Integrating Climate Vulnerability with Lists of At-Risk Species

By Tom Gardali and Dr. Nathaniel Seavy, PRBO Conservation Science

As managers struggle to identify actions they can take to prepare for climate change, one approach that appears promising is to modify existing conservation tools by integrating traditional conservation concerns with concerns associated with climate change. To this end, we have worked with the California Department of Fish and Game to complete a climate vulnerability assessment of bird species of greatest concern.

Traditional conservation planning has relied heavily on lists of at-risk species to guide policy and prioritize conservation actions.  In 2008, the California Department of Fish and Game updated its list of at-risk bird species in the California Bird Species of Special Concern monograph. This list identifies 39 species and 24 subspecies or distinct geographic populations for immediate conservation priority. While this list is a valuable tool for many pressing conservation issues, the threat of climate change was not considered when ranking conservation priority. Hence, to support statewide climate change conservation planning, we developed a framework for assessing climate change vulnerability of California’s at-risk birds and integrating it into the existing California Bird Species of Special Concern list.

In our analysis, we defined climate vulnerability based on the evidence that climate change will negatively impact a population. We quantified climate vulnerability by scoring sensitivity (intrinsic characteristics of a species such as physiological tolerances that make them vulnerable) and exposure (the magnitude and frequency of climate change parameters such as extreme weather events they are expected to experience) for 358 bird taxa in California.

After incorporating climate vulnerability into the existing Bird Species of Special Concern, ten taxa were raised in priority on the integrated list and five were new to the list

Using the combined sensitivity and exposure scores as an index, we identified 128 species as vulnerable to climate change.  Birds associated with wetlands had the largest representation on the list relative to other habitat groups.  Of the 29 state or federally listed taxa, 21 (72%) were also classified as vulnerable to climate change, increasing concern about their conservation. The complete analysis was recently published in PLoS ONE and the full dataset can be downloaded here.

What’s most exciting about the study is that our unique approach is one that other scientists and resource managers can duplicate to help them conserve wildlife in the face of climate change. Not only does our study look at which birds will be most at risk given a changing climate, it also evaluates how climate change, piled on top of all the existing threats such as development and invasive species, will affect birds.  This gives a more comprehensive picture, and provides the information necessary to help allocate scarce dollars for conservation.

Black Oystercatcher, one of five new species to be added to California’s Bird Species of Special Concern monograph © Wisconnelly

Black Oystercatcher, one of five new species to be added to California’s Bird Species of Special Concern monograph © Wisconnelly

Our approach to assessing climate change vulnerability benefited from extensive review of comparable systems, an overview of vulnerability assessments, and published literature on vulnerability. Still, our approach has several limitations. The scale of our assessment is California, which is suitable for the target audience, but may not identify taxa vulnerable at scales larger or smaller. Further, we only scored taxa during their primary role in California, which may not identify taxa vulnerable during a life stage occurring outside of the state. Finally, we did not include an important component of vulnerability, adaptive capacity. Adaptive capacity is used two ways in the vulnerability assessment literature: primarily to describe the capacity (evolutionarily or plasticity) of an organism to accommodate climate change impacts with minimal disruption, but also to describe conservation strategies that are designed to aid a species or a system to prepare for and cope with the impacts of climate change. We judged adaptive capacity, in either sense, to be too difficult to score given how little information and guidance exists upon which to make objective assessments but suggest it will be a critical component in future assessments and is a prime focal area for research.

Climate change does not act alone in threatening biodiversity. Biodiversity is threatened by familiar stressors such as habitat loss and degradation, invasive species, pollution, over-exploitation, and disease. Climate change exacerbates these familiar stressors which, together, are predicted to cause mass global extinctions. Our process illustrates a simple, immediate action that can be taken to inform climate-change adaptation strategies for wildlife.  Lists of at-risk species like ours are simply a first step. Now conservationists and resource managers need to use the list and other resources to identify how best to spend limited conservation dollars to benefit birds, other wildlife and human communities.

PRBO Conservation Science is a non-profit organization with a mission to conserve birds, other wildlife, and ecosystems through innovative scientific research and outreach. PRBO’s highest priority is to develop and promote conservation practices that address the challenges of rapid environmental change.