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Wood frog (Rana sylvatica). NPS / C. Shafer.
George Washington Memorial Parkway (GWMP), along the Potomac, is home to at least 14 amphibian species. The National Park Service monitors them in the park's wetlands as part of its Amphibian Monitoring in the National Capital Region series.
How the monitoring works
Field teams visit wetland pools and record which species they find at which sites. Across all sites, that gives each species's occupancy: the share of sites where it lives. The question is simple: is occupancy changing over time?
Some amphibians live outside the wetlands — red-backed salamanders on land, eastern spadefoot toads underground. The surveys are not built to track them; sightings are noted but left out of the analysis.
2023 results
- Species: nine seen in 2023; 14 wetland species in total since monitoring began in 2017.
- Effort: crews visited 32 wetlands once, in April, instead of the usual two visits a year — so 2023's numbers are lower.
- Most numerous: wood frogs (1 adult and 378 larvae).
- Most widespread: wood frogs and northern green frogs, each at 3 wetlands.
- Too few data yet: dusky salamanders and red-spotted newts stay out of the trend analysis until more surveys repeat them.
Occupancy trends
Occupancy probability by species in the parkway's wetland pools, 2017–2023. Chart: NPS.
Reading the chart:
| Mark | Meaning |
|---|---|
| Dark gray bars | occupancy from raw sightings |
| Black dots and lines | estimated occupancy, which allows for animals that hid and were missed |
| Light gray bands | 95% credible intervals |
| "Trend" box | a trend value, with its 95% interval in brackets; blue rising, white steady, yellow slightly falling, red falling |
| "Complex" | closely related gray treefrogs, or toads, grouped together |
Species appear in alphabetical order by common name.
Marbled salamander (Ambystoma opacum). NPS / L. Beimfohr.
These data are preliminary and may be revised. They have not received final approval from the U.S. Geological Survey, and are provided on the condition that neither the USGS nor the U.S. Government is liable for damages from their use.
Sources
Based on "George Washington Memorial Parkway Amphibian Monitoring 2023," part of Amphibian Monitoring in the National Capital Region, National Park Service; a work of the United States government in the public domain. See also Harpers Ferry and Manassas in the same series.
En estas publicacionesGeorge Washington Memorial Parkway
Licencia: CC0 1.0 (dominio público) · Adaptado de www.nps.gov
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