SAVS: A System for Assessing Vulnerability of Species to Climate Change



The SAVS is a questionnaire that combines 22 different criteria to predict vulnerability or resilience of an individual species to future climate change. Numerical scores indicating vulnerability or resilience for terrestrial vertebrate species are generated. In addition, SAVS identifies the source(s) of vulnerability, and the level of uncertainty associated with scores. Results can be used to guide management actions and develop planning strategies in an era of changing climates.


Numerical scores for species vulnerability/resilience and the level of uncertainty associated with each score. Scores are also given in each of the four categories of the questionnaire (habitat, physiology, etc.), so that primary sources of species vulnerability can be identified.

Developed by

USDA Forest Service Rocky Mountain Research Station. Authors include: Karen Bagne, Megan Friggens, and Deborah Finch.


Online interface with associated publications and case studies.



Scale (range)

User-defined scales from management unit to landscape level, but within a set of similar climate projections.


Tested and Published.

Potential Applications

Assessing the vulnerability of species to climate change, helping to guide management actions and develop planning strategies.

Caveats, Restrictions

Direct numerical scores must be interpreted very carefully. The numerical score indicates relative species risk for a group of species within a targeted area and should be used in conjunction with other species information to prioritize actions. The effectiveness of the scoring method depends heavily upon the quality of data used to conduct the scoring process. SAVS does not apply to plants or aquatic species.

Overview & Applicability

The SAVS uses an online questionnaire with 22 criteria to predict vulnerability or population response of species to provide a framework for assessing vulnerability to future climate change. The 22 multiple-choice questions are grouped into four categories by theme: habitat, physiology, phenology and biotic interactions. The questionnaire is completed using information gathered from published materials, personal knowledge, or expert consultation.

Submitting the questionnaire for a species provides the user with a quantitative score for species vulnerability or resilience. A positive score indicates vulnerability of the species to climate change, a negative score indicates resilience. In addition, SAVS identifies a level of uncertainty associated with the score, and the primary source(s) of species vulnerability by providing 'sub-scores' for each of the four categories.

SAVS can be used to assess the vulnerability of diverse species to climate change, for example the mountain quail (left) and desert tortoise (right). Credit: USFWS & USGS


The pilot version of the tool was created in 2009 and tested in two locations, Middle Rio Grande and Coronado National Forest (both reports available in the case studies section of the SAVS website). The tool was then modified and published as a general technical report in 2011 (GTR available here).

Inputs and outputs


SAVS is designed to score terrestrial vertebrate species. This tool requires a thorough literature review or expert knowledge of each species of interest in order to accurately fill out the questionnaire. Users are asked to answer 22 multiple choice questions, in addition to classifying the information used to answer each question as 'adequate' or 'not adequate or conflicting'. Since use of the vulnerability assessment tool involves predicting how species may respond to changes in their environment, the user applies the tool to a selected region with similar climate projections. Therefore, prior to your assessment, you need to characterize expected changes to climate, vegetation, and disturbance for your region.


This tool generates an overall score that scales from -20 (most resilient) to +20 (most vulnerable) and scores for each of the four categories that scale from -5 to +5. Overall scores can be used to identify highly vulnerable (or resilient) species or to rank species according to their vulnerabilities. Categorical scores provide information on what aspect of a species (e.g., habitat) are most sensitive to future climate conditions or changes. Uncertainty is represented as the percentage of questions with inadequate or conflicting information and is calculated to correspond with overall and categorical vulnerability scores. Species with high uncertainty values may be candidates for further monitoring or research efforts.

A natural outcome of compiling the species and climate data necessary to complete the questionnaire is the production of detailed species accounts. For each species assessed through the SAVS tool, data gathered will likely include climate-relevant biological data, the best available knowledge of future exposure to direct and indirect climate effects, and justification for score selection.

Restrictions and limitations

Predicting the future is inherently uncertain. SAVS does not include threats to species that are not climate-related nor can it include every possible response to climate change, but rather allows for a group of species to be assessed on equal criteria. The numerical score indicates relative species risk for a group of species within a targeted area and should be used in conjunction with other species information to prioritize actions. Categorical and individual scores identify vulnerabilities common to a group of species or for an individual species and can be used to direct management actions. However it would be erroneous to use the score to set a numerical cutoff for management actions or to interpret the score as a linear measure of vulnerability or population change. For example, a species with a score of 10 cannot be assumed to be twice as likely to decline as a species with a score of 5.

The effectiveness of this scoring method and the applicability of the information derived from this process depend heavily upon the quality of data used to conduct the scoring process. Scoring may require a substantial amount of input data both regarding species vulnerability and future climate scenarios. Uncertainty also exists in predictions for future climates and vegetation changes, which can affect the final scores even if the data are reliable and overall in agreement.

The SAVS Climate Change Tool focuses solely on the effects of climate change for terrestrial vertebrate species.

Accessing the tool and additional information

In addition to providing access to the online tool, the SAVS website features a good deal of background information on the tool and data requirements, and case studies that used early versions of the tool.

The published General Technical Report on SAVS is available at:

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