Genetic analysis has revealed that a black bear wandering near Point Reyes National Seashore last year came from Sonoma County’s Sugarloaf Ridge State Park, east of Santa Rosa—dozens of miles away. “We have no idea how it got there. But that’s not a long way for a bear,” said Meghan Walla-Murphy, the lead scientist of the North Bay Bear Collaborative, which conducted the research.  “The more curious thing is: How did it get across Highway 101?” Three samples of scat from the male bear, named M22, were collected in 2023 from an undisclosed location east of the seashore, according to Steven Hammerich of Sonoma County’s Pepperwood Preserve, which is organizing the collaborative genetic research. The scat was sent to U.C. Davis, where scientist Benjamin Sacks extracted DNA from cells and then genotyped it, using a suite of genetic markers that yield individual DNA “fingerprints.” The analysis, completed this summer, showed the DNA was a perfect match for scat collected in August 2020 at Sugarloaf Ridge State Park. The bear’s route to West Marin—about 34 miles as the crow flies, or 55 miles by road—is unknown, Ms. Walla-Murphy said. Perhaps it traveled south from Sugarloaf Ridge along the rural Mayacamas Mountains, which extend east of Petaluma, then crossed under Highway 101 along San Antonio Creek, south of Petaluma, and into the region, she said. The bear is likely young, she added. After leaving their families at about 18 months of age, male black bears tend to disperse and explore new territory. Young females, in contrast, stay closer to their home range with their mothers, aunts and sisters, she said. It is not known if the bear still lives in West Marin, but in April, a bear was seen crossing Lucas Valley Road, according to naturalist Peter Barto, a volunteer with the collaborative. Bear scat was spotted in June at Abbotts Lagoon but was too deteriorated to sample. The collaborative is currently investigating two new reports of potential bear scat: one on a ridge above Terra Linda and another near Paradise Drive in Tiburon. Historically, only the forests of northwestern Sonoma County had black bears. Grizzly bears dominated throughout Central California’s vast grasslands, but they were hunted to extinction in California in the early 1900s. Now black bears are moving into former grizzly habitat, especially in areas that are now forested. Statewide, the number of black bears has jumped to an estimated 50,000 to 80,000, according to the California Department of Fish and Wildlife. They’re especially abundant in Humboldt, Mendocino and Lake Counties—and they may be feeling hemmed in, resulting in a spread south into Sonoma County, Ms. Walla-Murphy said. The collaborative, a group of state agencies, nonprofit conservation groups, landowners and volunteers, aims to use DNA research to map the species’ expanding range and build a family tree, like Ancestry.com does for people. It also is teaching residents how to live among bears safely, such as by keeping garbage secure. While black bears are shy animals and usually avoid people, they’re well-adapted to living alongside us. As they move into Marin, “we need to learn how to coexist with these bears, creating good boundaries by cleaning up our trash, not leaving out food waste and taking other steps,” Ms. Walla-Murphy said. For more information, go to https://beingwithbears.org/. To report bear scat or send photos or videos, email Peter Barto at [email protected].