Every species of animal requires a unique combination of environmental conditions and other life forms in order to survive and reproduce. These factors constitute its 'niche', or in looser terms, its 'habitat'. For most species, the landscape is a sea of habitat islands: areas where the living is good, often surrounded by other areas where living is more difficult or impossible. Landscapes and species have evolved together as functioning ecosystems. Animals and plants have migrated and dispersed across landscapes for millennia in order to survive and reproduce.

Landscape-level processes such as wildfire and disease and hydrologic events such as periodic floods have been a part of these systems. Animal movements have been fine-tuned by evolution to function within the natural range of variation existing in the landscape. However, human alterations in modern times have changed the landscape too rapidly and too extensively for most animals to adapt. As one consequence, most animals must now try to move across landscapes that are often much more hostile than anything they are prepared to encounter.

To get from one good habitat island to another an animal often has to expose itself to predators, or travel through areas where there is nothing to eat or drink, or risk getting lost and never finding another secure island of suitable habitat. All this and more can happen if an animal chooses to leave its home range, or if it is forced out.

In many cases we have made the landscape so hostile to some wildlife species that they have virtually no chance of crossing to another patch of habitat. In other cases there remain corridors of suitable vegetation and topography with enough resources to sustain an animal as it wanders in search of a place to live.

Ever since scientists began to recognize that wildlife habitat was becoming more and more fragmented, there has been great interest in the concept of designing reserves and maintaining connectivity between those reserves of wildlife habitat. To do this requires identifying corridors or linkage zones.

A corridor can function at several scales. It can allow seasonal movements for a species; such as elk migration between summer and winter range. A corridor may provide a route for dispersing juveniles; for example a subadult cougar who has to leave habitat that is packed full of other adult cougars, and wander in search of unoccupied habitat and a mate. A corridor may also function over longer distances and lengths of time; for example it probably took many generations for grizzly bears to colonize Mexico from Texas, and it took thousands of years for grizzlies to travel from Siberia into Alaska and then down through Canada. If a patch of habitat is too small to support a population over time, corridors connecting this patch to other island patches can provide a larger habitat structure, and thus support a larger effective population.

In North America, corridors for maintaining biological diversity is an idea that has finally come of age. There is now an extensive library of baseline data available on the landscapes involved. At the same time, the technology for modeling wildlife habitat using Geographic Information Systems (GIS) has progressed to the point where a scientific analysis of potential corridor areas for the specific requirements of a given species can be made.

A corridor analysis project supported by American Wildlands examined the availability and characteristics of movement corridors between our last remaining core islands of habitat in the Rocky Mountains; for a variety of wildlife species and at appropriate time scales, seasonal, lifetime, or several generations. A first step to identify key corridors has been completed. Now the same scientists, working with the support of CERI will refine these maps as a part of a reserve design for the Northern Rockies Reserve Network and the hard work of implementing their protection will begin.

We are approaching the subject of corridors from a biological perspective using state-of-the-art technology. We are acquiring digital data which accurately represents the vegetation and topography of the Northern Rocky Mountain Region. We have begun to be able to 'see' a possible corridor in an electronic landscape as it would be 'seen' by an elk, or a bighorn sheep, or a mountain lion. In this way we can examine very large areas in a relatively short period of time. We have begun to be able to pinpoint any bottlenecks, or gaps, or obstacles which would hinder the movement of each species. Eventually we hope to go out on the ground and try to remedy those problem areas in order to provide a functional corridor for animal movement.

With the availability of this technology, many diverse interest groups are pursuing various aspects of the corridors concept.

The Wildlands Project is a coordinated effort supported by a wide array of conservation groups, academic institutions, and scientists; its goal is to maintain linkages throughout North America. As a subset of the Wildlands Project vision, the The World Wildlife Fund is considering corridors as a part of its Large Carnivore Conservation Project which focuses on the Rocky Mountains. Dr. Paul Paquet, a scientist with World Wildlife Fund Canada, has analyzed and mapped movement corridors for wolves and other species in the Canadian Rockies. He, Dr. Reed Noss, and Dr. Jim Strittholt are beginning a project to map habitat effectiveness and potential linkages from Jasper to the Greater Yellowstone Ecosystem with WWF support through the Conservation Biology Institute.

The Yellowstone to Yukon Conservation initiative is a coalition of U.S. and Canadian groups concerned about maintaining diversity and habitat connectivity throughout the Rocky Mountains from the Yukon to the Greater Yellowstone Ecosystem. Maps and information about this region are available through the The Crown Of The Continent Electronic Data Atlas. American Wildland's corridor analysis project focused on maintaining connections within the Northern Rockies between the large, protected core reserves that remain here: The Northern Continental Divide Ecosystem, The Greater Yellowstone Ecosystem, and the Salmon-Selway Ecosystem.

The Northern Rockies Ecosystem Protection Act, authored by the The Alliance For The Wild Rockies, seeks legal protection for the roadless areas and wildlife corridors in this area. The Montana Gap Analysis Project has mapped the entire region for biodiversity analysis. The Interagency Grizzly Bear Committee and U.S. Fish and Wildlife Service are looking at linkage corridors for bears between the large Recovery Zones.

The scope of corridor mapping is so broad, and the analyses are so complex however, that there is more than enough work to keep everyone busy for the next few years. The important thing is to determine what habitat is critical, and to work to preserve and augment it, before even more corridor habitat is lost. All the groups involved hope to work efficiently together to accomplish this goal.

The Craighead Environmental Research Institute has cooperated with the Montana Department of Fish, Wildlife, and Parks, to follow dispersing juvenile mountain lions when they leave their mother's home range in the Beartooth Game Range and strike out on their own. Recent results of this project will be displayed on our Dispersal Study pages along with future results from GPS radiotracking.