FOREST SERVICE CLOSES HABITAT SECTION OF TRAIL SHUT FOR STUDY OF FROG THREATS.

Byline: Charles F. Bostwick Staff Writer

ANGELES NATIONAL FOREST - The U.S. Forest Service has closed a six-mile section of the Pacific Crest Trail and about 1,000 acres around it for a study of how hikers, climbers and campers affect an endangered frog.

The closure of the mountain yellow-legged frog's habitat is described as temporary, but its duration depends on the completion of Forest Service and Fish and Wildlife Service studies in four Southern California forests.

``We are anticipating it's going be through this coming summer,'' said Cid Morgan, ranger for the Angeles National Forest district that includes the closure.

The closure will detour hikers onto Angeles Crest Highway for about 4 1/2 miles and also will bar climbers from a granite outcropping known as Williamson Rock, among the most popular rock-climbing spots in the San Gabriel Mountains.

Two or three inches long, its top side mottled with blotches that are usually yellow and brown, the mountain yellow-legged frog before 1970 was the most common in the San Gabriel Mountains. Now, researchers believe it is limited to fewer than 200 frogs in the upper reaches of eight Southern California streams.

Among those is shallow, rocky upper Little Rock Creek, which is paralleled and crossed by hikers along the popular Pacific Crest Trail.

The other San Gabriel Mountain streams where the frog survives are all in remote wilderness areas, Morgan said, but the Pacific Crest Trail draws hundreds of hikers.

An unofficial trail created by climbers also follows the creek on the way to Williamson Rock. Forest Service officials said they are working on a solution that will let climbing continue eventually on Williamson Rock.

The Pacific Crest Trail Association, which is a partner with the Forest Service for the administration and maintenance of the trail running from Canada to Mexico, is concerned that the highway route will be safe for both hikers and equestrians with pack stock, a member said.

``We would prefer to see the PCT itself remain open during the study and believe that hikers and equestrians who remain on the trail are not a threat either to wildlife or the study,'' said J.L. ``Pete'' Fish, the trail association's regional trail coordinator.

Fish said the highway route is acceptable as long as it remains closed to vehicle traffic, which Forest Service officials said will last through summer because of winter storm damage that Caltrans is still repairing.

The closed area includes the popular Cooper Canyon trail camp, one of Southern California's rare waterfalls - known as Zig Zag Falls - and the Eagles Roost picnic area, which will be accessible only by a 4 1/2-mile walk.

To help protect the area, Caltrans will lock a gate to block traffic on a segment of Angeles Crest Highway, already closed farther east by last winter's storms. The highway will be closed east of Buckhorn campground.

The closure follows a 2004 lawsuit by an environmental group, the Center for Biological Diversity, over the Fish and Wildlife Service's failure to designate ``critical'' habitat for the frog, which was declared endangered in 2002.

The proposed critical habitat, released in September, covers about 4,500 acres of the Angeles National Forest, as well as about 3,000 acres in the San Bernardino and San Jacinto mountains.

What has eliminated the frogs from 99 percent of their former San Gabriel Mountain habitat is not known, but it could include diseases, human activity and non-native predators such as the rainbow trout, researchers said.

People playing in creeks disturbs and damages egg masses and stirs up sediment that can settle on eggs, killing the embryos, researchers say. People also might step on tadpoles, or chase them and frogs to where they are seen by predators.

The frogs could also be particularly susceptible to rainbow trout, which were stocked for decades in Little Rock Reservoir and made their way upstream into the mountains. One researcher conducted tests that indicated yellow-legged frog tadpoles avoid native garter snakes, but not non-native rainbow trout.

Since 2002, the U.S. Geological Survey has pulled hundreds of trout out of the upper reaches of Little Rock Creek in an experiment into whether removing trout would let the frogs spread. The results are still inconclusive because researchers believe trout remain in the stream.

Frogs to repopulate streams are being bred at the Los Angeles Zoo, as endangered California condors have been. The zoo's breeding stock comes from young frogs pulled from a San Bernardino Mountains creek to protect them from mudslides and flooding expected to follow 2003 wildfires.

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(color) About 1,000 acres of Angeles National Forest will be closed through summer so scientists can study why numbers of the mountain yellow-legged frog, an endangered species, have diminished.

U.S. Geological Survey