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

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.

So far, no studies have been done to show that a particular animal in Griffith Park, for example, traveled there from Los Padres National Forest, he said.

Wayne last week outlined an extensive series of experiments he plans to conduct on Los Angeles’ coyote population to determine one link in the flow of wildlife. He plans to attach collars equipped with radio transmitters to coyotes found south of the Ventura Freeway. The coyotes would then be transplanted north of the freeway and tracked to see if, and how, they make their way back to their old territory.

Also, by testing the distinctive genetic blueprint of coyotes trapped in various areas, Wayne will be able to tell whether they are closely related or distant cousins. If a coyote from the Santa Susanas is a close match to one from Griffith Park, for example, that is evidence that the wildlife corridor is still intact, he said.

Another important area to study is the difference among migratory paths taken by various kinds of animals, Wayne said. “To different animals, getting around means different things,” he said. Coyotes seem adept at traversing freeway overpasses, but badgers, bobcats or mountain lions--of which there are only four or five in the Santa Monicas--would probably never take such a route, he said.

Search for Food

Researchers believe that wildlife corridors evolve when animals are forced--by territorial disputes, the search for food or simply by chance--out of their natural wilderness habitats into new, smaller and more isolated areas: from a continent toward an island, or from a vast forest toward a city, for example.

The likelihood of an animal reaching a new habitat depends on how much ground it has to cover and how difficult it is to get there. In the Los Angeles area, it is assumed that animals already are confronted with a great challenge in making their way south toward the Santa Monicas.

Thomas estimated, as an example, that only one or two mule deer might cross the Ventura Freeway in several years. “But even one in five years is enough” to help sustain the deer population to the south, he said.

If a wild area in a city is completely cut off from sources of new animals and plants, it will, over many generations, lose its richness. Species that die out will not be replaced by new ones. Inevitably, Thomas said, “the number of species in these urban ‘islands’ will diminish.”

With only a few species remaining, the area of wilderness would be much more vulnerable to disruption by fire, disease or other change.

If such a fate befell Los Angeles’ green space, the loss to future generations would be enormous, Thomas said.

Land Pieced Together

For nearly 10 years, federal, state and local agencies have slowly been piecing together tens of thousands of acres of public parks, nature preserves and undeveloped land in the Santa Monica Mountains, which split the greater Los Angeles area like a green wedge from Point Mugu State Park in the west to Griffith Park.

And more parkland is being added each year, with the eventual goal being an unbroken 55-mile-long string of public lands called the Santa Monica Mountains National Recreation Area, controlled by the National Park Service.

Although expansive, these public lands still cannot easily support a self-sustaining population of large animals such as mule deer or mountain lions without some influx of new animals, Thomas said.

Despite a lack of concrete data showing that the Santa Susana corridor amounts to more than just a theory, it has already influenced some planning decisions. City Councilman Hal Bernson has proposed the annexation of 1,011 acres of unincorporated land west of Chatsworth, in part to protect the wildlife route.

But, until its boundaries can be clearly defined and its importance proved, the wildlife corridor cannot be a strong priority in planning, task force members said.

The task force is focusing now on the Santa Susana Pass. It was the Santa Susana Mountain Park Assn., a nonprofit conservation group devoted to preserving open space in that area, that first pressed for the task force’s formation.

Chicago Model Described

A key goal of the task force is to identify clearly which areas in the mountains can be protected only if they are purchased by public agencies and which might be protected by special zoning.

According to the Cal State Northridge study, a good model to follow in devising a plan that can work across city and county lines exists south of Chicago. There, the Illinois and Michigan Canal National Heritage Corridor links diverse natural areas such as wetlands, prairies and forests.

Until such a plan is agreed to by Ventura and Los Angeles counties, the cities of Simi Valley and Los Angeles, and environmentalists, efforts to save the corridor will be fragmented, Thomas and other task force members say.

Development and wildlife migration can mix if substantial terrain is left in its natural state, according to the study. Thomas said the city of Simi Valley, for example, has developed an excellent land-use strategy to provide open spaces that can function as wildlife corridors. With new zoning rules, Simi Valley has encouraged developers to build housing in clusters, surrounded by large stretches of natural vegetation.

“We don’t want to preserve all the open space in southern California,” said Elliot McIntire at Cal State Northridge. “We want to give a rational basis for making decisions on what can be developed, and how it should be developed.”