Methods for identifying better wildlife corridors...

What makes for a good wildlife corridor? Let's ask the wildlife...
Scientists and managers have recognized the importance of wildlife corridors as a connection between fragmented patches of habitat. A challenge arises though in identifying and designing a corridor that will actually benefit the species you're trying to conserve.

A new study in the Journal of Applied Ecology addresses this issue. The researchers from the University of Alberta, tested out an interesting, field-based Two grizzly bears in a meadow in Yellowstone Park. Image credit, Chris Servheen, USFWS method for identifying corridors for the grizzly bear (Ursurus arctos) and cougar (Puma concolor) in two sites in Alberta - though the method is really applicable to any species. In the study they captured and collared 8 grizzly bears and 18 cougars. They then released them back into the wild and tracked their movements using GPS. The researchers used GIS to compare the movements of the animals against 19 potential explanatory variables including land cover, distance to water, distance to forest, greenness, elk density, road density, slope, etc. They used statistical analysis to determine which of these variables best predicted the animals' movements. The researchers named these variables 'Resource Selection Functions.'

For the grizzly, the study found that food resources, measured as greenness and soil wetness, were important predictors for distribution throughout the year at both sites. However, the results varied somewhat based on site and season. For example, at one of the sites, grizzly bears tended to be closer to water features, but this relationship was weak during autumn. Cougars were consistently associated with montane subregions throughout the year and shrub landcover types during winter.

Using what animals tell us to chart out the ideal corridor…
The researchers took the additional step of integrating these resource selection functions into a Least Cost Path analysis to identify the ideal corridors for both species. Least Cost Path analysis entails evaluating potential corridors based on a key criteria: minimizing the cost to the species (in fitness) for movement. The researchers then overlapped the ideal corridors for both species to see the extent to which they overlapped - as it turns out, only moderately.The researchers state the following about the benefit of integrating resource selection functions with Lease Cost Path analysis:

"While most least-cost modeling relies on expert opinion to parameterize the model and develop the cost surface, resource selection functions provide a data-based method for achieving this…. They rely on species and landscape-specific empirical data making the approach to corridor design more rigorous, defensible and transparent. They can be generated at multiple scales depending on the extent of the landscape and the scale of management application [and]… can be developed to reflect species- and landscape-specific variations in seasonal resource selection."

But how feasible is this approach on a site-by-site basis?

The benefits of using this integrated approach are magnified by the studies findings. The predictive factors for wildlife movement varied depending on the species, season, and site location. This suggests that conservation planners using intuition or even regional studies will often design corridors that seem good on paper but aren't ideal for the species.

What's the financial feasibility, though, of implementing this type of analysis on a site-by-site basis given that it involves fairly intense field work (e.g trapping and collaring) and heavy duty analysis? Often, political and economic factors severely limit our choices for selecting corridors. Yet, given the large amounts of money spent on acquiring and managing land, it probably makes sense to get the best data feasible about the extent to which these corridors will benefit the species we're trying to conserve.

If you're interested in finding out more information about the methodology of identifying resource selection function, I highly recommend checking this article out. It give a fairly comprehensive step-by-step approach. You can follow the link below to access the abstract and article.

Source:	Journal of Applied Ecology
Title:	Use of resource selection functions to identify conservation corridors
Authors:	a) Cheryl-Lesley Chetkiewicz and Mark Boyce
	a) University of Alberta