(PressDemocrat) - On a computer screen at St. Francis Winery & Vineyards is a profile of Rosemary, a woman who has commented about the Sonoma Valley winery on sites like Facebook and Pinterest hundreds of times.

Her mug shot, pulled from her profile on one of those sites, is alongside her full name and a log of everything she's said publicly about the brand online.

Software that St. Francis and other wineries use to monitor their brands on social media channels also has the ability to track where customers go after visiting their winery, based on the digital trail they leave in their wakes as they check into nearby businesses on Foursquare.

"It's so wild," said Christopher Silva, CEO of St. Francis. "It's really mind-boggling how far technology has come, and how technology has allowed us to track customers more effectively."

St. Francis is one of a growing number of wineries working to enhance their relationships with customers by observing their behavior in social media and online.

Marketing executives say the practice helps companies to deliver more targeted pitches and to get to know their customers better using public information.

But privacy advocates are concerned about whether ordinary consumers are aware that their information is being searched and funneled into online profiles, and they worry about where that data may end up down the road.