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Saving the California Red-Legged Frog from Extinction

With a collaborative spirit and great teamwork, The Nat is contributing to the recovery of the California red-legged frog (Rana draytonii) in both the United States and Mexico. The Nat’s Herpetology Department is collaborating with Fauna del Noroeste (FAUNO), a nonprofit conservation organization based in Ensenada, Mexico, as well as the U.S. Geological Survey, U.S. Fish and Wildlife Service, The Nature Conservancy, and the California Department of Fish and Wildlife to apply creative and effective strategies to improve the overall health of the California red-legged frog in our region.

The California red-legged frog is the largest native frog in southern California and Baja California, Mexico. A resting adult with its hind legs tucked in reaches up to 5 inches; when taking a big leap with their powerful legs extended, they double in length. The species once had a wide and continuous distribution from the northern edge of the Central Valley of California down through the Sierra San Pedro Martir mountains of Baja California.

Freshwater ecosystems such as rivers, creeks, and lakes in southern California and Baja California face immense pressures from human activities—water extraction, agricultural pollution, development pressures, and more. As a result, many species of birds, fish, reptiles, and amphibians that depend on freshwater habitats have been driven to near extinction, with 95% of our wetlands having been eliminated. Within the remaining wetlands, the California red-legged frog plays an important role in the ecological community as both predator and prey in streams, creeks, and ponds.

In San Diego County the California red-legged frog went extinct in the 1970s due to housing construction, agricultural development, invasive species, water diversion, drought, novel diseases, and pollution. However, our team’s reintroduction efforts this year have brought them back (learn more about that here). The Baja California populations also suffered major declines as a result of the same pressures.

The first priority for the California red-legged frog recovery team was to assess the stability of the remaining 10 populations in Baja California, and our regular monitoring efforts provide us with a baseline with which to evaluate any future population fluctuations. In addition to regular monitoring, we have also taken concrete actions to improve resiliency. For example, we dug deep water ponds to provide suitable breeding habitats that will hold water during droughts. Our reintroduction efforts that moved frog eggs from Mexico to southern California also improve resilience by establishing populations across a wider geographic range, reducing the risk of a single unpredictable event such as wildfire from decimating all the populations in one fell swoop.

While our work protecting the ecosystems of the California red-legged frog is ongoing, our collaborative team has already achieved some major milestones including:

  • Assessing the reproductive health of California red-legged frog populations in Baja California via detailed egg monitoring surveys.
  • Creating detailed maps to understand the preferred microhabitats of the frogs.
  • Building and restoring ponds to improve habitat suitability for the frogs.
  • Reintroducing frogs at sites in San Diego and Riverside Counties, where they were previously absent for more than 20 years.