Wildlife Highway Links Vital Habitats

Until 15 months ago, a highway underpass beneath the Riverside Freeway was a favorite hideaway for sleep-deprived truckers in search of a nap. Today, hopeful signs indicate that four-legged creatures are reclaiming the passageway as a critical wildlife crossing.

“Two weeks ago we had a beautiful mountain lion track right here after the rain. Deer, too. Look, these are probably skunk,” Chino Hills State Park Supt. Ron Krueper said, bending over delicate paw prints etched in the soft silt of a creek bed.

Under the smooth, arching concrete belly of the freeway, the harsh lighting and asphalt are gone. Caltrans shut down the Coal Canyon Road exit in 2003, ripping up the offramps. Bobcats, coyotes and songbirds are among the animals now spotted using the wide underpass.

“They can make a dash through 50 yards without getting really jumpy,” said Claire Schlotterbeck, executive director of Hills for Everyone, which fought for 18 years to eliminate the freeway exit and a proposal to build 1,550 homes and an industrial park alongside Coal Canyon Road.

The project was never built, and neither was Coal Canyon Road. The land, 650 acres, was bought with $53.5 million in state funds and is now part of Chino Hills State Park.

The only reminders of the project were offramps and the underpass that, essentially, led to nowhere.

Scientists lobbied to remove the exit because they recognized that wildlife long knew what humans discovered as they developed the region: The Coal Canyon area is at the center of several natural passageways.

“Restoring a natural linkage in what is now a road underpass would set a global precedent,” wrote a panel of conservation biologists in 1998 after studying area terrain and animal movement. “Conservation-minded citizens throughout the world could look to Coal Canyon as an example of how an ecological error was corrected through thoughtful public action.”

Southland commuters know a different Coal Canyon -- the former exit bordering Orange and Riverside counties that radio traffic reporters list daily as a major congestion point.

“The 250,000 cars and trucks that go by here every day probably have no idea they’re going over a wildlife crossing,” said Krueper.

Railroad tracks, a major sewer line and the Santa Ana River also all squeeze through the area, between the Chino Hills to the north and the Santa Ana Mountains to the south.

Using centuries-old trails, the wildlife funnels down from broad lateral canyons and steep mountain flanks at rough cross angles to the freeway.

“This is the pinch point,” said Krueper. “You’ve got this hourglass of a wildlife crossing bisecting this narrow main transportation point, with road, rail and the Santa Ana River.”

Krueper gestured to green ridges tipped with yellow mustard, and a flower-lined creek bed abutting the churning freeway. “Animals use ridges and creek beds for travel,” he said. “That’s their road map.”

The wildlife corridor is 3 miles across at its broadest point, with Yorba Linda crowding in on one side, and Corona on the other, but conservation biologists who champion connecting “islands” of habitat believe it is enough.

Providing proper wildlife linkages could help maintaining genetic diversity, they say, by hooking up large swaths of habitat to avoid inbreeding. They also provide escape routes to reach other wild lands in case of fire or drought, and keep large predators at the top of the food chain because they have enough room to roam, ensuring that mid-size skunks and raccoons and others don’t over-multiply and wipe out songbirds and frogs, for instance.

Like any construction project, there are bumps in the road, and there is years’ worth of additional work ahead.

It was box culverts -- pitch dark, 6-foot-high tunnels scrawled with fading graffiti -- that made biologists realize the area was a natural wildlife crossing. Biologist Paul Beier tracked one mountain lion through the culverts 22 times in a year and followed him by using a radio collar to Brea, 15 miles to the north. Mammals exiting the underpass on the south side tend to go west along a bike trail to Brush Canyon, or east through a golf course to Aliso Canyon, both part of Chino Hills State Park. Mountain lions can roam an area of 150 square miles, and Krueper said that from Chino, they can go through Puente Hills, across occasional roads and under the San Gabriel River Freeway from the Whittier Narrows to the San Gabriel Mountains.

On the south side, the state park links with the Cleveland National Forest, providing 420,000 acres of largely unbroken habitat stretching south through San Diego County. Endangered gnatcatchers nest here in coastal sage scrub, and the rare Tecate cypress clings to canyon walls.

But the specter of development bumping up against the wildlife corridor remains.

Anaheim officials and the Irvine Co. are preparing zoning for a master-planned community that could put more than 3,000 homes along and below a ridge that Krueper says is vital to cougars and other wildlife.

“We’re talking with them; we’re hopeful that we can keep a buffer zone ... that would save the ridge,” he said. Krueper said mountain bikers, hikers and others are welcome to pass through the undercrossing, which connects an extended network of trails.

“Humans use it during the daytime, and the animals use it at night,” said Krueper. “It works.”