Some people speed through the suburbs and see only pricey stucco homes and tangled freeways wrapped around the foothills of Southern California. Biologist Kevin Crooks surveys the same landscape and envisions lifelines for wildlife.
Crooks studies an Orange County map and imagines corridors where coyotes can glide at night. He views a mundane highway bridge as the perfect conduit for wandering mule deer. And he ponders how patches of land around the periphery of the Los Angeles megalopolis could be strung together like beads, allowing tenacious mountain lions and other wildlife to forage and hunt.
Big mammals need big swaths in which to roam. Such expanses are vanishing fast as builders carve land into pieces for new homes, malls and office parks. So much so that scientists consider this region an international epicenter of wildlife extinction, in part because its remaining wilderness is being sliced into islands in an urban sea.
"Connectivity is the key," said Crooks, 32, who has studied in Riverside, San Diego and Orange counties for five years to see how predators fare as their native lands are invaded by bulldozers and building cranes. His most recent studies focused on the Nature Reserve of Orange County, a 37,000-acre open space system created in 1996 to protect wildlife.
What he discovered is cause for both alarm and optimism.
Linking Islands of Animal Habitat
Even within the reserve, Crooks found a scarcity of land linkages that allow big mammals to roam. Some key roads, such as Crown Valley Parkway, were built without tunnels that would allow animals to cross safely without fear of traffic. Many man-made crossings are badly designed--too low and barren for deer.
A more serious flaw is that the reserve is divided in half--two major expanses of largely undeveloped land that are separated by interstate highways and miles of tract homes. Most animals can travel within those two areas, but cannot cross over barriers as formidable as Interstate 5.
One of the few feasible links between the two parcels runs along Serrano Creek under the notorious El Toro "Y," where the Santa Ana and San Diego freeways meet in a blur of traffic. The notion of wild animals crossing under car-choked asphalt as wide as the Mississippi River seems impossible.
"It's not necessarily the fault of the reserve design," said Trish Smith, senior project ecologist with the Nature Conservancy, which helps manage current and future reserve land. "If we had hindsight 30 years ago, we could have prevented a lot of the fragmentation that's occurred in that time."
Not all the news is bad. With better corridors and more science, Crooks believes, the big predators still may flourish. He was pleased to find mountain lions and bobcats thriving in remote reserve land close to the Santa Ana Mountains. Coyotes and bobcats can be found throughout the reserve's central and coastal areas, signaling a well-balanced food chain.
But if the ranks of large predators dwindle, Crooks says, the natural balance of the Orange County reserve and similar wild lands will be thrown into disarray. Smaller meat-eaters such as opossums, raccoons and domestic cats can grow in numbers and travel more widely. They, in turn, will eat small native birds and other creatures already in danger of extinction.
In short: Saving the mountain lions and other large predators in the region may well ensure the health of rare songbirds.
Crooks tracked predators using dozens of remotely triggered infrared cameras, foul-smelling liquids used as lures and even gypsum powder to capture their telltale tracks. He and his researchers filled bulging scrapbooks and computer discs with thousands of photographs of startled bobcats, coyotes, deer, skunks--and, yes, mountain lions--caught wide-eyed in the dark as the cameras flashed.
Those photos are proof they do exist in the nocturnal shadows.
"People need places where they can go and say the system is operating basically the same way that it has for the past few thousand years," said Paul Beier, associate professor of wildlife ecology at Northern Arizona University, who conducted what are considered classic studies of Southern California's mountain lion population. "When you lose your large carnivores, you can't say that anymore."
Crooks traces his fascination with predators to his youth spent near Denver, a grandson of a wildlife biologist. He received degrees in zoology and ecology before earning his doctorate at UC Santa Cruz, where he was one of Michael Soule's last graduate students. Soule, now professor emeritus of environmental studies, is considered one of the nation's preeminent conservation biologists.