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A private highway across the I-15 for big cats and other critters to be one of the world's largest wildlife crossings

UC Davis Wildlife Health Center

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Coexisting with wildlife has proved to be a unique balancing act for urban areas across Southern California. Sprawling development has expanded options for people but put animals in a tough position as their habitats are sliced up by roads and freeways.

UC Davis Wildlife Health Center

When wildlife becomes isolated without routes to explore new territory, their chances of survival greatly diminish. The mountain lions of the Santa Ana and Santa Monica mountains are a prime example of what happens when a population cannot travel and becomes too inbred. You can even see crooked-tailed big cats in the area– an indication of health problems caused by a lack of genetic diversity. 

Southern California is at the forefront of creative solutions to such problems. A stretch of land along Interstate 15 in Riverside County was recently purchased by The Nature Conservancy to develop a series of crossing areas so wildlife can have safe passage through the ten-lane freeway. And passage through I-15 means big cats in the Santa Ana and Palomar mountain ranges would have a path to one another, solving the inbreeding problem. It would also allow all local wildlife a chance to escape wildfire and drought.

UC Davis Wildlife Health Center

The Nature Conservancy and their partners are still in the research and fundraising stages so it will take a number of years before any structures are put into place. Whether an underground tunnel or overpass above the freeway would best serve the area is yet to be determined, but conservationists are intent on getting the ball rolling.

For local wildlife, the stakes are high. "If we don't find a way to connect wildlife across the highway, populations of mountain lions will likely be lost in the next 30 to 50 years," said Trish Smith, an ecologist with the Nature Conservancy. "It's kind of the canary in the coal mine with regards to warning us that there's problems with passage across our highways."