On misty hillsides in Sonoma County, Calif., cows graze under the shade of oak trees and lambs poke their snouts through white picket fences. The specialty markets and farm-to-table restaurants that abound celebrate the agricultural riches of a region that locals call “America’s Provence”: fresh eggs and locally produced pepper jack, not to mention world-class chardonnay.

The roughly 3,000 farms in the Northern California county have long had a reputation for being organic and humane, in a region where liberal values predominate.

But that has not been enough to spare them from a bitter feud with some of the country’s most extreme animal welfare activists.

The clash has involved lawsuits and restraining orders, heavily funded political campaigns and undercover videos of Sonoma County farm animals that have attracted the attention of celebrities such as Paris Hilton. Now, farmers and activists are waiting to see what transpires in a trial this month of a University of California, Berkeley, student for breaking into a local poultry farm and sneaking away four chickens that she says were being mistreated.

These are the actions of a new generation of radical activists, literate in the viral culture of social media and driven by the same goals as predecessors who sprayed fur coats with red paint in the 1980s. Organized by the group Direct Action Everywhere, they are seeking to end animal agriculture worldwide by breaking into farms and filming what they say are ill and abused hens, cows and other livestock.

In the Bay Area, organizers say they have focused on Sonoma County largely to make a point that a region that is “supposedly ethical and best of the best” still treats its animals poorly, said Cassie King, a spokeswoman for Direct Action Everywhere, which goes by DxE and is headquartered an hour south in Berkeley.