Researchers Aim to Keep Frogs From Croaking

It is frog heaven, this lovely oasis of quiet pools along Las Virgenes Creek on Ahmanson Ranch.

Lush brambles of wild blackberry border the creek, creating perfect hideaways. Tender patches of watercress and duckweed serve as enticing floating buffets.

Several frog species are happy to call this home, but the one drawing all the headlines and VIP attention is the California red-legged frog, which is listed as federally threatened.

On this creek, every red-legged frog is accounted for, especially “Marie,” the doyenne of pool No. 7. She stands her ground, researchers said, even when flashlight beams glare into her eyes.

Just as the California condor was rescued from the brink of extinction, researchers are crossing their fingers in hopes that the first-ever effort to breed this frog in captivity will succeed.

Researchers from the Los Angeles Zoo and the U.S. Fish and Wildlife Service plucked five “juveniles” from the creek in November and an egg mass in March.

Months later, the eggs hatched into healthy tadpoles that nibble on watercress harvested from the creek and on organic zucchini.

Aquariums house five youngsters--dubbed Alphie, Bella, Cameron, Duke and Enrico--and they are thriving on a diet of live crickets, rolled in vitamin powder, plus a banquet of other insects gathered from the creek. Sometimes their diet includes a baby mouse to satisfy the occasionally carnivorous tastes of the captive frogs.

Cleanliness Is Key for Frogs

The water in the tanks is drawn from the creek to maintain as similar a habitat to the wild as possible.

“The trick to amphibians is they have to be kept really clean,” said Russ Smith, curator of reptiles at the Los Angeles Zoo and a volunteer researcher for the frog breeding project. Water is changed twice a week, and the tanks are kept meticulously clean.

With just four dwindling populations of red-legged frogs in Southern California, the Ahmanson Ranch colony is vital. The long-range plan is to breed the frogs so that they can be reintroduced to the San Gabriel and Santa Monica mountains, said Douglas Krofta, branch chief for listing at the U.S. Fish and Wildlife Service.

If the Ahmanson frogs can procreate in captivity, the same techniques may be applied to other red-legged frogs from Baja California and Riverside County.

Biologists identified the red-legged frogs at the ranch in 1999.

The finding, coupled with the discovery of the San Fernando Valley spineflower, long thought to be extinct, threw another twist into the protracted battle over the proposed 3,050-home Ahmanson Ranch development. Los Angeles County and the city of Calabasas are fighting the residential project planned by Washington Mutual, Inc.

Scientists said cooperation from Washington Mutual, which has provided funding and a site for the captive breeding program, may give the frog a viable future.

“If we lose this population, we lose the chance for recovery of the frog,” said Krofta. “This is our learning ground, our university.”

In the wild, in addition to the Ahmanson colony of about 50 frogs, officials say one group in San Francisquito Creek in the Santa Clarita Valley is too diseased to be rehabilitated. Two other frog colonies are in Riverside County and Amargosa Creek near Ritter Ranch, outside Palmdale.

Measuring up to 5 inches in length, the California red-legged frog is the largest native frog in the western United States.

Its red or salmon-colored hind legs have contributed to both the amphibian’s lore and its demise.

They are believed to be the same celebrated hopping legs immortalized by Mark Twain in his tale about a Calaveras County frog jumping contest.

But those sinewy hind limbs were also such a highly sought gourmand’s delight that the species was practically wiped out in the 1800s and early 1900s. Bullfrogs that were introduced as an ersatz gourmet item wound up preying on the red-legged frog, exacerbating its decline. In 1996, the species was declared threatened under the Endangered Species Act.

On Friday, Krofta, Smith and Lenora Kirby of the Las Virgenes Institute, funded by Washington Mutual, led visitors on a survey of the frogs in Las Virgenes Creek.

Because the amphibians are so susceptible to outside viruses and infections, all visitors don rubber boots that are used only on ranch property.

Down in the creek, the water is clear and clean, gliding at a gentle pace--ideal for these amphibians which like to float with their snouts and eyeballs just above the surface, legs dangling lazily below.

The first sighting is preceded by a loud splash. The frogs blend in so well with the mud, rocks and mossy vegetation they don’t budge until visitors approach within inches.

Moments later Smith has netted a plump frog to examine. It is a youngster, Smith declares, but even then, with legs extended, it’s a good 5 inches.

State’s Largest Designated Habitat

The frogs don’t reach breeding maturity until they are 3 or 4 years old. That’s if they aren’t first devoured by raccoons, birds or bullfrogs or succumb to loss of habitat.

In March, the U.S. Fish and Wildlife Service designated 4.1 million acres in California as habitat for the frog.

It is the state’s largest designated habitat for a species--a patchwork of land that stretches across 28 California counties, from the northern half of the state south to Riverside County.

The habitat can affect proposed developments if federal permits are required. Activities such as water transfers, diversions and construction can be restricted or banned if they harm the amphibian or its habitat. Washington Mutual does not believe the frog’s threatened status will interfere with its own development plans.

Many local creeks where the frogs were once found are now filled with bullfrogs, bass, sunfish, goldfish, crayfish and other animals that disrupt the habitat, Smith said.

That’s one reason the Las Virgenes population is so well-surveyed--frogs are counted, temperatures of water and air are monitored, intruders are forbidden.

Not everyone supports captive breeding. Kieran Suckling, executive director of the Center for Biological Diversity, a Tucson-based environmental group that has sued Fish and Wildlife to designate frog habitat, said captive breeding should be a last resort if a species is about to become extinct.

“Amphibians tend to become genetically distinct in almost every drainage they occur in,” Suckling said. “So therefore, breeding frogs in one drainage and taking them to another is not a good idea. You are obliterating their genetic distinctness.”

Back at Las Virgenes Creek, in pool after pool, frogs and tadpoles are sighted, netted, examined and released. They all plop into the water, long legs propelling them quickly away. But, true to her reputation, at pool No. 7, an enormous Marie stays flat-footed, surrounded by tender watercress. “We call her the Queen of Las Virgenes,” Kirby laughs.