VENTURA COUNTY STAR‎ (Ventura, California) 18 December 13 Scores of red-legged frogs found in isolated Santa Monica Mountains population (Cheri Carlson)
The future of the red-legged frog in the Santa Monica Mountains may depend on an isolated, but healthy, population high up in Las Virgenes Canyon.
The California red-legged frog thrived in local streams until the 1970s, when it all but disappeared from the Santa Monicas.
The frog — named for the reddish underside of its legs and belly — was found again decades later. But this time, they were spotted in just a small stretch of pristine water running through Upper Las Virgenes Canyon.
“It’s not a big place,” said Katy Delaney, a wildlife biologist with the Santa Monica Mountains National Recreation Area.
But a recent survey found about 100 red-legged frogs there, she said. “I was very happy that it was that many.”
Plans call for reintroducing the frogs to other streams, hoping to boost the threatened species. While they appear to be thriving, such an isolated population could easily be wiped out in just a single event, whether a severe drought or disease, park officials said.
Before moving any eggs, however, researchers needed to make sure the existing population was strong, Delaney said.
A team of biologists spent several nights recently in chest-deep water to get an accurate count.
After sundown, they hiked about a mile to the site on the former Ahmanson Ranch property, waded into the pools of cold water, and measured and weighed each frog they caught.
They also slipped a tiny tag — like a microchip — under the frogs’ skin before releasing them.
Some eluded capture. They hopped away, or swam to the bottom of a deep pool and sat, as Delaney and others waited them out. The team used a tag reader to make sure they weren’t catching the same frogs multiple times.
The next step calls for moving partial egg masses to two streams in Ramirez Canyon and Solstice Canyon near Malibu. How many will depend on how many they find this spring.
“We want to take a minimal amount of egg masses, so we don’t affect that population,” Delaney said.
Work started several years ago to survey 25 to 30 streams to find suitable habitat before choosing the two locations.
Red-legged frogs need year-round water — a requirement that raises some challenges in Southern California. The team also looked for a spot without invasive species like crayfish that could prey on the eggs or tadpoles.
In 2001, scientists at Pinnacles National Monument near Soledad had success with a similar approach, moving hundreds of eggs from nearby streams to the Bear Gulch Reservoir.
After several years of moving egg masses, nearly 500 young frogs were counted at the reservoir, according to Pinnacles officials.
For more information, go to http://www.nps.gov/samo/naturescience/redleggedfrog.htm.
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