Historically, wildlife conservation efforts have tended to focus on single species. However, as humans continue to change the landscape, a species-by-species approach may not be the most effective means to conserve biodiversity (Franklin 1993). Maintenance of ecological processes rather than management for individual taxa may be a more effective way of using limited resources to benefit the greatest number of species. The WAP was developed upon this premise.

A comprehensive planning effort for each of the SGCN was not feasible, nor would that approach have achieved the goal of addressing the full array of wildlife in Michigan. Additionally, species have requirements for survival that are inextricably tied to their habitats, and degradation or loss of habitat is often the primary threat to species viability. Therefore, the WAP primarily uses a coarse-filter approach based on the habitat needs of wildlife (by definition, both aquatic and terrestrial species) to more effectively conserve rare, declining and common species statewide.

Individual wildlife species, however, cannot be ignored, and the set of SGCN provides a complementary fine-filter approach. Some species' needs may not be sufficiently met through habitat- or ecosystem-based approaches (Herkert 1994, Swengel & Swengel 1997), and the goal of this action plan is to address conservation needs of all wildlife species in Michigan.

When particular species do not respond positively to habitat- or ecosystem-based conservation approaches, additional management specifically directed toward their unique requirements will be necessary. These unique species include those that respond to very specific changes within their habitat or ecosystem, species for which degradation or loss of habitat is not the primary threat, and species that do not share habitat associations with other SGCN, and, therefore, may not be adequately conserved through efforts for species assemblages.

Using a species-based fine filter to assess and address the needs of these species in conjunction with the habitat-based coarse filter will allow comprehensive conservation of Michigan's wildlife diversity.

Additionally, the coarse filter is applied within a regional context (ecoregions for terrestrial systems and basins of Great Lakes for aquatic systems; see Methods for more details), and high priority wildlife conservation issues are identified and addressed at a statewide level. These considerations add even more potential broad-scale filters for identifying and addressing conservation needs of wildlife and wildlife habitats.