According to a recent study by comScore Media Metrix, more than half of MySpace’s US visitors are now aged 35 or older – which was attributed mostly to the media spotlight that’s been directed at the social networking site lately. And that, concluded the study, is why MySpace’s previous heavy users, youth 12-34, are now fleeing what they evidently no longer see as a cool venue.

The most significant shift has occurred among teens 12-17, who accounted for 24.7% of the MySpace audience in August 2005. As of mid-October, that cohort makes up only 11.9% of the site’s total audience. Meanwhile, a smaller but similar shift is happening among users aged 18-24.

All of which is not to say that MySpace isn’t still one of the most popular websites for teens and young adults. A recent Youthography study found that 41% of Canadians 9-29 who do social networking have a MySpace account. But marketers who were previously assured that MySpace is the top social networking site in Canada should be aware that its popularity is slipping.

Youthography found that MSN Windows Live Spaces, which launched in August, has already attracted 57% of young Canadian social networkers. And the international youth social networking site Hi5 (hi5networks.com) claims that 40% of young Canadian social networkers have registered accounts, just 1% less than MySpace. Bringing up the rear in the list of sites designed to appeal to youth are: Classmates, WAYN, Piczo, Nexopia, Friendster and Facebook.