Wildlife experts Friday called for construction of Ventura Freeway animal crossings and for a regional policy to protect a migration corridor that sustains bobcats, badgers and other animals in the Santa Monica and Santa Susana mountains and the Simi Hills.
A key question: Would cougars and other wild animals really use bridges over the freeway if they had them?
The appeals came during a daylong conference on urban wildlife corridors that drew about 140 planners, conservationists and wildlife authorities to the Franklin Canyon Ranch near Mulholland Drive.
Paul Edelman, staff biologist for the Santa Monica Mountains Conservancy, which sponsored the conference, called for a follow-up meeting this fall to draft a land-use policy to protect existing migration routes for wildlife. The policy would be submitted to planning and highway agencies for their endorsement, he said.
"You need a comprehensive regional plan," said Frank Meneses, head of the environmental impact analysis section of the Los Angeles County Department of Regional Planning. "We do need to establish better coordination."
Experts say animals need large, connected blocks of habitat that allow them to move freely to colonize new territories and avoid the inbreeding that leaves them genetically weakened and susceptible to disease. For example, none of the state parks or preserves in the area--even 10,000-acre Topanga State Park--by itself has enough territory for a single mountain lion, according to wildlife authorities.
Officials say roads and private development have all but severed connections between habitat blocks in the mountains rimming the western San Fernando Valley, particularly along the Ventura Freeway, where the Santa Monicas meet the Simi Hills in Agoura.
Indeed, the conference and a previous study by Edelman painted a gloomy picture of the corridor's future, which depends on vast expenditures for land and road crossings and unprecedented cooperation between land-use and highway agencies that lack policies on the corridor.
Several large private development projects are planned near the freeway in Agoura, and Los Angeles County officials envision four big road projects along the freeway corridor to service new growth.
Even without these barriers, road kill data suggests that animals are already having a tough time crossing the freeway.
Edelman called for construction of one or two wildlife tunnels or overpasses at two points on the freeway--at Crummer and Liberty canyons. But Edelman and others said they did not know who would pay for the crossings.
Bill Charbonneau, a supervising transportation engineer with the state Department of Transportation and a panelist at the conference, said wildlife tunnels beneath the freeway would be far more expensive than overpasses. A single overpass would cost about $800,000 to $1 million, but "for a 200-foot tunnel, we're talking 5, 5 1/2 million" dollars, Charbonneau said.
But some participants said there was data showing that wildlife use tunnels, but little to show that they use bridges.
"Do any of you know if these bridges will actually conduct wildlife?" asked Jack Reynolds, a biology instructor at Moorpark College.
Others conceded that such questions deserve more study. "This is an infant science in many ways," said Terry Lieberstein, a geographer and wildlife expert who spoke at the conference.
Some participants said the focus should be on acquiring threatened parcels of land, noting that road crossings would be useless without safe habitat on both sides. "We're putting the cart before the horse here," said Suzanne Goode, an associate resource ecologist with the state Department of Parks and Recreation. Still, the conference was "a good start," she said.
Several speakers said that if migration links are severed--eventually eliminating lions and other creatures--animals such as deer and squirrels that need less territory would still survive.
But Jared Diamond, an evolutionary biologist, said the extinction of large predators would have ramifications beyond their immediate loss.
He cited research on an area where the disappearance of coyotes caused a decline in canyon bird populations. It seemed a paradox, Diamond said, because coyotes eat birds.
But coyotes prefer to eat smaller mammals and rodents that "really love to eat birds." These mammals thrived and "proceeded to really clobber the birds," said Diamond--proving the truth of the maxim that "the enemy of my enemy is my friend."