Safe Passage for Wildlife

HOW SCIENTISTS AND PLANNERS ARE HELPING WILDLIFE GET OVER, UNDER, AROUND, AND THROUGH THE SOUTH BAY’S BUILT ENVIRONMENT.

 

This story was produced by Bay Nature magazine in partnership with Peninsula Open Space Trust. 

A black-tailed deer grazing at the edge of the staging area seems barely aware of visitors arriving to hike the Coyote Creek Parkway, a popular multiuse path in San Jose. Even when a car pulls in close behind, the deer doesn’t run.

Scenes like this can make it easy to imagine that Bay Area wildlife simply gets used to living among people. But from just beyond the parking lot, the roar of traffic on Highway 101 is a reminder that negotiating the landscape humans have created isn’t always so easy for other species.

Busy roads and the built environment pose formidable obstacles for animals trying to move from one protected space to another in search of food, water, or a potential mate. Populations hemmed in to one area risk becoming genetically isolated, which over time can send them spiraling toward extinction.

The geography of the Bay Area means that the stakes are high. Dense development separates protected lands in the Santa Cruz Mountains from those in the Diablo Range to the east. Maintaining connections between these two Bay Area habitats — and south to the Gabilan Range, inland of the Central Coast — is a top priority for Peninsula Open Space Trust (POST).

Working with many public and private partners, POST uses a range of strategies across the region to help support “wildlife connectivity” — the ability for animals to move safely between different habitats. From foundational research to hands-on habitat restoration, here’s how conservationists are working to make sure animals can get where they need to go.

RESEARCH

Starting with science

Connecting wildlife across habitats on a regional scale begins with learning about animals’ behavior. Which species are on the move? Where are they trying to go, when, and why? What obstacles stand in their way? Using tools like tracking devices, wildlife cameras, roadkill surveys, and habitat modeling, scientists can find out—and identify the locations most important to wildlife movement.

POST collaborates with organizations like Pathways for Wildlife, a specialty research organization, on scientific studies. In 2022, the partners released a study on wildlife connectivity in the southern Santa Cruz Mountains. It was a major milestone in understanding how wildlife are interacting with the roadways that lie between the southern Santa Cruz Mountains and adjacent mountain ranges to the east and south.

In addition to the more grim task of analyzing data on roadkill, researchers collected footage from more than 40 camera monitoring sites. Motion-activated cameras were placed at existing highway undercrossings to find out how often wildlife used this infrastructure to safely cross beneath roads. Amid all the data, two animal personalities stole the show: footage that showed a badger and coyote seeming to play together at the entrance to a highway undercrossing went viral on social media. The surprising moment put a playful face on the research—but the study’s real value to planners was in highlighting locations where improvements are needed to make highways safer for wildlife and people.

“This study is an example of applied research,” says Marian Vernon, who heads POST’s wildlife linkages program. “The findings are already being used to inform crossing projects.”

Caltrans has started design work on one such project, at a spot on Highway 101 in San Benito County that the study identified as especially hazardous for wildlife. In addition to POST and Pathways for Wildlife, partners include researchers at UC Santa Cruz and UC Davis, seven land trusts, state and federal Fish and Wildlife officials, the Amah Mutsun Tribal Band, and federal, local, and state nonprofit agriculture and environmental groups.

“It’s a lot of folks, all rowing together to try to get this stuff done,” says Bryan Largay, of the Land Trust of Santa Cruz County (LTSCC). “It’s really cool.”

CROSSINGS

Over, under, around, and through

Elsewhere, research recommendations have already moved past the design stage and into the realm of the concrete, in the form of crossings that help wildlife negotiate busy roads.

On Highway 17, a tight bend known as Laurel Curve is the site of one such crossing. The Santa Cruz Puma Project, a collaboration between UC Santa Cruz and the California Department of Fish and Wildlife, first identified Laurel Curve as a critical crossing point more than a decade ago. Researchers — including Pathways for Wildlife — found that 50 percent of recorded collisions between wildlife and vehicles on Highway 17 occurred at this one location.

Since then, says LTSCC’s Largay, “it became increasingly clear that facilitating movement of the animals across Highway 17 at Laurel Curve would be an important action to make sure that the mountain lions within the Santa Cruz Mountains could at least get across that highway.”

With Caltrans receptive to the idea of an undercrossing, the land trust began to acquire parcels on both sides of the highway, allowing construction of a tunnel underneath the busy road.

“It took about eight months to get our first mountain lion [in the crossing],” Largay says. “Deer started after maybe two months, and then at one point we had a mother deer and her two fawns sitting under the wildlife crossing in the shade.”

The success of the undercrossing at Laurel Curve has helped spur similar projects nearby, including an additional crossing on Highway 17 and another on Alma Bridge Road.

Encouraging wildlife to use these crossings requires a thoughtful design that considers the unique conditions of each project site. Part of the danger to wildlife at Laurel Curve is a break in the fencing that otherwise helps keep animals off the highway. To guard this gap, which drivers use to access surface streets, Caltrans embedded slightly electrified mats in the pavement. These help steer wildlife away from the road and toward the tunnel.

In addition to deterring animals from dangerous locations, planners can try attracting them to safe ones. POST’s Marian Vernon explains that crossings with wide openings and a clear line of sight to the opposite side are more inviting than small culverts with restricted entry points.

Soundproofing and barriers that block light from traffic can help make crossings feel more safe to wary species such as deer, while replacing paved surfaces with natural ones encourages use by smaller critters like salamanders, newts, and frogs.

LAND PROTECTION

Preserving the irreplaceable

Even a well-situated and well-designed crossing is of limited value to wildlife without protected habitat on either side. Acquiring land in the Bay Area is an expensive and complex undertaking — one where POST, whose core mission is to “protect open space for the benefit of all,” often plays a key role.

In Coyote Valley, on the southern edge of San Jose, the land-acquisition long game has netted big wins for wildlife. Situated where the gap between the Santa Cruz and Diablo ranges is at its narrowest, the valley forms a critical linkage between more than a million acres of wildlife habitat. It’s also one of the few remaining undeveloped valley floors in the greater Santa Clara Valley.

But “undeveloped” doesn’t necessarily mean “available.” Irina Kogan, POST’s director of landscape conservation, explains that some parcels identified as top priorities for conservation were privately held by landowners who planned to sell their parcels for use in industry or as tech campuses.

“There was intensive development envisioned for this area,” Kogan says, “and people were speculating based off of [that] potential.” Some landowners had been holding on to parcels for decades, envisioning steady growth in property values.

But times changed. “The City of San Jose was doing long-term planning and thinking about climate and carbon neutrality,” Kogan explains. “It realized the importance of protecting Coyote Valley as open space and agricultural land.”

As market conditions shifted, POST and other organizations raised funds and jumped on opportunities to buy and piece together parcels of land within Coyote Valley. Now, along with partners such as Santa Clara Valley Open Space Authority and the Santa Clara Valley Habitat Agency, POST has protected about 1,500 acres on the valley floor and another 4,500 acres on the hillsides beyond.

“In this particular case, POST was instrumental in being the party that bought the properties,” Kogan says. “The idea is to secure undeveloped land that can also be restored for wildlife habitat and support connectivity.”

HABITAT RESTORATION

Bringing landscapes back to life

In many cases, the land POST acquires needs work before it can reach its full potential as wildlife habitat.

One such “fixer-upper”: Calero Lakeview, a property in southern San Jose’s Almaden Valley that POST acquired in 2019. Calero Lakeview lies on the trajectory of animals’ movement in and out of Coyote Valley, and sits directly between the protected land of Calero and Santa Teresa county parks. While this is an ideal location to support wildlife, the parcel had some issues.

On the property were several structures that were not built to code. Much of the land was covered in a thick overgrowth of invasive weeds like black mustard, purple star-thistle, and stinkwort.

To improve the site for wildlife and prepare it for transfer to Santa Clara County Parks, POST undertook a multiyear landscape restoration effort. Workers removed 11 dilapidated structures, decommissioned sections of old road, and hauled away more than two million pounds of contaminated soil. They also upgraded 10,000 feet of boundary fencing, replacing old barbed wire with wildlife-friendly designs that allow animals such as coyotes, badgers, and bobcats to pass through without injury.

Similar habitat restoration work is underway on various properties in nearby Coyote Valley, where the Santa Clara Valley Open Space Authority is leading a planning process to shape the valley’s future. So far, efforts have included cleaning up trash, removing invasive plants, and planting native species along Fisher Creek—steps that help wildlife move more easily across the landscape.

Taylor Jang, a senior project manager for POST, says that effective restoration work has to consider species’ different habitat needs. “Some prefer cover — shrubs or other vegetation that provide for that type of passage—and others prefer more open conditions,” he says. Badgers, for example, like grasslands where they can dig burrows and hunt for prey like ground squirrels and gophers.

“If you know that there are specific points at which animals are crossing, then you can target habitat restoration, or other types of actions, around those specific locations.”

Good for wildlife, good for people

In explaining POST’s emphasis on landscape linkages, Irina Kogan points out that “wildlife habitat” is in some ways a misnomer: strategies that benefit threatened species — such as preserving open space and restoring native ecosystems — benefit people, too.

“Biodiversity is a critical part of climate resilience,” Kogan says. “Areas where there is a diversity of wildlife, diversity of plants — those are the places best able to handle the disturbances that climate change throws our way. A more climate-resilient future is certainly better for humans as well as wildlife.”

Her colleague Marian Vernon agrees. The wide array of benefits that come with safeguarding habitat connectivity is part of the reason so many different kinds of organizations — public and private — are prioritizing this work.

“It’s really an exciting time.” she says. “Partners across the region are coming together, pooling resources, learning from one another, and leaning on each other’s strengths, all in the hope of accelerating this work and making more of an impact.  Wildlife don’t recognize property boundaries or county lines, so organizations need to collaborate — and we are. We’re working toward a vision of a network of open spaces where people and wildlife can truly thrive.”

Amy Mayer is a reporter, producer, writer, and editor. She has written for the Boston Globe, The New York Times, Real Simple, BioScience, Wellesley, and Newsweek. Her podcast credits include Bay Curious, Caucus Land, and The California Report Magazine. She has been an editor for the California Newsroom and St. Louis Public Radio, a reporter at Iowa Public Radio/Harvest Public Media, and a contributor to KQED, WFCR and KUAC. AmyMayerWrites.com