Wildlife Corridors

Natural Capital

Ecosystem Services
  Ecosystem Services
  Watershed Services
  Soil Services
  Climate Services
  Biodiversity

Compact Towns and Cities
  Compact Towns & Cities
  Green Building
  Transit Access
  Ecological Infrastructure
  Urban Growth Boundaries
  Human Scale Neighborhoods

Ecological Land Use
  Ecological Land Use

Productive Rural Areas
  Productive Rural Areas
  Sustainable Forestry
  Sustainable Agriculture
  Sustainable Fisheries
  Ecotourism

Connected Wildlands
  Connected Wildlands
  Core Reserves
  Wildlife Corridors
  Buffer Zones

1) How The Pattern Works

   Wildlife corridors are necessary because they maintain biodiversity, allow populations to interbreed, and provide access to larger habitats.

   Wildlife Corridors connecting Core Reserves are crucial since they increase the effective amount of habitat that is available for species and effectively reverse habitat fragmentation. This is especially important for migratory animals and those with large home ranges. Larger habitats support greater Biodiversity, larger populations, and a wider range of food sources and shelter. They also allow populations to interbreed, improving long-term genetic viability. However, Wildlife Corridors cannot substitute for large areas of protected habitat like those in core reserve systems.

   At the largest scale, Wildlife Corridors must be wide enough to allow easy movement for even the largest mammals, including grizzlies, cougars, and wolves. Widths of several miles are typical. However, Wildlife Corridors can serve at smaller scales to provide habitat connectivity for other species, including amphibians, fish, and birds. They are particularly beneficial along riparian corridors, where they provide both aquatic and terrestrial connectivity. In urban areas, they can provide significant recreational opportunities and important linkages in a highly fragmented landscape. Whenever possible, urban and rural parks and open spaces should be linked to form functional Wildlife Corridors, which can then be joined to outlying core reserves.

   Since Wildlife Corridors are typically narrow and vulnerable, they must be managed with extreme caution. For instance, pesticide use next to a corridor might have destructive impacts on pollinators, in turn reducing plant diversity. In many cases, Sustainable Forestry, Sustainable Agriculture, and other non-extractive land-uses can be made compatible with Wildlife Corridors with special management practices acknowledging the needs of species using the corridor.

   When roads or other infrastructure cross a Wildlife Corridor, it is essential to maintain transportation connections that do not diminish the effectiveness of the corridor. Multiple intersecting Wildlife Corridors offering multiple pathways between Core Reserves provide important resiliency to a wildlands network.

   Identify critical existing or potential Wildlife Corridors between Core Reserves, protect them, and mange them for ecosystem connectivity.

2) Stories: Examples of this Pattern in Everyday Life

Safe Passage - Hyak to Easton

Wildlife overpass at Banff National Park, Alberta, Canada.
Photo: Paul Balle

    A 15-mile stretch of Interstate 90 just east of Snoqualmie Pass is due for an upgrade. Deteriorated pavement, congestion, substandard curves, exposure to avalanches, and collisions with wildlife pose risks to safety and reduce transportation efficiency.

    The same stretch of freeway bisects an area that US Forest Service biologists have long recognized as "a critical connective link in the north-south movement of [wildlife] in the Cascade Range." Washington State citizens and the United States Congress have recently invested about $70 million in acquiring and protecting wildlife corridors in the area.

    The Washington State Department of Transportation (WSDOT) is preparing a proposal to expand I-90 between Hyak and Easton. So far, only the environmental impact statement is funded, with a public draft due August 2004. A multi-agency team of biologists and hydrologists are reviewing options. By incorporating bridges and other structures that allow wildlife passage at strategic locations, the project can greatly improve wildlife connections while making travel safer and more efficient.

    The Partnership will support the project only if it provides wildlife passage of the highest standard in this critical habitat bottleneck. Without proper wildlife crossings, the proposed freeway expansion would almost certainly make the situation faced by wildlife significantly worse. Therefore the Partnership will only support the project if impacts are mitigated and crossings of the highest standards are incorporated into the design.

Birds-eye view of the I-90 project, with wildlife passage options in blue. To see
a larger map, including an interactive version, see the WSDOT I-90 Project map page.
Graphic : Washington State DOT website

Intended Benefits of the I-90 Hyak to Easton Project

Efficiency

On average, 27,000 vehicles a day go over Snoqualmie Pass, many of them semi-trucks. Demand is expected to increase steadily over the next 20 years. WSDOT proposes widening the highway from four lanes to six to increase capacity.
The project will also liminate road closures for avalanche control. It's estimated that for every 24 hours the pass is closed, the state economy loses $16 million.
Freight mobility will improve with longer truck climbing lanes.

Safety

In addition to reducing risk from snow avalanches, the project will reduce the risk from rocks and debris from reaching the highway.
Sight distance will improve as curves are straightened.
Wildlife passage structures will reduce collisions between vehicles and animals crossing the freeway.

Wildlife Connections

Improving wildlife connectivity is one of WSDOT's stated goals for this project, which can complement past and ongoing efforts to protect wildlife corridors in Washington's Central Cascades. This project can:

Allow large and small wildlife to safely move from one side of I-90 to the other by strategically elevating the freeway, installing larger culverts, and building bridges.
Help keep Cascades wildlife populations genetically viable by allowing genetic exchange. Larger populations of species are more resilient and allow wildlife and land managers greater flexibility.
Dovetail with recent, major land acquisition efforts (e.g., the I-90 Land Exchange of 1999 followed by a $70 million investment of private and public funds).
Mitigate I-90's impact to wetlands in the project area and improve function of the upper Yakima River system.

3) How Can I Help? - Ways that you and your church can help bring this pattern to life.

Earth Ministry Resolution to Endorse the I-90 Wildlife Bridges Coalition

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Earth Ministry has endorsed the I-90 Wildlife Bridges project in a formal resolution. Have your church prepare a similar endorsement and send it to the I-90 Wildlife Bridges Coalition and the Washington State Dept. of Transportation. Or write a letter of your own.

Wild Corridors text: A Conservation Economy © Ecotrust, 2002

Stories & Images: © Earth Ministry, 2004

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