Endangered Frogs at WSU

Northern Leopard Frogs (Rana pipiens)

Much like global climate change, the rapidly increasing number of endangered species in the world is an unfortunate consequence of burgeoning human populations and intensive modification or loss of critical habitats. Scientists are increasingly worried about declining amphibian populations, including those in Washington State.

The northern leopard frog is one such species and it has been declared state-endangered in Washington. Although the northern leopard frog has a large distributional range in North America, populations in the western United States have been declining or disappearing at a rapid rate.

The specific reasons for these declining populations are unknown and a number of interacting factors suggest that there could be more than one single cause. Climate change, increased UV radiation, pesticide contamination, wetland loss, introduced predators such as bullfrogs (Lithobates catesbianus; formerly Rana catesbeiana) or sport fish, and emerging diseases, such as chytrid fungus (see: chytridiomycosis fact sheet), are all among the potential contributors to amphibian declines in different regions.

In Washington, leopard frogs originally occurred in wetland systems along the Columbia River and its major tributaries (see: N. Leopard Frog Status Report). However, now they appear to be locally extinct everywhere in the state, except for populations in wetlands bordering Moses Lake in central Washington.

Several years ago, one of my graduate students, Scott Leach, began a project with the Washington Department of Fish and Wildlife to try and determine what environmental factors in different wetlands around Moses Lake were associated with successful or unsuccessful leopard frog populations. We also began what we hoped would become a captive breeding program by raising about 30 leopard frog tadpoles.

Now another graduate student, Erim Gomez, will be working with me in the endangered species lab at WSU to try and breed the now-mature adults that are entering their second breeding season. Northern leopard frogs commonly don't breed their first year, but must grow and become large enough to build sufficient body resources to enable them to reproduce. Consequently, we're hoping that these captive-reared frogs are large enough this spring and that they will find the constructed ponds we make for them suitable for mating and laying egg masses.

Frogs in the Arboretum

What do frogs have to do with an arboretum? Plenty if its the WSU Arboretum and Botanical Gardens. One of our educational and research goals is to support a better understanding of the ecological and environmental factors that may help conserve all biological diversity - both plant and animal.

Constructed ponds and wetlands, ranging from simple patio ponds to naturalized or restored wetlands, are often one of the central features of gardens, yards, and botanical gardens around the world. The WSU Arboretum has a small constructed pond as well as a small stream and vernal (seasonal) ponds that support several amphibian species (frogs and salamanders).

Washington State University is credited with once being a historical location for northern leopard frogs, however, we suspect that this occurrence came about by laboratory or other specimens that were released into ponds on campus. Amphibian surveys completed about three years ago failed to locate any leopard frogs and the prevalence of large released goldfish and other fish in these campus wetlands makes it unlikely that any leopard frogs still exist there.

Consequently, the only leopard frogs in the area are likely those in the endangered species lab at WSU and we hope to be able to breed them in captivity so that egg masses and tadpoles can be reintroduced into suitable wetlands to study the reintroduction process, their population ecology, and help determine methods for conserving amphibians in Washington.

One of the ways that biologists survey amphibians is to listen for their mating calls in spring. If you would like to hear what a bullfrog sounds like when calling in spring, visit this site. By comparison, visit the following National Geographic site and click on the multimedia link to hear what a northern leopard frog sounds like.

Contact the Arboretum if you would like more information on amphibian conservation in the Arboretum and at Washington State University. But whatever you do, please don't release captive bullfrogs into local ponds. They can become a devastating predator on other amphibian species. And also, please don't release unwanted goldfish into ponds. Their populations increase rapidly and soon overwhelm the food resources in ponds or wetlands and greatly reduce the capacity of any wetland to support other aquatic life.

R. Sayler