Evaluation of Highway Mitigation on the Frequency of Wildlife-Vehicle Collisions on the Highway and an Adjacent Railway in a Montane Ecosystem

• Author / Creator

  Gilhooly, Patrick S

• Transportation networks are expanding rapidly to meet increasing global demands to move people and cargo. These networks are essential to connect societies and economies but have several negative effects on wildlife populations including collisions with vehicles. Growing incidences and increasing awareness of wildlife-vehicle collisions have encouraged mitigation using a combination of wildlife fencing and crossing structures. Very litte attention has been paid to the problem of wildlife collisions with trains, or the effect of highway mitigation on rail mortality, despite frequent parallel alignment of roads and rails along transportation corridors. The objective of this thesis was to examine the effects of mitigating the TransCanada Highway between 1983 and 2013 on rates of wildlife-vehicle collisions on both the highway and an adjacent mainline of the Canadian Pacific railway in Banff National Park, Canada. A core motivation for this research was the recent increase in rail-caused mortality for the local population of grizzly bears (Ursus arctos horribilis). I examined a dataset provided by Parks Canada of collisions with large mammals (n = 2775) that were reported on either the highway or railway between 1981-2014. I attributed collisions to nine temporal spatial mitigation sections and compared collision frequency between binary types of transportation mode (highway vs. railway), guild (ungulates vs. carnivores), mitigation status (before vs. after mitigation), and their biologically-relevant two-way interactions. I further examined three species groups with particular importance to wildlife managers, which included elk (Cervus canadensis) other ungulates (family Cervidae) and bears (Ursus spp.). I anticipated that changes in population size and distribution could confound the effects of other variables, so I included spatially-referenced measures of population size for elk, the only species for which this information was available. I examined the effects of these variables on collision rates using generalized linear mixed models with mitigation section (road/rail segment) as a random effect and use of information theory to identify the best-supported models. My first analysis showed that collision frequency was generally higher on the highway, higher for ungulates, and higher before mitigation occurred, but several significant interactions revealed that lower collision rates on the railway were more pronounced for carnivores (relative to ungulates) and that lower collision rates after mitigation were more prevalent on the highway (relative to the railway), and for ungulates (relative to carnivores). Taken together, the effect of highway mitigation on collision frequency was most pronounced for ungulates on the highway. The analyses that separated transportation modalities and species groups revealed that railway collisions for elk increased with population size, but declined over time and more slightly in recent years, but with no effect of mitigation. For other ungulates, rail collisions increased in relation to the timing of mitigation, but not with mitigation status. For bears, rail collisions increased over time and were higher for black bears than grizzlies, but again with no apparent effect of highway mitigation per se via a simple or interacting effect. My results suggest that highway mitigation reduced the rate of collisions on the highway, mainly for ungulates, without causing increased mortality on the adjacent railway. Instead, it appears that increasing populations of all three species groups could explain increases in rail-caused mortality over time. The results of this research demonstrate the need to assess mitigation effects over long time periods and within a landscape context while emphasizing the importance of changes in wildlife population size and distribution. This holistic approach could improve the effectiveness and efficiency of mitigation intended to reduce human-caused wildlife mortality in locations around the world, especially where multiple transportation routes and modes have interacting effects.

• Subjects / Keywords

  • Wildlife-vehicle collisions
  • Large mammals
  • Grizzly bears
  • Populations
  • Highway mitigation
  • Wildlife-train collisions
  • Ursus arctos

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3BN9X783

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.