Direct impacts to special status wildlife species result from the direct loss of important habitat or a key habitat feature, such as a nest site or lek area, or from the immediate loss of life. Human activities can directly disturb special status wildlife, potentially causing nest, lek, or home range abandonment. Disturbance during sensitive periods (e.g., winter and breeding) leads to lower recruitment rates and higher mortalities, which results in adverse impacts to special status wildlife species.

Discussed in detail in the introduction to Biological Resources in this chapter and in Chapter 3, habitat loss and fragmentation result in adverse impacts to special status wildlife species. Habitat loss generally results in direct impacts to the individual or population that is immediately affected. The impacts of habitat fragmentation, however, operate indirectly through mechanisms such as population isolation (Saunders et al. 1991); edge effects, such as increased nest predation and parasitism (Paton 1994; Faaborg et al. 1995); encroachment of invasive species; and disruption of migration patterns.

Special status wildlife experience indirect impacts through changes in habitat characteristics or quality, which ultimately can change migration patterns, habitat use, carrying capacity, and long-term population viability. Indirect impacts to habitats for special status wildlife species can also occur when specific actions change habitat to make it unsuitable. Disturbance impacts can range from short-term displacement and shifts in activities to long-term abandonment of home range (Miller et al. 1998; Warmoloy et al. 1988; Connelly et al. 2000).

For the purpose of this analysis, short-term impacts (up to 5 years) to special status wildlife are those activities that an individual or species respond to immediately, but do not impact the population viability of the species. Long-term impacts (more than 5 years) are those that cause an individual or species to permanently abandon an area, or that alter the population viability and survival of the species. Examples of beneficial long-term impacts include restoration of habitat structure or health, or enhancement of forage base to improve populations of special status wildlife species over time.