Where Have All the Frogs Gone? : Wildlife: Biologist says the frog population in Southern California is dwindling. The decline could be a warning about the region’s ecosystems.

Mark Jennings, the Indiana Jones of the frog world, scaled two waterfalls to reach a remote canyon of the San Gabriel Mountains, only to find his worst nightmare confirmed.

“Nice stream. No frogs,” he said. A floppy felt hat shaded sunlight from his ruddy face. Big Mermaids Creek washed its cold waters around his boots. “It’s not like they are hiding. They’re just gone.”

Jennings, who works for the U.S. Fish and Wildlife Service, has spent the summer counting frogs in the Angeles National Forest. Along with Bonnie Dombrowski of the U.S. Forest Service, he is documenting the disappearance of the creatures, especially three varieties once abundant throughout the state:

There’s your foothill yellow-legged frog, your mountain yellow-legged frog and your California red-legged frog.

Anyone who doubts that Jennings is truly the Frog Man of California should check his scientific paper that sought to show, among other things, that when Mark Twain wrote about “The Celebrated Jumping Frog of Calaveras County,” he was talking about the red-legged one.

Jennings insists: “It wasn’t Mark Twain who made the frog famous. It was the frog who made Mark Twain famous.”

He points out that there are none left in that Northern California county, one of the trends that fuels his passion for scouring the state for frogs--and petitioning the government about them.

Last month, the 37-year-old Jennings won a major victory when federal officials announced a proposal to list the California red-legged frog as threatened or give it the most protective classification--endangered.

A July 19 notice in the Federal Register said habitat loss, predators, inadequate regulations, drought and recreational activities “imperil the continued existence of the red-legged frog.”

Jennings and other scientists say that floods, disease, and acid rain also contribute to the demise of the red-legged, along with other species of frogs and toads. And many are being eaten by descendants of East Coast bullfrogs imported in the 19th Century, he said.

With a final decision on the red-legged’s status expected within a few months, an “endangered” finding could provoke controversy if it poses an obstacle to development, as other such designations have. The federal agency also is considering if the foothill and mountain yellow-legged frogs merit further study to determine if they too should be listed as threatened or endangered.

In every case, Jennings has been among the loudest voices asking the government to declare a crisis. Yet even he acknowledges that saving frogs and toads doesn’t have quite the same environmental cachet as protecting the more majestic whale, wolf or grizzly.

“People ask: ‘What good is a frog?’ ” he said.

Jennings cites the evidence that he and a colleague marshaled from 1988 to 1991, when they conducted a state-financed study of amphibians in California. “Native frogs are in big trouble,” he said. Even common tree frogs, usually abundant, have begun to disappear.

To him, like the dying canary that warns miners of an oxygen shortage, the steady disappearance of frogs and toads in Southern California may signal the demise of the region’s ecosystems.

To monitor such developments, he and Dombrowski trek where few people go.

On a recent day, they bushwhacked their way through Big Mermaids Creek, thick with grass, alders, boulders and fallen trees. “Everything is here, except grizzly bear, wolves, condor and true frogs,” Jennings said. “It’s not a whole ecosystem.”

Wading up to his knees, he scooped up a two-striped garter snake and put it in a plastic bag for study.

The snake eats frogs and tadpoles. A shortage of frogs means snakes have less to eat. This robs other snakes, raccoons and birds of food. The implications, he said, travel eerily up and down the forest food chain. “You lose all these, and your ecosystem is going to fall apart,” he said.

A tawny newt circled his boots underwater. A granite-colored tree frog hopped into the muddy tracks made by a rare Nelson bighorn sheep.

To get to one of the few places he thought the frogs might be left--the rugged San Gabriel Wilderness, 36,500 acres of the Angeles National Forest--Jennings had hammered pitons into the rocky face of one waterfall about 30 feet high and used a rope to scale it. To climb another fall, he and Dombrowski fashioned a ladder from downed logs and stakes.

“There has to be frogs in here,” Dombrowski said, fighting her way through tall green grass whose sharp blades bloodied her hands. “If you were a frog, wouldn’t you be in here?”

“No, I’d be dead,” said Jennings, dejected after more than five hours of meticulously studying the stream and its banks. In the late 1970s, the frogs he sought had been spotted along nearby Bear Creek. This summer, he has found none on either creek, although he found two tiny groups elsewhere in the San Gabriels.

Years ago in Los Angeles County, the red-legged frogs could be found in the canyon bottoms of the San Gabriels and filled the banks of the San Gabriel and Los Angeles rivers. They were abundant in Pasadena’s Arroyo Seco at the turn of the century, when UCLA biology professors gathered them for studies.

Now, they are almost gone, save for in a few scattered sites, including one in Riverside County, where 30 adult frogs live.

“Whatever affects the true frogs has to be pretty nasty because they flat-out disappear,” Jennings said.

(True frogs have teeth in their upper jaws.)

The red-legged frog, which favors the populated lowlands and valleys, will likely become the subject of controversy with its inclusion on the federal list of endangered and threatened species, said Karen Miller, a biologist with the Fish and Wildlife Service.

Ninety percent of the places where red-legged frogs can be found are on private land, she said. In Contra Costa County, a reservoir is proposed for one of the six known homes of the species in the Central Valley.

In Southern California, the mountain yellow-legged and foothill yellow-legged are rarer. Once found as far south as the San Gabriels, the foothill frog is now found only in the Sierra and the state’s Central Coast. Jennings has found the mountain yellow-legged in only a few spots in the San Gabriels, San Bernardinos and San Jacinto mountains.

In the San Gabriels, one place is Little Rock Creek, where the mountain yellow-legged is threatened by rock climbers, hikers, swimmers--and, Jennings says, by a snow-making plan at Kratka Ridge Ski Area.

“This is a crisis in the making,” he said, as he perched frog-like by the creek and studied a lichen-colored, mountain yellow-legged frog, half in the water, its pop-eyes fixed on him. “I’m looking at the rarest frog in California.”

Ski resort operator Adrian Hensley said the frog is just the latest obstacle she and her husband, Ray, have run into during the eight years they have worked with the Forest Service on a snow-making proposal to restore a water pipeline from the creek.

When they proposed repairing the pipeline once used by forest crews, the Hensleys told the Forest Service about the mountain yellow-legged frogs there .

But not until last year, she said, did the Forest Service acknowledge that the disappearing species posed a problem to her plans.

When rains fall onto Angeles Crest Highway, Hensley said, the road sometimes is filled with frogs. Although not suggesting that these are mountain yellow-legged ones, she said that frogs “are the most resilient creatures. God, Mother Nature, or whatever you want to call it, gave them ways to survive.”

But Jennings wants to protect what he says are only 15 remaining mountain yellow-leggeds in that area. “Fairly simple things can be done,” he said, such as changing the proposed location of the pipe or moving a trail along the creek.

He says the public does not understand how fragile many creatures are, whether they be frogs, toads or turtles.

“I agonize over what to do for these guys,” he said, watching a mountain yellow-legged frog breaststroke its way around a pool of water.

Threatened Frogs

California red-legged. Rana aurora draytonii.

Once found throughout the state and Baja California. Now mainly in Central Coast. Restaurant delicacy at turn of century. Federal officials proposing to list it as a threatened or endangered species. Believed to be the frog Mark Twain made famous in “The Celebrated Jumping Frog of Calaveras County.” None now left in that county.

Foothill yellow-legged. Rana boylii.

Favors rocky stream banks in canyons and lower altitudes. Lives in similar locales as the mountain yellow-legged. No longer found in much of Southern California; their demise blamed partly on floods of 1969.

Mountain yellow-legged. Rana muscosa.

Likes to stay no more than a few leaps from water, in sunshine along rocky streams at high altitudes. A few groups left in the San Gabriels, San Bernardinos and San Jacinto mountains. Also in the Sierras.