Resource managers increasingly seek to identify which species are most vulnerable to climate change-induced declines. To meet this need, we developed a practical, multifaceted rapid assessment tool, the "climate change vulnerability index." The index considers climate change exposure and species sensitivity. Exposure is the magnitude of projected climate change across the species' range within the assessment area. Species sensitivity includes intrinsic factors such as natural and life history traits that may reduce resilience (such as habitat specialization or a strong potential for disruption of key species interactions) and traits that suggest potential inability to adapt (such as low dispersal ability or reduced genetic diversity). The index also includes extrinsic factors related to a species' distribution, such as dispersal barriers and proximity to predicted sea level rise. Exposure and sensitivity are combined to generate a categorical vulnerability score (Extremely Vulnerable, Highly Vulnerable, Moderately Vulnerable, Not Vulnerable/Presumed Stable, or Not Vulnerable/Increase Likely).

Results/Conclusions

Preliminary results from a study of 216 vertebrates and mollusks in Nevada show that the index effectively sorted species, with the majority being Moderately Vulnerable or Not Vulnerable/Presumed Stable. 100% of mollusks, 80% of fish, 38% of amphibians, 30% of reptiles, 35% of mammals, and 4% of birds assessed were at least Moderately Vulnerable. Key vulnerability factors included limited hydrological niche, impacts from climate change mitigation-related land use changes, migration to or through a few vulnerable locations or lack of facultative distribution shifts, and dependence on vulnerable aquatic/wetland habitats. Good dispersal ability, broad physical habitat, migration to broad geographical areas or tendency to facultatively shift distribution, and broad temperature tolerance were factors that decreased vulnerability. The importance of limited hydrological niche and dependence on vulnerable aquatic/wetland habitats highlights the need for further exploration of the interaction among increasing temperatures, moisture, and wildlife habitats in Nevada. Further testing of the index at the state/province level is warranted, as well as testing at larger spatial scales.