National Parks: Hotspots for Amphibian Biodiversity

Green tree frog

Parrish

Northern leopard frog

A RASMUSSEN

National parks play a central role in protecting biodiversity. Some species, like giant sequoia trees, are hard to miss. Other species are more secretive, often going unnoticed by park visitors. One such group are amphibians—the frogs, toads, and salamanders that are some of the most fascinating, sensitive, and threatened species on our planet.

A recent study, led by scientists with the National Park Service (NPS) and the U.S. Geological Survey's (USGS) Amphibian and Monitoring Initiative (ARMI), found that 65% (at least 230 species) of all amphibian species documented in the U.S. occur on lands protected by the National Park Service (NPS). The kicker—NPS lands make up just 3.5% of the U.S. landbase. This indicates that national parks are already hotspots for amphibian biodiversity. The study has three areas of focus:

• Diversity Hotspots: identify areas in national parks that have high concentrations of amphibian species.
• Threat Assessments: determine major threats to amphibians in different parks.
• Conservation Strategies: suggest methods to enhance biodiversity conservation in parks.

Canyon tree frogs

NPS/E. ZYLSTRA

Amphibian Biodiversity Hotspots

Park vs. Non-park Lands

The scientists found that national parks provide welcoming habitat for many common amphibians (those of "Least Concern" in the graphic below). Rare amphibians often live in very specific locations that sometimes don't exist inside park boundaries.

Other amphibians occur only or almost entirely in national parks. For example, the Shenandoah salamander exists solely within the boundaries of Shenandoah National Park in Virginia, and the Jemez Mountains salamander occurs primarily within Valles Caldera National Preserve and Bandelier National Monument in New Mexico.

Conservation status of amphibian species that have been found on U.S. National Park Service (NPS) lands throughout the U.S. These data are from a recently updated NPS dataset (https://irma.nps.gov/DataStore/Reference/Profile/2301647).

NPS

Bigger Isn’t Always Better

A large park doesn't necessarily protect more species than a small park. Yellowstone National Park protects over 2.2 million acres of land in Wyoming, Montana, and Idaho, but only supports five native species of amphibians. In contrast, Ocmulgee Mounds National Historical Park, in Georgia, supports at least 25 species of amphibians on a footprint of 3,000 acres of land tucked within an urban setting.

Geography Matters

National parks in the southeastern and northeastern U.S., where salamander species outnumber frogs and toads, have more species than the big western parks, where frogs and toads tend to outnumber salamanders. From a conservation perspective, this means that even small increases in the size of parks in the Southeast and Northeast can extend protection to many more species. For example, the recent expansion of Ocmulgee Mounds National Historical Park will benefit more amphibian species than if the same acreage were added to Yellowstone National Park.

In this circular stacked bar graph, each bar shows the number of amphibian species documented per park in each U.S. region. In each bar, the colors indicate the state-level conservation status for the different species. Non-native species are plotted in the negative direction, in black.

NPS

Jemez Mountains salamander

L. TRADER

Primary Threats to Amphibians

Most park lands are managed in ways that promote biodiversity. Some parks work to restore or even create new habitats important to wildlife. They may also limit development and manage the numbers of visitors that travel on and off trails, especially during critical periods (e.g., when bears are emerging from dens). Managers at Cuyahoga Valley National Park encourage visitors to avoid roads and drive more cautiously near wetlands during the salamander spring migration from overwintering sites to breeding ponds. Parks can also protect wildlife corridors that connect different habitats, allowing animals to move freely and exchange genetic information. This makes species more resilient to threats.

But park ecosystems and wildlife are also subject to many threats that boundaries can’t keep out.

Changing Climate Conditions

Amphibians require wetlands and other moist habitats to survive. When these areas become drier, amphibians have nowhere to lay their eggs, acquire food, and safely overwinter. Many national parks are expected to be somewhat buffered from the effects of changing climate conditions compared to their surrounding regions. This will only increase the importance of parks as refugia for native wildlife in the future. Overall, drier conditions are expected by mid-century (2040–2069), which could severely impact amphibian populations in national parks and beyond. Increases in dryness are expected to range from 20%, on average, in the already arid Southwest, to 56%, on average, for parks in the Midwest.

Lowland leopard frog

E. ZYLSTRA

Invasive Species

Invasive species can crowd out native species, causing severe disruptions to ecosystems. The American bullfrog (native to the eastern U.S. but invasive in the West), for instance, eats other frogs and even baby birds! Non-native amphibians are already found in or near 25% of parks. About 60% of national park lands have non-native crayfish (which prey on amphibians) either within the park boundary or within 30 miles of the park. As the crayfish move closer, the threat increases.

Enhancing Conservation Using a Biodiversity Focus

The bottom line is that parks need more tools than ever to address the many threats to U.S. amphibian populations. Several management options and partnership opportunities would further benefit amphibians in U.S. national parks—and beyond.

• Ongoing monitoring can identify critical habitat and populations most in need of protection, helping parks know where to focus management efforts.
• Rapid response programs can protect native amphibians in parks by removing non-native species before they become established.
• At-risk species can be translocated into the safe harbors of national parks, as demonstrated by the Yosemite toad in its namesake park.
• Targeted conservation partnerships can provide significant biodiversity benefits, particularly in regions with high amphibian species richness.

Red salamander

NPS

The NPS is already building partnerships with park neighbors who share conservation goals, zoos and wildlife rehabilitation facilities, and K–12 schools and universities, and is exploring opportunities to crowd-source amphibian observations in ways that expand conservation impact. In the Greater Yellowstone Area (GYA), the NPS is leveraging crowd-sourced data to better characterize the distribution and occurrence of native and non-native amphibians on lands adjacent to national parks. In the Southwest, the NPS is working with state and federal partners to control non-native amphibians and restore native amphibians across multiple national parks (Project Page: Amphibian and Garter Snake Recovery in Southwestern Parks). These collaborations are increasing awareness at park, regional, and national levels and boosting conservation impacts.

Information in this article was summarized from

LaFrance, B. J., A. M. Ray, M. T. Tercek, R. N. Fisher, and B. Hossack. 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.