Mule Deer Are Already Using California’s First Wildlife Crossing—and It’s Not Even Finished Yet
Construction on the $20 million bridge in Siskiyou County began last year and is expected to be complete by this fall, with miles of eight-foot-high fencing along the highway to help funnel animals toward it
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California’s first wildlife bridge isn’t finished yet, but that hasn’t stopped animals from using it.
Mule deer have been photographed wandering over an in-progress overpass in Siskiyou County, located in far northern California near the Oregon border.
Construction on the $20 million bridge started in July 2025 and is expected to wrap up by this fall. Nearly 100 cameras have been installed in and around the crossing and, in late May, one of them captured three mule deer using the structure.
The curious ungulates ambled across the overpass just 15 hours after crews wrapped up work for the day, according to the California Department of Transportation (Caltrans).
“While the contractor is still completing final touches, it’s incredible to see wildlife already embracing the new structure, even with workers still in the area,” the department wrote in a recent social media post. “Seeing animals use the structure this quickly is an exciting sign of the positive impact this project will have for both wildlife connectivity and public safety for years to come.”
Beyond deer, the crossing is expected to benefit other species, too, including mountain lions, black bears and gray wolves. A bobcat may have also already used the bridge in January, but officials can’t confirm that crossing, per SFGate’s Anna FitzGerald Guth.
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The bridge goes over a dangerous stretch of State Route 97, a two-lane highway where more than 50 deer and 16 elk were hit and killed by vehicles between 2015 and 2020, according to data from Caltrans and the Road Ecology Center at the University of California, Davis. One reason that section is so deadly is because it passes through an elk and mule deer migration corridor.
“The primary problem on the highway was the mortality,” Fraser Shilling, who directs the Road Ecology Center, tells SFGate. “There’s truck traffic that goes through there, and they don’t slow down. They hit whatever’s on the road, so a lot of deer and elk were getting killed.”
Officials hope the project will help make the highway safer for both animals and motorists. The bridge itself is roughly 100 feet long by 140 feet wide, and it’s being paired with a concrete box culvert under the road to give wildlife another option. Key to the project, officials are also installing some eight-foot-high fencing along the highway to help funnel animals toward the safe crossing.
“Wildlife crossings by themselves do not stop roadkill,” Shilling tells the Guardian’s Roque Planas. “It’s the fencing associated with them that stops roadkill.”
In a June 2024 report, researchers with the Road Ecology Center estimated that drivers killed more than 48,000 mule deer across California in 2023, more than double the number slayed by hunters in 2019. In 2023 alone, vehicle collisions wiped out more than 10 percent of the state’s total mule deer population.
“Roadkill is a preventable natural disaster,” researchers wrote in the report.
In addition to the Siskiyou County bridge, numerous other wildlife crossings are in the works in California and beyond. The now-$114 million Wallis Annenberg Wildlife Crossing over Highway 101 in Los Angeles County is expected to open in December after delays, reports the Los Angeles Times’ Caroline Petrow-Cohen. The 210-foot-long overpass will cross eight lanes of traffic on a busy section northwest of Los Angeles.
Additionally, two crossings are planned for sections of State Route 62 near Joshua Tree National Park. Three crossings are also being built on heavily trafficked sections of Interstate 15 between Los Angeles and the Nevada border, per the Los Angeles Times.
Quick facts: More wildlife crossings
- Colorado recently completed a new $15 million overpass over Interstate 25 near Monument, roughly 50 miles south of Denver. The structure is 200 feet wide by 209 feet long and links 39,000 acres of privately protected habitat with more than one million acres of Pike National Forest.
- Oregon has a new wildlife underpass beneath a stretch of U.S. Highway 30 northwest of Portland designed specifically for northern red-legged tree frogs.
The recent surge in wildlife crossing projects reflects a broader shift toward infrastructure that’s good for both people and animals.
“The national momentum around wildlife movement and connectivity has increased, and this issue has been pulled more into the spotlight,” Rachel Wheat, the wildlife connectivity coordinator for the Oregon Department of Fish and Wildlife, told the Salem Statesman Journal’s Rose Shimberg last year. “We’re starting to see more political [and] public support and awareness.”
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