More than half of California is mountain lion territory and that's led to several mountain lion sightings in San Diego County in recent months, as well as the deaths of two of them on local freeways.
Last week, a mountain lion was hit and killed on Interstate 8 in La Mesa. In March, a mountain lion was fatally hit by a car in Oceanside, just days after one was seen peering through the windows of a nearby movie theater.
As a result, there have been renewed calls for a wildlife crossing in the San Diego region, similar the Wallis Annenberg Wildlife Crossing that is being built near Agoura Hills on Highway 101 in Los Angeles County.
The most recent proposals for local crossings are in Temecula, just north of San Diego County and would link the mountain lion populations from the Santa Ana Mountain range with those in the Palomar Mountains. Currently, Interstate 15 is separating those two habitats.
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Winston Vickers, a wildlife research veterinarian with UC Davis, has been studying our local mountain lion population for decades. According to his research, the mountain lion population west of I-15 has a severely restricted habitat range, are inbred and isolated from mountain lion populations east of I-15.
"We’ve documented animals coming right up to the freeway, right along in that area and getting killed trying to cross. When you combine the sources of mortality with poor reproduction, then that’s a recipe for population to just steadily decline," Vickers said.
Where would the 2 wildlife crossings be located?
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In an effort to prevent further population decline, Vickers is part of a wildlife and governmental coalition that recently proposed and designed two wildlife crossing structures just north of San Diego County. One, a culvert that goes under I-15, the other a vegetated, wildlife crossing that goes over I-15. Both are similar to what’s being built in the Los Angeles area over Highway 101.
"It often times takes 10-15 years to get a crossing structure designed and built, so yeah the time to start is now," said Vickers.
These proposed crossings will link and reconnect not just mountain lions, but close to 40 other wildlife species in the area.
As with so many things, it will come down to money. The crossing could cost tens of millions to build.
According to Scott Quinnell, a biologist for Caltrans District 8, the Wildlife Conservation Board provided a $1.3 million grant for initial scoping on the project. The next steps involve environmental considerations and more money to really get the project into the construction phase.
The Nature Conservancy has completed plans and specifications for improving the function of the existing Temecula Creek I-15 Bridge with participating landowners (Riverside County Flood Control, California Department of Fish and Wildlife, Western Riverside County RCA, and Caltrans). The Nature Conservancy is also currently working with the landowners on determining timing for implementation of priority specifications (invasive plant control/habitat restoration, fencing), as there are some related projects that need to be integrated with final plans developed, but according to Trish Smith, a senior ecologist with the Nature Conservancy, it looks like priority plans could be implemented within the next five to seven years.
As the process for getting the crossings built plays out, Caltrans installed 3 miles of wildlife fencing on both sides of I-15 in 2020 - 2021 to prevent wildlife-vehicle collisions and mortalities.
