Caltrans Proposes Wildlife Overpass on 101 Freeway in Agoura Hills

Mountain lions, bobcats and other wildlife would have less chance of becoming roadkill if the state adopts a plan to build a landscaped bridge over the 101 Freeway in Agoura Hills, supporters of the proposal said. The 165 x 200 foot overpass near Liberty Canyon Road would connect the Santa Monica Mountains on the south with the Simi Hills and Santa Susana Mountains.

Since National Park Service biologists began researching mountain lions in the Santa Monica Mountains in 2002, motorists have struck and killed a dozen of the big cats in the study area, including a male puma hit on the 101 near Liberty Canyon two years ago.

Urbanization has taken a toll on Southern California’s mountain lion population, spurring battles over shrinking territory and a depletion of genetic diversity because of inbreeding.

Building the nation’s largest wildlife overpass would be ambitious, said Seth Riley, a wildlife ecologist with the Santa Monica Mountains National Recreation Area. At the proposed site, the highway has 10 lanes of pavement, including exit lanes. The overpass would feature drought tolerant vegetation placed so that it helps funnel wildlife across.

Wildlife Overpass

“I don’t know anywhere where people have tried to put such a large wildlife crossing over such a busy highway in such an urban landscape,” said Riley, who has led the mountain lion study.

Scientists long ago identified Liberty Canyon as the optimal location to build a wildlife passage because of the large swaths of protected public land on either side of the freeway. The projected cost would be from $33 to $38 million, according to the report. Proponents said they plan to seek most of the money from public coffers. The National Wildlife Federation and the Santa Monica Mountains Fund have launched an initiative to raise funds for the engineering design and construction expenses.

Wildlife overpasses and underpasses are popular in Canada, Europe and Africa. Christmas Island National Park in Australia features an overpass for the island’s millions of red crabs, a vital species that devours leaf litter in rainforests and recycles the nutrients.

The state of Washington recently broke ground on Interstate 90 near Snoqualmie Pass for the state’s first freeway overpass for animals. The 150 foot long structure is designed to provide passage for black bears, cougars, deer, elk and even squirrels, mice and lizards. Similar structures have aided wildlife in the Flathead Indian Reservation in Montana, where 30 species have been documented making more than 20,000 trips across the bridges a year.

WCCLAS News Reporter: Cherelle Wells

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