Work - Western Transportation Institute
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Item Exploring Apex Predator Effects on Wildlife-Vehicle Collisions: A Case Study on Wolf Reintroductions in Yellowstone(Western Transportation Institute, 2024-09) Bell, Matthew; Huijser, Marcel P.; Kack, DavidThis study investigates the impact of wolf reintroduction on wildlife-vehicle collisions (WVCs) along a segment of US-191 bordering Yellowstone National Park. Wolves were reintroduced in 1995–1996, and subsequent wolf pack establishment may have influenced the behavior and population dynamics of prey species, potentially altering WVC patterns. Using carcass data collected from 1989 to 2021, the analysis was divided into two primary phases: before wolves (1989–1996) and after wolves (1997–2021). A series of linear mixed-effects models were developed to assess changes in WVCs across these time periods. Predictor variables included average annual daily traffic (AADT), elk population estimates, and wolf counts. Results showed that WVCs significantly declined in the post-wolf period, suggesting that the presence of wolves may reduce WVCs directly by modifying prey behavior and movement patterns, or indirectly by reducing prey population densities. Further analysis revealed that while elk populations were a significant predictor of WVCs before wolves were reintroduced, this relationship weakened post-reintroduction. Traffic volume did not significantly influence WVC patterns in either period, nor did it interact significantly with wolf presence. The inclusion of wolf counts as a continuous variable showed a negative relationship with WVCs, indicating that higher wolf densities may contribute to a further reduction in collisions over time. These findings suggest that apex predators can play a role in mitigating human-wildlife conflicts, such as WVCs, by influencing prey species’ behavior and distribution. The study provides valuable insights for wildlife managers and transportation planners, highlighting the potential benefits of predator conservation for road safety and ecosystem health.Item Patterns of Domestic Animal-Vehicle Collisions on Tribal Lands in Montana, U.S.(Western Transportation Institute, 2024-09) Bell, Matthew; Huijser, Marcel P.; Kack, DavidAnimal-vehicle collisions (AVCs) are a significant concern for motorist safety and pose a risk to both wildlife and domestic animals. This report analyzes spatial patterns of wildlife-vehicle collisions (WVCs) and domestic animal-vehicle collisions (DAVCs) on Montana’s tribal lands to identify high-risk areas and inform mitigation strategies. Data from the Montana Department of Transportation (MDT) for large mammal carcasses (2008–2022) and reported crashes (2008–2020) were used to perform Kernel Density Estimation (KDE) and Getis-Ord Gi* (GOG) hotspot analyses for three tribal reservations with sufficient data: Blackfeet, Crow, and Flathead. The KDE results show distinct spatial patterns for DAVCs and WVCs on each reservation, with DAVC hotspots concentrated near agricultural and grazing areas, while WVC hotspots were associated with natural habitats and wildlife corridors. The GOG analysis further revealed that DAVC hotspots tend to be more temporally stable, suggesting that collisions with domestic animals are influenced by consistent factors such as livestock access points and grazing practices. In contrast, WVC hotspots were more variable, likely driven by changes in wildlife movement patterns and seasonal behavior. Overall, the findings indicate that the elevated rates of DAVCs on tribal lands, compared to non-tribal lands, are likely due to unique factors such as open range grazing practices and road infrastructure adjacent to grazing lands. This report emphasizes the need for targeted mitigation strategies on tribal roads, such as enhanced livestock fencing, road signage, and livestock underpasses in high-risk areas, to reduce collisions and improve safety for both motorists and animals. Understanding the distinct spatial and temporal patterns of DAVCs and WVCs is crucial for developing comprehensive mitigation approaches that enhance safety and connectivity on Montana’s tribal lands.Item Identification and prioritization of road sections with a relatively high concentration of large wild mammal-vehicle collisions in Gallatin County, Montana, USA(2024-09) Huijser, Marcel P.; Bell, Matthew A.The primary objective of this project is to identify and prioritize the road sections in Gallatin County that have a relatively high concentration of collisions involving large wild mammals. These road sections may then later be evaluated for potential future mitigation measures aimed at 1. Reducing collisions with large wild mammals, and 2. Providing safe passage across roads for large wild mammals, as well as other wildlife species in the area. We acquired the 3 datasets related to large wild mammal-vehicle collisions in Gallatin County: 1. Wildlife-vehicle crash data collected by law enforcement personnel, 2. Carcass removal data collected by road maintenance personnel; and 3. Grizzly bear road mortality data by the U.S. Geological Survey. The carcass removal data and grizzly bear road mortality data were merged into one carcass database. We conducted separate analyses for the crash data and the carcass data. We conducted two different types of analyses to identify and prioritize road sections with the highest number of wildlife-vehicle crashes and carcasses: 1. Kernel Density Estimation (KDE) analysis that identifies road sections with the highest concentration of collisions, and 2. Getis-Ord Gi* analysis identifies road sections that have statistically significant spatial clusters of collisions. There was great similarity between the hotspots identified through the Kernel Density Estimation analyses for 2008-2022 and 2018-2022 for both the crash and carcass removal data. The same was true for the Getis-Ord Gi* analyses. Especially sections of I-90 and US Hwy 191 between I-90 through Four Corners to the mouth of Gallatin Canyon had the highest concentration of wild animal crashes and large wild animal carcasses. Based on the Getis-Ord Gi* analyses, these road sections generally had concentrations of crashes and carcasses that were significantly higher than expected should the crashes and carcasses have been randomly distributed. In other words, these road sections do not only have the highest concentration of crashes and carcasses, but the identification of these road sections is not based on coincidence. These road sections have a concentration of crashes and carcasses that is beyond random.Item The effectiveness of electrified barriers to keep large mammals out of a fenced road corridor and a campground(Parks Canada Agency, 2024-06) Huijser, Marcel P.For this project the researchers investigated the effectiveness of electrified barriers designed to keep large mammals out of a fenced road corridor (Trans-Canada Highway through Banff and Yoho National Park) and a campground (Lake Louise Campground, Banff National Park). The barriers were designed for large ungulates (e.g. white-tailed deer, mule deer, elk, moose) and large mammal species with paws (e.g. black bear, grizzly bear). The barriers consisted of steel pipes that were partially electrified. None of the white-tailed deer, mule deer, elk, moose, black bears, grizzly bears, red foxes, and coyotes that were observed on the habitat side of the barriers crossed the electrified barriers into the fenced road corridor or the campground. A black bear attempting to exit the fenced road corridor failed to cross to the habitat side of the electrified barrier. Two red foxes and one wolverine did appear to exit the fenced road corridor to the habitat side of the electrified barrier, but these three crossings were all in winter when the voltage was likely compromised because of snow and road salt. In addition, crossings to the habitat side can be considered acceptable as they improve human safety on the main highway and keep the animals from being hit by vehicles. We conclude that, although sample sizes were limited, the electrified barriers (when voltage was adequate and when not filled with snow) were 100% effective in keeping both large ungulates and large species with paws out of a fenced road corridor and a campground.Item West-Wide Study to Identify Important Highway Locations for Wildlife Crossings(Western Transportation Institute, 2023-06) Paul, Kylie; Faselt, Jamie; Bell, Matthew; Huijser, Marcel P.; Theobald, David; Keeley, Annika; Ament, RobertWildlife-vehicle collisions (WVCs), reduced ecological connectivity, and associated impacts to wildlife and humans are widespread problems across road networks, but mitigation measures like wildlife crossings1 that can address those problems are often considered expensive. This effort aims to support transportation agencies, wildlife agencies and other decision-makers by identifying important road segments where cost-effective wildlife crossings can be deployed to address motorist safety, ecological connectivity and other conservation values across the eleven U.S. western conterminous states of Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.Item Exploration of opportunities to address the impacts of roads and traffic on wildlife around Rocky Flats National Wildlife Refuge(Western Transportation Institute, 2023-11) Huijser, Marcel P.; Begley, James S.Rocky Flats National Wildlife Refuge (“the Refuge”) in Colorado near Denver, Colorado, has a history (1952-1 989) of producing components for nuclear weapons. The current goal for the area is “to restore and preserve the native prairie ecosystems, provide habitat for migratory and resident wildlife, conserve and protect habitat for Preble’s meadow jumping mouse, and provide research and education opportunities”. The grasslands of the Refuge are surrounded by busy roads to the west (Hwy 93, 18,000 AADT), north (Hwy 128, 4,200 AADT) and east (Indiana St. 7,000 AADT), and there are houses and associated roads on its southern boundary. Other open space with non-motorized trails and protected areas with predominantly grassland are to the west, north and east. Large ungulates, including mule deer, elk, and moose cross the roads. This results in large ungulate -vehicle collisions and the roads also represent a barrier to the movements of animals. Creek crossings under the roads are a concern as they are likely a barrier for species dependent on riparian habitat, including the Preble’s meadow jumping mouse. The objectives of the current project were to 1. Formulate measures that reduce collisions with large wild mammals, and 2. Formulate measures that improve connectivity across roads for large wild mammal species and one small mammal species in specific, the Preble’s meadow jumping mouse. We suggest large open span bridges at creek crossings (for deer, moose, black bear, mountain lion, and Preble’s meadow jumping mouse) and designated wildlife overpasses for elk and also f or mule deer. The crossing structures may be combined with human co-use to connect the trails on the refuge with the trail system in the surrounding areas.Item Implementing wildlife fences along highways at the appropriate spatial scale: A case study of reducing road mortality of Florida Key deer(Pensoft Publishers, 2022-03) Huijser, Marcel P.; Begley, James S.Florida Key deer mortality data (1966–2017) showed that about 75% of all reported deer mortalities were related to collisions with vehicles. In 2001–2002, the eastern section of US Hwy 1 on Big Pine Key (Florida, USA) was mitigated with a wildlife fence, 2 underpasses, and 4 deer guards. After mitigation, the number of reported Key deer road mortalities reduced substantially in the mitigated section, but this was negated by an increase in collisions along the unmitigated section of US Hwy 1 on Big Pine Key, both in absolute numbers and expressed as a percentage of the total deer population size. The data also showed that the increase in Key deer collisions along the unmitigated highway section on the island could not be explained through an increase in Key deer population size, or by a potential increase in traffic volume. The overall Key deer road mortality along US Hwy 1 was not reduced but was moved from the mitigated section to the nearby unmitigated section. Thus, there was no net benefit of the fence in reducing collisions. After mitigation, a significant hotspot of Key deer-vehicle collisions appeared at the western fence-end, and additional hotspots occurred further west along the unmitigated highway. Exploratory spatial analyses led us to reject the unmitigated highway section on Big Pine Key as a suitable control for a Before-After-Control-Impact (BACI) analysis into the effectiveness of the mitigation measures in reducing deer-vehicle collisions. Instead, we selected highway sections west and east of Big Pine Key as a control. The BACI analysis showed that the wildlife fence and associated mitigation measures were highly effective (95%) in reducing deer-vehicle collisions along the mitigated highway section. Nonetheless, in order to reduce the overall number of deer-vehicle collisions along US Hwy 1, the entire highway section on Big Pine Key would need to be mitigated. However, further mitigation is complicated because of the many buildings and access roads for businesses and residences. This case study illustrates that while fences and associated measures can be very effective in reducing collisions, wildlife fences that are too short may result in an increase in collisions in nearby unmitigated road sections, especially near fence-ends. Therefore it is important to carefully consider the appropriate spatial scale over which highway mitigation measures are implemented and evaluated.Item On the Road Without a Map: Why We Need an “Ethic of Road Ecology”(Frontiers Media SA, 2021-11) Moore, Lauren J.; Arietta, A. Z. Andis; Spencer, Daniel T.; Huijser, Marcel P.Over the past two decades, our knowledge of the ecological impacts of roads has increased rapidly. It is now clear that the environmental effects of transportation infrastructure are inextricable from transportation benefits to economic, social, and cultural values. Despite the necessity of optimizing these multiple values, road planners, scientists, and practitioners have no established methodology or pluralistic approach to address growing ethical complexities. We articulate five ethical issues that could be addressed by developing an ethic of road ecology in order to facilitate the identification, reasoning, and harmonization of ethical dimensions of road planning and development. This inquiry into road ecology can draw lessons from existing applied ethics, such as in ecological restoration and urban planning, to build a narrative that is informed by both science and ethics. We illustrate five ethical issues presented through case studies that elaborate on the motivations, responsibilities, and duties that should be considered in ethically and scientifically complicated road building decisions. To address these issues, we encourage the development of a code of ethics, dedicated intellectual forums, and practical guidance to assist road planners, and more broadly transportation practitioners, to resolve complex ethical quandaries systematically. We hope this perspective encourages conversation for a holistic yet pragmatic approach to this applied ethics problem, while also assisting responsible parties as they navigate difficult moral terrain.Item Short and narrow roads cause substantial impacts on wildlife(2019) Magioli, Marcelo; Bovo, Alex A. A.; Huijser, Marcel P.; Abra, Fernanda D.; Miotto, Renata A.; Andrade, Victor H. V. P.; Nascimento, Adriana M.; Martins, Maisa Z. A.; Micchi de Barros Ferraz, Katia M. P.Short and narrow roads are generally overlooked when assessing road impacts on biodiversity. However, these roads bisect natural environments and may cause significant impacts on wildlife in local scale. Thus, we monitored roadkills along a short two-lane road (CPM road) in Southeastern Brazil and propose mitigation strategies to reduce wildlife mortality. We monitored roadkilled vertebrates along 5 km of CPM road from 2010 to 2016 and we also compiled data from previous studies along the same road. We conducted a hotspot analysis to identify CPM road areas with significant roadkill aggregation. We recorded 77 roadkilled vertebrates from 14 taxonomic groups along the CPM road. Mammals were the most frequently recorded group (91% of roadkills), which represented 56% of all medium- and large-sized mammal species known to occur in the study area. We identified three roadkill hotspots along the CPM road. Two of them were located at two stream crossings, where the road cut across the associated riparian forests, and the other was at a road section with water drainage from a pond, also connected to a riparian forest. These riparian forests are part of the remaining natural habitat that provides connectivity between the forest remnants in the landscape, and therefore, for wildlife. Our results showed that even short and narrow roads can have considerable roadkill, which may have severe effects for wildlife on a local scale. The results stress the need to carefully look at these types of roads and propose measures to reduce impacts. We propose the creation of safe crossing opportunities in the hotspot zones combined with wildlife fencing to keep the animals off the road and guide them towards the safe crossing opportunities.Item Performance of Arch-Style Road Crossing Structures from Relative Movement Rates of Large Mammals(2017-10) Andis, A. Z.; Huijser, Marcel P.; Broberg, LenIn recent decades, an increasing number of highway construction and reconstruction projects have included mitigation measures aimed at reducing wildlife-vehicle collisions and maintaining habitat connectivity for wildlife. The most effective and robust measures include wildlife fences combined with wildlife underpasses and overpasses. The 39 wildlife crossing structures included along a 90 km stretch of US Highway 93 on the Flathead Indian Reservation in western Montana represent one of the most extensive of such projects. We measured movements of large mammal species at 15 elliptical arch-style wildlife underpasses and adjacent habitat between April and November 2015. We investigated if the movements of large mammals through the underpasses were similar to large mammal movements in the adjacent habitat. Across all structures, large mammals (all species combined) were more likely to move through the structures than pass at a random location in the surrounding habitat. At the species level, white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) used the underpasses significantly more than could be expected based on their movement through the surrounding habitat. However, carnivorous species such as, black bear (Ursus americanus) and coyote (Canis latrans) moved through the underpasses in similar numbers compared to the surrounding habitat.