Wildlife Bridge Planned for 101 Freeway

Liberty Canyon in the city of Agoura Hills is a wildlife corridor between the Santa Monica Mountains and Simi Hills.
Liberty Canyon in the city of Agoura Hills is a wildlife corridor between the Santa Monica Mountains and Simi Hills. | Photo: Ken Lund/Flickr/Creative Commons License

Caltrans officials plan to build a bridge for mountain lions and other wild animals to cross the Ventura (101) Freeway west of Los Angeles, officials said last week.

The National Park System has been tracking mountain lions in the Santa Monica Mountains since 2002, and its biologists worry that the big cats are inbreeding because they are cut off from other lions in the mountains around Simi Valley and further north.

Caltrans officials announced that a $2 million planning and design grant is being sought from the federal government's infrastructure funding program. Earlier estimates for the wildlife corridor crossing cost were about $10 million.

"The new crossing will better integrate the environment and transportation systems, fostering better wildlife connectivity on either side of the 101, and increasing public safety by reducing the risk for collisions between vehicles and wildlife," said Carrie Bowen, the Caltrans director for Los Angeles and Ventura counties.

Tracking devices have in the past detected lions crossing back and forth over the Reagan (118) Freeway on a little-used road overpass at Rocky Peak. The new 101 overpass or underpass would link two fingers of wild state parkland just west of Liberty Canyon Road in Agoura Hills.

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Lions have been killed crossing the 101 at Agoura Hills -- most recently last October -- and attempting to cross the San Diego (405) Freeway at Sepulveda Pass. About 10-15 cougars range from Point Mugu east to the 405, and in one case further east into the Hollywood Hills and Griffith Park, according to NPS biologist Seth Riley.

The latest known litter of cubs, born in the mountains above Malibu, was the product of a male mountain lion mating with one of his daughters, Riley has said.

"If animals can't disperse out, you may be more likely to get close inbreeding, and we've seen a number of instances where fathers have mated with daughters," Riley told KPCC radio last winter.

One male mountain lion managed to cross south across the 101 to seek a mate in the Santa Monica Mountains. He fathered a litter with one Malibu-area cougar, but later mated again with a cub from that litter, Riley said.

The local lions eat deer, and biologists say they are an important part of the biology and ecological balance in the Santa Monica Mountains National Recreation Area.

No attacks on humans in western Los Angeles County have been reported in recent years. But two hikers have been mauled and killed by mountain lions in Orange and San Diego counties in the past two decades.

For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.

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