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• 1. [Article] A Behavior-Based Framework for Assessing Barrier Effects to Wildlife from Vehicle Traffic Volume

  Roads, while central to the function of human society, create barriers to animal movement through collisions and habitat fragmentation. Barriers to animal movement affect the evolution and trajectory of ...

  Citation × Citation Citation Abstract Copy Title: A Behavior-Based Framework for Assessing Barrier Effects to Wildlife from Vehicle Traffic Volume Author: Jacobson, Sandra L., Bliss-Ketchum, Leslie L., de Rivera, Catherine E., Smith, Winston P. Year: 2016 Roads, while central to the function of human society, create barriers to animal movement through collisions and habitat fragmentation. Barriers to animal movement affect the evolution and trajectory of populations. Investigators have attempted to use traffic volume, the number of vehicles passing a point on a road segment, to predict effects to wildlife populations approximately linearly and along taxonomic lines; however, taxonomic groupings cannot provide sound predictions because closely related species often respond differently. We assess the role of wildlife behavioral responses to traffic volume as a tool to predict barrier effects from vehicle-caused mortality and avoidance, to provide an early warning system that recognizes traffic volume as a trigger for mitigation, and to better interpret roadkill data. We propose four categories of behavioral response based on the perceived danger to traffic: Nonresponders, Pausers, Speeders, and Avoiders. Nonresponders attempt to cross highways regardless of traffic volume. Pausers stop in the face of danger so have a low probability of successful crossing when traffic volume increases. Hence, highway barrier effects are primarily due to mortality for Nonresponders and Pausers at high traffic volumes. Speeders run away from danger but are unable to do so successfully as traffic volume increases. At moderate to high volume, Speeders are repelled by traffic danger. Avoiders face lower mortality than other categories because they begin to avoid traffic at relatively low traffic volumes. Hence, avoidance causes barrier effects more than mortality for Speeders and Avoiders even at relatively moderate traffic volumes. By considering a species’ risk-avoidance response to traffic, managers can make more appropriate and timely decisions to mitigate effects before populations decline or become locally extinct. Title: A Behavior-Based Framework for Assessing Barrier Effects to Wildlife from Vehicle Traffic Volume Author: Jacobson, Sandra L., Bliss-Ketchum, Leslie L., de Rivera, Catherine E., Smith, Winston P. Year: 2016 Roads, while central to the function of human society, create barriers to animal movement through collisions and habitat fragmentation. Barriers to animal movement affect the evolution and trajectory of populations. Investigators have attempted to use traffic volume, the number of vehicles passing a point on a road segment, to predict effects to wildlife populations approximately linearly and along taxonomic lines; however, taxonomic groupings cannot provide sound predictions because closely related species often respond differently. We assess the role of wildlife behavioral responses to traffic volume as a tool to predict barrier effects from vehicle-caused mortality and avoidance, to provide an early warning system that recognizes traffic volume as a trigger for mitigation, and to better interpret roadkill data. We propose four categories of behavioral response based on the perceived danger to traffic: Nonresponders, Pausers, Speeders, and Avoiders. Nonresponders attempt to cross highways regardless of traffic volume. Pausers stop in the face of danger so have a low probability of successful crossing when traffic volume increases. Hence, highway barrier effects are primarily due to mortality for Nonresponders and Pausers at high traffic volumes. Speeders run away from danger but are unable to do so successfully as traffic volume increases. At moderate to high volume, Speeders are repelled by traffic danger. Avoiders face lower mortality than other categories because they begin to avoid traffic at relatively low traffic volumes. Hence, avoidance causes barrier effects more than mortality for Speeders and Avoiders even at relatively moderate traffic volumes. By considering a species’ risk-avoidance response to traffic, managers can make more appropriate and timely decisions to mitigate effects before populations decline or become locally extinct. Close

• 2. [Article] The Effectiveness of Vertebrate Passage and Prevention Structures: A Study of Boeckman Road in Wilsonville

  One of the most obvious impacts roads have on the natural world is direct mortality to individual animals that attempt to cross roads. A less obvious but likely more important impact of roads on many species ...

  Citation × Citation Citation Abstract Copy Title: The Effectiveness of Vertebrate Passage and Prevention Structures: A Study of Boeckman Road in Wilsonville Author: de Rivera, Catherine E., Bliss-Ketchum, Leslie L. Year: 2010 One of the most obvious impacts roads have on the natural world is direct mortality to individual animals that attempt to cross roads. A less obvious but likely more important impact of roads on many species is habitat fragmentation. The ability for individuals to travel between subpopulations is the key to genetic diversity as well as ultimately the survival of the species. Considering these impacts and management goals to increase habitat connectivity, increased attention has been given to creating road design that reduces wildlife collisions. Most studies, however, have been in other countries or regions and most focus on connectivity for just one or a few species and rarely in urban settings. This study examines the effectiveness of a variety of under-road passage structures for a community of animals in an urban wetland. Wildlife passage was taken into great consideration in the construction of the Boeckman Road Extension, the new road (2006) in Wilsonville, Oregon, examined in this study. As a result it includes a bridge, two box culverts and eleven round concrete culverts to facilitate wildlife passage as well as a mammal fence atop an amphibian/reptile wall. In order to monitor passage use we used a combination of sand-track monitoring and motion-detect cameras. We compared passage structure use to movement in the habitats surrounding the road by monitoring four habitat transects in addition to the passage structures (Road transect). We also conducted tag and release studies targeted to small mammals. Finally, camera data collected in passage structures were compared to camera monitoring at the end of the exclusionary fencing. A total of 26 species were detected in this study, 73% (19) of which were found to be using passage structures. 15% (4) of the identified species were detected on transects but not in passages and 11.5% (3) were detected in locations other than transects or passage structures. The bridge structure provided passage to the highest number of species (16), followed by the 24” and 18” culverts, which had a combined total of 11 species, and lastly the 9x4 culverts, which were flooded, with 2 species detected. Our results indicate that large and medium mammals overall did not use passages less than would be expected based on their local movement in habitats. In pit and Sherman traps sixteen of the 48 small mammals that were captured and tagged were re-caught, but only four of these moved from one transect to another, with two moving away from the road and the other two moving toward and under the road. Of the species detected with cameras at the passage structures and circumventing fencing, excluding small mammals, reptiles and amphibians (139), 19% (33) were found potentially crossing on the road surface. The proportion of deer detected using over-road crossings (23%) is of particular concern for driver safety. The bridge structure provided the greatest passage, in not only frequency of crossings but also species present. When maintenance factors, driver safety and species of greatest concern are included, the higher cost of the bridge structure would likely be even further balanced by the benefits. This study highlights the effectiveness and potential problems (and possible fixes) of some of the passage and prevention structures. Including passage and prevention structures such as these in road design is imperative for habitat connectivity and the need for this becomes even more apparent as Oregon’s native wildlife face an ever increasing urban landscape as well as the potential impacts of climate change. Title: The Effectiveness of Vertebrate Passage and Prevention Structures: A Study of Boeckman Road in Wilsonville Author: de Rivera, Catherine E., Bliss-Ketchum, Leslie L. Year: 2010 One of the most obvious impacts roads have on the natural world is direct mortality to individual animals that attempt to cross roads. A less obvious but likely more important impact of roads on many species is habitat fragmentation. The ability for individuals to travel between subpopulations is the key to genetic diversity as well as ultimately the survival of the species. Considering these impacts and management goals to increase habitat connectivity, increased attention has been given to creating road design that reduces wildlife collisions. Most studies, however, have been in other countries or regions and most focus on connectivity for just one or a few species and rarely in urban settings. This study examines the effectiveness of a variety of under-road passage structures for a community of animals in an urban wetland. Wildlife passage was taken into great consideration in the construction of the Boeckman Road Extension, the new road (2006) in Wilsonville, Oregon, examined in this study. As a result it includes a bridge, two box culverts and eleven round concrete culverts to facilitate wildlife passage as well as a mammal fence atop an amphibian/reptile wall. In order to monitor passage use we used a combination of sand-track monitoring and motion-detect cameras. We compared passage structure use to movement in the habitats surrounding the road by monitoring four habitat transects in addition to the passage structures (Road transect). We also conducted tag and release studies targeted to small mammals. Finally, camera data collected in passage structures were compared to camera monitoring at the end of the exclusionary fencing. A total of 26 species were detected in this study, 73% (19) of which were found to be using passage structures. 15% (4) of the identified species were detected on transects but not in passages and 11.5% (3) were detected in locations other than transects or passage structures. The bridge structure provided passage to the highest number of species (16), followed by the 24” and 18” culverts, which had a combined total of 11 species, and lastly the 9x4 culverts, which were flooded, with 2 species detected. Our results indicate that large and medium mammals overall did not use passages less than would be expected based on their local movement in habitats. In pit and Sherman traps sixteen of the 48 small mammals that were captured and tagged were re-caught, but only four of these moved from one transect to another, with two moving away from the road and the other two moving toward and under the road. Of the species detected with cameras at the passage structures and circumventing fencing, excluding small mammals, reptiles and amphibians (139), 19% (33) were found potentially crossing on the road surface. The proportion of deer detected using over-road crossings (23%) is of particular concern for driver safety. The bridge structure provided the greatest passage, in not only frequency of crossings but also species present. When maintenance factors, driver safety and species of greatest concern are included, the higher cost of the bridge structure would likely be even further balanced by the benefits. This study highlights the effectiveness and potential problems (and possible fixes) of some of the passage and prevention structures. Including passage and prevention structures such as these in road design is imperative for habitat connectivity and the need for this becomes even more apparent as Oregon’s native wildlife face an ever increasing urban landscape as well as the potential impacts of climate change. Close