Endangered Froglets with Radio Belts Released Into California Mountains

Release Date:

On Wednesday and Thursday this week, USGS Western Ecological Research Center scientists joined research partners in releasing 100 juveniles of the mountain yellow-legged frog (Rana muscosa) into the James San Jacinto Mountains Reserve near Idyllwild, Calif.

"Paging froglet number nine. How are you settling into your new digs?"

Okay, so maybe frogs can't talk back -- and their little transmitters aren't actually two-way radios. But a batch of tiny frogs released into the San Jacinto Mountains this week will hopefully tell scientists something new about how to conserve this endangered species.

Juvenile Mountain Yellow-legged frog readied for release

A juvenile Mountain Yellow-Legged Frog (Rana muscosa) readied for release into the James San Jacinto Mountains Reserve in California. (Credit: Ken Bohn, San Diego Zoo Global. ZSSD Copyright 2013 ©)

On Wednesday and Thursday this week, USGS Western Ecological Research Center scientists joined research partners in releasing 100 juveniles of the mountain yellow-legged frog (Rana muscosa) into the James San Jacinto Mountains Reserve near Idyllwild, Calif.

The Southern California population of this species is federally listed as endangered -- with estimates of 200 to 300 adults remaining in the San Gabriel and San Bernardino mountains of Southern California. The frogs are named for their preference for mountainous aquatic habitats -- these high-altitude hoppers are typically found in streams 1,200 to 7,500 feet above sea level -- some endure snowy winters. 

“We often think of endangered species as something exotic in far-away countries,” says Adam Backlin, a WERC ecologist who leads the field monitoring effort on the species. “But we’ve got this one right here in southern California, and what we learn from this reintroduction and monitoring effort will teach us a lot about how to help other declining amphibian species in the U.S. and around the world.”

The froglets set free at the University of California's James Reserve were raised by the San Diego Zoo Institute for Conservation Research.

Mountain yellow-legged frogs are native to the James Reserve, but the local population began declining in the 1970's and disappeared entirely in the 1990's. This latest reintroduction is yet another attempt to reestablish a thriving, refuge population in these mountains -- a much-needed safety net in case the San Gabriels and San Bernardino populations become decimated by fungal disease, wildfire debris or human impacts.

USGS Scientist Readies Mountain Yellow-Legged Frog for Release

USGS scientist Liz Gallegos readies a juvenile Mountain Yellow-Legged Frog (Rana muscosa) for release into the James San Jacinto Mountains Reserve.

(Used with permission from San Diego Zoo Global.)

To further assist this latest reintroduction effort, the baby frogs were dipped in a special bacterial solution, which could help them survive chytrid fungus -- a disease that has been killing off frog populations globally. Additionally, tiny radio-transmitter belts attached to some of the frogs will shed light on where the froglets end up along this protected creek habitat, possibly offering clues on the success and fate of these young amphibians.

Backlin, Liz Gallegos and other USGS WERC researchers have been surveying the status of Rana muscosa populations on behalf of the U.S. Fish and Wildlife Service, and will also monitor the success of this latest reintroduction. 

[-video:http://www.youtube.com/v/tiZoV6YUdW0|500|375]

The captive breeding effort for the species is being conducted by the San Diego Zoo Institute for Conservation Research and the Los Angeles Zoo and Botanical Gardens. Funding for the captivity and reintroduction program has been provided by the California Department of Transportation, and additional support comes from the USDA San Bernardino National Forest and California Department of Fish and Wildlife.

“We have cared for hundreds of mountain yellow-legged frogs and watched as they metamorphosed from tiny tadpoles into juvenile frogs, and we are excited to release them into the wild,” said Frank Santana, the San Diego Zoo Institute for Conservation Research specialist in charge of the captive breeding effort. “With a dedicated post-release monitoring plan we expect to learn a great deal of information from this reintroduction as we work towards restoring this native species to southern California mountain streams.”

Scientists Release Juvenile Mountain Yellow-Legged Frogs

USGS scientist Adam Backlin and San Diego Zoo Institute for Conservation Research scientist Frank Santana release juvenile Mountain Yellow-Legged Frogs (Rana muscosa) into the James San Jacinto Mountains Reserve.

(Used with permission from San Diego Zoo Global.)

The reintroduction effort yielded one more bit of good news this week.

Past efforts to reintroduce frog tadpoles and frog eggs in the James Reserve have been presumed to be unsuccessful, as no frogs have yet been sighted. However, after Wednesday's release session -- and ironically timed after local journalists had already left the site -- the team spotted two, very small frogs in the stream -- a complete surprise.

"They were so small -- like half the size of the ones we released this week -- so we think these two might be ones that metamorphosed from last tadpole release," says WERC scientist Robert Fisher, who supervises a number of Southern California amphibian research projects. "And we think they may have been attracted to the site when they smelled the new batch of frogs."

Fisher is referring to tadpoles released by the team in November 2010; the timing seems to fit, as this species is known to grow very slow. 

As always, further research is needed to confirm, but this simply adds another bright spot in the effort to preserve this endangered species.

-- Ben Young Landis

juvenile Mountain Yellow-Legged Frog

USGS WERC scientists will use these radio transmitter belts to keep track of released froglets, and replace the belts as the frogs outgrow them. (Credit: Ken Bohn, San Diego Zoo Global. ZSSD Copyright 2013 ©)