The Midpeninsula Regional Open Space District is partnering with Caltrans and the Santa Clara Valley Transportation Authority on the Highway 17 Wildlife and Trail Crossing project.

In January, a 2-year-old male mountain lion known to researchers as 157M found his way from the South Bay into the dense urban landscape of San Francisco. 

Recently, the need for California to reconnect fragmented landscapes was laid bare when a female mountain lion attempting to navigate Highway 17 was struck and killed by a vehicle. This all-too-familiar segment of mountain road just south of Los Gatos is the location where the Midpeninsula Regional Open Space District, a public land management agency, is advancing a major wildlife crossing project.

The district is partnering with Caltrans and the Santa Clara Valley Transportation Authority on the Highway 17 Wildlife and Trail Crossing project. The pair of crossings envisioned will connect more than 30,000 acres of protected public lands on either side of the highway, allowing wildlife to cross safely under the road and recreational trail-users to cross safely over it. It will serve as a key connection allowing mountain lions to naturally disperse from the Santa Cruz Mountains into the Diablo Range to the east and the Gabilan Range to the south and establish their own territories. 

Get Digital Access and Stay Informed With Trusted Local News.

Get Digital Access and Stay Informed With Trusted Local News.

In the Bay Area, mountainous, high-traffic roads like Highway 17 act as genetic fences, isolating populations and fragmenting habitat. Allowing at least one new mountain lion to join a local population every few years is enough to maintain healthy genetic diversity. According to Caltrans and the California Department of Fish and Wildlife, there are over 63,0000 daily vehicle trips on Highway 17, and it is a major wildlife-vehicle collision hotspot, making this roadway the “top priority barrier” to wildlife connectivity in the Bay Area.

Article continues below this ad

The roadkill numbers for Highway 17 are sobering. Since tracking at this location in 2017, 22 mountain lions have been killed on the 20-mile stretch of road between Los Gatos and Santa Cruz, according to unpublished Department of Fish and Wildlife data. More than half of those deaths occurred within 2 miles of the wildlife crossing project site. Without a crossing at this location, we expect to lose one to two mountain lions every year, along with numerous deer, coyotes, gray foxes and bobcats. 

In January, a 2-year-old male mountain lion known to researchers as 157M captured the public’s attention when he turned up in the dense urban landscape of San Francisco. Born around Rancho San Antonio Open Space Preserve near Cupertino, 157M made a 50-mile journey through a gauntlet of roads up the Peninsula, driven by the biological need to find a territory of his own. It’s no coincidence that Midpeninsula’s wildlife crossing project is located just 12 miles from where 157M was born.

See more S.F. Chronicle on Google

While 157M was safely relocated back to the Santa Cruz Mountains, his journey and the death of the female lion on Feb. 11 are two sides of the same coin. Reconnecting open space lands allows wide-ranging wildlife, including mountain lions, to access the food, water, habitat and mates they need to survive, making it less likely that they end up in neighborhoods or as tragic roadkill statistics. 

Last month, the California Fish and Game Commission officially listed mountain lions in the Santa Cruz Mountains as “threatened” under the California Endangered Species Act.  The commission recognized that the lack of genetic exchange caused by road barriers could lead to the population “winking out” or becoming locally extinct due to inbreeding. This recognition brings critical protection to these populations, acknowledging that they are at risk of what researchers describe as an extinction vortex.

Article continues below this ad

Guest opinions in Open Forum and Insight are produced by writers with expertise, personal experience or original insights on a subject of interest to our readers. Their views do not necessarily reflect the opinion of The Chronicle editorial board, which is committed to providing a diversity of ideas to our readership.

Read more about our transparency and ethics policies

Reconnecting landscapes does more than just keep drivers and wildlife safe — it sustains long-term ecological health. Mountain lions are considered a keystone species due to their role in the ecosystem. As top-of-the-food-chain predators, mountain lions keep deer populations in check and regulate the movement of other mammals, which in turn supports overall ecosystem health and helps control the spread of wildlife-borne diseases. Mountain lions cache their prey, allowing other scavengers such as turkey vultures, eagles, coyotes, foxes and invertebrates to feed and get nutrients from their decomposition to return to the environment.

Midpeninsula and other partners in this region and beyond are working toward a network of landscape linkages and safe passages to build a resilient landscape where mountain lions and other wildlife have the “room to roam” they need.  

Ana María Ruiz is the general manager of the Midpeninsula Regional Open Space District, a public land management agency caring for more than 70,000 acres throughout the Santa Cruz Mountains region.

© San Francisco Chronicle