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.
Developing Future Habitat Condition Scenarios for Wildlife in the Imperiled Pine Rockland Ecosystem of South Florida
The pine rockland ecosystem is found only in south Florida and the Bahamas and provides important habitat for numerous rare and endemic plants and animals. These include 18 species that are already federally listed as threatened or endangered and four other species petitioned for listing that are scheduled for development of Species Status Assessments (SSAs). Today, south Florida’s pine rockland e...
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.
Elucidating mechanisms underlying amphibian declines in North America using hierarchical spatial models
Amphibian populations are declining globally at unprecedented rates but statistically rigorous identification of mechanisms is lacking. Identification of reasons underlying large-scale declines is imperative to plan and implement effective conservation efforts. Most research on amphibian population decline has focused on local populations and local factors. However, the ubiquity of declines across
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.
How will Florida’s Biodiversity Respond to Climate Change?
Florida is home to 50 endangered species, 23 National Wildlife Refuges, 9 national parks, and 119 state parks. Straddling both temperate and sub-tropical zones, the state is also unique in that it is a long and narrow peninsula, surrounded on three sides by warm water, creating a dynamic environment. The impacts of climate change, such as sea-level rise and severe storms, threaten the state’s uniq...
Fish, amphibian, and conductance data from Panacea Unit, St. Marks National Wildlife Refuge, FL, 2009-2016
These data are meant to support a publication "Disentangling direct and indirect effects of extreme events on coastal wetland communities" in the Journal of Animal Ecology. This dataset contains both amphibian and fish observations based on our use of plastic minnow traps. Additionally we present (specific) conductance values observed during our trapping periods.
Data release for Predicting the impacts of future sea level rise on specialist snake species in the imperiled pine rockland ecosystem of South Florida
Approximately 90% of pine rockland habitat in South Florida and the Florida Keys, USA, has been lost, fragmented, and degraded due to urbanization and other anthropogenic disturbances. Low-lying islands and coastal areas are also becoming increasingly vulnerable to sea-level rise and high tide flooding, which is rapidly increasing in frequency, depth, and extent, putting these areas and the pine r
Corticosterone release rates, water quality, microbiome, and mucosome data for analysis of Pseudacris ornata sites
We measured environmental variables at multiple spatial scales and their effect on three physiological health metrics of ornate chorus frog (Pseudacris ornata) tadpoles to identify potential correlates of population declines. To accomplish this, we measured corticosterone (glucocorticoid hormone associated with the stress response in amphibians) release rates, as well as the skin mucosal immune fu
Specific conductance of flatwood salamander breeding ponds: pre- and post-Hurricane Michael, 2013-2018
Hurricane Michael impacted the gulf coast of the southeastern USA in October 2018. During this storm, St. Marks National Wildlife Refuge, located along the northern Gulf of Mexico's coast in the panhandle region of Florida, experienced storm surge that was 2.3 to 3.3 m above sea level. Storm surge pushed sea water into some ephemeral freshwater ponds used for breeding by the federally-threatened F
Hydrological measurements of 300 US temporary wetlands from 2004-2014
This dataset includes hydrological measurements of 300 US temporary wetlands from 2004-2014.
Computer automated frog vocalization results from Picayune Strand State Forest, Florida 2011-2012
This dataset includes the results of a computer automated anuran vocalization recognition analysis of audio recordings made at Picayune Strand State Forest in 2011 and 2012. The audio files were scanned for 11 species of frogs and toads using the commercially available software program Song Scope (ver. 4.1.3). All detections by the software are listed here along with a "result" field which indicat
Filter Total Items: 51
Future changes in habitat availability for two specialist snake species in the imperiled rocklands of South Florida, U.S.A.
Rockland habitat in South Florida, USA, is a threatened ecosystem that has been lost, fragmented, or degraded because of urbanization or other anthropogenic disturbance. Furthermore, low-lying islands and coastal areas are experiencing sea level rise (SLR) and an increased frequency and intensity of tidal flooding, putting rockland habitats there at increasing risk of ecological change. We evaluat
Maximizing species distribution model performance when using historical occurrences and variables of varying persistency
Occurrence data used to build species distribution models often include historical records from locations in which the species no longer exists. When these records are paired with contemporary environmental values that no longer represent the conditions the species experienced, the model creates false associations that hurt predictive performance. The extent of mismatching increases with the numbe
Informing future condition scenario planning for habitat specialists of the imperiled pine rockland ecosystem of South Florida
This project evaluated habitat conditions for two species found in the imperiled pine rockland ecosystem—the Rim Rock Crowned Snake (Tantilla oolitica) and the Key Ring-Necked Snake (Diadophis punctatus acricus). The Rim Rock Crowned Snake historically occurred in eastern Miami-Dade County (hereafter, mainland) as well as throughout the Florida Keys, whereas the Key Ring-Necked Snake occurs only i
Batrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians
The salamander chytrid fungus (Batrachochytrium salamandrivorans [Bsal]) is causing massive mortality of salamanders in Europe. The potential for spread via international trade into North America and the high diversity of salamanders has catalyzed concern about Bsal in the U.S. Surveillance programs for invading pathogens must initially meet challenges that include low rates of occurrence on the l
Changes in physiology and microbial diversity in larval ornate chorus frogs are associated with habitat quality
Environmental change associated with anthropogenic disturbance can lower habitat quality, especially for sensitive species such as many amphibians. Variation in environmental quality may affect an organism’s physiological health and, ultimately, survival and fitness. Using multiple health measures can aid in identifying populations at increased risk of declines. Our objective was to measure enviro
Editorial: Contributions of behavior and physiology to conservation biology
Conservation biology is a rapidly evolving discipline, with its synthetic, multidisciplinary framework expanding extensively in recent years. Seemingly disparate disciplines, such as behavior and physiology, are being integrated into this discipline's growing portfolio, resulting in diverse tools that can help develop conservation solutions. Behavior and physiology have traditionally been consider
Category count models for adaptive management of metapopulations: Case study of an imperiled salamander
Managing spatially structured populations of imperiled species presents many challenges. Spatial structure can make it difficult to predict population responses to potential recovery activities, and learning through experimentation may not be advised if it could harm threatened populations. Adaptive management provides an appealing framework when experimentation is considered too risky or time con
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 examine how the disciplines of behavior and physio
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 the 21st century. Despite this escalating threat, e
A new parameterization for estimating co‐occurrence of interacting species
Models currently used to estimate patterns of species co‐occurrence while accounting for errors in detection of species can be difficult to fit when the effects of covariates on species occurrence probabilities are included. The source of the estimation problems is the particular parameterization used to specify species co‐occurrence probability. We develop a new parameterization for estimating pa
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 community responses to environmental change is tied to the
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 needs within the context of disease-associated amphibian decline, in order
By
Ecosystems Mission Area, Water Resources Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Patuxent Wildlife Research Center, Eastern Ecological Science Center, Forest and Rangeland Ecosystem Science Center, Fort Collins Science Center, National Wildlife Health Center, New Jersey Water Science Center, Northern Rocky Mountain Science Center, Western Ecological Research Center (WERC), Wetland and Aquatic Research Center
Science and Products
- Science
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.Developing Future Habitat Condition Scenarios for Wildlife in the Imperiled Pine Rockland Ecosystem of South Florida
The pine rockland ecosystem is found only in south Florida and the Bahamas and provides important habitat for numerous rare and endemic plants and animals. These include 18 species that are already federally listed as threatened or endangered and four other species petitioned for listing that are scheduled for development of Species Status Assessments (SSAs). Today, south Florida’s pine rockland e...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.Elucidating mechanisms underlying amphibian declines in North America using hierarchical spatial models
Amphibian populations are declining globally at unprecedented rates but statistically rigorous identification of mechanisms is lacking. Identification of reasons underlying large-scale declines is imperative to plan and implement effective conservation efforts. Most research on amphibian population decline has focused on local populations and local factors. However, the ubiquity of declines acrossCoping 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.How will Florida’s Biodiversity Respond to Climate Change?
Florida is home to 50 endangered species, 23 National Wildlife Refuges, 9 national parks, and 119 state parks. Straddling both temperate and sub-tropical zones, the state is also unique in that it is a long and narrow peninsula, surrounded on three sides by warm water, creating a dynamic environment. The impacts of climate change, such as sea-level rise and severe storms, threaten the state’s uniq... - Data
Fish, amphibian, and conductance data from Panacea Unit, St. Marks National Wildlife Refuge, FL, 2009-2016
These data are meant to support a publication "Disentangling direct and indirect effects of extreme events on coastal wetland communities" in the Journal of Animal Ecology. This dataset contains both amphibian and fish observations based on our use of plastic minnow traps. Additionally we present (specific) conductance values observed during our trapping periods.Data release for Predicting the impacts of future sea level rise on specialist snake species in the imperiled pine rockland ecosystem of South Florida
Approximately 90% of pine rockland habitat in South Florida and the Florida Keys, USA, has been lost, fragmented, and degraded due to urbanization and other anthropogenic disturbances. Low-lying islands and coastal areas are also becoming increasingly vulnerable to sea-level rise and high tide flooding, which is rapidly increasing in frequency, depth, and extent, putting these areas and the pine rCorticosterone release rates, water quality, microbiome, and mucosome data for analysis of Pseudacris ornata sites
We measured environmental variables at multiple spatial scales and their effect on three physiological health metrics of ornate chorus frog (Pseudacris ornata) tadpoles to identify potential correlates of population declines. To accomplish this, we measured corticosterone (glucocorticoid hormone associated with the stress response in amphibians) release rates, as well as the skin mucosal immune fuSpecific conductance of flatwood salamander breeding ponds: pre- and post-Hurricane Michael, 2013-2018
Hurricane Michael impacted the gulf coast of the southeastern USA in October 2018. During this storm, St. Marks National Wildlife Refuge, located along the northern Gulf of Mexico's coast in the panhandle region of Florida, experienced storm surge that was 2.3 to 3.3 m above sea level. Storm surge pushed sea water into some ephemeral freshwater ponds used for breeding by the federally-threatened FHydrological measurements of 300 US temporary wetlands from 2004-2014
This dataset includes hydrological measurements of 300 US temporary wetlands from 2004-2014.Computer automated frog vocalization results from Picayune Strand State Forest, Florida 2011-2012
This dataset includes the results of a computer automated anuran vocalization recognition analysis of audio recordings made at Picayune Strand State Forest in 2011 and 2012. The audio files were scanned for 11 species of frogs and toads using the commercially available software program Song Scope (ver. 4.1.3). All detections by the software are listed here along with a "result" field which indicat - Publications
Filter Total Items: 51
Future changes in habitat availability for two specialist snake species in the imperiled rocklands of South Florida, U.S.A.
Rockland habitat in South Florida, USA, is a threatened ecosystem that has been lost, fragmented, or degraded because of urbanization or other anthropogenic disturbance. Furthermore, low-lying islands and coastal areas are experiencing sea level rise (SLR) and an increased frequency and intensity of tidal flooding, putting rockland habitats there at increasing risk of ecological change. We evaluatMaximizing species distribution model performance when using historical occurrences and variables of varying persistency
Occurrence data used to build species distribution models often include historical records from locations in which the species no longer exists. When these records are paired with contemporary environmental values that no longer represent the conditions the species experienced, the model creates false associations that hurt predictive performance. The extent of mismatching increases with the numbeInforming future condition scenario planning for habitat specialists of the imperiled pine rockland ecosystem of South Florida
This project evaluated habitat conditions for two species found in the imperiled pine rockland ecosystem—the Rim Rock Crowned Snake (Tantilla oolitica) and the Key Ring-Necked Snake (Diadophis punctatus acricus). The Rim Rock Crowned Snake historically occurred in eastern Miami-Dade County (hereafter, mainland) as well as throughout the Florida Keys, whereas the Key Ring-Necked Snake occurs only iBatrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians
The salamander chytrid fungus (Batrachochytrium salamandrivorans [Bsal]) is causing massive mortality of salamanders in Europe. The potential for spread via international trade into North America and the high diversity of salamanders has catalyzed concern about Bsal in the U.S. Surveillance programs for invading pathogens must initially meet challenges that include low rates of occurrence on the lChanges in physiology and microbial diversity in larval ornate chorus frogs are associated with habitat quality
Environmental change associated with anthropogenic disturbance can lower habitat quality, especially for sensitive species such as many amphibians. Variation in environmental quality may affect an organism’s physiological health and, ultimately, survival and fitness. Using multiple health measures can aid in identifying populations at increased risk of declines. Our objective was to measure enviroEditorial: Contributions of behavior and physiology to conservation biology
Conservation biology is a rapidly evolving discipline, with its synthetic, multidisciplinary framework expanding extensively in recent years. Seemingly disparate disciplines, such as behavior and physiology, are being integrated into this discipline's growing portfolio, resulting in diverse tools that can help develop conservation solutions. Behavior and physiology have traditionally been considerCategory count models for adaptive management of metapopulations: Case study of an imperiled salamander
Managing spatially structured populations of imperiled species presents many challenges. Spatial structure can make it difficult to predict population responses to potential recovery activities, and learning through experimentation may not be advised if it could harm threatened populations. Adaptive management provides an appealing framework when experimentation is considered too risky or time conIntegrating 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 examine how the disciplines of behavior and physioSeeking 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 the 21st century. Despite this escalating threat, eA new parameterization for estimating co‐occurrence of interacting species
Models currently used to estimate patterns of species co‐occurrence while accounting for errors in detection of species can be difficult to fit when the effects of covariates on species occurrence probabilities are included. The source of the estimation problems is the particular parameterization used to specify species co‐occurrence probability. We develop a new parameterization for estimating paLinking 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 community responses to environmental change is tied to theIdentifying 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 needs within the context of disease-associated amphibian decline, in orderByEcosystems Mission Area, Water Resources Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Patuxent Wildlife Research Center, Eastern Ecological Science Center, Forest and Rangeland Ecosystem Science Center, Fort Collins Science Center, National Wildlife Health Center, New Jersey Water Science Center, Northern Rocky Mountain Science Center, Western Ecological Research Center (WERC), Wetland and Aquatic Research Center - News