Just outside of Los Angeles, in one of the most human-modified parts of the planet, a rare coastal ecosystem is pinching against the Pacific coast. The mountain range is home to one of the highest concentrations of threatened and endangered species in the country.
And some are suffocating.
For most of the last century, the Santa Monica Mountains have been effectively cut off from the larger world, hemmed in by seawater and sprawl. Highway 101, carved over the northern reaches of the mountain range, “has become this impenetrable wall for wildlife,” said Beth Pratt, regional director of the National Wildlife Federation in California. “And both plants and animals need exercise to be resilient and survive.”
This spring, construction crews in Southern California are expected to find a solution: a 200-foot bridge, complete with light guides, noise suppressors and nursery-grown willow trees. The wildlife crossing will be the largest and most expensive of its kind, spanning ten lanes of snarling traffic and reconnecting a severed landscape.
“You’re going to see this ecological transformation,” said Pratt, who has raised money for the project over the past decade. “And that part of it will be on one of the busiest highways in the world — that’s such a hopeful explanation to me for what’s possible.”
“We can exchange a freeway.”
Wildlife crossings, such as the kind planned at Liberty Canyon in Agoura Hills, have been shown to help species navigating a fragmented world. There are about a thousand such structures in the US, according to proponents of crossing over. Bridges, underpasses, culverts and tunnels.
Help maintain overpasses in Wyoming a 6,000-year-old migration route for pronghorn.
And in Utah, flyovers allow large mammals like moose to move across major highways.
Underpasses and culverts in Florida allow otters and alligators to move between habitats.
Soon there may be more. For the first time ever, Congress has made a major investment in wildlife crossing, allocating $350 million in the recently approved bipartisan infrastructure package for a Wildlife Crossing Pilot program that will help fund projects in all 50 states.
“Unlike so many issues we face today, there are actually these solutions to make roads safer for people and wildlife,” said Renee Callahan, executive director of ARC Solutions, a group that researches and promotes crosswalks. “And we could build them tomorrow.”
Millions of miles of roads help animals to die out
Up to 1 million species are threatened with extinction – many within decades – by human activities. Climate change, development, pollution, deforestation, overfishing and hunting are the driving forces behind the crisis.
Roads are an important part of that.
It is estimated that there are as many as 1 million animals killed in the US weigh every day† And it’s not all squirrels and deer. A Department of Transportation report identified 21 federally endangered or threatened species that are… in immediate danger through our arteries, including the desert tortoise and the Florida panther.
Just look at a road map of the US. The landmass is traversed and split in two, fragmented like a broken windshield, by more than 4 million miles of roads.
A mountain lion walks under the 405 highway in California. A second mountain lion was killed on the highway shortly after.
“There isn’t a lot of land that isn’t affected by roads and traffic in some way,” said Marcel Huijser, a road ecologist at Montana State University’s Western Transportation Institute.
For many species and people, the impact is literally immediate. But roads can also be deadly in more subtle ways, affecting habitats on either side of their path and blocking movement.
Along Highway 101, in Southern California, the latter is in danger of extinction.
Last year, mountain lion researchers began to notice something troubling in the big cats they studied in the Santa Monica Mountains. Mountain lions have been seen on game cameras and in person with kinked tails. Others experienced something called cryptorchidism, where one or both testicles failed to fall during puberty.
Audra Huffmeyer, a researcher at the University of California, Los Angeles, took it a step further and completed post-mortem analyzes for five deceased men. “All five individuals we sampled showed what we call teratospermia, which is a form of impaired fertility,” she said.
The findings were: the first documented reproductive signs from inbreeding in the area’s long-isolated cougars. Mountain lions, secluded in the 60-kilometer mountain range, mate with close relatives. They had been for a while.
Roads fragment the habitat of the mountain lions of the Santa Monica Mountains, affecting them both directly and indirectly.
National Park Service
It was no surprise. Researchers had seen collared mountain lions approaching Highway 101, intending to cross from the Santa Monica Mountains to more habitat in the Santa Susana Mountains to the north, only to stop and turn around, startled by the cacophony of the away.
“We know there was low genetic diversity,” said Seth Riley, a wildlife ecologist with the National Park Service. “I mean, we knew before we started the studies that that was a possibility, but we weren’t really hoping to get to the point where we started seeing these physical manifestations.”
“It definitely increases the urgency to do something about it.”
The wild crossing at Liberty Canyon should help. It is being designed to give mountain lions and other species an inviting escape valve, connecting isolated populations in the Santa Monica Mountains to the larger world.
Wildlife crossing can also be safer for people and save money
A survey of nearly 500 state and federal transportation employees by the Western Transportation Institute and ARC Solutions found that the biggest challenge to building more wildlife crossings is funding.
Wildlife crossing is expensive. The crossing at Liberty Canyon is expected to cost $87 million.
But until Congress’ recent investment, they haven’t received the same specific funding as other infrastructure problems like rotting bridges and potholes, said Huijser of Montana State University.
Transportation agencies in the US tend to prioritize projects that immediately address people’s safety. But Huijser said there is a compelling economic case for building more. “The problem with thinking it’s more expensive to pay for this [wildlife] projects is that it assumes that doing nothing costs nothing,” he said.
A 2008 Department of Transportation study found that animal-vehicle collisions cost Americans $8 billion each year in property damage and associated health care costs. In today’s dollars, Callahan said, it’s closer to $10 billion.
“It’s kind of like setting that money on fire every year,” Callahan said.
Crossing wildlife and associated infrastructure such as roadside fences has been shown to reduce collisions between animals and vehicles by 97 percent. They can help avoid the 30,000 roadside injuries and 200 deaths that happen each year when motorists hit animals in the wild.
Wildlife advocates like Pratt believe Congress’ recent investment in wildlife crossings is a sign that decision-makers are beginning to recognize these benefits. Her hope is that money for nature-oriented structures will be embedded in future infrastructure budgets from the start.
“So many of the environmental problems we’re working on, like climate change — they’re hard to solve. There’s no magic solution,” she said, looking at the sun-kissed peaks of the Santa Monica Mountains from Agoura Hills. “There’s a magic here.”
“This is a problem that we can actually solve quite easily. It just costs money.”