If you’ve driven to Ventura on the 101 lately, you’ve probably noticed the Annenberg Wildlife Crossing taking shape over 10 lanes of highway. The $90 million project is shaping up to be the world’s largest and most ambitious way to protect and promote biodiversity.
But there are other, less sexy ways to get animals safely across a road.
Look carefully under five bridges along Highway 118, and you might notice some additions to structures that were originally built in the early half of the 20th century. They are deceptively simple: a ramp, a fence, a ramp-shaped pile of rocks.
These particular modifications, completed in 2021, represent an effort by Caltrans, the National Park Service (NPS), and other government and non-government agencies to change the age-old definition of what roads are for: serving not just humans, but every living thing trying to get from place to place.
A coyote uses the concrete ramp in a drainage culvert running under Highway 118. Courtesy of National Parks Service.
Roads connect people but isolate everything else. What we’ve built is getting in the way of the movement of animals and their genes. And that’s bad for biodiversity.
The state has really only prioritized linking habitats for the last 20 or 30 years. It was 2022 before California finally passed a law requiring Caltrans to include wildlife connectivity in its planning.
“We completely dissected the landscape across Southern California, and really across most of the U.S.,” says Justin Brown, a biologist for the National Parks Service who conducted road surveys along Highway 118 — counting roadkill and using trail cameras to see how animals were crossing (or not crossing) the road.
“Not one single project is going to fix the issue. It's road after road after road. So really, 118 is just one tiny little blip of the overall issue, trying to get it so that these wildlife populations are interconnected across the entire landscape.”
Caltrans biologists survey a drainage culvert at Long Canyon under Highway 118. Photo by Brandon R. Reynolds.
These underpasses — tunnels under the bridges — were made for moving water, not animals, so they include high walls that have prevented most critters from crossing.
So state and federal officials have been crawling around drainage channels all over the state to figure out efficient ways of adapting existing infrastructure so that animals, not just water, can get from one side to the other — small additions that keep animals away from traffic.
After Brown’s study, Caltrans went out and added ramps and fencing. And they were very successful, says NPS biologist Seth Riley.
“I mean, we thought they would work, but it was pretty awesome,” he says. Standing under one of the bridges, he talks about the secret animal highway they built: “We had all kinds of species: bobcats, coyotes, raccoons, skunks, opossums. We've had mountain lions come through here, and we had a bear using one of the ramps, which was cool.”
Caltrans biologists Francis Appiah (left) and Celina Oliveri (center) survey a fence with NPS biologist Seth Riley (right). Photo by Brandon R. Reynolds.
Brown conducted another survey after the crossings were built, and found that not only were animals using the ramps, they were also getting killed less often on the roads — by something like 75%.
And these secret crossings only cost $350,000 all in — less than 1% of the total of the Annenberg crossing.
Caltrans is planning seven more crossings just in this area, and dozens more statewide. The goal is to reconnect the green spaces severed by roads, a series of secret animal highways stretching from the Santa Monica mountains all the way up to Los Padres National Forest.
Nature abhors a vacuum, as they say, but it’s also no fan of an 18-wheeler.