Susan Walls, Ph.D.
Biography
RESEARCH
Susan Walls is a research wildlife biologist who serves as the coordinator and lead scientist for the southeastern region of the Amphibian Research and Monitoring Initiative (ARMI). ARMI is a national program for which funding was appropriated by Congress in 2000 in response to mounting evidence and concern for declines of amphibians in the U.S. and worldwide. Susan's research group establishes and implements long-term monitoring of amphibians at key sites within the southeastern U.S. (AL, GA, FL, SC, NC and TN) and conducts research on potential causes of declines. The team focuses on model-based monitoring to assess the impacts of climate change, emerging diseases, habitat restoration, and invasive species on amphibian communities.
Science and Products
Informing Future Condition Scenario Planning for Habitat Specialists of the Imperiled Pine Rockland Ecosystem of South Florida
South Florida's pine rockland ecosystem represents less than 3% of its original extent. This project will evaluate habitat conditions for two pine rockland snake species to develop future habitat condition scenarios for Species Status Assessments.
Monitoring of Amphibians at St. Marks National Wildlife Refuge in Northwest Florida
Freshwater wetlands provide critical habitat for a diverse array of organisms, including many amphibians. Yet, under the threat of climate change, these habitats are among the most imperiled ecosystems on Earth.
Population Demography and Food Web Analysis of Large Aquatic Salamanders (Siren and Amphiuma) in North Florida
Understanding amphibian's life-histories can help predict how they may persist in aquatic habitats in the face of droughts and other climate change-associated events.
Adaptive Habitat Conservation for Flatwoods Salamanders
USGS scientists investigate adaptive habitat conservation for Flatwoods salamanders.
Evaluating the Prevalence of the Amphibian Chytrid Fungus, Batrachochytrium dendrobatidis, in the Southeastern U.S.: Any Evidence of Disease-Related Population Declines?
Pathogens and infectious disease play a role in some recent species extinctions and are likely to impact biodiversity in the future. Environmental DNA - eDNA - is coupled with traditional amphibian sampling methods to determine the distribution and prevalence of the amphibian chytrid fungus, also known as Bd, in the southeastern US.
A Decision Support Tool for Repatriation of Aquatic Fauna: A Case Study Involving the Striped Newt (Notophthalmus perstriatus) at St. Marks National Wildlife Refuge, Florida
The Striped Newt is a small salamander found in xeric habitats (e.g., scrub, sandhill, dry flatwoods) of the lower coastal plain and northern peninsular Florida. Though once considered "common," they are currently a candidate species for federal listing.
Use of Amphibian Communities as Indicators of Restoration Success in the Greater Everglades
Habitat alteration and climate, when combined, are serious threats to amphibians and other wildlife. Habitat suitability models are being used to predict the responses of an amphibian community to hydrological and habitat restoration in the Greater Everglades Ecosystem.
Coping with Invasive Alien Species and Environmental Stressors: Linking Behavioral Studies with Management for Anuran Amphibians
Climate change and invasive species are two key drivers of biodiversity loss. Knowing how amphibians respond to climate change and invasive species can greatly improve predictions of species' persistence in the face of these factors and can help guide resource managers and conservation biologists in developing strategies to manage for these encroaching disturbances.
Integrating behavior and physiology into strategies for amphibian conservation
The amphibian decline crisis has been challenging to address because of the complexity of factors—and their multitude of interactive effects—that drive this global issue. Dissecting such complexity could benefit from strategies that integrate multiple disciplines and address the mechanistic underpinnings of population declines and extirpations. We...
Walls, Susan; Gabor, Caitlin R Seeking shelter from the storm: Conservation and management of imperiled species in a changing climate
Climate change is anticipated to exacerbate the extinction risk of species whose persistence is already compromised by habitat loss, invasive species, disease, or other stressors. In coastal areas of the southeastern United States (USA), many imperiled vertebrates are vulnerable to hurricanes, which climate models predict to become more severe in...
Walls, Susan; Barichivich, William; Chandler, Jonathan; Meade, Ashley M.; Milinichik, Marysa; O'Donnell, Katherine; Owens, Megan E.; Peacock, Terry; Reinman, Joseph; Watling, Rebecca C.; Wetsch, Olivia E. Linking variability in climate to wetland habitat suitability: Is it possible to forecast regional responses from simple climate measures?
Temporary wetlands have value to both ecological and social systems. Interactions between local climate and the surrounding landscape result in patterns of hydrology that are unique to temporary wetlands. These seasonal and annual fluctuations in wetland inundation contribute to community composition and richness. Thus, predicting wetland...
Davis C; Miller D; Campbell Grant, Evan H.; Halstead, Brian; Kleeman, Patrick M.; Walls, Susan; Barichivich, William Identifying management-relevant research priorities for responding to disease-associated amphibian declines
A research priority can be defined as a knowledge gap that, if resolved, identifies the optimal course of conservation action. We (a group of geographically distributed and multidisciplinary research scientists) used tools from nominal group theory and decision analysis to collaboratively identify and prioritize information...
Campbell Grant, Evan H.; Adams, M.J.; Fisher, Robert N.; Grear, Daniel A.; Halstead, Brian J.; Hossack, Blake R.; Muths, Erin L.; Richgels, Katherine L. D.; Russell, Robin E.; Smalling, Kelly L.; Waddle, J. Hardin; Walls, Susan C.; White, C. LeAnn Quantifying climate sensitivity and climate-driven change in North American amphibian communities
Changing climate will impact species’ ranges only when environmental variability directly impacts the demography of local populations. However, measurement of demographic responses to climate change has largely been limited to single species and locations. Here we show that amphibian communities are responsive to climatic variability, using >...
Miller, David A.W.; Campbell Grant, Evan H.; Muths, Erin L.; Amburgey, Staci M.; Adams, M.J.; Joseph, Maxwell B.; Waddle, J. Hardin; Johnson, Pieter T.J.; Ryan, Maureen E.; Schmidt, Benedikt R.; Calhoun, Daniel L.; Davis, Courtney L.; Fisher, Robert N.; Green, David M.; Hossack, Blake R.; Rittenhouse, Tracy A.G.; Walls, Susan C.; Bailey, Larissa L.; Cruickshank, Sam S.; Fellers, Gary M.; Gorman, Thomas A.; Haas, Carola A.; Hughson, Ward; Pilliod, David S.; Price, Steven J.; Ray, Andrew M.; Sadinski, Walter; Saenz, Daniel; Barichivich, William J.; Brand, Adrianne B.; Brehme, Cheryl S.; Dagit, Rosi; Delaney, Katy S.; Glorioso, Brad M.; Kats, Lee B.; Kleeman, Patrick M.; Pearl, Christopher; Rochester, Carlton J.; Riley, Seth P. D.; Roth, Mark F.; Sigafus, Brent A new framework for analysing automated acoustic species-detection data: occupancy estimation and optimization of recordings post-processing
The development and use of automated species-detection technologies, such as acoustic recorders, for monitoring wildlife are rapidly expanding. Automated classification algorithms provide a cost- and time-effective means to process information-rich data, but often at the cost of additional detection errors. Appropriate methods are necessary to...
Chambert, Thierry A.; Waddle, J. Hardin; Miller, David A.W.; Walls, Susan C.; Nichols, James D. Identifying small depressional wetlands and using a topographic position index to infer hydroperiod regimes for pond-breeding amphibians
Small, seasonal pools and temporary ponds (<4.0 ha) are the most numerous and biologically diverse wetlands in many natural landscapes. Thus, accurate determination of their numbers and spatial characteristics is beneficial for conservation and management of biodiversity associated with these freshwater systems. We examined the utility of a...
Riley, Jeffrey W.; Calhoun, Daniel L.; Barichivich, William J.; Walls, Susan C. The significant surface-water connectivity of "geographically isolated wetlands"
We evaluated the current literature, coupled with our collective research expertise, on surface-water connectivity of wetlands considered to be “geographically isolated” (sensu Tiner Wetlands 23:494–516, 2003a) to critically assess the scientific foundation of grouping wetlands based on the singular condition of being surrounded by uplands. The...
Calhoun, Aram J.K.; Mushet, David M.; Alexander, Laurie C.; DeKeyser, Edward S.; Fowler, Laurie; Lane, Charles R.; Lang, Megan W.; Rains, Mark C.; Richter, Stephen; Walls, Susan C. Structured decision making as a conservation tool for recovery planning of two endangered salamanders
At least one-third of all amphibian species face the threat of extinction, and current amphibian extinction rates are four orders of magnitude greater than background rates. Preventing extirpation often requires both ex situ (i.e., conservation breeding programs) and in situ strategies (i.e., protecting natural habitats). Flatwoods salamanders (...
O'Donnell, Katherine; Messerman, Arianne F; Barichivich, William J.; Semlitsch, Raymond D.; Gorman, Thomas A.; Mitchell, Harold G; Allan, Nathan; Fenolio, Dante B.; Green, Adam; Johnson, Fred A.; Keever, Allison; Mandica, Mark; Martin, Julien; Mott, Jana; Peacock, Terry; Reinman, Joseph; Romañach, Stephanie; Titus, Greg; McGowan, Conor P.; Walls, Susan C. Species interactions and the effects of climate variability on a wetland amphibian metacommunity
Disentangling the role that multiple interacting factors have on species responses to shifting climate poses a significant challenge. However, our ability to do so is of utmost importance to predict the effects of climate change on species distributions. We examined how populations of three species of wetland-breeding amphibians, which varied in...
Davis, Courtney L.; Miller, David A.W.; Walls, Susan C.; Barichivich, William J.; Riley, Jeffrey W.; Brown, Mary E. Life history plasticity does not confer resilience to environmental change in the mole salamander (Ambystoma talpoideum)
Plasticity in life history strategies can be advantageous for species that occupy spatially or temporally variable environments. We examined how phenotypic plasticity influences responses of the mole salamander, Ambystoma talpoideum, to disturbance events at the St. Marks National Wildlife Refuge (SMNWR), FL, USA from 2009 to 2014. We observed...
Courtney L. Davis; David A.W. Miller; Walls, Susan C.; Barichivich, William J.; Riley, Jeffrey W.; Brown, Mary E. Extinction debt as a driver of amphibian declines: An example with imperiled flatwoods salamanders
A comprehensive view of population declines and their underlying causes is necessary to reverse species loss. Historically, in many cases, a narrow view may have allowed species declines to continue, virtually undetected, for long periods of time (perhaps even decades). We suggest that extinction debt is likely responsible for numerous (perhaps...
Semiltsch, Raymond D; Walls, Susan C.; Barichivich, William J.; O'Donnell, Katherine
A Unified Research Strategy for Disease Management
As wildlife diseases increase globally, an understanding of host-pathogen relationships can elucidate avenues for management and improve conservation efficacy. Amphibians are among the most threatened groups of wildlife, and disease is a major factor in global amphibian declines.
Large-scale Review of Amphibian Species and Community Response to Climate Change
Amphibian species and community richness has been declining in North America and climate change may play a role in these declines. Global climate change has led to a range shift of many wildlife species and thus understanding how these changes in species distribution can be used to predict amphibian community responses that may improve conservation efforts.