Frogs and toads are quick to show when something is wrong with fresh water. They need clean water to survive and breed, and anuran communities — frogs, toads and treefrogs — respond fairly fast to environmental stress. So since 2012, the National Park Service's Southeast Coast Inventory and Monitoring Network (SECN) has been listening to them, in 15 parks from North Carolina to Florida.
Why the Southeast
The southern United States has the highest amphibian diversity in North America, with at least 45 species of anurans. Thirty-two have been documented in the 15 monitored parks. Changes in which species are present, how many and where can reveal changes in a park's underlying ecological conditions.
| Monitored parks |
|---|
| Cape Hatteras NS · Cape Lookout NS · Canaveral NS · Chattahoochee River NRA · Congaree NP |
| Cumberland Island NS · Fort Frederica NM · Fort Matanzas NM · Fort Pulaski NM · Fort Sumter & Fort Moultrie NHP |
| Horseshoe Bend NMP · Kennesaw Mountain NBP · Moores Creek NB · Ocmulgee Mounds NHP · Timucuan E&HP |
How the listening works
- Where. Up to 30 permanent sample locations per park, chosen randomly but spread evenly, allowing for park size, expected variation in wildlife and logistics. Five parks are sampled each year, so each is revisited every three years.
- When. Automated recording devices go out from March to June. They record every fourth night, for 60 seconds every 20 minutes from 8:00 p.m. to 4:40 a.m.
- Sorting the calls. Software (Kaleidoscope Pro) extracts potential calls; a share of them are classified by hand. Only anurans identified to species count.
Recorders at Fort Sumter and Fort Moultrie and at Horseshoe Bend, and a green treefrog (Dryophytes cinereus), one of the network's most common species. Credit: NPS/SECN staff and NPGallery.
What the recordings measure
| Measure | What it means |
|---|---|
| Species richness | the number of distinct species, for the whole park and at each location, native and non-native counted separately |
| Naïve occupancy | the percentage of locations where a species was heard in at least one recording |
| Spatial distribution | maps of where each species was detected, to guide management of species and their habitats |
Repeated over years, these measures can show trends in distribution and community makeup, and point to what drives them — land use and habitat condition, climate, and water.
Frog and toad species richness at 22 locations in Ocmulgee Mounds National Historical Park, 2022. Credit: NPS.
The network
SECN spans eighteen administrative areas and twenty park units, fifteen with significant natural resources, across North Carolina, South Carolina, Georgia, Alabama and Florida — more than 184,000 acres of federal land, and more than 253,000 acres with jointly managed non-federal land. The parks range from slightly more than 20 acres to nearly 60,000.
Sources
Based on "SECN Vocal Anuran Community Monitoring Program Summary" from the National Park Service's Southeast Coast Inventory and Monitoring Network, a work of the United States government in the public domain. The printed summary is in the NPS DataStore.
Licence: CC0 1.0 (public domain) · Adapted from www.nps.gov
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