The National Capital Region Network (NCRN) has identified amphibians as a priority taxonomic group for its Inventory and Monitoring program. Amphibian monitoring was initiated in 2005, and is currently concentrated in Antietam National Battlefield (ANTI), Catoctin Mountain Park (CATO), Chesapeake and Ohio Canal National Historical Park (CHOH), George Washington Memorial Parkway (GWMP), Harpers Ferry National Historical Park (HAFE), Manassas National Battlefield Park (MANA), Monocacy National Battlefield (MONO), National Capital Parks-East (NACE), Prince William Forest Park (PRWI) and Rock Creek Park (ROCR).
The objectives of the monitoring program are to develop an efficient long-term sampling design to: describe the current distribution of amphibians and explore factors that may influence occupancy probabilities or distributional patterns, determine if amphibian distributions are changing annually, and if so, explore whether occupancy changes are relate to habitat quality and provide information to aid in the generating and testing of hypotheses that differentiate among possible causes of long-term changes in the proportion of area occupied among species, habitats, and park areas.
Wetland habitats
We detected 22 amphibian species or species complexes across the Capital Region Network since the start of the monitoring program in 2005. We found that detection probabilities (the probability of detecting a species, given it is present at a site) were less than one and were strongly influenced by when sampling occurred (i.e., day of the year) but were only mildly variable between years. Surveys are conducted with two observers to minimize observer bias and wetlands are surveyed multiple times per year to increase detection probabilities for species with different life history strategies.
We are investigating the relationships between wetland species richness and two important limiting variables in amphibian communities--habitat area and hydroperiod. Lentic species richness is generally highest in permanent, followed by semi-permanent, and lowest in temporary wetlands. The mean estimated richness for each year of the survey was variable in each of the wetlands, with some wetlands having fairly constant richness and others experiencing large annual changes. Annual wetland variability in richness varied independently of hydroperiod category. Increasing wetland area generally had a positive effect on species occurrence probabilities, but the result was fairly minimal.
Stream habitats
We observed four species of stream salamanders in each year of our study: Desmognathus fuscus, Eurycea bislineata, E. longicauda, and Pseudotriton ruber. Detection probabilities varied among these species and years. In general, initial occupancy estimates were higher for stream transects in CHOH compared to ROCR and PRWI, except for E. bislineata which had high occupancy probabilities in all parks. D. fuscus and P. ruber had higher occupancy probabilities at transects near the stream headwaters, but our a priori hypothesis that proximity of the stream origin to the park boundary or road would result in lower occupancy probabilities was not well supported for any of the species. As with our lentic sampling, more years of data, encompassing both wet and dry years, are needed to further elucidate the potential relationship between spatial covariates and site occupancy and related rate parameters for stream salamander species. We are also investigating how dry years change the distribution of a population, which will inform the monitoring program design and future studies of stream salamander populations.
In addition to the annual monitoring, sampling in 2010-2011 included intensive effort to survey 3 complete second- and third-order stream networks in CHOH over 3 seasons each year to assess the effectiveness of the stream monitoring design for the National Capital Region. The completeness of these surveys allows us to evaluate seasonal dynamics in amphibian occupancy for four stream salamander species as well as design considerations such as transect length, placement within the network, sampling season, and sampling frequency. We are currently investigating relationships between occupancy dynamics, habitat covariates, and stream network structure in order to determine the most cost-effective and informative monitoring design for streams in this study area. Ideally, information learned from the monitoring program will provide data useful for discriminating among future management decisions.ng and testing of hypotheses that differentiate among possible causes of long-term changes in the proportion of area occupied among species, habitats, and park areas.
Summary and synthesis of 15 years of the Amphibian Vital Sign monitoring in the National Capital Region Inventory and Monitoring Network
A comparison of monitoring designs to assess wildlife community parameters across spatial scales
Looking ahead, guided by the past: The role of U.S. national parks in amphibian research and conservation
Site- and individual-level contaminations affect infection prevalence of an emerging infectious disease of amphibians
A synthesis of evidence of drivers of amphibian declines
A hierarchical analysis of habitat area, connectivity, and quality on amphibian diversity across spatial scales
- Overview
The National Capital Region Network (NCRN) has identified amphibians as a priority taxonomic group for its Inventory and Monitoring program. Amphibian monitoring was initiated in 2005, and is currently concentrated in Antietam National Battlefield (ANTI), Catoctin Mountain Park (CATO), Chesapeake and Ohio Canal National Historical Park (CHOH), George Washington Memorial Parkway (GWMP), Harpers Ferry National Historical Park (HAFE), Manassas National Battlefield Park (MANA), Monocacy National Battlefield (MONO), National Capital Parks-East (NACE), Prince William Forest Park (PRWI) and Rock Creek Park (ROCR).
The objectives of the monitoring program are to develop an efficient long-term sampling design to: describe the current distribution of amphibians and explore factors that may influence occupancy probabilities or distributional patterns, determine if amphibian distributions are changing annually, and if so, explore whether occupancy changes are relate to habitat quality and provide information to aid in the generating and testing of hypotheses that differentiate among possible causes of long-term changes in the proportion of area occupied among species, habitats, and park areas.
Wetland habitats
We detected 22 amphibian species or species complexes across the Capital Region Network since the start of the monitoring program in 2005. We found that detection probabilities (the probability of detecting a species, given it is present at a site) were less than one and were strongly influenced by when sampling occurred (i.e., day of the year) but were only mildly variable between years. Surveys are conducted with two observers to minimize observer bias and wetlands are surveyed multiple times per year to increase detection probabilities for species with different life history strategies.
We are investigating the relationships between wetland species richness and two important limiting variables in amphibian communities--habitat area and hydroperiod. Lentic species richness is generally highest in permanent, followed by semi-permanent, and lowest in temporary wetlands. The mean estimated richness for each year of the survey was variable in each of the wetlands, with some wetlands having fairly constant richness and others experiencing large annual changes. Annual wetland variability in richness varied independently of hydroperiod category. Increasing wetland area generally had a positive effect on species occurrence probabilities, but the result was fairly minimal.
Stream habitats
We observed four species of stream salamanders in each year of our study: Desmognathus fuscus, Eurycea bislineata, E. longicauda, and Pseudotriton ruber. Detection probabilities varied among these species and years. In general, initial occupancy estimates were higher for stream transects in CHOH compared to ROCR and PRWI, except for E. bislineata which had high occupancy probabilities in all parks. D. fuscus and P. ruber had higher occupancy probabilities at transects near the stream headwaters, but our a priori hypothesis that proximity of the stream origin to the park boundary or road would result in lower occupancy probabilities was not well supported for any of the species. As with our lentic sampling, more years of data, encompassing both wet and dry years, are needed to further elucidate the potential relationship between spatial covariates and site occupancy and related rate parameters for stream salamander species. We are also investigating how dry years change the distribution of a population, which will inform the monitoring program design and future studies of stream salamander populations.
In addition to the annual monitoring, sampling in 2010-2011 included intensive effort to survey 3 complete second- and third-order stream networks in CHOH over 3 seasons each year to assess the effectiveness of the stream monitoring design for the National Capital Region. The completeness of these surveys allows us to evaluate seasonal dynamics in amphibian occupancy for four stream salamander species as well as design considerations such as transect length, placement within the network, sampling season, and sampling frequency. We are currently investigating relationships between occupancy dynamics, habitat covariates, and stream network structure in order to determine the most cost-effective and informative monitoring design for streams in this study area. Ideally, information learned from the monitoring program will provide data useful for discriminating among future management decisions.ng and testing of hypotheses that differentiate among possible causes of long-term changes in the proportion of area occupied among species, habitats, and park areas.
- Data
Summary and synthesis of 15 years of the Amphibian Vital Sign monitoring in the National Capital Region Inventory and Monitoring Network
This data set is comprised of four files related to the counts of amphibian species in the National Capital Region of the United States. Data was obtained from surveys of both lentic (wetland) and lotic (stream) sites within national parks. - Publications
A comparison of monitoring designs to assess wildlife community parameters across spatial scales
Dedicated long-term monitoring at appropriate spatial and temporal scales is necessary to understand biodiversity losses and develop effective conservation plans. Wildlife monitoring is often achieved by obtaining data at a combination of spatial scales, ranging from local to broad, to understand the status, trends, and drivers of individual species or whole communities and their dynamics. HoweverAuthorsAlexander Wright, Evan H. Campbell Grant, Elise F. ZipkinLooking ahead, guided by the past: The role of U.S. national parks in amphibian research and conservation
Protected areas like national parks are essential elements of conservation because they limit human influence on the landscape, which protects biodiversity and ecosystem function. The role of national parks in conservation, however, often goes far beyond limiting human influence. The U.S. National Park Service and its system of land units contribute substantively to conservation by providing proteAuthorsBrian J. Halstead, Andrew M. Ray, Erin L. Muths, Evan H. Campbell Grant, Rob Grasso, Michael J. Adams, Kathleen Semple Delaney, Jane Carlson, Blake R. HossackSite- and individual-level contaminations affect infection prevalence of an emerging infectious disease of amphibians
Emerging infectious disease outbreaks are one of multiple stressors responsible for amphibian declines globally. In the northeastern United States, ranaviral diseases are prevalent in amphibians and other ectothermic species, but there is still uncertainty as to whether their presence is leading to population level effects. Further, there is also uncertainty surrounding the potential interactionsAuthorsKelly Smalling, Brittany A. Mosher, Luke R. Iwanowicz, Keith Loftin, Adam Boehlke, Michelle Hladik, Carly R. Muletz-Wolz, Nandadevi Córtes-Rodríguez, Robin Femmer, Evan H. Campbell GrantByEcosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Eastern Ecological Science Center, California Water Science Center, Geology, Geophysics, and Geochemistry Science Center, Kansas Water Science Center, New Jersey Water Science CenterA synthesis of evidence of drivers of amphibian declines
Early calls for robust long-term time series of amphibian population data, stemming from discussion following the first World Congress of Herpetology, are now being realized after 25 yr of focused research. Inference from individual studies and locations have contributed to a basic consensus on drivers of amphibian declines. Until recently there were no large-scale syntheses of long-term time seriAuthorsEvan H. Grant, D. A. W. Miller, Erin L. MuthsA hierarchical analysis of habitat area, connectivity, and quality on amphibian diversity across spatial scales
Habitat fragmentation can alter species distributions and lead to reduced diversity at multiple scales. Yet, the literature describing fragmentation effects on biodiversity patterns is contradictory and inconclusive, possibly because most studies fail to integrate spatial scale into experimental designs and statistical analyses. As a result, it is difficult to extrapolate the effects of fragmentatAuthorsAD Wright, Evan H. Campbell Grant, EF Zipkin - Partners