New technique developed for designing multiple species wildlife corridors

Researchers at several U.S. institutions have developed a computer model that could be applied to wildlife corridors for multiple species.

The efforts, by researchers at Oregon State University, the Georgia Institute of Technology, the U.S. Forest Service Research and Development, Cornell University and the U.S. Geological Survey, will assist managers of public and private lands that provide routes for animals to roam.

Researchers have known that such migration corridors are crucial for conserving rare and endangered species. However, focusing on one species at a time has proved to be expensive. And the new method can meet most of the migratory needs of two species simultaneously while reducing the total cost of buying land by about three quarters.

Results of the collaborated work over a five-year period was published in the journal Conservation Biology.

"We demonstrate that a lot of potential gain can be made at moderate increases in cost as you try to connect habitat areas," Claire Montgomery, a forest economist at Oregon State and one of the researchers on the project, was quoted as saying in a press release. "Looking at trade-offs between target species is something that no one has done, as far as I know, in terms of corridor design."

Species such as grizzly bears and wolverines range over large areas, some of which overlap, and the animals need to be able to move between wilderness, parks and other reserves to avoid becoming inbred and losing genetic diversity.

Asked to help identify parcels of potential interest if opportunities arose to purchase land for wildlife corridor purposes, the researchers developed a method for combining two types of landscape data in a computer model: tax records that show the market values of land and ecological information about the ease with which animals can move across the landscape. They then applied the model to the design of corridors to serve grizzlies and wolverines.

The cost of buying land to serve as ideal migration corridors for wolverines and grizzlies separately came to about 31 million U.S. dollars. By combining corridors that meet most of the animals' needs, the researchers cut the cost to about 8 million dollars.

The corridors pass through key breeding habitat for wolverines in western Montana, a state in the western United States, and connect the Greater Yellowstone Ecosystem in and around Yellowstone National Park with the Northern Continental Divide Ecosystem, which extends as far north as the Canadian border. The closest points of the two reserves are 130 miles, or 211 kilometers, apart as the crow flies, but the corridors are longer, reflecting the animals' complex habitat needs. A corridor that meets the ideal needs of grizzlies was calculated to be about 231 miles, or 372 kilometers, long.

Presented as a potential example of connectivity, the corridors were not an actual project involving a land purchase. More information would be useful to implement such a proposal. "Even with high-profile species like grizzly bears and wolverines, more data about habitat needs would be beneficial for long-term planning," said Rachel Houtman, a research assistant at Oregon State.

"This approach could revolutionize the process of corridor design," said lead author Bistra Dilkina at Georgia Tech. "By incorporating economic costs and multiple species needs directly into the planning process, it allows for a systematic exploration of cost-effective conservation plans and informs policy-makers about trade-offs, both between species as well as between costs and connectivity benefits." Endit