A motion-triggered wildlife camera on the San Mateo County coast has photographed an animal biologists didn't expect to see there: a North American river otter.
The Midpeninsula Regional Open Space District, known as Midpen, said independent researcher Ken Hickman spotted the otter while reviewing footage from a camera in Cloverdale Ranch Open Space Preserve, the district's newest preserve, which sits in the hills near Pescadero and Pigeon Point.
"Checking wildlife cameras can be like Christmas, but river otters haven't been known to occur on the San Mateo Coast since the 1800s," Hickman said in Midpen's announcement. He said he knew Midpen and State Parks biologists would be as surprised as he was.
A comeback from the fur trade
River otters once lived along the California coast as far south as Santa Barbara, but the 19th-century fur trade nearly wiped them out, Midpen said. In recent decades they've become far more common north of the Golden Gate, in Marin and in parts of Alameda and Contra Costa counties. In San Mateo and Santa Clara counties, the few sightings have mostly been in bay wetlands.
On the ocean side of the Peninsula, the only well-known recent case was "Sutro Sam," a lone otter who took up residence at San Francisco's Sutro Baths in 2012.
The nonprofit River Otter Ecology Project, which has tracked the Bay Area's recovering otter population with camera traps since 2012, describes otters as an indicator species whose presence and health say a lot about the condition of a watershed.
Why biologists are excited
Midpen biologist Matt Sharp Chaney made the same point. "River otters thrive in clean water and areas with abundant food supplies," he said, adding that the otter's arrival at Cloverdale Ranch is evidence of the species' recovery and of an ecosystem healthy enough to support prey such as coho salmon and steelhead trout.
Cloverdale Ranch covers about 5,100 acres of coastal grassland, scrub and creek habitat. The Peninsula Open Space Trust spent more than $60 million buying, restoring and caring for the land between 1997 and 2012, including work with the San Mateo Resource Conservation District to reconnect Butano Creek to its historic floodplain. Midpen bought the uplands from the trust for $16.2 million, and the preserve opened in 2023.
Public access is still limited. The only open trail is the 1-mile, out-and-back Wilbur's Watch Trail, which starts at a small lot off Highway 1 just south of Pigeon Point Lighthouse. Dogs and bikes aren't allowed, and Midpen asks visitors not to approach wildlife.