Maintaining Wildlife Connectivity across Roads through Tested Wildlife Crossing Designs

A permeable road network that allows all types of wildlife to move across the roaded landscape is based on the science of animal behavior and physiology; specifically, how animals respond when they encounter roads and potential crossing structures. This synthesis takes an individual species and taxonomic approach to crossing structures and modifications of existing infrastructure that are proven to pass wildlife. Although designing crossings for ecosystem function rather than individual target species are far more important, this paper can help readers understand the designs that are confirmed to work for different species groups and, in turn, how those design aspects may be combined to help pass a variety of wildlife and ecosystem processes such as the flow of water. The authors present two classification systems to achieve this: Species Movement Guilds, which organize wildlife into classes based on similar sizes and reactions to culverts and bridges; and Structure Functional Classes, which classify culverts, bridges and large span viaducts based on size and how different species respond to them. Tested wildlife crossings designs for the eight different Species Movement Guilds are presented. Low mobility fauna such as frogs and ground insects prefer passages that mimic ambient conditions. Crossings for them must provide specific habitat consistent with the outside environment. Moderate mobility small fauna are small to medium sized mammals and reptiles. These animals typically need some hiding cover and may use all kinds of wildlife crossings. Adaptive high mobility fauna are the medium sized carnivores that can use closed spaces such as culverts. They will also pass under bridges and use overpasses. High openness high mobility carnivores are the grizzly bear, mountain lion, and wolf. They prefer good visibility and typically need larger sized structures such as large bridge underpasses and wildlife overpasses. Adaptive ungulates such as deer, moose, and mountain goat prefer good visibility in a crossing and need a certain degree of openness. They will tolerate culverts up to 120 feet (36 m) long; longer culverts will have a higher rate of repellence. Very high openness fauna are the more wary ungulates such as elk, pronghorn, and bighorn sheep. These species are very wary of being enclosed and, for the majority of populations will not use culverts, instead requiring medium to large underpasses, extensive bridge, or overpasses. Typical Arboreal fauna are flying squirrels. They move through canopies and need canopy-level structures such as a rope bridge or towers that allow them to jump from perch to perch over a road. Aerial fauna are birds and insects that need to be directed to fly over the flow of vehicles. Vegetation improvements and diversion structures may be used to keep these animals up and over the roadway. This paper helps to elucidate the characteristics of new structures or the changes needed to retrofit structures that make them more functional for the movement of species from all of these guilds.

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• Summary URL:
  https://icoet.net/links
• Supplemental Notes:
  • Abstract used with permission from the International Conference on Ecology and Transportation, organized by the Center for Transportation and the Environment, Institute for Transportation Research and Education, North Carolina State University.
• Corporate Authors:

  North Carolina State University, Raleigh

  Center for Transportation and the Environment
  Raleigh, NC  United States  27695-8601
• Authors:
  • Cramer, Patricia
  • Kintsch, Julia
  • Jacobson, Sandra
• Conference:
  • 2011 International Conference on Ecology and Transportation (ICOET 2011)
  • Location: Seattle Washington, United States
  • Date: 2011-8-21 to 2011-8-25
• Publication Date: 2012

Language

• English

Media Info

• Media Type: Digital/other
• Features: References; Tables;
• Pagination: pp 448-460
• Monograph Title: Proceedings of the 2011 International Conference on Ecology and Transportation (ICOET 2011)

Subject/Index Terms

• TRT Terms: Animal migrations; Design; Habitat (Ecology); Highways; Networks; Wildlife crossings
• Subject Areas: Design; Environment; Highways; Planning and Forecasting; I15: Environment; I20: Design and Planning of Transport Infrastructure; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 01558514
• Record Type: Publication
• Files: TRIS
• Created Date: Mar 31 2015 8:53AM