An objective road risk assessment method for multiple species: ranking 166 reptiles and amphibians in California

Authors: Cheryl S Brehme; Stacie A Hathaway; Robert N Fisher
Contribution Number: 615


Transportation and wildlife agencies may consider the need for barrier structures and safe wildlife road-crossings to maintain the long-term viability of wildlife populations. In order to prioritize these efforts, it is important to identify species that are most at risk of extirpation from road-related impacts. Our goal was to identify reptiles and amphibians in California most susceptible to road mortality and fragmentation. With over 160 species and a lack of species-specific research data, we developed an objective risk assessment method based upon road ecology science. Risk scoring was based upon a suite of life history and space-use characteristics associated with negative road effects applied in a hierarchical manner from individuals to species. We evaluated risk to both aquatic and terrestrial connectivity and calculated buffer distances to encompass 95% of population level movements. We ranked species into five relative categories of road-related risk (very-high to very-low) based upon 20% increments of all species scores. All chelonids, 72% of snakes, 50% of anurans, 18% of lizards and 17% of salamander species in California were ranked at high or very-high risk from negative road impacts. Results were largely consistent with local and global scientific literature in identifying high risk species and groups. This comparative risk assessment method provides a science-based framework to identify species most susceptible to negative road impacts. The results can inform regional-scale road mitigation planning and prioritization efforts and threat assessments for special-status species. We believe this approach is applicable to numerous landscapes and taxonomic groups.

Publication details
Published Date: 2018-05-08
Outlet/Publisher: Landscape Ecology
Media Format: .PDF

ARMI Organizational Units:
Southwest, Northern California - Biology
Southwest, Southern California - Biology
Management; Species and their Ecology; Stressors
Place Names:
California; Mojave Desert; San Diego County, CA
connectivity; conservation; land cover/land use; management; movement; roads; stressors; wildlife habitat
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