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

Karen E. Bagne, Megan M. Friggens, Deborah M. Finch
Posted on: 7/18/2022 - Updated on: 3/10/2023

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Sustained conservation of species requires integration of future climate change effects, but few tools exist to assist managers. The System for Assessing Vulnerability of Species (SAVS) identifies the relative vulnerability or resilience of vertebrate species to climate change. Designed for managers, the SAVS is an easily applied tool that uses a questionnaire of 22 predictive criteria to create vulnerability scores. The user scores species' attributes relating to potential vulnerability or resilience associated with projections for their region. Six scores are produced: an overall score denoting level of vulnerability or resilience, four categorical scores (habitat, physiology, phenology, and biotic interactions) indicating source of vulnerability, and an uncertainty score, which reflects user confidence in the predicted response. The SAVS provides a framework for integrating new information into the climate change assessment process.


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 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.

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:


Bagne, Karen E.; Friggens, Megan M.; Finch, Deborah M. 2011. A System for Assessing Vulnerability of Species (SAVS) to Climate Change. Gen. Tech. Rep. RMRS-GTR-257. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 28 p.

Affiliated Organizations

The United States Department of Agriculture (USDA) works to support the American agricultural economy to strengthen rural communities; to protect and conserve our natural resources; and to provide a safe, sufficient, and nutritious food supply for the American people. The Department’s wide range of programs and responsibilities touches the lives of every American every day. This factsheet provides information about some of our agencies and offices, their missions, responsibilities, and services they provide.

The U.S. Department of Agriculture Forest Service is a Federal agency that manages public lands in national forests and grasslands. The Forest Service is also the largest forestry research organization in the world, and provides technical and financial assistance to state and private forestry agencies. Gifford Pinchot, the first Chief of the Forest Service, summed up the purpose of the Forest Service—"to provide the greatest amount of good for the greatest amount of people in the long run."

The Rocky Mountain Research Station (RMRS) is one of seven regional units that make up the USDA Forest Service Research and Development organization—the most extensive natural resources research organization in the world. We maintain 12 field laboratories throughout a 12-state territory encompassing the Great Basin, Southwest, Rocky Mountains and parts of the Great Plains (see map). Our research program serves the Forest Service as well as other federal and state agencies, international organizations, Tribes, academia, non-profit groups and individuals.


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