State and Federal Conservation Status Does Not Account for Species Climate Change Sensitivity
Climate change poses a serious threat to species and ecosystems across the globe. However, conservation assessments often fail to incorporate species’ vulnerability to climate change. A recent study developed an approach to compare a species’ conservation status and climatic sensitivity and found little relationship between these factors, highlighting a critical gap between on-the-ground policy and ecology in a changing climate.
by Fern Crossway | @thiswildwonderland
Fig 1.|The Gray Treefrog (“Hyla versicolor”). Dubose et al. describe how the sensitivity of anuran species to climate change is not currently aligned with species’ conservation status, but that this will be an important consideration in a rapidly changing climate. Photo by Fern Crossway.
Article by University of Washington graduate student, Fern Crossway.
Assigning a conservation status to at-risk species can provide populations with increased protection, yet these listings often fail to consider species’ vulnerability to climate change (De Grammont & Cuarón 2006; Harris et al. 2012). Many species facing novel or compounding stressors due to climate change are still poorly studied or excluded from multispecies vulnerability assessments, creating a knowledge gap in determining their appropriate conservation status (Lawler et al. 2002; DuBose et al. 2023). Species life history, physiological, and spatial data are required to predict responses to environmental change. When these data are lacking, it can lead to reduced accuracy in predicting species response to, and subsequent vulnerability to climate change, increasing their risk of local extirpation or extinction. In their 2023 Biological Conservation study, DuBose et al. sought to address these gaps for a subset of anuran species using intrinsic sensitivity analyses.
Intrinsic sensitivity, or the susceptibility and persistence capacity associated with ecological change due to a species’ biological limitations, is a critical component of extinction vulnerability in the face of climate change. Two dominant factors influencing a species’ inherent risk and vulnerability to climate-related extinction include the size of their realized climate niche breadths and their geographical rarity. Species with small climate niches or that are considered geographically rare have a higher intrinsic sensitivity to changing environments. DuBose et al. systematically described the intrinsic climate sensitivity of 90 anuran species with ranges in the United States, evaluating the relationship between their sensitivity score and conservation status at the international, national, and local levels.
Data for their study were collected from the publicly available databases GBIF (the Global Biodiversity Information Facility) and HerpMapper, a citizen science, non-profit organization where individuals can submit observations of reptiles and amphibians. The authors were clear about the limitations of these data sources, including their opportunistic nature and inability to encompass the full climate gradient likely associated with each species. Nevertheless, these and other citizen science databases such as iNaturalist and eBird are important tools for collecting observation data, particularly for rare and understudied species, and can safely be used to rank species’ area of occurrence at similar spatial grains. In this instance, 1 km buffer zones around observation points and combined HUC12 watershed sub-basins and HydroBASIN watersheds were used for grain size. The researchers used 5 bioclimatic variables to calculate climate specificity, or realized climate niches, including precipitation seasonality, annual precipitation, mean annual temperature, maximum temperature of the warmest month, and minimum temperature of the coldest month. Sensitivity scores were then calculated for each of the 90 anuran species based on their habitat specificity and geographic rarity. Following this, the authors compared sensitivity scores between taxa and conservation status lists at the international (IUCN Red List, [International Union for Conservation of Nature]), federal (ESA, [Endangered Species Act]), and state (SGCN, [Species of Greatest Conservation Need]) levels.
As hypothesized, the authors found no relationship between a species’ intrinsic sensitivity to climate change and their conservation status at the federal or state levels. For example, the Rio Grande chirping frog (Eleutherodactylus cystignathoides) is currently unlisted yet was found to have one of the highest intrinsic sensitivity scores of all species included in the study. The Florida bog frog (Lithobates okaloosae) and Amargosa toad (Anaxyrus nelsoni) are similarly excluded from state and federal listings despite inclusion on the IUCN Red List. The authors found that species with small areas of occurrence and narrow climate niches were excluded from conservation lists at all three levels.
These results emphasize the need for systematic, multispecies assessments of intrinsic sensitivity in order to accurately inform status designations. This approach can be of particular benefit to geographically rare species with high habitat specificity likely to face increased isolation and biological pressure as climate change modifies existing stressors and introduces new ones. Applying this approach to other taxa may help guide future conservation listings and aid biologists in selecting management priorities in a changing world.
References
De Grammont PC, Cuarón AD. 2006. An Evaluation of Threatened Species Categorization Systems Used on the American Continent. Conservation Biology 20:14–27.
DuBose TP, Moore CE, Silknetter S, Benson AL, Alexander T, O’Malley G, Mims MC. 2023. Mismatch between conservation status and climate change sensitivity leaves some anurans in the United States unprotected. Biological Conservation 277:109866.
Harris JBC, Reid JL, Scheffers BR, Wanger TC, Sodhi NS, Fordham DA, Brook BW. 2012. Conserving imperiled species: a comparison of the IUCN Red List and U.S. Endangered Species Act. Conservation Letters 5:64–72.
Lawler JJ, Campbell SP, Guerry AD, Kolozsvary MB, O’Connor RJ, Seward LCN. 2002. The Scope and Treatment of Threats in Endangered Species Recovery Plans. Ecological Applications 12:663–667. Ecological Society of America.