FoSA: Focal Species Analysis

WCS/MCA concentrates survey efforts on wildlife species which respond specifically to development impacts including habitat loss and habitat fragmentation. Such species are termed “focal taxa,” and can be further divided into two broad categories. Many focal taxa experience population declines as a result of urbanization. These species, referred to as “development-sensitive” focal species, are usually habitat specialists, with relatively narrow ecological requirements and/or complex life-history requirements that involve use of multiple interconnected habitat types. These specialized habitats and interconnections are often compromised by development. Examples include Neotropical migrant bird species, vernal pool-breeding amphibians, and long-lived species such as box turtles. Such taxa tend to disappear from the landscape as their habitats are altered or fragmented. Populations of other focal taxa increase in response to urbanization. These species, referred to as “development-associated” focal species, are usually habitat generalists, with much less-specific habitat requirements. They tend to be found in areas that have already been degraded or along edges; human alterations to landscapes favor, or subsidize, these generalists. Examples of such species include Corvids (crows and jays), Canada geese, bullfrogs, and white-tailed deer. As urbanization proceeds, development-sensitive species are out-competed by more adaptable development-associated species. In this manner, development-associated species tend to increase and, over time, replace development-sensitive species, resulting in an overall reduction of biodiversity.

WCS/MCA refers to this novel process of evaluating the mix of focal taxa, and its implications for ecosystem health and land use, as the “Focal Species Approach,” or “FoSA.” The results of FoSA analysis can enhance planning efforts by assessing the importance of individual sites for conservation. For example, development should be discouraged within areas that support healthy populations of development-sensitive focal species, and redirected toward sites that are already degraded (i.e., those that are dominated by development-associated species).

FoSA represents an innovative departure from traditional conservation efforts. By expanding the scope of investigation beyond federal- or state-listed threatened and endangered species, we are able to more proactively conserve natural resources. There are many species, currently unlisted and unprotected, whose populations are declining in response to sprawl. At the current pace of exurbanization (development outside of urban and suburban areas), these species are highly likely to be candidates for official listing in the near future. Rather than waiting until they are on the brink of extinction (when recovery efforts are not only dangerously uncertain, but also very expensive), it makes sense to attempt to address their habitat requirements and to stabilize their populations now. In addition, ecosystems contain complex interactions among many species. FoSA evaluates systems more reliably by considering a much broader suite of species and their relative abundances, as opposed to basing land use recommendations on a single threatened or endangered species. FoSA methods are not intended to replace existing and necessary efforts to conserve threatened and endangered species; instead, they add value to ongoing conservation and land use planning efforts.