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Slim 'Wildlife Corridor' Called Key to L.A. Parks' Biological Richness

June 11, 1987|ANDREW C. REVKIN | Times Staff Writer

When biologist Robert Wayne joined UCLA's faculty in January with plans to study the movements of predators in the Santa Monica Mountains, he was startled at the diversity of species he found.

After several weeks of trapping in the area's rugged state parks, he discovered that the mountains, despite being surrounded on almost every side by Los Angeles' sprawl, sustain species ranging from the common coyote to the more exotic gray fox, badger and bobcat.

In fact, said Wayne, who previously studied jackals on Africa's plains, "small-predator diversity here is comparable to anywhere I trapped in Africa."

But the biological richness of Los Angeles' parks--predators, prey, plants and all--may not last for long.

The steady spread of development is threatening to choke off a vital "wildlife corridor" that connects the urban parks with inland wilderness in Angeles and Los Padres national forests, according to Wayne and other wildlife experts, urban planners and conservationists.

The corridor, a narrowing swath of land in the Santa Susana Mountains and Simi Hills, acts as a lifeline, supplying a steady influx of animals to replenish populations in the urban parks and an infusion of new blood to keep species vigorous, said Timothy Thomas, a resource management specialist at the National Park Service.

'Choke Points'

Last week, a research team at California State University, Northridge, completed a study that uncovered three specific "choke points" where commercial hillside development is squeezing the wildlife corridor so tightly that few passageways remain for animals. The study was conducted for the park service.

All three points lie where the corridor is crossed by a freeway. The freeways themselves pose a daunting, but not necessarily impassable, barrier to many species, Thomas said. Coyotes, for example, are known to cross overpasses. And many animals can scuttle through underpasses or stream channels running beneath the roadway.

But, when both sides of a freeway become populated with car dealerships or condominiums, the barrier is virtually insurmountable. The most threatened points, according to the study, are:

At the western edge of Angeles National Forest, where the Golden State Freeway meets the Foothill Freeway, the corridor is being pinched by the southerly expansion of Santa Clarita Valley housing and the northerly growth of Granada Hills and Sylmar.

In the Santa Susana Pass, which runs through the craggy sandstone formations above Chatsworth, luxury developments to the east, recently approved by the county over objections of environmentalists, are matched by the growth of Simi Valley to the west.

Along the Ventura Freeway, between Agoura Hills and Hidden Hills, a gap is shrinking, with only a couple of spots where animals can cross over or under the busy freeway.

An informal task force of about 30 planning officials, conservationists and scientists will use the study as a starting point to devise a strategy for saving the corridor, Thomas said.

Must Satisfy Agencies

The challenge, he said, is that any plan must satisfy the myriad agencies and local governments with jurisdictions in the region. The task force, headed by the Santa Monica Mountains Conservancy, a state parks agency, includes representatives from the planning offices of Los Angeles and Ventura counties and the cities of Simi Valley and Los Angeles.

"There are only a few key points left," Thomas said. "If we don't act now and get these planning agencies involved, the corridor will be shut down forever."

The result would be thousands of acres of urban parks devoid of the richness of wild species--when that is what prompted parks agencies to spend millions on the species' preservation, Thomas said.

"There's a higher quality of life when you walk into a canyon and see a mule deer," he said. "If all you've got is ground squirrels and houseflies and cats, it's just not the same."

And the few animals that remained would be vulnerable to disease, fires or other sudden disasters and would be genetically weakened.

A key goal of the task force, which was first convened in January and will have its next meeting in June, is to encourage more research. The Santa Susana-Simi Hills wildlife corridor is well-established as theory, but few experiments have been done to measure its width or to study how many animals pass along it, Thomas said.

Natural Laboratory

"We really don't know very much about this idea of linking up areas in terms of wildlife and vegetation," said Elliot McIntire, the Cal State Northridge geography professor whose students conducted the study for the Park Service. "This is really just the first look."

Luckily, Los Angeles, with its dramatic mixture of urban development and wilderness areas, is a natural laboratory for studying the wildlife-corridor concept, unmatched anywhere in the United States, Wayne said.

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