Why didn’t the lynx
cross the road?

Seeking remedies to a modern day dilemma

By Julia Kintsch

The Colorado Mountain Club is a member of the Southern Rockies Conservation Alliance, a coalition of twenty-six non-profit organizations concerned about the future of recreation, wildness, and biodiversity in the Southern Rockies. As an active coalition member, the CMC works closely with other conservation and recreation organizations including the Southern Rockies Ecosystem Project (SREP), a small organization with a big vision for protecting the mountainous heart of the continent.  Last year, CMC, SREP, and the Denver Zoo teamed up to publish the Southern Rockies Network Wildlands Vision, which we hope will fundamentally improve and energize conservation in this spectacular region.

 Stretching north from the cathedral cirques of Wyoming’s Laramie Range, tracing the continental divide along the rugged peaks and passes of Colorado, and reaching south to the sculpted rocks of the Pecos Wilderness in northern New Mexico, the southern Rockies are blessed with a wealth of biological diversity. Alpine tundra, sagebrush grasslands, and forests mixed with pine and aspen are just a few of the native habitat types that contribute to the biological complexity of the region. Native cutthroat trout spawn in pure alpine streams; grand stands of ponderosa pine grace the slopes of remote foothills; and reintroduced lynx are gradually making a comeback in Colorado’s montane forests. The natural abundance of the southern Rockies is supported by large expanses of wild and remote lands that define the landscape.

Yet persistent human activities and developments diminish this biodiversity and fragment the landscape. The very abundance that draws people and economies to the southern Rockies continues to be subjected to a combination of natural resource extraction, recreation, residential development, and road building. Together, these factors have taken their toll and threaten to leave the native Rocky Mountain landscape a skeleton of its former biological glory.

Photo by Chuck_Bartlebaugh.
A grizzly bear attempting to cross a road
in Yellowstone National Park.

The Southern Rockies Ecosystem Project is dedicated to protecting and restoring these large, continuous networks of land that mark the intersection of the continent, connecting north with south and east with west. In a collaborative effort with the Denver Zoo and the Wildlands Project, SREP developed the Southern Rockies Wildlands Network Vision. This document, published by the Colorado Mountain Club Press in December of 2003, proposes a bold and comprehensive blueprint for “rewilding” the southern Rockies of Wyoming, Colorado, and New Mexico. Rewildling recognizes the importance of top-down regulation: for example, the role that large carnivores play in maintaining sustainable prey populations. In addition, rewilding emphasizes functional landscape connectivity and the vital role of keystone species and processes, such as natural wildfires, in maintaining healthy ecosystems.

The vision is the result of numerous scientific analyses and expert interviews, culminating in the Network Design, a science-based map that designates appropriate land management guidelines, accounting for the needs of wildlife, ecosystem processes and acceptable human activities (see map).

The landscape-perspective offered by the vision specifies areas where various activities and consumptive uses are acceptable, versus areas that require protection for wildlife habitat or movement corridors.

While SREP works with partners across the eco-region to realize the goals set forth by the vision, we recognize that the vision is only the first step towards a working, dynamic plan for the southern Rockies. Yet, united under a common vision, the protection and restoration of native habitats and species in the Southern Rockies becomes an attainable goal.

Making connections

Protecting and restoring landscape connectivity emerged as one of six overarching goals described in the vision. In Colorado alone, more than 86,000 miles of roads crisscross the landscape (CDOT, 2004). Designed to facilitate the movement of humans, this paved network not only destroys habitat, but also alters and obstructs wildlife movement. Habitat and wildlife resources have diminished to such an extent that the survival of many species—both endangered and common—is dependent on the restoration of landscape connectivity. Leading conservation biologist E.O. Wilson notes, “without connectivity, landscapes may be reduced to pathetic remnants that sustain few species and provide little ecological value.”

Interstate 70 (I-70), as it cuts across the heart of the Southern Rockies and eastern plains, is the most conspicuous barrier to wildlife movement, but by no means the only one. Other roads similarly deter wildlife movement or increase the risk of mortality for those that attempt passage. Deer and elk, in addition to small mammals, turtles, and snakes, are frequent victims of vehicular collisions. Urban and suburban development, particularly along the Front Range and in mountain valleys, effectively blocks traditional movement corridors between low and high elevation habitats. These are just a few of the obstacles that Colorado’s wildlife faces in pursuit of a livelihood, and they impact not only individual animals but entire populations that depend on connected landscapes for dispersal, migration, and genetic diversity.

Roads fundamentally inhibit and alter wildlife migration. Large roads such as Interstate 70 can block migration altogether unless migration structures are incorporated into the road design.

People are similarly endangered by these conflicts. According to State Farm insurance company, some 700,000 animal-vehicle collisions kill on average 120 people annually in the United States, leaving numerous others with bodily injuries. The economic impact of these collisions adds up to approximately $1.2 billion in damages. As Colorado’s population continues to grow, we can only anticipate that human-wildlife encounters will also increase if measures are not taken to protect both wildlife and people.

To address these issues, the Colorado Department of Transportation (CDOT) and the Federal Highway Administration (FHWA) has joined SREP, the Colorado chapter of the Nature Conservancy, and Colorado State University to identify and prioritize critical wildlife linkages across the state of Colorado. This partnership marks a new commitment by state transportation authorities to consider wildlife needs in transportation planning.

Both FHWA and CDOT have begun promoting wildlife crossings in their transportation plans and construction projects. While much of the work to date is preliminary, CDOT recently completed an analysis of the Interstate 70 (I-70) transportation corridor that identified 13 key wildlife-crossing areas. Agency support for wildlife connectivity is critical to the survival of wildlife populations at both a local and a regional scale. Under this new partnership, SREP will be expanding upon CDOT’s work to assess connectivity needs for wildlife across the entire state, with the goal of providing transportation planners, communities, and conservationists a statewide vision for reconnecting landscapes.

Linking Colorado’s Landscapes is a project designed to achieve this goal. The first phase in the project is to identify and prioritize wildlife movement linkages across the state. To this end, SREP has instituted a two-track approach, integrating local and regional expertise, as well as computer modeling. The first track, or “expert track,” involved a series of workshops that were held across the state this spring, which brought together experts from various agencies, local communities, and academia to identify wildlife corridors that are vital to maintaining healthy populations of native species. The information from these workshops is being compiled and scored based on a prioritization scheme that evaluates conservation significance, opportunity, and threat.

The second track, or “computer modeling track,” considers these same questions within the framework of a geographic information system. Colorado State University research scientist Dave Theobald, Ph.D., is leading this effort. Theobald is combining layers of spatial data about the physical characteristics of the landscape (e.g., topography, vegetation, roads, and development) with information about wildlife habitat preferences and movement patterns to create models of the landscape that are key to wildlife movement.

By the fall of 2004, the results from each track will be combined to highlight the top ten priority linkages in the state of Colorado. These results will provide a comprehensive framework that will serve as a guide for FHWA and CDOT as well as community planners working to develop more wildlife-friendly transportation networks. In the implementation phase of the project beginning next winter, SREP will continue working with CDOT and transportation engineers to implement on-the-ground mitigation measures to facilitate wildlife movement in each critical linkage.

There is no one-size-fits-all approach, and further in-depth analysis of each critical linkage will ensure that mitigation measures are responsive to the individual sites and species movement needs. Such analysis based on additional investigation will help to determine specific stretches of road where animals are continually attempting to cross, and it will provide the basis for individualized mitigation recommendations at each site. The questions that need to be answered range from “Which species are trying to move through this area?” to “What natural landscape features abet animal movement?” and “What types of road crossing structures will these animals utilize?”

What does mitigation look like?

Mitigation structures for wildlife to cross roads and highways come in many shapes and forms. To name a few, vegetated overpasses, span bridges, culverts, tunnels, and fencing have been installed from Florida to Alberta and across Europe. In southern California a highway exit was recently closed and is being restored to provide a pathway for mountain lions crossing under the highway. In Canada a series of two vegetated overpasses and twenty-two underpasses built across the Trans-Canada Highway through Banff National Park are successfully facilitating wildlife movement across this heavily-trafficked highway. Monitoring studies conducted by wildlife biologist Tony Clevenger show that these structures have helped to reduce wildlife mortalities along this fifty-mile stretch of highway by ninety-five percent. The Linking Colorado Landscape’s project is fortunate to have examples from around the world to build on and learn from.

Photo by C. LeClerc. A vegetated overpass across the Trans-Canada Highway in Banff National Park, Canada, constructed to facilitate wildlife migration

In addition to crossing structures, on-the-ground mitigation work must ensure that once having crossed a road, there is sufficient and adequately protected habitat so that animals can continue to disperse safely across the landscape. Such protection could include working with local non-profit organizations to purchase development rights on key private properties or assisting communities in making informed decisions to avoid conflicts in important wildlife corridors.

Helping wildlife to move across our roadways safely has far-reaching consequences that bring together a diverse group of constituents and allies to discuss the importance of wildlife crossings and the human and economic costs that animal-vehicle collisions are inflicting on the citizens of Colorado. As SREP delves into the business of making our roadways safer for both people and animals, the organization will focus even greater effort in engaging transportation engineers, local officials, policy makers, business groups, insurance companies, and conservation organizations in a multifaceted collaboration.

Restoring wildlife connections is no simple task. Retrofitting, or in some cases removing, roads is an expensive and complex undertaking that requires an on-going commitment from both state and federal transportation agencies. Support and involvement by local communities and public land managers is key to ensuring that once having successfully traversed a road obstacle, an animal has continued safe passage across the landscape. Landscape connections are crucial to healthy wildlife populations, and human commitment is critical to realizing these goals.

For more information on SREP’s linkages work, please contact Julia at 720-946-9653 or Julia@RestoreTheRockies.org, or visit SREP’s website at www.RestoreTheRockies.org.

To order a copy of the Southern Rockies Wildlands Network Vision, please visit the Colorado Mountain Club Press at http://www.cmc.org/press/southern_rockies_vision.htm.