Susan Walls, Ph.D.
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
Filter Total Items: 54
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 most) amphibian declines and that this perspective sh
Authors
Raymond D Semiltsch, Susan C. Walls, William J. Barichivich, Katy O'Donnell
Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines
Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a “smoking gun” was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extin
Authors
Evan H. Campbell Grant, David A. W. Miller, Benedikt R. Schmidt, M. J. Adams, Staci M. Amburgey, Thierry A. Chambert, Sam S. Cruickshank, Robert N. Fisher, David M. Green, Blake R. Hossack, Pieter T.J. Johnson, Maxwell B. Joseph, Tracy A. G. Rittenhouse, Maureen E. Ryan, J. Hardin Waddle, Susan C. Walls, Larissa L. Bailey, Gary M. Fellers, Thomas A. Gorman, Andrew M. Ray, David S. Pilliod, Steven J. Price, Daniel Saenz, Walt Sadinski, Erin L. Muths
Do geographically isolated wetlands influence landscape functions?
Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy, and organisms with other elements in hydrological and habitat networks, contributing to landscape functions, such as flow generation, nutrient and sediment retention, and biodiversity support. GIWs constitute most of the wetlands in many North American landscapes, provide a disproportionately large fr
Authors
Matthew J. Cohen, Irena F. Creed, Laurie C. Alexander, Nandita Basu, Aram J.K. Calhoun, Christopher Craft, Ellen D’Amico, Edward S. DeKeyser, Laurie Fowler, Heather E. Golden, James W. Jawitz, Peter Kalla, L. Katherine Kirkman, Charles R. Lane, Megan Lang, Scott G. Leibowitz, David Bruce Lewis, John Marton, Daniel L. McLaughlin, David M. Mushet, Hadas Raanan-Kiperwas, Mark C. Rains, Lora Smith, Susan C. Walls
Testing hypotheses on distribution shifts and changes in phenology of imperfectly detectable species
With ongoing climate change, many species are expected to shift their spatial and temporal distributions. To document changes in species distribution and phenology, detection/non-detection data have proven very useful. Occupancy models provide a robust way to analyse such data, but inference is usually focused on species spatial distribution, not phenology.We present a multi-season extension of th
Authors
Thierry A. Chambert, William L. Kendall, James E. Hines, James D. Nichols, Paolo Pedrini, J. Hardin Waddle, Giacomo Tavecchia, Susan C. Walls, Simone Tenan
Geographically isolated wetlands: Rethinking a misnomer
We explore the category “geographically isolated wetlands” (GIWs; i.e., wetlands completely surrounded by uplands at the local scale) as used in the wetland sciences. As currently used, the GIW category (1) hampers scientific efforts by obscuring important hydrological and ecological differences among multiple wetland functional types, (2) aggregates wetlands in a manner not reflective of regulato
Authors
David M. Mushet, Aram J.K. Calhoun, Laurie C. Alexander, Matthew J. Cohen, Edward S. DeKeyser, Laurie G. Fowler, Charles R. Lane, Megan W. Lang, Mark C. Rains, Susan C. Walls
Anuran site occupancy and species richness as tools for evaluating restoration of a hydrologically-modified landscape
A fundamental goal of wetland restoration is to reinstate pre-disturbance hydrological conditions to degraded landscapes, facilitating recolonization by native species and the production of resilient, functional ecosystems. To evaluate restoration success, baseline conditions need to be determined and a reference target needs to be established that will serve as an ecological blueprint in the rest
Authors
Susan C. Walls, J. Hardin Waddle, William J. Barichivich, Ian A. Bartoszek, Mary E. Brown, J. M. Hefner, Melinda J. Schuman
Identifying monitoring gaps for amphibian populations in a North American biodiversity hotspot, the southeastern USA
I review the primary literature to ascertain the status of amphibian monitoring efforts in the southeastern USA, a “hotspot” for biodiversity in North America. This effort revealed taxonomic, geographic and ecological disparities in studies of amphibian populations in this region. Of the species of anurans and caudates known to occur in the Southeast, 73.8 and 33.3 %, respectively, have been monit
Authors
Susan C. Walls
Wetland Reserve Program enhances site occupancy and species richness in assemblages of anuran amphibians in the Mississippi Alluvial Valley, USA
We measured amphibian habitat use to quantify the effectiveness of conservation practices implemented under the Wetland Reserve Program (WRP), an initiative of the U.S. Department of Agriculture’s Natural Resources Conservation Service. From February to June 2007, we quantified calling male anurans in cultivated cropland, former cultivated cropland restored through the WRP, and mature bottomland h
Authors
Susan C. Walls, J. Hardin Waddle, Stephen P. Faulkner
Nest site selection by diamond-backed terrapins (Malaclemys terrapin) on a Mid-Atlantic Barrier Island
We scored 48 Malaclemys terrapin nests destroyed by raccoons on Fisherman Island, Virginia, for the presence or absence of tree canopy, shrub canopy, no canopy, bare sand, grass cover, and herbaceous cover. Significantly more nests than expected were found in the open with no vegetation cover and observed distances of predator-destroyed nests from the edge of the nearest habitat island of woody ve
Authors
Joseph C. Mitchell, Susan C. Walls
Variation in salinity tolerance among larval anurans: implications for community composition and the spread of an invasive, non-native species
Amphibians in freshwater coastal wetlands periodically experience acute exposure to salinity from hurricane-related overwash events, as well as chronic exposure associated with rising sea levels. In a comparative experimental approach, we examined whether seven species of anuran amphibians vary in their tolerance to changes in salinity. In a laboratory study, we exposed larval Hyla cinerea (Green
Authors
Mary E. Brown, Susan C. Walls
Trends in amphibian occupancy in the United States
Though a third of amphibian species worldwide are thought to be imperiled, existing assessments simply categorize extinction risk, providing little information on the rate of population losses. We conducted the first analysis of the rate of change in the probability that amphibians occupy ponds and other comparable habitat features across the United States. We found that overall occupancy by amphi
Authors
M. J. Adams, David A.W. Miller, Erin Muths, Paul Stephen Corn, Evan H. Campbell Grant, Larissa L. Bailey, Gary M. Fellers, Robert N. Fisher, Walter J. Sadinski, Hardin Waddle, Susan C. Walls
Influence of drought on salamander occupancy of isolated wetlands on the southeastern Coastal Plain of the United States
In the southeastern U.S., changes in temperature and precipitation over the last three decades have been the most dramatic in winter and spring seasons. Continuation of these trends could negatively impact pond-breeding amphibians, especially those that rely on winter and spring rains to fill seasonal wetlands, trigger breeding, and ensure reproductive success. From 2009 to 2012, we monitored Spri
Authors
Susan C. Walls, William J. Barichivich, Mary E. Brown, David E. Scott, Blake R. Hossack
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Filter Total Items: 54
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 most) amphibian declines and that this perspective shAuthorsRaymond D Semiltsch, Susan C. Walls, William J. Barichivich, Katy O'DonnellQuantitative evidence for the effects of multiple drivers on continental-scale amphibian declines
Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a “smoking gun” was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinAuthorsEvan H. Campbell Grant, David A. W. Miller, Benedikt R. Schmidt, M. J. Adams, Staci M. Amburgey, Thierry A. Chambert, Sam S. Cruickshank, Robert N. Fisher, David M. Green, Blake R. Hossack, Pieter T.J. Johnson, Maxwell B. Joseph, Tracy A. G. Rittenhouse, Maureen E. Ryan, J. Hardin Waddle, Susan C. Walls, Larissa L. Bailey, Gary M. Fellers, Thomas A. Gorman, Andrew M. Ray, David S. Pilliod, Steven J. Price, Daniel Saenz, Walt Sadinski, Erin L. MuthsDo geographically isolated wetlands influence landscape functions?
Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy, and organisms with other elements in hydrological and habitat networks, contributing to landscape functions, such as flow generation, nutrient and sediment retention, and biodiversity support. GIWs constitute most of the wetlands in many North American landscapes, provide a disproportionately large frAuthorsMatthew J. Cohen, Irena F. Creed, Laurie C. Alexander, Nandita Basu, Aram J.K. Calhoun, Christopher Craft, Ellen D’Amico, Edward S. DeKeyser, Laurie Fowler, Heather E. Golden, James W. Jawitz, Peter Kalla, L. Katherine Kirkman, Charles R. Lane, Megan Lang, Scott G. Leibowitz, David Bruce Lewis, John Marton, Daniel L. McLaughlin, David M. Mushet, Hadas Raanan-Kiperwas, Mark C. Rains, Lora Smith, Susan C. WallsTesting hypotheses on distribution shifts and changes in phenology of imperfectly detectable species
With ongoing climate change, many species are expected to shift their spatial and temporal distributions. To document changes in species distribution and phenology, detection/non-detection data have proven very useful. Occupancy models provide a robust way to analyse such data, but inference is usually focused on species spatial distribution, not phenology.We present a multi-season extension of thAuthorsThierry A. Chambert, William L. Kendall, James E. Hines, James D. Nichols, Paolo Pedrini, J. Hardin Waddle, Giacomo Tavecchia, Susan C. Walls, Simone TenanGeographically isolated wetlands: Rethinking a misnomer
We explore the category “geographically isolated wetlands” (GIWs; i.e., wetlands completely surrounded by uplands at the local scale) as used in the wetland sciences. As currently used, the GIW category (1) hampers scientific efforts by obscuring important hydrological and ecological differences among multiple wetland functional types, (2) aggregates wetlands in a manner not reflective of regulatoAuthorsDavid M. Mushet, Aram J.K. Calhoun, Laurie C. Alexander, Matthew J. Cohen, Edward S. DeKeyser, Laurie G. Fowler, Charles R. Lane, Megan W. Lang, Mark C. Rains, Susan C. WallsAnuran site occupancy and species richness as tools for evaluating restoration of a hydrologically-modified landscape
A fundamental goal of wetland restoration is to reinstate pre-disturbance hydrological conditions to degraded landscapes, facilitating recolonization by native species and the production of resilient, functional ecosystems. To evaluate restoration success, baseline conditions need to be determined and a reference target needs to be established that will serve as an ecological blueprint in the restAuthorsSusan C. Walls, J. Hardin Waddle, William J. Barichivich, Ian A. Bartoszek, Mary E. Brown, J. M. Hefner, Melinda J. SchumanIdentifying monitoring gaps for amphibian populations in a North American biodiversity hotspot, the southeastern USA
I review the primary literature to ascertain the status of amphibian monitoring efforts in the southeastern USA, a “hotspot” for biodiversity in North America. This effort revealed taxonomic, geographic and ecological disparities in studies of amphibian populations in this region. Of the species of anurans and caudates known to occur in the Southeast, 73.8 and 33.3 %, respectively, have been monitAuthorsSusan C. WallsWetland Reserve Program enhances site occupancy and species richness in assemblages of anuran amphibians in the Mississippi Alluvial Valley, USA
We measured amphibian habitat use to quantify the effectiveness of conservation practices implemented under the Wetland Reserve Program (WRP), an initiative of the U.S. Department of Agriculture’s Natural Resources Conservation Service. From February to June 2007, we quantified calling male anurans in cultivated cropland, former cultivated cropland restored through the WRP, and mature bottomland hAuthorsSusan C. Walls, J. Hardin Waddle, Stephen P. FaulknerNest site selection by diamond-backed terrapins (Malaclemys terrapin) on a Mid-Atlantic Barrier Island
We scored 48 Malaclemys terrapin nests destroyed by raccoons on Fisherman Island, Virginia, for the presence or absence of tree canopy, shrub canopy, no canopy, bare sand, grass cover, and herbaceous cover. Significantly more nests than expected were found in the open with no vegetation cover and observed distances of predator-destroyed nests from the edge of the nearest habitat island of woody veAuthorsJoseph C. Mitchell, Susan C. WallsVariation in salinity tolerance among larval anurans: implications for community composition and the spread of an invasive, non-native species
Amphibians in freshwater coastal wetlands periodically experience acute exposure to salinity from hurricane-related overwash events, as well as chronic exposure associated with rising sea levels. In a comparative experimental approach, we examined whether seven species of anuran amphibians vary in their tolerance to changes in salinity. In a laboratory study, we exposed larval Hyla cinerea (GreenAuthorsMary E. Brown, Susan C. WallsTrends in amphibian occupancy in the United States
Though a third of amphibian species worldwide are thought to be imperiled, existing assessments simply categorize extinction risk, providing little information on the rate of population losses. We conducted the first analysis of the rate of change in the probability that amphibians occupy ponds and other comparable habitat features across the United States. We found that overall occupancy by amphiAuthorsM. J. Adams, David A.W. Miller, Erin Muths, Paul Stephen Corn, Evan H. Campbell Grant, Larissa L. Bailey, Gary M. Fellers, Robert N. Fisher, Walter J. Sadinski, Hardin Waddle, Susan C. WallsInfluence of drought on salamander occupancy of isolated wetlands on the southeastern Coastal Plain of the United States
In the southeastern U.S., changes in temperature and precipitation over the last three decades have been the most dramatic in winter and spring seasons. Continuation of these trends could negatively impact pond-breeding amphibians, especially those that rely on winter and spring rains to fill seasonal wetlands, trigger breeding, and ensure reproductive success. From 2009 to 2012, we monitored SpriAuthorsSusan C. Walls, William J. Barichivich, Mary E. Brown, David E. Scott, Blake R. Hossack - News