Facebook isn’t in any danger of experiencing a MySpace-style implosion anytime soon, but that doesn’t mean the social networking giant isn’t in danger of seeing its clout slowly erode over time. The Guardian reports that a new study from SocialBakers shows that Facebook lost around 6 million visitors in the United States in just the last month alone, which represents a 4% decline of its total user base. The most recent drop in American Facebook visitors is part of a sustained decline, since SocialBakers estimates that the social networking site has seen a drop of around 9 million visitors over the past six months. The good news for Facebook is that its own photo-sharing social network Instagram has apparently picked up the slack and has “seen surges in popularity with younger age groups.”