A few days after Thanksgiving last year, a male mountain lion approached Highway 17, the twisty, traffic-filled, high-speed corridor that connects San Jose with Santa Cruz. In previous years, the mountain lion might have turned around. Or it might have jumped out and been hit by a car—like four other mountain lions recently killed on this stretch of the highway.
Instead, the male mountain lion safely sauntered through ^(https://www.blogquicker.com/goto/https://www.youtube.com/watch?v=fKTQpl1iw4k) a newly constructed, $12.5 million tunnel—the first major crossing designed specifically for wildlife in the Bay Area.
“It was the moment we had all been waiting for,” says ecologist Tanya Diamond, co-owner of Pathways for Wildlife, which has performed habitat connectivity studies along Highway 17 and other Bay Area motorways.
California has historically lagged behind other Western states in building wildlife crossings, but momentum has in the past few years shifted in their support. “Before, you would say, ‘I want to build an overpass,’ and people would laugh at you,” Diamond says. The California Department of Transportation, known as Caltrans, “really didn’t have the means or the money.”
State officials now hype up wildlife crossings as a much-needed solution to the myriad animals killed and hemmed in by our massive road network. “California leads the world in so many ways,” Chuck Bonham, director of the California Department of Fish and Wildlife, said in a recent promotional video ^(https://www.blogquicker.com/goto/https://www.youtube.com/watch?v=KOCnVLlPb2Q). “Right now, we need to become the leader on wildlife connectivity projects.”
Where crossings are coming
Words have now been backed up with cash, particularly during the 2022-2023 legislative session (a budget surplus year for California). Although this year’s much leaner budget has stunted progress somewhat, state officials tell Bay Nature they intend to continue their connectivity work. Moreover, the state Wildlife Conservation Board has already awarded nearly $100 million in grants over the past few years to plan crossings, including:
- $7.1 million for crossings of I-580 near Livermore and of I-680 and Highway 84 near Sunol in Alameda County.
- $5 million for a crossing of U.S. 101 and Monterey Road in Coyote Valley south of San Jose.
- $5.6 million for a crossing of U.S. 101 near San Juan Bautista.
- $3.1 million for a crossing of Highway 152 around Pacheco Pass, near Henry Coe State Park.
- $5 million for a second underpass of Highway 17, along with a recreational trail overpass.
Though years from completion—and millions of dollars short—these five projects would connect big swaths of habitat in the Santa Cruz Mountains, the Diablo Range, the Gabilan Range, and the East Bay. Still more Bay Area wildlife crossings are planned for newts ^(https://www.blogquicker.com/goto/https://www.openspace.org/stories/newt-passage-project-reach-major-milestone)near Petaluma and near Lexington Reservoir in the Santa Cruz Mountains ^(https://www.blogquicker.com/goto/https://static1.squarespace.com/static/5f3d9069e5ec7573ec5d5c48/t/646e4f8bc11b2b79648a29e5/1684950923774/CVNB+Press+Release+-+CDFW+grant+award+2023.pdf), and for salamanders on Highway 1 near Santa Cruz. More projects are being planned or completed elsewhere in the state, especially in southern California and around Lake Tahoe.
So far, the Wildlife Conservation Board grants have been the driving force behind many of these, with the California Department of Fish and Wildlife chipping in tens of millions of additional dollars and local bond measures playing a key role as well. If California voters approve Proposition 4, the $10 billion climate bond on the ballot this November, another $180 million will go to wildlife crossings and corridors.
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Pots of federal money are also hypothetically available ^(https://www.blogquicker.com/goto/https://arc-solutions.org/wp-content/uploads/2022/09/IIJA-Wildlife-Infrastructure-Funding-Guide_FINAL.pdf), and individuals and nonprofits have contributed, too. The Land Trust of Santa Cruz County, for example, bought conservation easements on hundreds of acres on either side of the completed Highway 17 tunnel, and it has also protected more than 2,600 acres ^(https://www.blogquicker.com/goto/https://landtrustsantacruz.org/protected-areas/rocks-ranch-wildlife-crossing) near one of the proposed U.S. 101 crossings.
Popular, but spendy
In a rarity for our polarized times, wildlife crossings garner support from Democrats and Republicans alike, as well as both urban and rural residents, and everyone from conservationists to construction workers, according to Mari Galloway, California program director at the nonprofit Wildlands Network, which has compiled a statewide map of crossings built or planned. “People hate to see roadkill,” and hunters “want to see their deer populations thrive.” Galloway says. “I haven’t talked to one person who said we shouldn’t have them.”
Still, Galloway acknowledges that the dollar figures associated with wildlife crossings can be “really shocking to folks.” “Transportation projects are just expensive,” she says. She hopes costs decrease as crossings become more commonplace. “We won’t have to start from scratch each time,” Galloway says.
Funds are also needed to monitor roads after the crossings are built. “If you’re going to spend a few million dollars on something, then you want to know that it’s working,” says Fraser Shilling, director of the Road Ecology Center at UC Davis. “We need to not treat these as one-offs that we celebrate” and then forget about. Shilling adds that wildlife crossings must be combined with “miles and miles and miles” of roadside fencing to direct animals toward safe crossing sites.
Why do the animals cross the roads?
Animals constantly run up against roads when trying to “access daily resources, like food and water,” Galloway says. In addition, “they need to find genetically diverse mates,” she explains, “and they also need to move to adapt to climate change, including extreme weather events like droughts, wildfires and floods.”
A shocking number don’t make it across the pavement. Scientists estimate ^(https://www.blogquicker.com/goto/https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8457620/) that vehicles kill around 1 million vertebrate animals (and countless invertebrates) each day in the United States. According to federal officials, wildlife-vehicle crashes kill around 200 humans ^(https://www.blogquicker.com/goto/https://highways.dot.gov/newsroom/biden-harris-administration-awards-110-million-grants-improve-safety-americas-roadways) per year as well, injure some 26,000 more, and cause more than $10 billion in annual economic damages.
Using data from the California Highway Patrol and its own crowd-sourced California Roadkill Observation System ^(https://www.blogquicker.com/goto/https://www.wildlifecrossing.net/california/), the Road Ecology Center at UC Davis calculates that ^(https://www.blogquicker.com/goto/https://roadecology.ucdavis.edu/sites/g/files/dgvnsk8611/files/files/CROS-CHIPs_Hotspots_2023_Fin_0.pdf), in 2022, nearly 250 black bears and more than 70 mountain lions were killed by cars and trucks in the Golden State alone—figures that are almost certainly undercounts. The center furthermore estimates that nearly 50,000 mule deer ^(https://www.blogquicker.com/goto/https://roadecology.ucdavis.edu/sites/g/files/dgvnsk8611/files/files/CROS-CHIPs_Hotspots_2024_fin.pdf) became roadkill last year in California. Hundreds of smaller or lesser-known species have likewise been found dead along roads, including thousands of squished newts ^(https://www.blogquicker.com/goto/https://baynature.org/2019/02/06/traffic-is-driving-a-newt-massacre-in-the-santa-cruz-mountains/) on Alma Bridge Road, near Lexington Reservoir, at the site of the proposed crossing there.
In the Bay Area, some of the worst roadkill hotspots ^(https://www.blogquicker.com/goto/https://roadecology.ucdavis.edu/hotspots/map) include U.S. 101 in Marin, I-680 and Highway 24 in the East Bay, I-280 on the Peninsula, and Highway 17, each of which killed hundreds of large wild mammals between 2016 and 2022.
On top of direct mortality, roads prevent animals from accessing habitat on the other side, and in some cases cause behavioral changes. “Animals can literally starve” when they refuse to cross, Shilling says, pointing out that some wildlife won’t even go near a road because of the noise, lights and smell. “There’s only a few places within the entire Bay Area where you have a dark, quiet environment,” Shilling says.
When animals can’t roam, they may mate with their relatives—and inbred populations can surface genetic disorders that can wipe them out. In the Santa Cruz Mountains, scientists have found that mountain lions don’t have enough suitable habitat ^(https://www.blogquicker.com/goto/https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.6723) to maintain a healthy amount of genetic diversity, and they’ve documented lions with kinked tails, a telltale sign of inbreeding. Ground squirrel populations on either side of U.S. 101 in Coyote Valley, south of San Jose, have been found to be genetically distinct—meaning they’re not reproducing with each other. Badgers likewise are failing to reach potential mates across U.S. 101 and Highway 1, scientists say.
In a 2022 report ^(https://www.blogquicker.com/goto/https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=204648&inline), the California Department of Fish and Wildlife named 12 top-priority wildlife barriers statewide that included three in the greater Bay Area: Highway 17 in the Santa Cruz Mountains, Highway 152 around Pacheco Pass, and U.S. 101 and surrounding roads south of San Jose. The agency also identified many other Bay Area roads that block wildlife ^(https://www.blogquicker.com/goto/https://apps.wildlife.ca.gov/bios6/?al=ds2867), including Highway 12 near Santa Rosa, Highway 13 in Berkeley and Oakland, and I-280 near San Mateo.
Adapted from an interactive map by the Wildlands Network ^(https://www.blogquicker.com/goto/https://wn.maps.arcgis.com/apps/instant/sidebar/index.html?appid=e16c15ec12724112866fd6da02f5a77a), using 2022 priorities from the California Department of Fish and Wildlife. (Kate Golden)
‘Each one was a battle’
Recognition about these problem areas—and about habitat connectivity in general—has dawned slowly, and Caltrans has been slow to act—though Shilling notes that some biologists at the agency have championed wildlife crossings for years. In 2006, a wildlife underpass opened on Harbor Boulevard in Los Angeles County, and planning for the Highway 17 crossing near Santa Cruz got going around 2013.
According to Shilling, “each one was a battle.”
“It was a fairly tepid effort on the part of the state,” he says, “and a hugely inspiring effort on the part of a few individuals.”
Galloway credits celebrity mountain lion P-22 ^(https://www.blogquicker.com/goto/https://www.nps.gov/articles/000/puma-profiles-p-22.htm) and his isolated brethren ^(https://www.blogquicker.com/goto/https://www.nps.gov/samo/learn/nature/pumapage.htm) in SoCal’s Santa Monica Mountains with turning the tide. With the help of private donations from P-22’s fans, the $92 million Wallis Annenberg Wildlife Crossing ^(https://www.blogquicker.com/goto/https://annenberg.org/initiatives/wallis-annenberg-wildlife-crossing/)—the largest wildlife bridge in the world—is now under construction and slated to open in 2026. That project has “captured the imagination” of the public, Galloway says, in addition to putting Caltrans (which is overseeing the project) “in a positive spotlight” and spurring the state Legislature to act.
In addition to allocating funds, the California legislature passed a bill ^(https://www.blogquicker.com/goto/https://biologicaldiversity.org/w/news/press-releases/california-legislature-passes-safe-roads-bill-putting-statewide-wildlife-connectivity-within-reach-2022-08-29/) in 2022 that requires Caltrans to identify barriers to wildlife movement before constructing or expanding roadways and to prioritize animals’ safe passage. Another bill ^(https://www.blogquicker.com/goto/https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202320240AB1889), currently pending, would require city and county governments to do much the same.
“To the extent possible, Caltrans is committed … to reduc[ing] habitat fragmentation caused by roadways,” Caltrans spokesperson Pedro Quintana says in an email. He adds that “as lanes have been added and traffic has increased, animal/vehicle roadkill rates have also increased.”
How crossings are born
A crossing usually takes around a decade from start to finish. First comes the planning and research phase, which typically includes roadkill surveys—Ahíga Sandoval, co-owner of Pathways for Wildlife, does these by bicycle, on smaller roads. Researchers also install cameras, analyze data from radio-collared animals, and use computer modeling to determine key movement points. Often, animals are already using pre-existing bridges and culverts. On Highway 152, for example, Pathways for Wildlife and its colleagues found ^(https://www.blogquicker.com/goto/https://f54a9910-d839-457d-b569-ad57b1ba42e8.filesusr.com/ugd/fa05b5_2b3ef4a5611d4fa3a5a9ae45a1048bb4.pdf) native animals traversed one popular box culvert 376 times over a span of 100 nights.
On Highway 17, by contrast, it was found that wildlife couldn’t get to the other side without crossing the road itself. “There was no easy fix,” Diamond says. “This needed a whole new structure.”
A site was eventually selected at Laurel Curve, a roadkill hotspot (and notoriously dangerous curve for humans) that slices through known mountain lion territory. Caltrans contracted with Watsonville-based Graniterock to build a concrete bridge over a wildlife underpass, replete with newly planted native shrubbery, roadside fencing running a quarter-mile in each direction, and electrified concrete mats to block animals from accessing Highway 17 from a nearby side road and driveway. Graniterock also applied a high-friction surface treatment ^(https://www.blogquicker.com/goto/https://highways.dot.gov/safety/rwd/keep-vehicles-road/pavement-friction/hfst) to make the pavement safer for drivers.
Wildlife crossings won’t solve all our connectivity problems. They won’t help animals that are reluctant to even approach roads. Moreover, we might need a lot of them to truly boost genetic flow and population sizes. “If your solutions are the size of postage stamps and your problems are the size of cities, then you can’t really patch it back together,” Shilling says.
But if well-placed crossings proliferate, Bay Area animals will use them. A bobcat was the earliest adopter of the new Highway 17 tunnel in January 2023, recorded ^(https://www.blogquicker.com/goto/https://www.youtube.com/watch?v=PYifUN0Upek) in the first hour that the cameras were on. Gray foxes came next. Then deer—including does and fawns comfortable enough to bed down inside the structure. That first mountain lion strolled through later, in November 2023. (Another was killed just beyond the fencing, prompting calls for it to be extended.)
The old Laurel Curve, according to Pathways for Wildlife, used to claim about two deer per month. Since the tunnel opened, as of this June, not a single deer had been struck.
#Dont #Cross #Road
