Monocacy Amphibian Monitoring, 2023

Wood frog (Rana sylvatica). NPS / C. Shafer.

At least 12 amphibian species

Field teams monitor wetlands at Monocacy National Battlefield, recording which amphibians they find at which pools. Across all sites, that gives each species' occupancy: the share of sites where it occurs. The question: is occupancy changing over time?

A few species live outside the monitored wetlands — terrestrial red-backed salamanders, for example. They may live in the park, but the monitoring isn't designed to find them; incidental sightings are recorded but left out of the analysis.

Wetland amphibians in 2023

• Five wetland species were seen in 2023; 11 since monitoring began in 2015. The burrowing eastern spadefoot toad is also in the analysis.
• Fewer visits: crews usually visit twice a year; in 2023 they visited 28 wetland sites once, in April, so the numbers are lower.
• Most abundant: wood frogs (229 larvae), then pickerel frogs, American toads and northern green frogs.
• Most widespread: northern green frogs and wood frogs, each at 2 of 28 wetlands.

Figure 1. Occupancy probability by species in Monocacy's wetland pools. NPS.

How to read the figure

• Dark gray bars: occupancy from raw sightings.
• Black dots and lines: estimated occupancy. Amphibians hide well, so more are usually present than crews count; estimates fill the gaps.
• Light gray bands: 95% credible intervals.
• "Gray treefrog complex" and "Toad complex": closely related species grouped together.
• "Trend" box atop each graph: a number and a color for the direction of the estimated trend — blue positive, white neutral, yellow slightly negative, red negative. The numbers in parentheses are the 95% credible interval.
• Species are in alphabetical order by common name.

American toad (Bufo americanus). NPS / C. Shafer.

These data are preliminary and may be revised. They have not received final approval by the U.S. Geological Survey and are provided on the condition that neither USGS nor the U.S. Government is liable for damages from their use.

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Sources

Based on "Monocacy Amphibian Monitoring 2023," part of the series Amphibian Monitoring in the National Capital Region, National Park Service; a work of the United States government in the public domain.