National Parks as Hotspots for Amphibian Diversity

National parks protect some species that are hard to miss, like giant sequoias. Others go almost unnoticed, among them amphibians: the frogs, toads and salamanders that are among the most fascinating, sensitive and threatened animals on the planet.

A study led by scientists with the National Park Service and the U.S. Geological Survey's Amphibian Research and Monitoring Initiative (ARMI) found that at least 230 species, 65% of all amphibian species recorded in the United States, occur on Park Service lands, even though those lands make up just 3.5% of the country's land area. The parks, in other words, are already hotspots of amphibian diversity. The study set out to identify those hotspots, assess the main threats in different parks and suggest ways to strengthen conservation.

Canyon tree frogs. NPS/E. Zylstra.

Common species, rare species

Parks offer good habitat for many common amphibians, those listed as of "least concern." Rare species often depend on very particular places that do not always fall inside park boundaries. But some amphibians live only, or almost only, in parks: the Shenandoah salamander exists solely within Shenandoah National Park in Virginia, and the Jemez Mountains salamander lives mainly within Valles Caldera National Preserve and Bandelier National Monument in New Mexico.

Conservation status of amphibian species found on National Park Service lands. National Park Service.

Bigger is not always better

A large park does not necessarily protect more species. Yellowstone National Park covers more than 2.2 million acres in Wyoming, Montana and Idaho but supports only five native amphibian species. Ocmulgee Mounds National Historical Park in Georgia, 3,000 acres in an urban setting, supports at least 25.

Geography matters

Parks in the Southeast and Northeast, where salamanders outnumber frogs and toads, hold more species than the big western parks, where frogs and toads dominate. That means even small additions to parks in the Southeast and Northeast can protect many more species. The recent expansion of Ocmulgee Mounds, for instance, will benefit more amphibians than the same acreage added to Yellowstone would.

Amphibian species documented in each park, by region, colored by state-level conservation status; non-native species are plotted in black. National Park Service.

What parks do, and the threats they face

Most park lands are managed to promote biodiversity. Parks restore or create habitat, limit development and manage visitor traffic on and off trails at sensitive times. At Cuyahoga Valley National Park, managers ask visitors to avoid roads, or drive carefully near wetlands, during the spring salamander migration from wintering sites to breeding ponds. Protecting corridors between habitats lets animals move and exchange genes, making species more resilient. But some threats ignore park boundaries:

• A drying climate. Amphibians need wetlands and moist habitats to breed, feed and survive winter. Many parks are expected to be somewhat buffered compared with their surroundings, making them even more important as refuges. Still, by mid-century (2040–2069), conditions are expected to become drier, by 20% on average in the already arid Southwest and by 56% on average in Midwestern parks.
• Invasive species. Non-native amphibians are already in or near 25% of parks. The American bullfrog, native to the East but invasive in the West, eats other frogs and even baby birds. About 60% of park lands have non-native crayfish, which prey on amphibians, inside the park or within 30 miles, and the threat grows as they move closer.

Strengthening protection

The authors conclude that parks need more tools than ever. Options include:

• ongoing monitoring to find the habitats and populations most in need of protection
• rapid response to remove non-native species before they become established
• moving at-risk species into the safe harbor of parks, as with the Yosemite toad in Yosemite National Park
• targeted partnerships, especially in regions rich in amphibian species

Red salamander. National Park Service.

The Park Service is already working with neighbors who share its goals, zoos and wildlife rehabilitation centers, schools and universities. In the Greater Yellowstone Area it uses crowd-sourced observations to map native and non-native amphibians on lands next to the parks, and in the Southwest it is working with state and federal partners to control non-native amphibians and restore native ones across several parks.

Sources

• National Park Service, "National Parks: Hotspots for Amphibian Biodiversity." https://www.nps.gov/articles/000/national_parks-amphibian_hotspots.htm
• LaFrance BJ, Ray AM, Tercek MT, Fisher RN, Hossack B. "Amphibian richness, rarity, threats, and conservation prospects across the U.S. National Park System." npj Biodiversity 3, 35 (2024). https://doi.org/10.1038/s44185-024-00067-1
• The source calls the USGS program the "Amphibian and Monitoring Initiative"; its acronym, ARMI, is for the Amphibian Research and Monitoring Initiative, used here. Photographs credited only to individual photographers are not reproduced.