Bikers Compete With Rare Toad Over Stream Bed : Wildlife: The amphibian has already lost 75% of its habitat. Motorcyclists say they have a historic right to a Los Padres forest trail that cuts into creek.

One of the few surviving populations of the arroyo toad could be wiped out if a motorcycle trail is reopened through a breeding pool in a rocky backcountry stream bed of Ventura County, biologists say.

The same fate could await at least three other species that depend on the cool water and sheltering rocks of Piru Creek, which cuts its path through the Los Padres National Forest adorned with a ribbon of golden-leafed cottonwoods, high in the county’s northeast corner above Pyramid Lake.

Along with the nearly extinct toad, pond turtles, the two-striped garter snake and the red-legged frog are candidates for the federal endangered species list, according to scientists with the U.S. Fish and Wildlife Service. These animals also live and breed in and along Piru Creek near the crossing of the popular Snowy Trail, which is used by about 7,500 motorcyclists a year.

The U.S. Forest Service is expected to decide as early as today whether to reopen the trail to cyclists. It was closed in 1990 while rangers evaluated the vehicles’ effects on the toads and other wildlife.

If the species disappears from the forest, biologists say little-understood but vital links in a natural system could be forever lost.

“An ecosystem is more than the sum of its parts,” said Cathy Brown, a biologist with the fish and wildlife service, which recommends permanent closure of Snowy Trail. “There might be greater impacts than you would ever guess from the removal of this one little toad.”

In addition, she said, preservation of a species is mandated by law.

“It’s a moral obligation not to cause the extinction of another species with whom we share the planet,” she said.

Due to encroaching development, use of streams for recreation and mining, and five years of drought, the arroyo toad has now disappeared from 75% of the area it once inhabited, said Samuel Sweet, a UC Santa Barbara biologist and world expert on the arroyo toad. That makes the remaining riparian, or stream bed areas, disproportionately valuable, he said.

“Virtually all riparian habitat in the rest of Southern California is gone,” said Sweet, who also heads a forest watchdog group. “The survival of the species has become hinged on what happens in the Los Padres National Forest.”

But motorcycle advocates say they have a historic right to the challenging and rugged trail, which winds down a steep and narrow canyon before it crosses the stream.

“We’ve been riding this trail for more than 30 years,” said Dana Bell, district legislative officer for the Southern California branch of the American Motorcyclist Assn. “Common sense tells us that if we were impacting this toad, there wouldn’t be any left now.”

Bell said that if the toad’s survival depends on one small section of a stream at the Snowy Trail crossing, the amphibious critter would probably not survive on its own anyway.

The Forest Service should reopen the trail and construct a motorcycle crossing to protect the toads, she said. “Now that’s good management.”

Mount Pinos District Ranger Trinidad Juarez, who has a federal mandate to manage the forest by balancing biological protection and recreational use, must decide whether the trail is reopened. He declined to comment on the case before his decision is made public.

Whether he decides in favor of the toads or the motorcyclists, his decision is likely to be appealed, people on both sides of the issue said.

“You have a built-in conflict you are always trying to resolve,” said Don Trammell, district recreation officer for the 480,000-acre Mount Pinos district of the forest. “People are drawn to the water, but that’s also the most important habitat for wildlife.”

The trail makes a 9 1/2-mile loop from the sage and grasslands of Hungry Valley State Vehicular Recreation Area through canyons and chaparral-covered hills to the 100-year-old Jeffrey pine forest on top of Alamo Mountain, and back.

The difficult trail, which requires expert motorcycling skills, is often closed during dry seasons to minimize fire danger. It was closed for the summer of 1990.

The following November, rangers decided to keep the trail closed to motorcycles while they evaluated their effect on the toads and other wildlife.

Biologists say the effects of thousands of vehicles on the toads are many and devastating. During breeding season in spring, the males come out on rocks to attract females, and while they are exposed, they can be run over. The female deposits her eggs in the stream, laying about 4,500 of them like a string of beads, Sweet said. The eggs are in danger of being crushed by the motorcycles or covered with silt stirred up when the bikers splash through the stream bed.

Once the eggs hatch in five or six days, tadpoles emerge. In two to three months, they lose their tails and sprout legs. Even without interference from man, only one of the 4,500 eggs is likely to become a juvenile toad. The juveniles that survive seek shelter under loose rocks in and along the stream bed, where they can be crushed by tires.

The three-inch-long toads, which once numbered in the tens of thousands in Los Padres forest, are now down to about 340 adults and 800 juveniles living along Piru and Sespe creeks in Ventura County and the Santa Ynez River in Santa Barbara County, said Sweet, whose research project has taken him along 280 miles of toad habitat.

Between 75 and 80 of the adults live along the Piru Creek, and up to 10 adults live at the Snowy Trail crossing on the Smith Fork of the creek, Sweet said.

Although juvenile toads survived from previous years, Sweet said he has found none from the eggs laid last year.

Before he makes a decision on whether to reopen the trail, Juarez is evaluating several alternatives, including a concrete path through the stream to prevent cycles from stirring up silt, with barriers to prevent the estimated 5% of motorcyclists who spin circles in stream beds or otherwise veer off marked trails.

Building a bridge over the creek is impossible because of the waterway’s changing nature during the rainy season, the Forest Service’s Trammell said. A recent hike through the area revealed a tumbling stream about 15 to 20 feet wide and a foot deep. But after a good rain, the creek can swell to 100 feet across, he said.

“It’s not just this mellow little stream that people see most of the time when they walk down here,” Trammell said.

The topography of the stream makes it difficult to relocate the crossing to a less sensitive spot, he said.

“So we are kind of led to this one spot,” he said.

Trammell said the Forest Service is also considering a seasonal closure, keeping the motorcyclists out during the crucial spring breeding period. But that would not address the summer and fall, when the juveniles sometimes search out sunny flat surfaces, such as a concrete crossing, for lounging, Sweet said.

And even if the trail were rerouted around the pool, it might spare a few animals only to destroy a significant portion of their habitat, Sweet said.

“If our intention is to save any of the species at all,” he said. “It’s got to be done in the Los Padres.”